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ICHIGAN STATE UNIVERSITY LIBRARIES

3 1293 01026 9789

This is to certify that the

thesis entitled

GRAZING SYSTEMS FOR DIRECT-SEEDED
ALFALFA PASTURES

presented by

Michael Lynn Schlegel

has been accepted towards fulfillment
of the requirements for

M.S. Animal Science

degree in

 

 

7

Major professor

Date l/‘/8 ‘ 93

0.7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

 

LIBRARY
Michigan State
University

 

 

 

PLACE II RETURN BOX to mnovomb chockou from your rocord.
TO AVOID FINES rotum on or bdoro duo duo.

DATE DUE ‘ DATE DUE DATE DUE '

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MSU tummmwomlm
W1

 

GRAZING SYSTEMS FOR DIRECT-SEEDED ALFALFA PASTURES
By

Michael Lynn Schlegel

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Animal Science

1993

ABSTRACT
GRAZING SYSTEMS FOR DIRECT-SEEDED ALFALFA PASTURES
By

Michael Lynn Schlegel

A four-year study was conducted to determine the effects of grazing method and
stocking rate on animal and plant productivity of alfalfa pastures; to compare the forage
productivity of pasture systems to a mechanically harvested system, to ascertain the effect
of grazing system on subsequent cattle performance fed concentrate diets; to determine
intake of steers grazing alfalfa; and to calculate a net energy value for alfalfa pasture.
Ten pasture plots (.76 ha) were divided into 2 replicates of 5 pastures each. Five
treatments were assigned to each replicate of 5 pastures. Treatments were 1) 4
paddocks-low stocking rate, 2) 4 paddock-high stocking rate, 3) 13 paddock-low stocking
rate, 4) 13 paddock-high stocking rate, and 5) mechanical harvest. Grazing method did
not affect daily gains or gain/ha. High stocking rates decreased (P < .05) daily gains, but
increased (P < .01) gains/ha in the third and fourth year. Daily organic matter intake of

graZing steers was estimated to be 3.84 kg/d.

Dedicated to my parents,
Kay and Sid Schlegel

iii

 

ACKNOWLEDGEMENTS

The completion of the research reported in this thesis would not have been
possible without the assistance of numerous people.

I would like to thank my major professor Dr. Steven Rust for his guidance,
assistance and allowing me the opportunity to develop, implement and experience two
wonderful years of grazing research at Michigan State University.

Special thanks go to Dr. Margaret Benson who was willing to listen, counsel,
reduce stress on the links and kept me going in the right direction.

My appreciation goes to the additional members of my guidance committee; Dr.
Roy Black, Dr. Robert Cook, Dr. Walley Moline, Dr. Harlan Ritchie, and Dr. Gerry
Schwab for their guidance, insight, encouragement and patience.

The surgical cannulations of steers would not have been possible except for the
assistance of Dr. Kent Ames. I would like to thank Dr. Ames for lending his expertise
to this project.

This project could not have be completed without the help of Cheryl Wachenheim.
She was there from the very beginning, collecting samples, watering and weighing cattle,
overall support, and not to mention putting up with me. She should be lucky to have

known me, but I realize I was lucky to have her unending assistance and friendship.

iv

There were numerous other graduate students who assisted in forage sampling,
weighing and observing cattle. I would like to thank Shan Chung, Tadd Dawson, Mark
Edwards, Mark Henry, David Lust, Scott Kramer, Dale Persing, Terri Stroman, and
Frank Wardynski for their friendship and assistance.

The staff members at the Beef Cattle Research Center and University Farrns were
also instrumental in the completion of this project, and I thank them.

Above all others, I thank my parents, Sid and Kay Schlegel, for their never-
ending love, support, and encouragement over the five years it has taken me to complete

my Masters’s degree; and for making me the person I am today.

TABLE OF CONTENTS

vi

LIST OF TABLES ...................................... x
LIST OF FIGURES ...................................... xiv
LIST OF ABBREVIATIONS ................................ xvii
CHAPTER 1: INTRODUCTION ............................. 1
CHAPTER 2: LITERATURE REVIEW ......................... 4
GRAZING METHODS ............................... 4
Continuous stocking ............................. 4

Rotational stocking .. ............................ 6

Strip grazing ................................. 8

First and last grazers ............................ 8

Stockpiling .................................. 8

THE USE OF ALFALFA AS A PASTURE CROP .............. 9

Origin and Development .......................... 9

Growth characteristics ........................... 10

Continuous stocking ............................. 11

Rotational stocking ............................. 11

Rest period .................................. 12

Occupation period .............................. 13

Stocking rate ................................. 14

Animal performance ............................ 17

Nutrient quality ............................... 19

Alfalfa - grass pastures ........................... 19

BLOAT ......................................... 20
INTAKE AND ITS PREDICTION IN GRAZING ANIMALS ....... 24
Physiological and chemical factors affecting intake regulation 24

Physical factors of the animal affecting feed intake .......... 25
Environmental factors affecting feed intake ............... 27

Ingestive behavior .............................. 27

Intake prediction ............................... 28

Pasture based methods ....................... 29

Use of internal and external markers .............. 29

Changes in animal weight ..................... 3O

Calculations based on ingestive behavior ............ 31
PHOTOSENSITIVITY ............................... 3 1
Primary photosensitivity .......................... 32
Hepatogenous photosensitivity ....................... 32
Aberrant pigment metabolism ....................... 35
Photosensitization of unknown origin .................. 38
Clinical signs and treatment ........................ 39

CHAPTER 3: EVALUATION OF GRAZING METHODS AND STOCKING
RATES OF ALFALFA PASTURES ON ANIMAL AND PLANT

PRODUCTIVITY .................................. 40
SUMMARY ...................................... 40
INTRODUCTION .................................. 41
MATERIALS AND METHODS ......................... 42
Year 1: 1989 ................................. 46

Cycle 1: pasture management .................. 47

Cycle 2 and 3: pasture management .............. 48

Year 2: 1990 ................................. 49

Cycle 1: pasture management .................. 50

Cycle 2 and 3: pasture management .............. 50

Year 3: 1991 ................................. 51

Cycle 1: pasture management .................. 52

Cycle 2 and 3: pasture management ............... 52

Year 4: 1992 ................................. 53

Cycle 1,2 and 3: pasture management ............. 53

Mechanical Harvest ............................. 54
Feedlot management ............................ 55

Data collection and analysis ........................ 55
Forage data collection and analyses ............... 55

Esophageal extrusa collection and analysis ......... . . . 56

Pasture botanical composition .................. 58

Ingestive behavior observations ................. 58

Statistical analysis .............................. 58
RESULTS AND DISCUSSION .......................... 60
Year 1: 1989 ................................. 60

Year 2: 1990 ................................. 66

Year 3 and 4: 1991 and 1992 ....................... 73
Mechanical Harvest ............................. 78
Botanical composition ............................ 81
Ingestive behavior .............................. 83

Four year summary ............................. 86
IMPLICATIONS .................................... 90

vii

CHAPTER 4: EVALUATION OF A SLOW-RELEASE CHROMIUM
BOLUS, PREDICTION OF INTAKE OF HOLSTEIN STEERS
GRAZING ALFALFA AND ESTIMATION OF THE ENERGY

VALUE OF ALFALFA ............................... 93
SUMMARY ...................................... 93
INTRODUCTION .................................. 94
MATERIAL AND METHODS .......................... 95
Pasture and animal management ...................... 95
Forage sample collection and analysis .................. 97
Total fecal collection ............................ 98
Fecal output and intake prediction .................... 98
Development of regression equations and net energy values ..... 100
Statistical analysis .............................. 101
RESULTS AND DISCUSSION .......................... 102
Forage production and nutritive quality ................. 102
Steer performance and fecal output .................... 102
Fecal output prediction procedures .................... 105
Predicted DM Intake ............................ 109
Regression equations ............................ 112
Net energy of alfalfa ............................ 114
IMPLICATIONS ................................... 122
CHAPTER 5: CHARACTERIZATION OF PHOTOSENSITIVITY OF
CATTLE GRAZING ALFALFA PASTURES ................. 123
SUMMARY ...................................... 123
INTRODUCTION .................................. 124
MATERIALS AND METHODS ......................... 125
Background .................................. 125
Photosensitivity characterization. ..................... 127 '
Microbial assay ....... g ........................ 128
RESULTS AND DISCUSSION .......................... 130
IMPLICATIONS ................................... 135
CHAPTER 6: CONCLUSIONS .............................. 136

APPENDIX A: TERMINOLOGY OF GRAZING LANDS AND GRAZING
ANIMALS ....................................... 140

APPENDIX B: COMMON AND SCIENTIFIC NAMES OF GRASSES AND
LEGUMES ...................................... 144

APPENDIX C: TEMPERATURE AND RAINFALL DATA FOR 1989
THROUGH 1992 ................................... 145

viii

APPENDIX D: RAW DATA FROM THE GRAZING SYSTEM STUDY,
INTAKE STUDY AND CHARACTERIZATION OF
PHOTOSENSITIVITY ............................... 147

APPENDIX E: EFFECT OF GRAZING METHOD AND STOCKING
METHOD ON HEIFERS GRAZING STOCK-PILED ALFALFA

PASTURES IN THE FALL ............................ 190
APPENDIX F: PROBLEMS ENCOUNTERED THROUGHOUT THE 4 ‘
YEAR GRAZING STUDY ............................. 192
APPROVAL LETTER FROM THE ALL-UNIVERSITY COMMITTEE ON
ANIMAL USE AND CARE ............................ 196
LIST OF REFERENCES .................................. 197
ix

LIST OF TABLES

Table 2.1. Effect of rotational grazing on live-weight gain and gain per

hectare when compared to continuous grazing ................. 7
Table 2.2. Effect of stocking rate on performance of animals grazing alfalfa . . . 16
Table 2.3. Summary of alfalfa grazing studies in the United States ......... 18
Table 2.4. Summary of alfalfa-grass grazing studies in North America ...... 21
Table 2.5. Cause of primary photosensitivity ...................... 33
Table 2.6. Causes of hepatogenous photosensitivity .................. 34
Table 3.1. Ingredient composition of poloxalene-mineral mix ............ 46

Table 3.2. Characterization of the grazing season, stocking rate and initial
weights during the four year grazing study ................... 54

Table 3.3. Effect of grazing method and stocking rate on animal productivity
(1989) .......................................... 61

Table 3.4. Effect of grazing method and stocking rate on forage yield, canopy
height and forage quality (1989) .......................... 62

Table 3.5. Effect of grazing method and stocking rate on subsequent gain, dry
matter intake and feed efficiency in the feedlot (1989) ............ 65

Table 3.6. Effect of grazing method and stocking rate on subsequent carcass
weight and quality following a feedlot phase (1989) .............. 67

Table 3.7. Effect of grazing method and stocking rate on animal productivity
(1990) .......................................... 68

Table 3.8. Effect of grazing method and stocking rate on forage yield, canopy
height and forage quality (1990) .......................... 70

Table 3.9. Effect of grazing method and stocking rate on subsequent gain, dry

matter intake, and feed efficiency in the feedlot (1990) ............ 72
Table 3.10. Effect of grazing method and stocking rate on subsequent carcass

weight and quality following the feedlot phase (1990) ............. 74
Table 3.11. Effect of grazing method and stocking rate on animal and plant '

productivity (1991-1992) .............................. 75
Table 3.12. Effect of grazing method and stocking rate on subsequent gain,

dry matter intake, and feed efficiency in the feedlot (1991-1992) ...... 77
Table 3.13. Effect of grazing method and stocking rate on subsequent carcass

weight and quality grade following a feedlot phase (1991-1992) . . . . 79
Table 3.14. Comparison of forage presentation from grazed and harvested

plots (1989-1991) ................................... 80
Table 3.15a. Effect of grazing method and stocking rate on pasture botanical

composition ...................................... 82
Table 3.15b. Effect of treatment on pasture botanical composition ......... 84

Table 3.16. Effect of grazing method and stocking rate on steer activity
during daylight hours as assessed by visual observation (1990) ....... 85

Table 3.17. Four year summary of animal performance and forage production . 87

Table 3.18. Four year summary of feedlot performance and carcass
characteristics ..................................... 91

Table 4.1. Forage production, canopy height, and nutritive quality of alfalfa
' pasture used to determine dry matter intake ................... 103

Table 4.2. Effect of grazing method and grazing time on weight gain of steers . 104

Table 4.3. Effect of grazing method and grazing time on fecal DM, OM, and
CP ............................................ 106

Table 4.4. Effect of grazing method and grazing time on fecal output ....... 107

Table 4.5. Effect of grazing method and grazing time on predicted DM1 and
OM] from total fecal collections .......................... 110

xi

Table 4.6. Effect of grazing method and grazing time on predicted DM1 and
OMI from Cr-estimated fecal outputs ....................... 111

Table 4.7. Regression and correlation coefficients of fecal N and intake
versus ADG ...................................... 113

Table 4.8. Predicted intakes derived from regression equations developed
from six intake prediction procedures ....................... 118

Table 4.9. Predicted net energy values of alfalfa derived from regression
equations developed from six intake prediction procedures .......... 119

Table 4.10. Net energy values for common grasses and alfalfa (NRC, 1984) . . 121

Table 5.1. Plant specimens used to determine primary phototoxic potential of

alfalfa pasture ..................................... 129
Table 5.2. Effects of photosensitization on live-weight gains ............ 131
Table 5.3. Effects of photosensitization on liver enzyme profiles .......... 132

Table A.1. Factors for converting the number of grazing animals of different

species and weight into standard livestock units ................ 143
Table D1. Individual performance and carcass characteristics (1989) ....... 148
Table D2. Individual performance and carcass characteristics (1990) ...... 154
Table D.3. Individual performance and carcass characteristics (1991) ....... 158
Table D4 Individual performance and carcass characteristics (1992) ....... 162
Table D5 Forage presentation per rotation and over the entire grazing season (1989

to 1991) ........................................ 166
Table D6. Nutrient composition of forage samples (1989) .............. 167
Table D7. Canopy heights (1989) ............................ 169
Table D8. Esophageal extrusa nutrient composition .................. 170
Table D9. Nutrient composition of forage samples ................. 171
Table D.10. Canopy heights (1990) ............................ 173

xii

Table D.11.

Table D.12.

Table D.13.

Table D.14.

Table D.15.

Table D.16.

Esophageal extrusa nutrient composition (1990) ............ 174
Forage sample fiber analysis (1989) ................... 176
Individual animal performance and plot gains from fall grazing (1989) 82
Individual performance of steers used for intake study ........ 186
Daily fecal output and fecal DM, OM, CP, and Cr concentrations . 187

Individual live-weight and enzyme levels of photosensitive Steers . . 189

Table E.1. Effect of grazing method and stocking rate on live-weight gains
and forage presentation ............................... 191

xiii

Figure 2.1.

Figure 2.2.

Figure 2.3.

Figure 3.1.

Figure 3.2.

Figure 4.1.

Figure 4.2.

LIST OF FIGURES

Outline of grazing systems. (a) continuous stocking; (b) strip grazing
(alternative methods); (c) intensive continuous stocking; (d) integrated
grazing and conservation; (e) rigid rotational grazing; (f) leader and
follower rotational grazing; (g) daily rotational paddocks; (h) flexible
rotational paddocks. Permanent fence , semi-permanent fence — -
- -, movable fence ---- (Holrnes,1989). .................. 5

Relationship between stocking rate and live-weight gain per animal and
per ha (based on average conditions with 200 kg N ha"): daily live-

weight gain per animal , live-weight gain per hectare - - - -
( adapted from Holmes, 1989). ....................... 15
Biosynthesis of heme from porphobilinogen (Rawn, 1989). ..... 37

Diagram of pasture plots. Each plot is 29 x 265 m equalling .76 ha.
Two strands of 20 gauge wire (heavy lines) separates each plot. Polywire
(light lines) divides the plot into 4 or 13 paddocks. ........... 44

Alfalfa grazing experiment design. Twelve hectares were divided into 12
plots (.76 ha) plus a supplemental pasture. Plots 1 to 10 were used to
evaluate grazing methods and stocking rates. Treatment assignments were
4-L (plots 1,7), 4oH (plots 4,8). 13-L (plots 2,9), and l3-H (plots 3,6). '
Plots ll (4-H) and 12 (13-H) were used to determine intake of grazing
steers. ...................................... 45

Total fecal collection schedule. Days of study are given below time line.

Collection periods are represented as boxes above the time line. Rotation

of paddocks is indicated by treatment abbreviation below the time line.
.......................................... 99

Effect of procedures for determining fecal output. Solid and open bars
represent total fecal collection and Cr-predicted fecal output, respectively.
*** P < .001. ................................. 108

xiv

Figure 4.3.

Figure 4.4.

Figure 4.5.

Figure 5.1

Figure C.1.

Figure C.2.

Figure D.l.

Figure 13.2.

Figure D.3.

Relationship between average daily gain and organic matter intake as
determined by total fecal collection and two OM digestibilities a) IVOMD,
b) IVOMD increased 15%. Solid line is the regression equation based on
12 steers from two grazing methods (4-H, open points and 13-H closed
points) and three grazing time allotments (6 h, D I; 10 b O O; and 24 h,
0 A) ....................................... 115

Relationship between average daily gain and dry matter intake as
determined by CR-predicted fecal output and two DM digestibilities a)
IVDMD, b) IVDMD increased 15 %. Solid line is the regression equation
based on 12 steers from two grazing methods (4-H, open points and 13—H
closed points) and three grazing time allotments (6 h, Ell; 10 h 0 O;
and 24 h, 0A). ............................... 116

Relationship between average daily gain and organic matter intake as
determined by Cr-predicted fecal output and two OM digestibilities a)
IVOMD, b) IVOMD increased 15%. Solid line is the regression equation
based on 12 steers from two grazing methods (4-H, open points and l3-H
closed points) and three grazing time allotments (6 h, Ell; 10 h 0 O;
and 24 h, C) a). ............................... 117

Steer exhibiting erythema, hair loss and skin necrosis following removal
from an alfalfa pasture ........................... 126

Daily high (solid line) and low (dashed line) temperatures and daily
rainfall (solid bars) from May to September 1989 and 1990. . . . 145

Daily high (solid line) and low (dashed line) temperatures and daily
rainfall (solid bars) from May to September 1991 and 1992. . . . . 146

Crude protein (a) and IVOMD (b) composition of forage (solid lines) and

. extrusa (dashed lines) over the 1989 grazing season collected from 4

paddock (circles) and 13 paddock (squares) systems at the low (open) and
high (closed) stocking rates. ........................ 178

Rumen DMD (a) and UDP (b) of extrusa samples over the 1989 grazing
season collected from 4 paddock (circles) and 13 paddock (squares)
systems at the low (open) and high (closed) stocking rates. ..... 179

Crude protein (a) and IVOMD (b) composition of forage (solid lines) and
extrusa (dashed lines) over the 1990 grazing season collected from 4
paddock (circles) and 13 paddock (squares) systems at the low (open) and
high (closed) stocking rates. ........................ 180

XV

Figure D.4. Rumen DMD (a) and UDP (b) of extrusa samples over the 1990 grazing
season collected from 4 paddock (circles) and 13 paddock (squares)
systems at the low (open) and high (closed) stocking rates. ..... 181

xvi

LIST OF ABBREVIATIONS

13-H .............................. l3 paddocks, high stocking rate
13-L .............................. 13 paddocks, low stocking rate
4-H ............................... 4 paddocks, high stocking rate
4-L ................................ 4 paddocks, low stocking rate
ac ............................................... ‘ . .acre
ADG ...................................... average daily gain
AST ................................... aspartate transaminase
BCP ............................ Bovine Congenital Protoporphyria
bu ............................................... bushel
BW ........................................... body weight
°C ......................................... degree Celsius
cm ............................................ centimeter
CP .............. - ............................ crude protein
Cr ............................................ chromium
CR .............................. chromium predicted fecal output
CR-15D . . . chromium predicted fecal output and forage digestibility increased 15%
CR-D .............. chromium predicted fecal output and forage digestibility
d ................................................. day
DM ............................................ dry matter
DMD .................................. dry matter degradation
DMI ....................................... dry matter intake
EPP .................................. Erythropoietic Porphyria
g . ............................................... gram
GLM .................................... General linear model
GM ......................................... grazing method
h ................................................ hour
ha ............................................... hectare
1BR .............................. Infectious Bovine Rhinotracheitis
IU ........................................ International unit
IVDMD ............................ in vitro dry matter digestibility
IVOMD .......................... in vitro organic matter digestibility
kg .............................................. kilogram
km ............................................ kilometer
L ................................................. liter
LWG ................................ _ ....... live-weight gain
m ................................................ meter

xvii

Meal .......................................... megacalorie

mg ............................................ milligram
MH ...................................... mechanical harvest
mm ............................................ millimeter
N .............................................. nitrogen
NDF ................................... neutral detergent fiber
NE, ...................................... net energy for gain
NE“, ................................ net energy for maintenance
nm ............................................ nanometer
NSC ................................ non-structural carbohydrates
OBS ....................................... observation date
OM ......................................... organic matter
OMI .................................... organic matter intake
OP ....................................... occupation period
P ............................................. probability
PI3 ..................................... Parainfluenza 3-Virus
r ................................. simple correlation coefficient
r2 .............................. simple coefficient of determination
RP ............................................ rest period
SDH ................................... sorbitol dehydrogenase
SED .............................. standard error of the difference
SEM ................... , .............. standard error of the mean
SR .......................................... stocking rate
TC ...................................... total fecal collection
TC-15D ........... total fecal collection and forage digestibility increased 15%
TC-D ..................... total fecal collection and forage digestibility
TDN .................................. total digestible nutrients
UDP .................................... undegradable protein
UV ........................................... ultra violet
VFA ...................................... volatile fatty acid
wt ............................................... weight
x ........................................... multiplied by
yr ................................................ year

xviii

CHAPTER 1: INTRODUCTION

In recent years, grazing of livestock has regained its popularity.
Recommendations by animal scientists in the 1960’s and early 1970’s moved cattle
indoors for improved animal performance. Although, confinement operations have lead
to concerns over handling animal waste, animal health, and nutrient runoff. In addition,
urban sprawl has been increasing in agricultural areas, compelling agricultural practices
to become more urban and environmentally friendly. This may mean adapting
agricultural practices that reduce odor, protect ground water, prevent soil erosion and
emphasize animal welfare. Pasture systems may meet these demands.

Alfalfa, Michigan’s most productive forage for harvested feedstuffs, may be an
ideal grazing forage as well. Over 485 thousand hectares of alfalfa are grown in
Michigan annually (Michigan Agricultural Statistics Service, 1992). Alfalfa has been
regarded as a superior forage crop in terms of quality, palatability and yield potential
(Van Keuren and Marten, 1972).

Animal production from alfalfa pastures has ranged from 392 kg/ha in heifers
(Marten et a1., 1987) to 783 kg/ha in lambs (Marten et a1., 1990). More recently,
studies in Kentucky have shown live-weight gains from 535 to 820 kg of beef produced
per hectare on rotationally stocked alfalfa pastures (Burris et a1., 1993). This level of

production may allow alfalfa to compete with cash crops grown in Michigan.

2

Until recently, most alfalfa grazing system research has been done in New
Zealand and Australia. There is a paucity of information on the correct methods for
optimal management of grazed alfalfa pastures in the United States. Of major concern
when developing a grazing system is plant survival. Under continuous stocking, alfalfa
stands are not maintained (Brownlee, 1973; Van Keuren and Matches, 1988), therefore,
a rotational stocking method must be employed. Selection of an adequate rest period,
occupation period and stocking rate are critical to the maintenance of plant populations.

To ensure a profitable enterprise, an estimate of the productivity of the pasture
is needed. In a pen feeding situation, the intake and gain of an animal can be used to
determine the energy value of the feed consumed. The intake of grazing cattle is difficult
to determine. Knowing the intake of grazing animals would allow the producer to
determine stocking rates based on intake and expected forage production. In addition,
energy intake could be determined and gain predicted.

For alfalfa pasture systems to be readily adopted, the systems must be
economically competitive ‘with traditional production systems in Michigan. The intent
of this thesis is not to determine the economical viability of such an enterprise, but to.
determine the methods and management practices needed to successfully manage a
productive alfalfa pasture system. The objectives of this thesis were:

1) to determine the effect of grazing method and stocking rate on animal and

plant productivity of alfalfa pastures;

2) to compare the forage presentation of a pasture system to a mechanically

harvested system;

 

3

3) to ascertain the effect of grazing systems on subsequent performance of
cattle fed high concentrate diets;
4) to determine the intake of steers grazing alfalfa; and

5) to calculate a net energy value for alfalfa pasture.

Chapter two reviews literature on grazing systems, the use of alfalfa as a pasture
crop, bloat, predicting intake of grazing animals, and photosensitivity. Studies to answer
objectives one through three are discussed in chapter three. Chapter four discusses the
experiment design to address objectives four and five. Based on the first two years of
this Study, the economic impact and feasibility of an alfalfa grazing system was
summarized in a companion thesis by Wachenheirn (1991).

A drawback to grazing experiments is the uncontrollable environment. Annual
variations in rainfall, temperature, and weed and pest infestation can affect the production
of forage and the efficiency of animal gains. One such anomaly occurred in the first
year of the experiment. Holstein steers exhibited photosensitivity unexpectedly during
the first 24 days of the experiment. Chapter five attempts to characterize the
photosensitivity condition observed and determine a possible origin of the photodynamic

agent.

CHAPTER 2: LITERATURE REVIEW

GRAZING METHODS

Grazing management is "the manipulation of animal grazing in pursuit of a
defined objective" (The Forage and Grazing Terminology Committee, 1991). Defined
grazing procedures or techniques are know as the grazing method, and one or more
methods make up a grazing system. Terms used to describe grazing and methods are in
accordance with The Forage and Grazing Terminology Committee (1991) and appear in
Appendix A. The basic grazing methods include continuous stocking, rotational
stocking, strip grazing, first and last grazers, stockpiling and variations thereof (Figure

2.1).

Continuous stocking

Continuous stocking has been referred as continuous grazing. The former is the
preferred term because animals do not graZe continuously (The Forage and Grazing
Terminology Committee, 1991). With continuous stocking, livestock graze a given area
of land without subdivision throughout a grazing season. The forage does not receive
defined rest periods (Whittier and Schmitz, 1990). Advantages of continuous stocking
include low input costs (i.e. fencing, watering facilities), low labor requirements and

requires fewer management decisions (Matches and Burns,1985). Disadvantages of

Conserve early Conserve late

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striking later—Tn {SOOSDIT

 

Figure 2.1. Outline of grazing systems. (a) continuous stocking; (b) strip grazing
(alternative methods); (c) intensive continuous stocking; (d) integrated grazing and
conservation; (e) rigid rotational grazing; (f) leader and follower rotational grazing; (g)
daily rotational paddocks; (h) flexible rotational paddocks.

Permanent fence , semi-permanent - - - - , movable fence ----. (Holmes,l989).

6

continuous stocking are poor grazing distribution and no control over the frequency of
forage defoliation. This allows unpalatable plants to proliferate in under-grazed areas
and the loss of palatable plant species in over-grazed areas (Dodds et a1., 1985;

Smetham, 1990).

Rotational stocking

Rotational stocking is "a grazing method which utilizes recurring periods of
grazing and rest among two or more paddocks in a grazing management unit throughout
the period when grazing is allowed" (The Forage and Grazing Terminology Committee,
1991). The number of paddocks is determined from the desired rest (RP) and occupation
(OP) periods and is calculated by dividing RP by OP and adding 1 (Voisin, 1988).
Advantages of rotational stocking include improved plant persistence, timely forage
utilization, the opportunity to conserve excess forage (Matches and Burns, 1985),
increased forage quality, increased stocking rate (SR), decreased selective grazing, and
decreased weed infestation (Smetham, 1990). Responses in animal performance from
rotational stocking are mixed (Table 2.1.). Caution must be used in interpreting the data
in Table 2.1. In all but one experiment, SR of the rotational system was greater than the
continuous system. Stocking rates were determined utilizing put-and-take procedures or
increased according to expected improvements in forage yield. In either case,
production/ha is confounded with SR. Disadvantages of a rotational stocking system are
that it requires a greater capital investment and a higher degree of management than a

continuous stocking system (Matches and Burns, 1985).

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Strip grazing

Strip grazing "confines animals to an area of grazing land to be grazed in a
relatively short period of time, where the paddock size is varied to allow access to a
specific land area" (The Forage and Grazing Terminology, Committee, 1991). This
method is closely related to rationed grazing described by Voisin (1988), where animal
graze a variable area of land based on the animal’s requirements and forage production.
The main limitation of this method is the need for a greater intensity of management, and
a manager to be able to coordinate both the animal and forage production (Matches and
Burns, 1985). Strip grazes does increase forage utilization and decreases the waste of

forage from trampling (Matches and Burns, 1985; Smetham, 1990).

First and last grazers

The first and last grazing method allows the producer to divide the animals into
two groups based on differing nutrient requirements. The animals with the highest
nutrient requirements graze a paddock first followed by the second lower-nutrient-
requiring animals which graze the residue left by the first group. This method is also.
referred to as creep or forward grazing, where young animals graze ahead of their dams

on pastures of higher quality (Matches and Burns, 1985; Blaser et a1., 1986).

Stockpiling
The concept of stockpiling is " to allow forage to accumulate for grazing at a later
period" (The Forage and Grazing Terminology Committee, 1991). Forage accumulates

and is grazed during periods of little or no pasture growth (Blaser et a1., 1986). The

9

most common practice is to stockpile forage for fall or winter grazing. Tall fescue has
been shown to be the preferred forage for stockpiling in the transition zone of the United
States (southern Illinois and Ohio south to northern Mississippi and Georgia, eastern
Oklahoma east to the Piedmont in Virginia and the Carolinas; Thompson et al., 1993).
Few legumes can be stockpiled because leaves are lost due to disease, maturation or frost
in the fall, but, sainfoin and birdsfoot trefoil may have potential. Although, forage yield

increases with stockpiling; forage quality decreases (Matches and Burns, 1985).

THE USE OF ALFALFA AS A PASTURE CROP
Origin and Development

According to Smith et al. (1986), "alfalfa is the oldest crop grown solely for
forage”. Alfalfa (Medicago sativa) originated in the mountainous region east of the
Mediterranean in southwestern Asia. The earliest account of alfalfa is in 700 BC from
a Babylonian text, and called aspasti, meaning best fodder (Smith et al., 1986).

Alfalfa culture was advanced by the Medes, Persians, Romans, Arabs and Moors
as each invaded Europe (Smith et al., 1986; and Barnes and Sheaffer, 1985). Alfalfa
was brought to the Americas by Cortez around 1540 AD and cultivated in Mexico. The
use of alfalfa spread throughout South America with the Spanish conquest of the New
World. The introduction of alfalfa into California coincided with the Gold Rush of 1848.
Ships sailing around Cape Horn of South America picked up the ’Spanish alfalfa’ in
route. From California, alfalfa spread eastward, and was widely grown in the states west

of the Missouri river by 1900 (Smith et al., 1986).

10

Colonists introduced alfalfa into the eastern United States around 1736, but the
alfalfa was less productive than in the west due to acidic soils, lack of basic nutrients,
less solar radiation and winter losses (Smith et al., 1986; and Barnes and Sheaffer,

1985).

Growth characteristics

Alfalfa is a herbaceous perennial legume with pinnately trifoliate leaves alternately
arranged on the stem. Mature plants have 5 to 25 stems and normally 60 to 90 cm in
height. The crown is first formed at the cotyledon node, at or beneath the surface of the
soil. Secondary and tertiary buds, and development of the stem occur at this node and
other basal nodes. Following harvest, growth can occur from crown or axillary stem
buds depending on cutting height and plant type. Alfalfa utilizes a taproot which
penetrates the soil 7 to 9 m and may be branched (Barnes and Sheaffer, 1985). Smith
et al. (1986) lists several characteristics of an ideal alfalfa variety for the northern
temperate region which include;

High yield capacity

Forage of high quality, that is, leafy and fine stemmed
Strong survival value with respect to winter injury and
resistance to bacterial wilt

Resistance to leaf, stem, root and crown diseases

Rapid recovery after cutting

Resistance to insect pests

Strong, vigorous establishment

Good competitive capacity and drought tolerant,
particularly during the first season

9. Broad and submerged crown

10. Branching root system

11. Persistence under grazing

12. Low animal bloat potential when grazed

l3. Prolific seed producer

GIN—-

W999.“

l 1
Continuous stocking

Continuous stocking causes the rapid decline of alfalfa stands in the North Central
United States (Van Keuren and Matches, 1988). In Australia, Brownlee (1973)
demonstrated a loss of alfalfa within three months with continuous stocking. The decline
of alfalfa with continuous grazing occurs due to frequent defoliation resulting in the
decreased accumulation of non-structural carbohydrate (NSC) reserves in the roots.
Plants that do not accumulate NSC, fail to regrow (Blaser et al., 1986). In addition,
continuous stocking may increase plant susceptibility to stressors such as drought or
flooding leading to increased loss of plants (Leach, 1978). Decreasing the SR to prevent
regrazing of alfalfa is not practical because the highly palatable alfalfa will be selectively
grazed (Leach, 1978). For continuous stocking to be successful, a new type of alfalfa
needs to be developed which produces a continuous succession of new shoots (Leach,
1978). A new cultivar of alfalfa, Alfagraze, which does survive successive defoliation
is being developed in Georgia (Brummer and Bouton, 1991). Grazing tolerant cultivars
are characterized by decumbent growth, thin stems and low yields. Alfagraze combines
the high yield trait from the hay-type cultivars with the high stem numbers of grazing-
type cultivars (Brummer and Bouton, 1992). One reason Alfagraze persists under

continuous stocking is its ability to maintain higher stores of NSC.

Rotational stocking
Studies by Ittner et al. (1954) determined soiling (green chopping) and strip
grazing produced 69% and 39% more beef/ha than a 4—paddock rotational stocking

system. Meyer et al. (1956), using the same treatments as Ittner et al. (1954), confirmed

12

that strip grazing and soiling produced 3 to 7% and 29 to 57% more live-weight gain/ha
than a rotational stocking system. Since traditional grazing—type alfalfas do not persist
under continuous stocking, rotational stocking must be practiced. Important
considerations with rotational stocking include: occupation period (OP), rest period (RP),
and their relationship to plant growth, development, weather, and severity of grazing.

Rest period is of primary importance (Leach 1978).

Rest period

The RP is the period of time that a specific land area is allowed to rest between
the end of one OP and the start of the next OP (Voisin, 1988; The Forage and Grazing
Terminology Committee, 1991). The RP allows the plant to produce new vegetation,
thereby, increasing its photosynthetic capacity and regenerate the loss of NSC used for
the initial regrowth (Blaser et al. , 1986). With adequate rest periods, alfalfa can tolerate
grazing activity. In Utah, alfalfa persisted nine years with a 35 or 42-d RP (Bateman and
Keller, 1956, as referenced by Van Keuren and Matches, 1988) and a 36-d RP provided
the greatest persistence in New Zealand (Iversen, 1967). O’Connor (1970) concluded
that the RP should be from 36 to 54 d, but 18 d was not sufficient as total forage yield,
alfalfa yield and stand density were decreased. McKinney (1974) determined a minimum
RP of 39 (1 during the summer and 56 d in the winter was required to maintain stands
in Australia. Alfalfa did not persist with a 21-d RP in Canada (Wilson and Clark, 1961)
nor a 14-d rest in England (Davis, 1947).

Jason ( 1974) observed similar lamb gains when grazing was started early in the

spring by decreasing grazing cycle and RP. Southwood and Robards (1975) also

13

reported similar gains of lambs grazed with short RP in the spring. If animal
requirements dictate a decreased RP, the drop in forage production will be short-term and
if the RP is returned to 35 to 42 d, little long-term damage will occur (Jason, 1975b;

Douglas and Wilkinson, 1976).

Occupation period

Iversen (I967) recommends a short OP (4 d) and a high stocking density than
leaves less than 5 cm of residual DM and allows a 36-d RP. Although in Australia,
Leach (1979) demonstrated alfalfa survival was decreased with a 4-d OP than when
grazed 8 or 16 d. The longer OP is also supported by work published by O’Connor
(1970) in which, a 12-d OP increased forage production as compared with a 6, 18 or 24-
d OP each with a 36-d RP. Although earlier work by O’Connor (1970) determined 6 or
18-d OP was not different than the 12—d OP. With a very short OP, 2 to 4 d, there is
a lag of regrowth because basal shoots are immature (Jason, 1975a). When the OP is
increased, basal shoots have time to develop allowing regrowth to begin as grazing
continues. With very long OP, the early developing shoots are topped and the plant must
rely on slower growing shoots which reduces regrowth rate and overall forage production
(Jason, 19753)

Competition from grass was greatest with a 4~d OP (I.each,1979). In agreement
with that study, a 14-d OP as compared with a 3-d OP reduced grass infiltration
(O’Connor and Vartha, 1968). Douglas (1986) suggested that a longer OP for alfalfa

prevents competition from faster-growing plants during the lag phase of growth following

 

14

defoliation. Grazing competing species until alfalfa buds develop, gives alfalfa the
competitive edge, therefore allowing a shorter OP.

Plant maturity can be a determining factor in selecting an optimum OP. Jason
(1975a) investigated the effect of maturity and OP on basal shoot development from the
crown and determined that as maturity of the plant increased, OP should decrease. Basal
shoots are absent at the immature mid-vegetative stage. As the plant matures through
flowering, the number and size of the basal shoots increases, which decreases the lag

time of regrowth (Jason, 1975a).

Stocking rate

Live-weight gains per animal decrease with increasing SR but gains per unit land
area follow a quadratic relationship (Douglas, 1986; Figure 2.2). Therefore, a
compromise must be made to achieve acceptable individual animal gains and desirable
land area yields (Douglas, 1986). In the evaluation of SR, Thompson et al. (1976)
concluded that rates above 12 ewes/ha decreased rotationally-stocked alfalfa stands. In
support of the Thompson et al. (1976) study, Reeve and Sharkey, (1980) demonstrated.
a decline in alfalfa in rotationally-stocked alfalfa pastures with SR above 12.4 ewes/ha,
but alfalfa was maintained at rates of 7.4 and 9.9 ewes/ha. Studies by Joyce and
Brunswick (1977) and Marsh and Brunswick (1978) illustrate the effect of SR on ADG
and gain/ha of steers grazing alfalfa and an alfalfa-prairie grass pasture (Table 2.2). The
results from these studies clearly demonstrate the negative impact SR has on individual
animal weight gains, but is offset by an increase in production/ha. Marten and Jordan

(1972)

 

15

 

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Stocking rate. cattle (350 kg) ha“

Figure 2.2. Relationship between stocking rate and live-weight gain per animal and per
ha (based on average conditions with 200 kg N ha"): daily live-weight gain per animal
, live-weight gain per hectare - - - - . ( adapted from Holmes, 1989).

16

 

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17

suggest that to set the SR regardless of the yield potential of a pasture is unwise since
this can cause over- or understocking of specific treatments. Studies by Marten and
Jordan (1972) did not show a difference in animal production/ha between put-and-take
stocking and set stocking, but the researchers had previous yield information to predict

pasture yield to select the appropriate SR.

Animal performance

Dougherty et al. (1990) reported beef cattle gains of up to 1.36 kg/d are possible
on a rotationally-stocked alfalfa pasture. Studies from Australia and the United States
(Table 2.3) do not support the superior gains suggested by Dougherty et al. (1990), but
gains from .9 kg to 1.2 kg/d are documented on alfalfa (Joyce and Brunswick, 1977;
Marsh and Brunswick, 1978‘; Reardon, 1980) in Australia. Forage utilization is a major
factor in determining gain potential (Joyce and Brunswick, 1977; Marsh and Brunswick,
1978). Joyce and Brunswick (1977) determined that a 70% forage utilization in the
spring would produce 1 kg/d live-weight gain, but to achieve the same performance in
the summer, only 27% utilization is permitted. Similarly, Marsh and Brunswick (1978)
reported that a spring forage utilization of 86% achieved 1 kg/d beef gains but the same
utilization in the summer produced only .47 kg/d gains. This difference in optimum
utilization is due to the decrease in the nutrient quality through the grazing season and
not total intake of the animal (Marsh and Brunswick, 1978; and Reardon, 1980).
Reardon (1980) determined that cattle given a daily forage allowance of 4 kg/d per 100
kg BW did not have increased live-weight gains compared to cattle receiving 3 kg/d per

100 kg BW. For rapid growth rates of cattle, the OP should allow only the leaves and

I8

 

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19
the tops of stems to be grazed (Christian et al., 1970, McKinney et a1. , 1970). A major

factor affecting animal performance is intake of digestible DM (McGraw and Marten,
1986). A decrease in animal gains follows a decrease in stem digestibility (Fletcher,

1976).

Nutrient quality

The nutritive quality of forage is high at immature stages of growth and then
declines with increasing maturity (McGraw and Marten, 1986). Leaves contain high
concentrations of IVDMD and CP and only exhibit a slow loss of quality as the plant
matures (Christian et al., 1970; Fletcher, 1976; McGraw and Marten, 1986). In
contrast, stems lose significant digestibility as the plant matures. Marten et al. (1987)
determined that alfalfa had lower IVDMD than cicer milkvetch and birdsfoot trefoil, but
greater than sainfoin. Alfalfa’s C? content was similar to birdsfoot trefoil and cicer
milkvetch and greater than sainfoin. The authors suggested that cicer milkvetch and
birdsfoot trefoil may be good alternatives to alfalfa but cicer milkvetch is very
unpalatable (Marten et al., 1987). McKinney (1974) suggests that if RP is too long, the

alfalfa’s leaf-stem ratio decreases which decreases the quality per unit yield of alfalfa.

Alfalfa - grass pastures

Alfalfa-grass mixtures produce greater individual ADG, more weight gain per
land area and have greater carrying capacity than grass alone (Van Keuren and Matches,
1988), although one problem with an alfalfa-pasture is finding a cool-season grass that

has compatible growth characteristics. Most cool-season grasses do not persist under

20

alfalfa harvest schedules, are too competitive with alfalfa, or not palatable to the grazing
animal (Jung et a1., 1982). Orchardgrass, smooth bromegrass, ryegrass and tall fescue
are the most common cool-season grasses seeded with alfalfa (Rather and Harrison,
1944; Van Keuren and Heinemann, 1958; Hubbard and Nelson, 1964; Cooke et al.,
1965; and Jung et al., 1982). Smooth bromegrass was the preferred addition to alfalfa
when compared to intermediate wheatgrass under rotational stocking, but an alfalfa-
intermediate wheatgrass mixture was preferred when the pasture was continuously
stocked (Cooke et a1. , 1965). In a study by Jung et al. (1982), alfalfa-ryegrass produced
more protein/ha than alfalfa-orchardgrass pastures.

Over a 3-yr period, alfalfa-orchardgrass and alfalfa-tall fescue mixtures produced
52% more weight gain/ha than the grasses alone (Van Keuren and Heinemann,
1958). When the two mixtures were compared, the alfalfa-orchardgrass pasture was
found to be more productive in terms of animal performance. A summary of alfalfa-

grass grazing studies is presented in Table 2.4.

BLOAT
Bloat as defined by Howarth (1975), ”results from a failure in eructation of gases
produced by microbial fermentation in the rumen”. Bloat occurs in two forms, frothy
and free-gas bloat. Frothy bloat refers to gas trapped in tiny bubbles which cannot be
eructated. Free-gas bloat denotes the separation of the gas, which cannot be eructed,
from the rumen (Howarth, 1975). Howarth (1975) further classifies bloat as legume

pasture bloat, legume hay bloat, high concentrate bloat and free-gas bloat.

l
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22

Legumes such as alfalfa, red clover, white clover, ladino clover, sweet clover and alsike
clover have been shown to cause bloat (Howarth, 1975). Subterranean clover has
moderate bloat potential (Howarth, 1975) and birdsfoot trefoil, crownvetch, sainfoin
(Howarth, 1975, Marten et al., 1987) and cicer milkvetch (Marten et al. , 1987) are non-
bloat provocative legumes. Legumes are primarily associated with bloat, but bloat can
occur in cattle grazing lush, rapidly-growing grass pastures as well (Reid and Johns,
1957). Legume pasture bloat will be discussed further in this section. For a complete
review of bloat, see reviews by Howarth (1975), Clark and Reid (1974), or "Bloat " a
symposium held at the University of New England, Annidale, N.S.W. Australia (Leng
and McWilliam, 1973).

Grazing animals develop bloat through the interaction between the plant, animal,
rumen microbes and the environment (McClymont, 1973). Soluble leaf proteins are
responsible for foam stabilization and bloat in pasture legumes (Jones and Lyttleton,
1972). These authors reported a positive correlation between fraction I protein and the
severity and incidence of bloat. Fraction I protein is the major protein in leaf tissue
(Jones and Lyttleton, 1972), and accounts for 3.4 to 6.8% of the leaf tissue (Miltmore
et al. , 1970). Miltrnore and co-workers (1970) defined the threshold of fraction I protein
which produces bloat to be 1.8%. Plants below this threshold are non-bloat provocative.
Non-bloat provocative legumes, such as those mentioned previously, contain less than
1.5 % fraction 1 protein. Saponins, glycosides and pectins, are interrelated with the bloat—
producing capabilities of fraction I proteins, and bloat-provocative legumes contain

larger amounts of saponins than non-bloat provocative legumes (Cheeke, 1971).

23

The identification of genetic factors that may predispose animals to bloat
susceptibility are difficult to determine (Mendel and Boda, 1961). Factors which may
be important in reducing bloat include: salivary flow, salivary composition, ruminal fluid
transfer, rumen motility, gas production, microbial population, rate of eating, rumen pH,
and rate of nitrogen metabolism (Clarke and Reid, 1974). Clark and Reid (1970) have
determined that animals with low susceptibility eat 1.5 times faster and have greater
salivary flow than animals with high susceptibility. Clark and Reid (1970) concluded that
large microbial populations are associated with greater incidence of bloat in highly-
susceptible animals. In addition, McIntosh and Cockrem (1977) showed that the absence
of specific salivary proteins may contribute to decreased susceptibility of bloat.

There are no reports or studies on the adaptability of cattle to bloat-provocative
legumes. Howarth (1975) stated that bloat can occur any time on dry forage, warm days
and at full bloom; therefore, the occurrence of bloat is difficult to predict. Prevention
of bloat includes the use of non-bloat provocative legumes, use of a grass-legume pasture
mixtures, and filling cattle with dry feed before grazing bloat-provocative legumes
(Howarth, 1975). Even though an alfalfa-grass pasture was used in a study by Van
Keuren and Heinemann (1958), six animals died of bloat during the three-year
evaluation.

Other approaches deal with spraying bloating pastures with oils or antifoaming
agents (Van Keuren and Matches, 1988) and feeding poloxalene to cattle. Poloxalene
is a synthetic, water-soluble detergent-type compound (Heath et al. , 1985) which has
been shown to be 100% effective in reducing bloat (Bartley et al., 1983, Katz et al.,

1986). Ionophores such as monensin and lasalocid are not as effective in reducing bloat

24

as poloxalene, but have been demonstrated to reduce bloat 41 to 73% and 12-30%.

respectively (Bartely et al., 1983, Katz et al., 1986).

INTAKE AND ITS PREDICTION IN GRAZING ANIMALS

Animal performance in a grazing environment can be enhanced through increased
intake or efficiency of digestion and metabolism. The understanding of what controls
feed intake in ruminants is limited (Grovum, 1988). Feed intake is controlled through
physiological, physical, chemical, and environmental factors (Arnold, 1970; Campling,
1970). Physiological and chemical factors generally are more important in controlling
intake of high concentrate diets (Grovum, 1988). Physical characteristics of the diet may
limit the intake of roughages. Environmental factors associated with the grazing
environment such as temperature, shade, forage availability and height of the pasture

also influence intake.

Physiological and chemical factors affecting intake regulation

The control of energy balance and feed intake is associated with functions of the
central nervous system. In particular, the hypothalamus is the region of the brain which
controls feeding (Baile and Mayer, 1970). Removal of the ventromedial area of the
hypothalamus produces obesity through hyperphagia (Hetherington and Ranson, 1942;
Mayer et al., 1955). In contrast, ablation of the lateral areas of the hypothalamus causes
aphagia and adipsia (lack of eating and thirst, Baile and Mayer, 1968). Receptors for
temperature, glucose and osmolarity have been found to be important in the control of

feeding in monogastrics (Baile and Mayer, 1970). Baile and Mayer (1968) reported an

25

increase in feed intake of satiated goats when the hypothalamus was cooled but
concluded, this mechanism would not be a primary controller of feed intake. Neuronal
cells which only respond to changes in glucose concentrations have been found in the
ventromedial hypothalamus of monogastrics (Anand et al., 1964). It is unlikely that
glucose is a signal for intake in ruminants because glucose concentrations are low and
change little (Baile and Mayer, 1970). Therefore, volatile fatty acid (VFA)
concentrations, an important source of energy in ruminants, may have a role.

Baile and Mayer (1970) list three characteristics which may suggest that volatile
fatty acids contribute to the control of feed intake: 1) VFA are produced in the reticulo-
rumen and are absorbed prior to entering the abomasum, 2) rates of VFA production and
absorption are closely correlated to feeding behavior, and 3) the intraruminal injection
of VFA decrease intake of cattle, sheep and goats. Intraruminal infusion of acetate and
propionate, but not butyrate, decreased feed intake (Baile and Mayer, 1969). Acetate
decreased intake more when infused into the dorsal rumen as compared with the jugular
vein. This suggests receptors for acetate are present in the dorsal rumen. Baile and
Mayer (1970) suggest a different mechanism with regards to propionate. Feed intake is.
decreased with infusion of propionate into the ruminal vein, but not the carotid artery,

which implies, propionate receptors are present in the portal system.

Physical factors of the animal affecting feed intake
Physical factors are thought to play a role in determining the intake of roughages
(Grovum, 1988). Factors reported to influence intake of forages are palatability, rumen

fill and capacity, rate of digesta disappearance, and distension of the abomasum and

26

intestine (Arnold, 1970, Campling, 1970). Palatability is the first determinant of what
a moderately hungry animal will eat. Palatability includes smell, taste, flavor, and
texture of the forage (Grovum, 1988). As the variety of feed decreases due to high
grazing pressure or drought, the animals are less able to satisfy their needs from
preferred species; and species, which were rejected previously, are consumed
(McClymont, 1967).

Campling and Balch (1961) demonstrated that rumen fill affects feed intake.
Addition of esophageal masticates into a fistulated cow decreased intake and removal of
ingested feed increased intake to a point when fatigue from mastication limited intake.
In addition, the size and weight of the empty reticulo—rumen is directly associated with
voluntary intake of cattle and sheep (Balch and Campling, 1962). The growing fetus and
abdominal fat will also influence rumen capacity and therefore intake (Campling, 1970).

The rate of disappearance of digesta from the reticulo-rumen is also associated
with voluntary intake. Factors which influence the rate of digesta flow include: 1) the
efficiency of chewing during eating and rumination, 2) the rate of digestion within the
rumen, and 3) the propulsion activity of the gut and transfer of roughage residues
(Campling, 1970). As the rate of digesta disappearance increases, rumen fill decrease
and allows greater intake.

Burlison and Hodgson (1985) determined that bite size, depth of biting, and
volume of each bite by sheep were positively correlated to sward height. Penning et al. ,
(1984) showed that swards less than 3 cm in height decreased the intake of ewes by 50%

as compared to ewes grazing pastures 6, 9, or 12 cm in height.

27

Environmental factors affecting feed intake

Forage allowance has a curvilinear relationship with intake of calves, and beef or
dairy cows (Minson, 1990). As the allowance of forage becomes less than twice the
maximum intake there is a decrease in the amount of forage eaten (Ernst et al., 1980 as
referenced by Minson, 1990). Maximum intake of immature temperate forages was
achieved when cows left a 8 to 10 cm stubble height. When the cows were forced to
graze down to 5 cm, intake was reduced 10 to 15% (Ernst et al., 1980 as referenced by
Minson, 1990). Beef calves provided a daily forage allowance of 30 g DM/kg BW had
an 18% lower intake than calves provided an allowance of 90 g DM/kg BW (Jamieson
and Hodgson, 1979 as referenced by Minson, 1990). The lower forage allowance
resulted in a lower residual stubble height and decreased OM digestibility. The effects
of forage allowance on intake are similar for steers between 5 and 18 months of age
(Minson, 1990). Forage allowance is partly determined by SR. Zoby and Holmes
(1983) reported that animals on high-stocked spring pastures consumed 32% less forage
than animals on low-stocked pastures. The same trend continued through the summer,
but the magnitude of the difference narrowed and was not statistically significant in the

summer .

Ingestive behavior

Forage intake is the result of grazing time, the rate of biting, and size of each bite
(Minson, 1990). The final outcome of prolonged grazing or any physical activity is
fatigue. When pasture density decreases, bite size also decreases. To overcome the

decrease in bite size, the rate of biting and the duration of biting increases. The

28

maximum duration of grazing is about 13 h/d even on sparse pastures (McClymont,
1967). Consequently, the possibility exists that an animal may reach the point of fatigue
before the consumption of adequate energy to maintain live-weight gain near 1 kg/d.
Stocking rate was determined by Zoby and Holmes (1983) to influence grazing
behavior. Especially in the spring, animals in the high stocked pastures had increased
grazing times, bite frequency and total bites/d when compared to the low stocked
counterparts. As mentioned above, herbage allowance was decreased in the high stocked
pastures. This explains why the animals on the high stocked pastures behavior changed,

but still was not sufficient to compensate for the decrease in forage availability.

Intake prediction

There are several questions that Leaver (1982) proposed that still remain
unanswered about intake and efficiency of grazing. How much are grazing animals
consuming? Do differences in intake explain the differences in animal performance on
different forages? Does intake reflect ease of forage prehension and mastication? Can
these physical properties of the plant be changed?

The absence of techniques to accurately determine the intake of grazing animals
has slowed the progress of forage utilization. Agronomists have concentrated on factors
that can be easily measured such as yield per hectare, longevity, and winter survival, but
little progress has been made in improving intake of pastures (Leaver, 1982).

Direct measurements of the intake of grazing animals are very difficult.

Therefore, indirect methods are utilized. These include pasture based methods, use of

29

internal and external markers, changes in animal weight, calculations based on animal

performance, and ingestive behavior (Leaver, 1982).

firsture based methods

Changes in forage mass utilizes the same principles as for pen-feeding where

intake is measured by difference:
Forage intake = forage offered - forage refused (Meijs et al., 1982).

Forage mass is determined at the beginning and the end of a grazing event. The
difference is the apparent quantity of forage consumed by the grazing animal. Non-
destructive methods to measure. forage mass include, height and(or) density
measurements, and non-vegetative attributes such as capacitance (Meijs et al., 1982).
The key to achieve reliable intake estimates is to reduce possible systematic error
in measuring the difference in forage mass. When using non-destructive techniques,
systematic and random errors may occur when applying the regression equations derived

from the sampling method (e. g., canopy height) and herbage mass (Meijs et al., 1982).

Use of internal and external markers

Internal markers are natural constituents of the plant that are not digested or
absorbed (Pond et al., 1987). Internal markers include: the use of nitrogen in a fecal
nitrogen index; and the concentration of lignin, chromogen, acid insoluble ash, or

indigestible fiber as it passes through the animal. The difference in concentration of the

30

internal marker between the consumed forage and the feces allows calculation of the
digestibility of the forage. The amount of indigestible residue is divided by the
indigestibility value to obtain the intake of the animal. Intake or digestibility of animals
consuming the pasture can then be calculated from regression equations (Cochran et al.,
1987) based on pen fed animals.

Like internal markers, external markers should not be digested or absorbed.
External markers can be fed, drenched or given as a bolus. Examples of external
markers include: chromic oxide, ferric oxide, silver sulfide, polyethylene glycol,
preparations of chromium, cobalt,hafnium, and rare earth metals (Pond et al., 1987).
External markers are used to determine fecal output, and with DM indigestibility, can

determine DMI using the following formula (Pond et al., 1987):
Intake (g/d) = DM output of feces (g/d) -I- [l- (% DM digestibility -:— 100)].
Changes in anim_al weight
Intake can be calculated from animal performance. Based on the energy
requirements for maintenance, the gain of grazing animals, and energy concentration of
the forage (Baker, 1982), intake can be calculated by:

Forage intake = Energy for maintenance and gain + Forage energy concentration .

Changes in animal weight over short-term periods have been investigated as a method

to determine intake. At the Oklahoma Agricultural Experiment Station, steers were fitted

31

with 'bovine b00ts’, load cells under each hoof to measure weight changes (Horn and

Miller, 1979).

Calculations based on ingestive behavior
The use of ingestive behavior to calculate intake requires determination of grazing

time, rate of biting during grazing and forage intake per bite, thus:

Intake = grazing time x rate of biting x forage intake per bite (Hodgson, 1982).

As discussed by Meijs et a1. (1982), the best procedure to estimate intake is one which

produces sufficiently precise estimates with the least cost.

PHOTOSENSITIVITY

Photosensitivity is the sensitization of the superficial layers of lightly pigmented
skin to sunlight (Clare, 1955; Johnson, 1986; Scott, 1988) and is an abnormal reaction
requiring the presence of a photodynamic agent (Clare, 1952). Photosensitivity differs.
from sunburn in that sunburn is a normal reaction of unprotected skin and occurs from
the overexposure to ultraviolet rays from the sun (Clare, 1952). Photosensitivity
develops from photodynamic compounds in the skin, which when excited by sunlight,
damages the cells in the vicinity (Scott, 1988). The effective light in photosensitivity
is determined by the absorption spectrum of the photodynamic agent and extends into the

visible light region, wavelengths greater than 320 nm (Clare, 1952). Photosensitivity has

32

been categorized into four groups: primary, hepatogenous, aberrant pigment metabolism.

and photosensitization of unknown origin (Clare, 1955; Johnson, 1986; Scott, 1988).

Primary photosensitivity

Primary photosensitization is due to ingestion of a photodynamic compoundwhich
enters the blood unchanged and causes a reaction in the skin (Clare, 1955, Scott, 1988).
Plants containing a phototoxin and chemicals which cause primary photosensitivity when
ingested are presented in Table 2.5. Primary photosensitivity is the only true form of
photosensitivity. In animals diagnosed with hepatogenous photosensitivity or aberrant
pigment metabolism, photosensitivity is a secondary condition developed from liver

damage or aberrant heme synthesis (Clare, 1952).

Hepatogenous photosensitivity

Hepatogenous photosensitivity is the most common form of photosensitivity
among ruminants (Scott, 1988). Hepatogenous photosensitivity is a secondary condition
due to liver damage which decreases the excretion of phylloerythrin in the bile (Clare,
1955; Scott, 1988). Phylloerythrin is derived from the anaerobic breakdown of
chlorophyll by microorganisms in the rumen and lower gastrointestinal tract.
Hepatogenous photosensitivity can result from liver damage associated with ingestion of
plants, molds and chemicals (Table 2.6) and can be induced experimentally via surgical
ligation of the bile duct to impair normal bile flow (Glenn et al. 1964).

Ingestion of a hepatoxin is the primary cause of hepatogenous photosensitivity

(Cornelius et al. , 1965), but a rare genetic defect in Southdown and Corriedale sheep can

33

Table 2.5. Cause of primary photosensitivity

 

 

 

Source

Plants
Bishop’s weed Rain Lily
Ammi majus Cooperia pedunculata
Buckwheat St. John’s Wort
Fagopyrum esculentum Hypericum perforatum
Burr trefoil Spring parsley
Medicago denriculata Cymopterus watsom'i
Dutchmans breeches Wild carrot
Thamnosma texana Daucus carota
Perennial ryegrass
Lolium perenne

Chemicals

Acridine dyes Rose bengal
Acriflavines Sulfonamides
Eosin Tetracyclines
Methylene blue Thiazides

Phenothiazine
_

Adapted from Scott, 1988

34

Table 2.6. Causes of hepatogenous photosensitivity

 

 

Source

Plants
Alecrim Lechuguilla
Holocalyx glaziovii Agave lecheguilla
Bog asphodel Millet, panic grass
Nanhecium ossifragum Panicum spp.
Burning bush, fireweed Ngaio tree
Kochia scoparia Myoporum spp.
Caltrops Ragworts
Tribulus lerresm's Senecio spp.
Coal-oil brush, spineless horsebush Rape, kale
T etradymia spp. Brassica spp.
Crotalaria, rattleweed Sacahuiste
Crotalaria spp. Nolina texana
Ganksweed Salvation Jane
Larsopermum bipinnatum Echium chopsis
Heliotrope Tarweed, fiddle-neck
Heliotropium europaeum Amsinckia spp.
Kleingrass Vervain
Panicum coloramm Lippa rehmanni
Lantana
Lamana camara

Mycotoxicoses

 

Anacystis (Microcystis) spp. (blue-green algae in Pen'conia spp. (on Bermudagrass)
water)

 

 

 

Aspergillus spp. (on stored feeds) Phomopsis leptosrromrfomtis (on lupines)
Fusan'um spp. (on moldy corn) Pirhomyces chanarum (on pasture, especially
rye)
Infection
Leprospirosis Parasitic liver cyst (flukes, hydatids)
Liver abscesses Rift Valley fever
Neoplasia
Hepatic carcinoma Lymphosarcoma
Chemical
Carbon tetrachloride Phenanthridium
Excess copper Excess phosphorus

—
Adapted from Scott, 1988

35

produce hepatogenous photosensitivity as well. An autosomal recessive trait in
Southdown sheep produces congenital hyperbilirubinemia and photosensitivity (Hancock,
1950). The defect impairs the ability of the liver to remove plasma bilirubin (Gronwall,
1970; McGavin et al. 1972) and decreases the excretion of bilirubin and phylloerythrin
in the bile (Cornelius et al., 1986; McGavin et al., 1972). The ovine kidney is capable
of excreting phylloerythrin but in the case of congenital hyperbilirubinemia, renal damage
occurs which inhibits phylloerythrin excretion (McGavin et al., 1972). The excess
circulating phylloerythrin causes green discolorization of the teeth, periosteum, fascia,
serosa, and mucous membranes. The elevated plasma bilirubin causes yellow
discoloration of the inner lining of the aorta and endocardium (McGavin et al., 1972).
Livers of affected sheep appear normal unlike the condition observed in the Corriedale
sheep where a dark brown to black discoloration of the liver occurs (Cornelius et al.,
1965).

The condition in Corriedale sheep, inherited by an autosomal recessive gene,
impairs the excretion of bilirubin and phylloerythrin (Gronwall, 1970; Blood et al.,
1983). Affected lambs appear normal until grazing or consumption of a chlorophyll-
containing diet (Clare, 1955). Photosensitivity in both breeds is lethal if the chlorophyll
diet or sunlight is not removed (Clare, 1955; Cornelius et al., 1965). Mutant

Southdowns if surviving photosensitivity will die of renal failure (McGavin et al. , 1972).

Aberrant pigment metabolism
The third form of photosensitivity is aberrant pigment metabolism. This condition

is a result of the accumulation of porphyrins in the blood and body tissues due to

36

aberrant porphyrin synthesis (Scott, 1988). Bovine congenital protoporphyria (BCP) and
bovine erythropoietic porphyria (EPP, pink tooth) are both examples of photosensitivity
due to aberrant pigment metabolism. Bovine erythropoietic protoporphyria, originally
thought to affect Limousin cattle only (Fraser, 1986), has been shown to affect the
Blonde d’Aquitane breed as well (Schelecher et al., 1991). Bovine erythropoietic
protoporphyria is characterized by the accumulation of protoporphyrins in the blood due
to the decreased activity of ferrochelatase (Schelecher et al., 1991, Ruth et al., 1977,
Sassa et al., 1981; Figure 2.3), the enzyme which adds the ferrous ion to protoporphyrin
IX to form heme (Rawn, 1989.). This rare condition is inherited as a simple autosomal
recessive trait unlike the similar condition in humans which is inherited as an autosomal
dominant trait (Ruth et al., 1977). Homozygous animals have 10% and heterozygous
animals have 50% of the normal ferrochelatase activity, respectively (Sassa et al., 1981).

Bovine congenital porphyria, as EPP, is inherited as an autosomal recessive trait
(Wass and Hoyt, 1965) and affects both sexes (Ellis et al. 1958). The condition has been
diagnosed in Hereford (Railsback, 1938), Holstein-Friesian (Ellis et al., 1958), Jamaica
Red and Black (Nestel, 1958), and Shorthorn, (Fourie, 1936; Amoroso et al., 1957),
breeds. Uroporphyrin I and coproporphyrin I, are the photodynamic agents (Clare,
1952), and accumulate in the blood and body (Rhode and Cornelius, 1958) due to a
depressed function of uroporphyrinogen III cosynthase (Levin, 1968; Romeo and Levin,
1969).

Uroporphyrin I and coproporphyrin I are not intermediates in the biosynthesis of

protoporphyrin IX. Uroporphyrin I and coproporphyrin I are products of the oxidation

37

(4) Porphobilinogen

Uroporphyrinogen I synthase and
Uroporphyrinogen III cosynthase Uroporphyrinogen I synthase

Hydroxymethyl Bilane
(tetrapyrrl methane)

 

 

Uroporphyrinogen III Uroporphyrinogen I

Uroporphyrinogen decarboxylase

Coproporphyrinogen Ill —-) Protoporphyrinogen IX

Coproporphyrinogen oxidase
Protoporphyrinogen oxidase

Protoporphyrin IX

l Fenochelatase and Fe 2+

Heme

Figure 2.3. Biosynthesis of heme from porphobilinogen (Rawn, 1989).

38

of uroporphyrinogen I and its decarboxylated derivative coproporphyrinogen I (Romeo
and Levin, 1969). Uroporphyrinogen I is formed from the monopyrrole compound
porphobilinogen by uroporphyrinogen I synthase, but in the presence of
uroporphyrinogen III cosynthase, uroporphyrinogen III is produced (Romeo and Levin,
1969). Uroporphyrinogen III is converted to protoporphyrin IX and then to heme by the
enzyme ferrochelatase (Romeo and Levin, 1969).

The accumulation of uroporphyrin I and coproporphyrin I produces a
discolorization of the teeth and bones, which vary from pinkish—red to mahogany, hence
the name ”pink-tooth”; and affected animals excrete reddish-brown urine (Ellis et al.
1958). Animals with EPP or BCP will exhibit photosensitivity if not protected from the

sun and will be unthrifty (Ellis et al., 1958).

Photosensitization of unknown origin

When photosensitization occurs and the causative agent cannot be determined as
primary, hepatogenous or aberrant pigment metabolism, the agent is classified as
unknown (Clare, 1955; Johnson, 1986. Scott, 1988). Reports of photosensitivity often
occur when common pasture plants are grazed. These include alfalfa (Medicago sativa),
clovers (Tnfolium spp.), vetches (Vicia spp.), and oats (Avena sativa; Clare, 1955;
Johnson, 1986; Scott, 1988). Frequently, cases occur when cattle are grazing lush

pastures (Scott, 1988) or when fed water-damaged alfalfa hay (Putnam et al., 1986).

39

Clinical signs and treatment

Clinically, photosensitive animals show photophobia and may rub the ear, eyelids
and muzzle. Lesions are usually confined to lightly pigmented skin exposed to sunlight.
In severe cases, black pigmented skin may be affected. The skin becomes inflamed and
swollen. If not prevented at this stage, the affected area develops lesions. The lesions
are characterized by serum exudation, scab formation and skin necrosis. The ears, face,
back, base of tail, vulva, udder and coronets are the most common sites of lesions. In
the case of aberrant pigment metabolism, photodennatitis is the predominant clinical
sign. In addition to photoderrnatitis, cattle with EPP exhibit teeth varying in color from
light pink to mahogany, with reddish-brown urine (Fraser, 1986). Treatment of
photosensitivity involves:

1. Remove animals from sunlight (Fraser, 1986).

2. Prevent reexposure to the photodynamic agent (i.e. decrease the amount

of high chlorophyll feeds; change feed and pasture, remove moldy hay,
etc.; Fraser, 1986).

3. Treat symptomatically with antibiotics and corticosteroids. (Manning,
1984)
4. Secondary skin infections should be treated and fly strike prevented

(Fraser, 1986).

5. Animals with congenital photosensitivity and carriers should not be used
for breeding (Scott, 1988).

Skin lesions will heal even after severe necrosis. Productivity of affected animals is

influenced by the site and severity of the lesions (Fraser, 1986).

CHAPTER 3: EVALUATION OF GRAZING METHODS AND
STOCKING RATES OF ALFALFA PASTURES ON ANIMAL AND
PLANT PRODUCTIVITY

SUMMARY

A four year study was conducted to determine the effects of grazing method and
stocking rate on animal and plant productivity of alfalfa pastures, to compare the forage
presentation of a pasture system to a mechanical harvested system, and to ascertain the
effect of grazing system on subsequent performance of steers fed a high concentrate diet.
Ten pasture plots (.76 ha) were seeded in 1988 with alfalfa. Plots were divided into 2
blocks of 5 pastures each. Two grazing methods, 4 or 13 paddocks, at two stocking
rates (SR), 5.5 and 9.5 steers/ha, and a mechanically harvested systems were evaluated.
Pastures were managed to allow a 36-d rest period with an average grazing season of 110
days. Following the grazing season, steers were placed in a feedlot and fed a corn
silage-high moisture corn diet for an average of 211 d. In each year, steers from high
SR systems had lower pasture ADG (P < .02) than steers from low SR systems. In 1989,
low SR systems produced 104% greater (P=.07) live-weight gain/ha than high SR
systems. Thirteen paddock high SR systems in 1990 tended (P< .10) to produce more
live-weight gain/ha than 4-paddock high SR systems, but similar to the 4- and 13-
paddock low SR systems. In 1991 and 1992, after a 25% decrease in the high SR, high

SR systems produced 24% greater live-weight gain/ha than low SR systems. Forage

4O

41

presentation was similar for the mechanical harvest and the grazing systems in 1989 and
1990, but in 1991, the mechanical harvested system had 42% less (P< .05) forage
presentation than the grazing systems. Low SR steers entered the feedlot heavier
(P< .01), and had greater (P< .06) live-weights after 48 to 64 d. Weight gain and feed
conversion efficiency were similar after 211 d in the feedlot. Increasing paddock number
did not improve live-weight gain/ha or forage presentation. Optimum SR was between

5.3 and 7.9 steers/ha.

INTRODUCTION

Alfalfa is the most productive forage produced in Michigan with 485,000 ha
grown annually (Michigan Agricultural Statistics Service, 1992). Alfalfa is regarded as
a superior forage crop in terms of quality, palatability, and yield potential (Van Keuren
and Marten, 1972). In recent years, alfalfa has been considered as a pasture cr0p.
Production of 392 kg/ha (Marten et al., 1987) and 783 kg/ha (Marten et al., 1990) have
been reported for grazing heifers and lambs, respectively. More recently, studies in
Kentucky has shown gains from 535 to 820 kg of beef produced/ha with rotational
stocking of alfalfa (Burris et al., 1993).

Alfalfa stand persistence is not maintained with continuous stocking (Cooke et al. ,
1965; Brownlee, 1973; Van Keuren and Matches, 1988); therefore, a rotational stocking
system must be implemented. McKinney (1974) determined that alfalfa stands were
maintained and more profitable with 2 or 4-paddocks than 6 or 12-paddocks or
continuous stocking. With an alfalfa based pasture, Smith ( 1970) demonstrated the

decrease of the alfalfa component of the pastures with continuous stocking as compared

42

with a 3 or 4-paddock system, and in Utah, an alfalfa pasture persisted 9 yr with
rotational stocking (Bateman and Keller, 1956 as referenced by Van Keuren and
Matches, 1988).

There has been no consensus on the OP needed to maintain alfalfa in pastures.
Iversen (1967) and Jason (1975a) recommend a 2 to 4-d OP, whereas Leach (1979)
recommends 8 to 16 d. The RP to maintain alfalfa in the pasture has been determined
to be between 35 to 54 d (Bateman and Keller, 1956 as referenced by Van Keuren and
Matches, 1988; Iversen, 1967; O’Connor, 1970).

The goal of this study was to develop methods and management practices needed
to successfully manage a productive alfalfa pasture system. Therefore the objectives of
this study were to determine the effect of two grazing methods and two stocking rates on
animal and plant productivity of alfalfa pastures, to compare the forage productivity of
a pasture system to a mechanically harvested system, and to ascertain the effect of the
grazing systems on subsequent cattle performance fed high concentrate diets. To
accomplish these objectives, a direct-seeded alfalfa field was subdivided into ten pasture

plots, and two grazing methods with two SR were evaluated.

MATERIALS AND METHODS
This study was conducted under the approval of the Michigan State University
All-University Committee on Animal Use and Care (AUF # 8/88—321-01). The study
was initiated in the summer 1988 and continued through the spring of 1993. In August
1988, 8 ha were direct-seeded with alfalfa variety WL 225 (17 kg/ha). Prior to seeding,

the previous wheat field stubble was plowed, treated with Eptam (2.4 L/ha) and fertilized

43

with 290 kg/ha of potash (0-0-60). The soil consists of Capac loam, Sisson fine sandy
loam, and Riddles-Hillsdale sandy loams. These soils are within the Marlene-Capac-
Owosso association, which are nearly level to rolling, well drained to somewhat poorly
drained loam soils (USDA, 1979).

The 8 ha were seeded in 1988 and divided into 10 pasture plots (.76 ha/plot,
Figure 3.1). Four hectares, contiguous to the 8 ha was seeded to alfalfa variety Big Ten
in 1987 and subdivided into two pasture plots (.76 ha/plot) and a supplemental pasture.
Each pasture plot was surrounded by a double strand of 20 gauge electrified wire (Kiwi
Fence Systems, Inc., Waynesburg, PA; Table 3.2). The pasture plots were further
subdivided utilizing electrified polytape (Kiwi Fence Systems, Inc., Waynesburg, PA)
into 4 or 13 paddocks (Table 3.2). The 10 pasture plots in the 8 ha field were divided
into two replicates of five pastures each, and used to evaluate grazing methods and
stocking rate. The additional pasture plots in the 4 ha field (plots 11 and 12) were used
to determine the intake of grazing Holstein steers and a net energy value for grazed
alfalfa (Chapter 4).

A mechanical harvest system was compared to the four grazing systems. The
grazing systems were comprised of two grazing methods (GM), 3 traditional four-
paddock rotation and a more intensive l3-paddock rotation, each at a low and high SR.
The mechanically harvested plots were assigned to the plots 5 and 10 because these
contained low lying areas. The four grazing systems were randomly assigned within the
remaining four plots per replicate. The five treatments were as follows: 1) 4 paddocks-
low SR, (4—L); 2) 4 paddocks-high SR (4—H); 3) 13 paddocks-low SR (13-L); 4) 13

paddocks-high SR (13-H); and 5) a mechanical harvest system (MH).

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45

Each plot area = .76 ha
Plot 1 Plot 2

paddock

double
strand of 20
gauge wire

polytape

 

(.-..58 '11—.)

Figure 3.2. Diagram of pasture plots. Each plot is 29 x 265 m to equal .76 ha.
Two strands of 20 gauge wire (heavy lines) separates each plot. Polywire (light
lines) divides the plot into 4 or 13 paddocks.

46

Occupation periods were 12 and 3 (1 per paddock for the 4 and 13-paddock GM,
respectively. Grazing cycles, were 48 and 39 for the 4 and 13-paddock methods. As
a result, each paddock was allowed a 36-d RP between grazing events. The initial SR
were set at 7.9 steers/ha (1885 kg/ha) and 15.8 steers/ha (3770 kg/ha) for the low and

high SR, respectively. The SR resulted in 4 and 8 steers per pasture plot.

Year 1: 1989

Seventy-two Holstein steers (239 kg) were received between April 15 and 20.
The steers were weighed, ear tagged, dehomed, vaccinated against IBR, P13, and treated
for parasites with iverrnectin (MSDAGVET, Rahway, NJ). Steers were fed a corn
silage-hay diet from arrival date to May 11. An alfalfa haylage diet was fed from May
11 to 20. The haylage diet-was supplemented with a poloxalene (SmithKline Beecham,
West Chester, PA)-mineral mix (Table 3.1). The expected intake of mineral supplement

227 g steer" d".

Table 3.1. Ingredient composition of poloxalene-
mineral mix

 

 

Ingredient Percent in supplement
Dicalcium phosphate 26
Magnesium oxide 26
Trace mineral salt 26
Poloxalene 12
Selenium 200 IQ
Total 100

47

Steers were implanted with estradiol-l7B (ELANCO, Indianapolis. IN), weighed
full, and blocked by weight into two groups (218 kg, 260 kg) on May 17. Steers within
blocks were randomly allocated to the four grazing systems. On May 19, steers were
weighed and tagged with a fly repellant ear-tag (Coopers Animal Health Inc., Kansas
City, KS). Steers in block one, plots 1 to 4, were sorted into systems groups on May
19, fed alfalfa haylage and supplement; and transported .8 km to the pasture site. Steers
assigned to block two, plots 6 to 9, were sorted by treatment and taken to the pasture site
on May 20. The start of the blocks was staggered to allow ease of sample collection.
Before transport to pasture, steers were allowed to consume alfalfa haylage and
poloxalene-mineral mix to appetite to minimize bloat problems. Steers had ad libitum

access to mineral-poloxalene mix and water while on pasture plots.

Cycle 1: pasture man_agement

To prevent forage from becoming mature, the OP of the paddocks was decreased
to 8 and 2 d for the 4 and 13-paddock systems, respectively, during the first grazing
cycle. Stocking rate was maintained at the original levels. For the first cycle, the RP
was 24 d.

Every 2 or 8 d, steers were moved to a new ungrazed paddock during the
morning. On June 1, excessive rainfall resulted in severe trampling damage in the
occupied paddocks and cattle were moved to a new paddock 1 d earlier than scheduled.

Alfalfa weevils presented a problem early in the grazing season. To prevent

further weevil damage, paddocks grazed before June 9 were sprayed with 1.4 L of Sevin

48
insecticide (Carbaryl [l-napthyl N-methyl carbamate], RHONE-POULENC AG

COMPANY, Research Triangle Park, NC).

By June 13, it was obvious the SR was too high for the forage available and the
SR were decreased by 33% to 5.3 and 10.5 steers/ha for the low and high SR,
respectively. Concurrently, 21 steers developed symptoms of photosensitivity. These
steers were part of the 37 steers removed to reduce the SR. In order to maintain pre-
established RP, cattle were removed from the experimental plots for a brief period. On
June 13, steers in the 13-paddock GM (plots 2,3,6,9) were removed to supplemental
paSture. Steers from the 4-paddock GM were removed on June 15 (plot 4) and 21 (plots
1,7,and 8).

From June 21 to June 26, all steers (plots 2,3,6,9) were grazing supplemental
pasture. On June 26, steers were placed in a holding pen and fed alfalfa hay (2.3 kg
DM/steer), watered and provided access to the poloxalene—mineral mix. The steers were
removed from feed and water at 1600 h. After a 16 h shrink, steers were weighed (June
27, d 38), fed hay, sorted and placed onto the originally assigned pasture plots,

beginning the second grazing cycle.

Cycle 2 grid 3: pasture management

The OP during the second and third grazing cycles was increased to the original
3 and 12 d. Stocking rates were maintained at 5.3 and 10.5 steers/ha. Forage
availability was determined daily by visual estimation of forage stubble height. Steers

were removed to supplemental pasture, comprised primarily of alfalfa, when the forage

49

Stubble was below 10 cm. Once moved to supplemental pastures, steers remained there
until the scheduled move to the next paddock.

In August, steers from two pasture plots 4 and 8 (4-H) were removed for lack of
forage. Since supplemental pastures were depleted, steers were fed hay. Prior to reentry
into assigned pasture plots, steers were provided alfalfa hay and placed onto supplemental
pasture. Approximately 4 h later, 4 steers died from bloat.

Steers were weighed full on d 63 and 87. At the conclusion of the 1989 trial
(August 29), steers were removed from pasture (d 102), held off feed and water 16 h and
weighed. To calculate overall daily gain from a full initial weight and a shrunk final
weight, the shrunk weight was divided by .96, assuming a 4% shrink.

To determine gain/ha for each pasture plot, ADG was multiplied by SR and the
number of days on pasture. Days on pasture is the number of days the steers spent on
the experimental plots. Days on pasture does not include days spent on supplemental

pasture. This procedure was used to determine gain/ha for each year.

Year 2: 1990

Forty-eight Holstein steers (232 kg) were received on March 7. Steers were
weighed, ear-tagged, vaccinated against IBR, P13 and treated for parasites with ivermectin
(MSDAGVET, Rahway, NJ). A com silage-hay diet was fed from March 7 to May 7,.
As in Year 1, steers were fed an alfalfa haylage diet one week (May 7 to May 14) prior
to grazing and received poloxalene-mineral supplement 3 d (May 11 to May 14) before

initiation of the grazing trial.

50

On May 13 steers were weighed, blocked by weight into two groups (225 kg, 240
kg) and randomly allocated to the four grazing systems within a weight block. Steers
were weighed on May 14, implanted with estradiol-176 (ELANCO, Indianapolis, IN),
tagged with a fly repellant ear-tag (Coopers Animal Health Inc., Kansas City, KS) and
sorted into system groups. Having been fed haylage and supplement, the steers. were

transported .8 km to the pasture site.

Cycle 1: pasture management
Prior to grazing (April 26), the alfalfa pasture was fertilized (0-17-34 with .5%

boron) with 1254 kg/ha according to a soil test taken the previous fall. Cycle 1 was
accelerated as in year 1 for similar reasons. Unlike year 1, the OP were not the same but
increased with each subsequent paddock. The OP for the four-paddock system were 4,
8, 12, and 12 d for paddocks 1 through 4, respectively. This system resulted in a 32-
d RP for paddock l. The 13-paddock system utilized OP of 2 d for the first 6 paddocks
and 3 d for the remaining 7 paddocks. The accelerated system for the 13-paddock
system provided a 31-d RP for paddock l. Stocking rates were set at 5.3 and 10.5
steers/ha (1161 and 2322 kg/ha) for the low and high SR, respectively. Paddocks were

grazed in numerical order for the first and subsequent grazing cycles.

Cycle 2 and 3: pasture management

Unlike the first year, the pastures had sufficient regrowth after the first grazing
cycle to continue with the second and third cycle uninterrupted. Occupation periods were

maintained at 12 and 3 d for the 4 and 13-paddock GM, respectively. Steers were

51

moved to new paddocks every 3 or 12 d. When forage availability became limiting.
steers were removed to supplemental pastures, with the same criteria mentioned
previously, until the next scheduled move.

Steers were weighed full on June 8, (d 25) and every 24 d (d 49, 73, and 97),
thereafter. On August 30, (d 108) steers were removed from pasture and weighed on
two consecutive days. The steers were then placed on an alfalfa haylage diet for 7 d and
weighed to equalize rumen fill.

On June 2, the poloxalene content of the mineral mix was decreased to 6% due
to decreased possibility of bloat. Trace mineral salt, dicalcium phosphate, and magnesium
oxide each increased to 28%. The poloxalene content of the supplement was returned
to 12% on July 24 to prevent bloat because of low forage availability and immaturity of

the alfalfa.

Yw 3: 1991

Forty Holstein steers were received from April 23 through May 6. Steers were
processed upon arrival as before and fed a corn silage-hay diet. Cattle received on May
6 were placed directly on an alfalfa haylage diet. The poloxalene-mineral mix was added
to the haylage diet as in the previous years from May 6 to 13. On May 9, steers were
implanted with estradiol-17B (ELANCO, Indianapolis, IN), received a fly repellant ear-
tag (Coopers Animal Health Inc., Kansas City, KS), weighed full to block the steers into
two weight groups (216 kg, 258 kg) and randomly assigned to plots. As in year 1 and
2, initial steer full-weights were determined on two days (May 11 and 13) during the

week of adaptation to an alfalfa haylage diet. Steers were transported .8 km to pasture

52

on May 13 after being offered alfalfa haylage and poloxalene-mineral supplement. Steers

had ad libitum access to water and poloxalene-mineral supplement while on pasture.

Cycle 1: pasture management
Prior to grazing, the pastures were fertilized with 225 kg/ha of potash (0-0-60)

according to a soil test. Grazing of paddocks was accelerated as in the previous two
years. The accelerated scheme followed the schedule utilized in year 2. Problems with
the electric fence resulted in a loss of 6 and 3 d in cycle 1 of the 4 and 13-paddock GM,
respectively. This change in the calculated rotation resulted in RP of 26 and 29 d for the
4 and 13-paddock GM, respectively during the first grazing cycle. Stocking rates were
5.3 and 7.9 steers/ha (1186 and 1874 kg/ha) for the low and high SR. The high SR was
reduced compared with the two previous years. The decrease in SR was an attempt to

increase the steer ADG and gain/ha as compared with the low SR.

Cycle 2 and 3: pasture management

Occupation and rest periods were the same as year 2. Visual appraisal was made

 

each day to determine forage adequacy. Forage was adequate throughout 1991 and steers
did not require supplemental pasture. Steers were weighed on June 6 (d 24), August 2
(d 81) and at the conclusion of the grazing season September 2 (d 122). Following
pasture removal, steers were placed on the standard alfalfa haylage diet for 7 d as in year

2, and weighed on two consecutive days, September 9 and 10.

53
Year 4: 1992

Forty Holstein steers (265 kg) were received on April 19. Steers were processed
at arrival as before and fed a corn silage-hay diet until May 5. From May 5 to 12, steers
were fed the adjustment diet of alfalfa haylage and poloxalene-mineral mix prior to the
grazing season. Steers received an estradiol 17-6 implant (ELANCO, Indianapolis, IN)
and a fly repellant ear-tag (Coopers Animal Health, Inc., Kansas City, KS), weighed,
grouped into two weight blocks (249 kg, 281 kg) and randomly assigned to plots. On
May 13, steers were weighed, fed alfalfa haylage and supplement, and transported .8 km
to the pasture site. Steers had ad libitum access to water and poloxalene-mineral mix
while on pasture. Stocking rates were as in year 3, 5.3 and 7.9 steers/ha (1324 and 2093
kg/ha). Steers were weighed on June 10 (d 28), July 8 (d 56), and September 8 and 9

(d 118, 119).

C cl 1 an 3: asture mana ement

Unlike the three previous years, the first grazing cycle was not accelerated. This
was due to the cool weather which retarded the growth of the pasture. Therefore the 12
and 3 d OP for the 4 and l3-paddock GM, respectively, were maintained throughout
cycle 1,2 and 3. Steers were weighed off pasture on September 8 and 9 (d 118, 119) and
fed the standard alfalfa haylage and poloxalene-mineral mix diet for seven days. After
the post-adaption period, steers were weighed on two consecutive days September 15 and
16. A summary of grazing season, SR and initial weights used in each year is presented

in Table 3.2.

54
Mechanical Harvest

The MH plots, 5 and 10, were harvested as haylage in 1989 and 1990. First

cuttings were made on June 7 and May 30, and second cuttings on August 9 and July 30

from 1989 and 1990, respectively. Fresh cut haylage samples were collected at the time

of chopping to determined DM content and yield. In 1991, the MH plots were harvested

Table 3.2. Characterization of the grazing season, stocking rate and initial weights
during the four year grazing study

 

 

Grazing season Stocking rate,

steers/ha Tom] Steer

Year . number initial
Start End Length, LOW 11%" of steers weight, kg
d

1989 May 19 Aug. 29 103 5.91 11.7 72 239
1990 May 14 Aug. 30 108 5.3 10.5 48 232
1991 May 13 Sept. 2 112 5.3 7.9 40 237
1992 May 13 Sept. 8 118 5.3 7.9 40 265

‘Stocking rates during the first 24 d were 7.9 and 15.8 steers/ha and then reduced
for the remainder of the grazing season to 5.3 and 10.5 steers/ha for the low and
high SR, respectively

as large round-bale hay. The first cutting was made on June 8 and the second in late
July. Hay samples were not collected for DM analysis, therefore, an 85% DM content

was used to calculate DM yield/ha. The MH plots were not harvested in 1992.

55
F eedlot management

Steers from each pasture plot were fed as a group in the same pen throughout the
feedlot phase. Following the rumen equilibration period, steers were adjusted to a high
concentrate diet. The diet consisted of 81% high moisture corn or dry com, 14% corn
silage and 5% protein-mineral supplement. The CP content of the diet was 10.5% (DM
basis), and the energy density was 2.33 Mcal/kg NE“, and 1.54 Mcal/kg NEE. Weights
obtained after the rumen equilibration period were used as the initial weights for the
feedlot phase with steers being weighed at 28 or 56 d intervals until slaughter. Dry
matter intake was determined from orts collected during each weigh period. Steers were
on feed for 222, 234, 194, and 194 d for 1989, 1990, 1991, and 1992, respectively. At
the conclusion of the feedlot phase, the steers were weighed on two consecutive days and
transported to the slaughter plant. Carcass weight, quality grade and yield grade were

determined.

Data collection and analysis
Forage data collection and flalyses

Pasture samples were collected in 1989, 1990 and 1991 to determine pasture
yield. Nutritive quality as measured by crude protein (CP, total N x 6.25), organic
matter (OM), and in vitro organic matter digestibility (IVOMD) was determined on
forage samples for 1989 and 1990. Prior to steer entry, paddock-forage samples were
randomly collected from three (.5 x .5 m) quadrants in each paddock. In 1989 and 1990,
extended canopy heights were also determined at four random sites within each paddock

prior to steer entry.

56

Forage samples from the three quadrants were composited and split into two
subsamples. Both subsamples were weighed. One subsample was frozen for wet
analyzes, the other subsample dried at 55°C for 48 h (AOAC, 1984). The dried sample
was ground through a 1 mm screen in a Wiley mill. In duplicate, 1 g of each ground
sample was placed in a 5000C muffle furnace for 12 h to determine ash content and OM
(100 - %Ash). A 1 g sample, in triplicate, was used to determine IVOMD using the
Tilley and Terry (1963) procedure with urea (.5 g/L) added to 1 part strained ruminal
fluidzl part McDougall’s Buffer (McDougall, 1948) and a 24-h acid-pepsin digestion
phase (Mader and Horn (1986). Residual DM was collected in a Buchner funnel fitted
with a pre-weighed, ovenodried Whatrnan No. 541 filter paper. The residual DM and
filter paper were placed in a pre-weighed 50 ml beaker and dried 12 h in a 60°C oven.
The beaker, containing the filter paper and residual DM, was weighed and then placed
in a 5000C muffle furnace for 12 h to determine residual ash content.

The frozen sample was thawed, chopped with a Hobart chopper and assayed for
total nitrogen by the Kjeldahl procedure using a Technicon auto-analyzer system (AOAC,

1984).

Esophageal extrusa collection and analysis
In 1989 and 1990, extrusa boluses were collected from esophageally fistulated

steers fitted with esophageal cannulas (Precision Machine Co., Inc., Lincoln, NE) to
determine the nutritive quality of forage consumed. Sampling coincided with the
movement of the 4-paddock GM (12 d). This resulted in every fourth paddock sampled

for the 13-paddock GM and every paddock for the 4-paddock GM. ESOphageally

57

fistulated steers were removed from pasture for 2 h prior to sampling. Steers were fitted
with collection bags (Cheyenne Awning Co. , Cheyenne, WY) which covered the fistulae
and collected the extrusa boluses. Cannulated steers were then placed in an ungrazed
paddock for .5 h. Samples were removed from the collection bags and kept cool until
all paddocks were collected and then frozen for later analysis. Bolus samples were
freezed-dried and ground through a 2 mm screen in a Wiley mill. The dried samples
were analyzed for DM, OM, CP, and IVOMD as described above.

In situ ruminal DM and CP degradation of the esophageal extrusa samples were
determined by the methods described by Wilkerson, (1990) and Karges et al. (1992).
A 5 g dried and ground sample of esophageally collected extrusa was placed in a labeled
and weighed 10 x 20 cm dacron bag (Ankom, Fairport, NY). The bag was sealed with
a #8 stopper and two #18 rubber bands. Four bags were prepared for each sample.
Each replicate (one of the 4 bags) was placed in a larger mesh bag and soaked in warm
(39°C) water for 20 min prior to rumen incubation. Two rumen fistulated steers were
used for the analysis. The steers were fed a bromegrass diet. Two large mesh bags
containing approximately 25 dacron bags were placed in the rumen of each steer just
prior to feeding. After the 16 h of rumen'incubation, the mesh bags were placed in
warm water and rinsed until all particulate matter was gone, .5 to l h. Next, individual
dacron bags were rinsed with warm water as the rubber bands and stopper were
removed. The residue remaining was washed to the bottom of the bag and the bag was
air dried. The air-dried bags containing residue were dried in a 65°C oven overnight.
The oven-dried bags were allowed to equilibrate to room conditions for three hours then

weighed. One gram of the residue was used to determine total nitrogen. From these

58

analyses, ruminal DM degradation and ruminal undegradable protein could be

determined.

Pasture botanical composition

On April 23, 1989, prior to the initiation of grazing, alfalfa plant densities were
determined. Plant counts were determined from 60 randomly placed quadrants (.5 x .5
m). Before grazing was initiated in years 3 and 4, three quadrants were collected from
each plot. The samples were combined and separated into alfalfa and other plant
material. The plant species subsamples were dried at 55° C for 48 h to estimate the

percent alfalfa in the pastures.

Ingestive behavior observations

Visual observations of cattle behavior were recorded on June 20 and August 7,
1990. Observations began at 0600, with steers being observed every 15 min until 2145
and 2100 for June 20 and August 7, respectively. The difference was due to the decrease
in daylight. Observers recorded whether steers were grazing, ruminating, drinking,
consuming mineral, or idle. To determine time spent in each activity, steers were

assumed to be engaged in an activity until the next observation was made.

Statistical analysis
For statistical analysis, the pasture plot was treated as the experimental unit in
both the grazing and feedlot phases. Data were analyzed using the General Linear Model

subroutine of SAS (1987). Grazing systems in year 1 (1989) and 2 (1990) were analyzed

59

individually, whereas animal performance data from year 3 (1991) and 4 (1992) were
pooled. The model for year 1 and 2 included; block, GM, SR, and the interaction GM
x SR. The probabilities for the main effects, GM and SR, and the interaction GM x SR
were determined. If there was a significant GM x SR interaction (P < .10), the treatment
means were separated using a Bonferroni t-test. Statistical differences were denoted by
superscripts. This procedure was also used to analyze forage presentation in 1991, and
pasture botanical composition collected in 1991 and 1992.

To analyze year 3 and 4, the 4 year average of animal performance on pasture,
and the 3 year average of forage presentation, a model including; year, block, GM, SR,
GM x SR, year x GM, year x SR, and year x GM x SR within the GLM procedure of
SAS (1987) was utilized. If there was a significant GM x SR interaction (P< .10), the
treatment means were separated using a Bonferroni t-test and denoted as discussed
previously. Significant year interactions were determined and denoted by superscripts.

Comparisons of MH forage presentation and botanical composition with the
grazing systems utilized a model which included treatment and block, in the GLM
procedure of SAS (1987). A Dunnett’s t-test (Gill, 1978a) was used to determine if the
grazing systems were different from MH. Differences were denoted with superscripts.

Visual observations from year 2 were analyzed with a GLM including; block,
GM, SR, observation date (OBS); and OBS x GM, OBS x SR, GM x SR, and OBS x
GM x SR interactions. Although OBS was significant (P< .10) for each activity,
interactions involving OBS were not and the interactions were dropped from the model.

There were no significant (P) .10) GM x SR interactions.

60
RESULTS AND DISCUSSION

Year 1: 1989

In 1989, SR impacted animal and plant productivity to a greater extent than the
grazing method (Table 3.3). As expected, when SR is increased, individual animal
performance decreased (Joyce and Brunswick, 1977; Marsh and Brunswick, 1978). In
this experiment, 4-H and 13—H steers had 14% lower (P=.002) live-weight at the end
of the grazing season than 4—L and l3-L steers. The lower weight was a result of a 72%
lower (P=.002) ADG than 4-L and 13-L. When determining the correct SR to use,
individual animal performance must be weighed against production of the land area. The
4-H and 13-H plots were over-stocked initially and even after a 33% decrease in SR,
were not able to produce the quantity of live-weight gain as compared to the 4-L and 13-
L systems. Due to the over-stocking, steers consumed a greater proportion of the
available forage and required more days on supplemental pasture. Steers on the 4-L
plots remained on the assigned plots 26.5 days more (P< .05) than the 4-H steers with
13-L and 13-H steers intermediate. The 43% decrease in the number of days on pasture
and lower ADG for 4-H steers resulted in a 51% decrease (P: .07) in live-weight gain
per hectare. The decrease in animal performance due to increased SR, can in part be
explained by the negative impact on forage presentation (Table 3.4). High SR tended to
have 22% less (P= .09) forage presentation over the 103-d grazing season than low SR.
Further evidence shows the tendency for high SR to have 19% lower (P=.103) canopy
heights than low SR.

Although forage presentation was decreased in 4-H and 13-H plots, forage

nutritive quality was increased, as measured by CP and IVOMD. Numerically, forage

61

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63

from 4-H and 13-H pastures showed a trend (P: .14) of increased CP content of 20.57
and 19.65%, respectively, as compared to 16.75 and 17.50% for 4-L and 13-L pastures.
Forage IVOMD was affected by GM and SR with forage from 4-1-1 tending to have 7%
more (P< . 10) IVOMD than forage from 4-L, 13-L, or 13-H. These observations agree
with Hintz and Albrecht (1991) who determined a negative relationship between stem
height and CP content; and a positive correlation between height and NDF content. This
may explain the inverse relationship observed in this study between CP and IVOMD
content of the forages and the measured canopy height.

Esophageal extrusa samples were collected to determine the selectivity of cattle
when first placed into the ungrazed paddocks. Clearly, the cattle used to collect the
extrusa samples selected forage high in CF and IVOMD. There was a tendency for
steers on the low SR to select forage higher in CF than the average C? content of clipped
forage samples. Although, the CP content of esophageal and clipped forage was similar
in the high SR. There were no differences in the quality of selected forages between the
grazing systems. Extrusa samples were further evaluated to determine rumen dry matter
degradation (DMD) and undegradable protein (UDP) content. Rumen DMD ranged from
78.19 to 81.76 % with no differences between grazing systems. Likewise, rumen UDP
was similar for all grazing systems and ranged from 13.51 to 18.28%. Rumen UDP
values were not adjusted for microbial attachment to the residue, and thus, values may
be overestimated. According to Anderson et al. (1988), rumen UDP may be limiting in
lush pastures and therefore needs to be supplemented. Anderson et a1. (1988)

demonstrated a linear increase in daily gain with the addition of .11 to .34 kg steer" d'1

64

of corn gluten and blood meal mixture to crossbred steers grazing smooth bromegrass.
Rumen UDP of the smooth bromegrass ranged from 9.2 to 13.1% of the nitrogen.

Following the 103-d grazing season in 1989, the steers were placed into a feedlot
for 222 d. Steers that entered the feedlot with the heaviest weights (4-L and 13-L), were
heavier (P=.001) after 56 d (d 159) and there was a numerical advantage for low SR
steers to have greater live—weights than high SR steers at the end of the 222 d (d 325.
Table 3.5). Steers had similar ADG throughout the feedlot period, although there was
a trend for 4-H and 13-H steers to have greater ADG than 4-L and l3-L steers. This
trend may suggest these steers were exhibiting some compensatory gain. Dry matter
intakes of 4-H and 13-H steers during the first 56 d were 14% lower (P=.02) than 4-L
and l3-L steers resulting in a 22% increase in feed efficiency. Waggoner et al. (1988)
demonstrated compensalory gain in steers placed in the feedlot following summer
pasture. Daily gains were 100% greater during the first 28 d as compared with the
second 28-d period. Waggoner et al. (1988) did not see a consistent difference in ADG
of steers from continuous or rotationally-stocked pastures at moderate (.41 steer/ha) or
high (.55 steers/ha) SR. When ADG was expressed over the entire 325-d study, 4-L and
13-L had 13% greater (P: .04) ADG than 4-H and 13~H steers. Most of the advantage
was achieved during the pasture phase when ADG of 4-L and 13-L were 258% greater
(P=.002) than 4-H and 13-H (Table 3.3).

Dry matter intake tended to be depressed 6% (P=.09) in 4-H and 13-H steers
during the last 167 d of the feedlot phase and were 8% lower (P: .005) over the entire
222-d feeding period. Steers from the 4-paddock GM (4-L and 4-H) tended to have

greater (P= .08) intakes during the last 167 d and over the entire 222 d (P=.01) than

65

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66

13-L and 13-H steers. The cause of the increased intake is unclear. Feed efficiency was
similar for steers during the last 167 d of feeding. but over the entire 222 d, 4-H and 13-
H steers tended to have 7% better (P= .08) feed efficiency than 4-L and 13-L steers.
At slaughter, 4-L and l3-L steers had heavier (P=.002) hot carcass weights but
similar dressing percentages and yield grades as 4—H and 13-H steers (Table 3.6). 'The
proportion of carcasses that graded choice for 13-H was 20% lower (P< .05) than 4-L.
4-H or 13-L carcasses. Although the difference cannot be explained, the 13-H steers had
the lowest carcass weight, dressing percent and yield grade which would suggest lower

carcass fat.

Year 2: 1990

In year 2, steers were placed on a standard alfalfa haylage diet before and after
grazing alfalfa pasture to equalize gut fill and accurately report changes in steer weight.
Therefore, steer weight and ADG were based on weights determined following a week
on the standard haylage diet. As in year 1, SR had a strong influence on final steer
weight and ADG. The 4-H and 13~H steers had 12% lower (P= .003) weight than 4-1.’
and 13-L steers on d 115 (Table 3.7).

Steers had similar ADG during the first 25 d, but during d 26 to 115, 4-L and 13-L
steers had greater (P= .003) ADG than 4-H and 13-H steers. In addition, 13-L and 13-H
steers tended to have greater (P=.07) ADG than 4-L and 4-H steers during the same
period. Over the entire 115—d period. 4-H and 13-H steers had 38% lower (P=.002)

ADG than 4-L and 13-L steers.

67

.8sz .5 622w 5:25 8.2.0.
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68

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69

Utilizing the reduced SR throughout year 2 reduced the over-stocking of the 4-H
and 13-H plots and increased the number of days those steers remained on their assigned
plots. Although weather conditions were more favorable in year 2, damage to pasture
stands in the second block of plots still necessitated the need for supplemental pastures.
The 4-H steers spent fewer (P < .05) days on pasture than the 4-L, 13-L and 13-H steers
which were 86.3, 106.5, 108 and 100.8 d, respectively.

With the increased ADG and days on pasture as compared to year 1, live-weight
gains per hectare were improved. The 13-H steers produced 653 kg/ha followed by 13-
L, 4-L and 4-H with 557, 508 and 496 kg/ha, respectively. The 13—H steer live-weight
gain tended to be greater (P< .10) than 4-L and 4-H steer live-weight gain. In addition,
live-weight gain of 13-L steers tended to be greater (P< .10) than 4-H.

Forage presented (Table 3.8) increased in year 2 as compared numerically with
year 1 and may have contributed to the increase in steer production. The 4-H and 123-H
plots produced 21% less (P=.O4) forage than 4-L and 13-L. There was also a trend
toward decreased (P: .14) canopy heights of 4-H and 13-H plots as seen in year 1. As
in year 1, there was a slight trend (P= .21) for 4-H and 13-H forage to have greater CP
content than 4-L and 115-1. pastures. In vitro organic matter digestibility followed a
similar trend as observed with CP. Forage from 4-H and 13-H plots had 6% greater
(P= .02) IVOMD than 4-L and 13-L forage samples.

Based on composition of esophageal extrusa and clipped forage samples, steers did
not select forage of higher CP. This observation is not in agreement with year 1,
although extrusa samples were numerically higher in IVOMD content than the clipped

forage samples. As seen with clipped forage samples, extrusa samples from steers

70

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S. 8. 8. 8. 8.8 2.... 8.8 8.2 a... 5202

8. N... n... 2.: 8.8 8.2 2.: 8.8 a: .522. 8:...

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71

grazing 4-H and 13-H plots contained a higher proportion (P=.03) of IVOMD than
samples from 4-L and 13-1. plots. There were no differences in rumen DMD or UDP
between the grazing systems. Rumen DMD was numerically greater in year 2 than year
1 and rumen UDP was less than year 1. Rumen UDP in year 2 was from 10.64 to
12.43% and was within the range of UDP which showed a benefit to escape protein
supplementation (Anderson et al., 1988).

The heaviest steers entering the feedlot were also the heaviest at the end of the
feedlot period (Table 3.9). In year 1 there was only a numerical difference in steer
weight between SR at the end of the feedlot period, but in year 2, 4-L and 13-L steers
were heavier (P= .004) at the end of the 227-d feedlot period than 4-H and 13-H steers.
Although steer weight showed similar trends as in year 1, compensatory gain was not
evident in year 2. All steers had similar ADG throughout the feeding period. The 4-L
and 13-L steers had 18% greater (P= .003) ADG over the entire 342-d study than 4-H
and 13-H steers. This observation is in agreement with the analysis reported in year 1.
Again, the advantage in ADG was attained during the pasture phase when 4-L and 13-L
steers had 62% greater (P= .002) ADG than 4-H and l3-H steers.

Dry matter intake was similar for all steers during the first 48 d (d 115 to 163) of
the feeding program; but during the last 179 d, 4-H and 13-H had lower DMI than 4-L
and 13-L steers. Over the entire 227—d feedlot period, steers from plots with low SR had
greater DMI (P=.005) than high SR; and steers from 4-paddock GM consumed more
than 13-paddock GM (P= .01). The difference in DMI is confounded with difference in

BW. When expressed as a percent of BW. 4-L steers consumed 1.7% and the 13-H

72

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73

steers 1.5% of BW. Feed efficiencies over the 227 d tended to be greater (P=.10) for
l3-paddock steers.

Steers from grazing systems in year 2 showed similar trends in carcass weight and
quality as those from year 1 (Table 3.10). Carcasses from 4-L and 13-L systems were
heavier (P=.002) and had higher (P=-.01) yield grades than 4-H and 13-H steers. In
year 1, dressing percentages were similar among grazing systems but in year 2, 4-L and
l 3-L steers had greater (P= .03) dressing percents than 4-H and 13-H steers. The l3-H
steers had a lower percentage of choice carcasses than the three other grazing systems.

Again, this may be due to the lower slaughter weights and decreased dressing percent

and yield grade.

Year 3 and 4: 1991 and 1992

Years 3 and 4 are unique from the previous years because the high SR was reduced
by 25%, from 10.5 to 7.9 steers/ha. The premise that individual animal performance
decreases with increasing SR was discussed earlier, therefore, when SR was decreased,
individual animal performance should improve. In fact, ADG was increased for the 7.9
Steers/ha in years 3 and 4 compared with 10.5 steers/ha in year 2 by 35.6% (.80 versus
- S9 kg/d, Table 3.11). Whereas the high SR reduced the off-pasture weight by 14 and
1 2% in year 1 and 2, the reduction in steer weight was only 5% less in years 3 and 4.

Average daily gain was similar for all grazing systems during the first 26 d, but
during the remainder of the grazing season, 4-H and 13-H steers tended to have 17%
lOwer (P= .09) ADG than 4-L and 13-L steers. This was also the case when ADG was

eValuated over the entire 122-d grazing season.

74

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75

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76

Unlike the previous two years. cattle did not require supplemental pasture for part
of the grazing season. The increase in days on pasture and the increase in ADG of the
4-H and 13-H steers increased the live-weight gain/ha. The live-weight gains/ha of the
4-H and 13-H plots were 24% greater (P=.008) than gains from 4-L and 13-L plots.
It would appear, based on the improved live-weight gain/ha that the optimum SR is
between 5.3 and 7.9 steers/ha. Forage presentation increased numerically in 1991 to
11270 kg/ha up from 5726 and 7601 kg in 1989 and 1990, respectively. This suggests
that an alfalfa pasture stand increases yields through the third year of production. This
was not the case in Northwest Saskatchewan where the productivity of smooth
bromegrass-alfalfa and intermediate wheatgrass-alfalfa pastures declined with successive
years (1955 to 1961, Cooke et al., 1965).

When the steers were placed in the feedlot, 4-L and 13-L steers had greater
(P=.O6) live-weights after 64 (1 than 4-H and 13-H steers. This trend in steer live-
weight was observed in years 1 and 2 as well. By slaughter, all steers had similar BW
(Table 3.12). Average daily gains were similar for the first 64 d, but steers from the
13-paddock GM tended to have greater (P=.O9) gains during the last 123 d. Over the
entire 187-d feedlot period, all steers had similar ADG. During the first 2 years, 4-L
and 13-L steers had greater ADG over the entire study, whereas, all steers had similar
ADG over the 309-d study in year 3 and 4. The primary reason was the reduction in
high SR which decreased the difference in ADG between the low and high SR while on

pasture.

77

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78

Dry matter intake over the first 64 d in the feedlot was similar for all steers but
there was a tendency for 4-H and 13-H steers to have greater (P= .10) intake during the
last 123 d and over the entire feeding period (P=.11) as compared to 4-L and 13-L
steers. This was an opposite response to that observed in the first two years where
intake was closely associated with body weight. Although DMI tended to be different
between SR, feed efficiency was similar for all steers throughout the feeding period.

Hot carcass weight, dressing percentage and proportion of choice quality grade
were similar for all steers (Table 3.13). The 13-H steers had lower quality grades than
cattle from the other grazing systems over the four-year study. The reason for this is
unclear as stated previously, but in previous years, may have been associated with
decreased carcass weights, dressing percents and yield grades. In this case, 13—H steers
did not have the lowest carcass weight or dressing percent but still graded below the

other groups.

Mechanical Harvest

In 1989, forage presentation from-13-L was 132% greater (P<.05) than MH
(Table 3.14). The other grazing systems had forage presentations which were
numerically 53 to 116% greater than MH. The reason for the large difference in forage
presentation may be due to the poor harvesting schedule and weather in 1989. The first
cutting was made at the appropriate time, but the haylage remained in the field for nearly
two weeks before removal. During this time, the cut alfalfa was rained on numerous
times. Most harvesting schedules for alfalfa recommend 3 to 4 harvests per season

(Sheaffer et al., 1988) as compared to the 2 harvest scheme used in this study.

79

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80

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81

Forage presentation in 1990 was similar among the grazing systems and MH plots.
Favorable weather allowed the timely harvest of the MH plots preventing the loss of DM
seen in the previous year from leaching.

One noticeable difference in 1991 is while the forage presentation of the grazing
systems increased, the forage presentation of MH did not. In addition, forage
presentation of the grazings systems were 66 to 78% greater (P< .01) than MH. This
may be due to the way the MH plots were harvested. In 1991, the MH plots were
harvested as round bale hay instead of haylage. Harvesting alfalfa at a lower moisture
content increases the amount of field loss, primarily from leaf shatter (Baylor, 1991;
Harrison and Fransen, 1991).

Over the three years in which forage presentation was determined, forage
presentation of 4-L, 4-II, 13-L and l3-H was 27 to 53% greater (P< .05) than MH.
Some caution must be used when interpreting these numbers because there was a
significant year x treatment interaction, possibly as a result of the weather or harvesting

method.

Botanical composition

Essentially, the botanical composition of the pastures when first grazed in 1989
were 80 to 90% alfalfa with plant densities at 97 i 4.2 alfalfa plants per .25 m2. In
the spring of 1991, alfalfa constituted 24 to 33% of the forage DM in each pasture
(Table 3.15a). There were no differences in botanical composition between the grazing

systems in 1991 or 1992. In 1992, the percentage of DM from alfalfa increased to 34

82

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83

to 41% of the pasture DM. The reason for the increase is unclear, unless, weather
influenced the growth rate of the alfalfa or weeds differently in the respective years.
The grazing system plots had similar alfalfa composition as the MH plots in 1991
and 1992 (Table 3.15.b). The percentages of alfalfa DM in MH plots were numerically
50 and 21% greater than the grazing systems in 1991 and 1992, respectively. As seen
i 11 Table 3.14, the total forage presentation did not decrease with the loss of alfalfa, but

was offset by the addition of grasses and weeds.

Ingestive behavior

Steers grazed an average of 9.8 h/d (Table 3.16). This is in agreement with
Studies by Forbes and Hodgson (1985) and Walker and Heitschmidt (1989) which
Observed grazing times for cows from 9.5 to 10.9 h. Lofgreen et al. (1957) observed
Steers grazing considerably less time ranging between 5.6 to 7.9 h. Steers from 13-L and
1 3-H systems grazed 14% longer (P=.0009) than 4-L and 4-II steers. This could
eXplain, the numerical improvement in ADG and gain/ha seen in 13-L and l3-H as
c()mpared with 4-L and 4-H grazing systems. Steers from the 13-paddock GM ruminated
32% longer (P=.012), but spent 39% less (P=.OOO6) time inactive. Steers were
Observed to ruminate 1.5 to 2.2 h; this is lower than 4 to 7.8 h determined by Lofgreen
et al. (1957) and Welch and Hooper (1988). Ruckebusch (1988) states that 2/3 of the
t‘urnination occurs at night. Since ingestive behavior was not measure at night, this may
eXplain why the rumination times the author observed were lower.

Stocking rate affected time spent consuming water and mineral. The 4-H and l3-I-I

Sveers drank and consumed mineral 75 % longer (P= .06) than 4-L and 13-L steers. One

84

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86

explanation for the phenomenon is that alfalfa is a natrophobic specie. Natrophobic
species preferentially accumulate sodium in the roots rather than in the leaves and stem
(Douglas, 1986). Therefore, alfalfa is unlikely to contain adequate sodium for livestock.
Joyce and Brunswick (1975a,b) demonstrated that sodium supplementation of beef cattle
grazing alfalfa increased live-weight and carcass weight 16 to 48% and 22 to 30% faster
than non-supplemented animals. Because 4-H and 13-H steers presumably had less

alfalfa intake, increased mineral intake would be required.

Four year summary

A four-year summary of the grazing study is presented in Table 3.17. Over the 4-
y ear study, ADG on pasture of 4-L and 13-L steers were 49% greater (P=.0001) than
4—-H and 1311. Increasing SR decreased ADG in a similar manner as demonstrated by
Joyce and Brunswick (1977) and Marsh and Brunswick (1978, Table 2.2) in New
Zealand. Maximum production per hectare from rotationally stocked alfalfa was
achieved with 7.7 and 6.7 steers/ha by Joyce and Brunswick (1977) and Marsh and
Brunswick (1978), respectively. These SR would be in agreement with the findings of
the present study in which maximum gains per hectare were produced with SR of 5.3 to
7 - 9 steers/ha. The per hectare gains of the New Zealand studies were 923 and 886 kg.
The production from New Zealand is greater due to the longer grazing seasons used by
J che and Brunswick (1977) and Marsh and Brunswick (1978), which were 130 and 179
(1. respectively.

In 1989 and 1990, steers did not remain on the experimental plots during the entire

grazing season. With improved weather and a decrease in the high SR in 1991 and

87

 

 

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89

l 992, availability of forage permitted grazing on the experimental plots during the entire
grazing season. The 4-L and l3-L steers spent 4% more (P< .01) days on pasture than
13-H and 11% (P<.Ol) more than 4-H; and 13-H spent 7% more (P< .01) days on
pasture than 4-H.

The 13-H system was the most productive system, in terms of beef gain per hectare
(averaging 568 kg/ha), three out of four years. Stocking rate nor GM influenced gain/ha
when analyzing the 4-year average. Because SR varied over the 4 years, differences in
the high SR masked the differences seen in individual years. With respect to GM, the
1 3-paddock GM had greater gain/ha, numerically, as compared to its 4-paddock GM
counterpart in every year except in 1989 when 4—H was greater than l3—H. This may
Su ggest that at high SR, there would be an advantage to the 13-paddock GM. At the low

SR, the 13-paddock systems consistently had numerically greater ADG and live-weight
gains/ha and forage presented.

Previous alfalfa grazing studies reported beef production/ha from 317 to 828 kg
(Table 2.3) which is similar to the present study, but the 1120 to 2017 kg beef gain per
hectare suggested by a Great Plains States extension bulletin (Corah and Bartley) would
be difficult to achieve in Michigan with a 100 to 120 d grazing season.

As stated previously, forage presented increased with each year of the study. In

1 989 and 1990, 4-L and 13-L had greater forage presentation than 4-H and 13—H, but
fOrage presented was similar in 1991. The 3-year average demonstrated that SR did
itl'lpact forage presentation by decreasing it 13% (P= .004) when comparing the high to

the low SR.

90

A four year summary of the feedlot phase and carcass characteristics are present
in Table 3.18. Grazing method did not impact final slaughter weight, ADG during the
feedlot phase or over the entire study. In addition, DMI, feed efficiency, HCW, DP,
and the number of carcasses grading choice were similar between the GM. As stated
previously, caution must be used to interpret the results because SR change three times
throughout the four-year study. Stocking rate did decrease (P< .0001) slaughter weight
5% but had no affect on ADG during the feedlot phase. Over the entire study steers for
high SR plots had 8% lower (P < .0001) ADG than low SR steers. Dry matter intake and
feed efficiency were similar for all systems. Hot carcass weight was 7% greater
(P< .05) for 13-L than 4-L, 4-H, and 13-H, but DP were similar. Throughout all four
year, 13-L had a greater (P< .05) number of steers achieving the choice quality grade

than 13-H steers.

IMPLICATIONS

Increasing paddock number from 4 to ‘13 did not improve ADG or live-weight
gain/ha; therefore the additional expense of 13 paddocks was not warranted. Optimal
stocking rate for this alfalfa pasture was 5.3 to 7.9 steers/ha. Supplementation of a
rumen undegradable protein may be necessary to increase gains due to the high rumen
digestibility of protein in alfalfa.

Forage presentation of alfalfa pastures increased into the third year after
establishment, although the low yields during the establishment year may suggest

mechanical harvest for hay or silage is preferred. Although, over the 3 years which

91

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92

forage presentation was determined. grazing systems had greater forage presentation than
the mechanical harvest system.

Compensatory gain was not consistently observed in steers entering the feedlot off
alfalfa pasture. If steer ADG on pasture was suppressed below .59 kg/d as a result of
increasing the stocking rate, these steers would not reach comparable slaughter weights

after 226 days on feed as steers gaining 1 kg/d on pasture.

CHAPTER 4: EVALUATION OF A SLOW-RELEASE CHROMIUM
BOLUS, PREDICTION OF INTAKE OF HOLSTEIN STEERS
GRAZING ALF ALF A AND ESTIMATION OF THE ENERGY

VALUE OF ALF ALFA

SUMMARY

A study was conducted to determine the intake of Holstein steers grazing alfalfa
pasture and estimate the net energy of the grazed alfalfa. Twelve steers (262 :1: 5.9 kg)
were randomly assigned to two grazing methods, 4 or 13 paddocks (6 steers/method),
and one of three grazing times; 6, 10 or 24 h (2 steers/time period). Steers grazed an
alfalfa pasture from May 20 till August 25. Occupation periods were 12 and 3 d for the
4 and 13 paddocks grazing methods, respectively, resulting in a 36-d rest period. Initial
weights were measured as the average of two weights taken on consecutive days and
intermediate weights determined every 12 d. Pasture DM, OM, CP, IVDMD, and
IVOMD were determined from a composite of 3 quadrants ( .5 x .5 m) collected each
time steers moved to the next paddock. Fecal DM and OM output were determined by
total collection and Cr-marker dilution over a 3 or 4 d-period. Intake (DM and OM) was
determined from fecal output and forage digestibility. From ADG and intake estimates,
a regression equation was developed. From the regression equations, alfalfa NE"1 was
predicted from intake when ADG = O kg/d and the estimated NE", requirement (NRC,

1984) of the animal. Likewise, alfalfa NE; was calculated from intake at various ADG

93

94
and the corresponding NE, (NRC, 1984) required to attain that ADG. Fecal DM and

OM output estimates by Cr-marker were 39 and 38% greater (P< .001), respectively.
than total collection. Daily intakes were 3.84 :1; .40 kg OM and 4.28 j; .45 kg DM.
Based on regression equations, alfalfa NE", ranged from 1.18 to 1.56 Meal/kg and NEg
from .85 to 1.15 Meal/kg. Based on this study, NRC (1984) underestimates the net

energy value of grazed alfalfa.

INTRODUCTION

A major concern in grazing research and forage evaluation is the inability to
measure intake of grazing animals. Prediction of intake is critical in determining SR and
consequently, animal performance. Would cattle consume similar amounts of forage
whether grazing or as soilage? Lofgreen et al. (1956) demonstrated that steers
consuming alfalfa soilage had intakes which were 22 to 43 % greater than steers grazing
alfalfa pasture (5.9 versus 4.1 to 4.8 kg). Average daily gain (.74 kg), alfalfa
digestibility (59%) and TDN (57%) were similar. Lofgreen et al. (1956) concluded that
utilization of TDN was greater in grazing steers and suggested that the pasture had a
higher net energy value than soilage. Presumably, the higher energy value of grazed
forage resulted from selective grazing.

Lofgreen et al. (1956) used pre- and post-grazing clippings and total fecal
collections with chromogen analysis to determine intake of grazing steers. The difference
technique overestimates intake due to sampling error (Lofgreen et al., 1956), and
chromogen was not quantitatively recovered (Cochran et al., 1987). Total fecal

collections can be accomplished but may change grazing behavior (Le Du and Penning,

95

1982). Momont et al. (1990) found a good correlation between total fecal collection and
fecal output predicted from a slow release Cr-bolus.

Recognizing the need to measure and predict forage intake, the objectives for this
study were to evaluate the use of a slow release Cr-bolus, predict intake of steers grazing

alfalfa and to calculate a net energy value foralfalfa pasture.

MATERIAL AND METHODS

Pasture and animal management

This experiment was conducted in conjunction with year 1 (1989) of the study to
determine the effect of GM and SR on animal and plant productivity (Chapter 3). In
addition, this study was completed under the approval of the Michigan State University
All-University Committee on Animal Use and Care (AUF# 8/88-321-01). Twenty-four
Holstein steers were received in April, weighed, ear tagged, dehomed, vaccinated against
IBR, P13, and treated for parasites with ivermectin (MSDAGVET, Rahway, NJ). Steers
were placed on a corn silage-hay diet upon arrival until May 11. On May 11, steers
were offered an alfalfa haylage diet supplemented with a poloxalene-mineral mix (Table
3.1) till May 20. Initial weights (250 kg) were determined on May 17 and 19. On May
19, steers were implanted with estradiol 17-6 (ELANCO, Indianapolis, IN), tagged with
a fly repellant ear tag (Coopers Animal Health Inc. Kansas City, KS), and randomly
assigned to two GM. On May 20, steers were fed alfalfa haylage and poloxalene-mineral
mix in the morning and were transported .8 km to the pasture site at 1400. Each group

of 12 steers were placed into a .76 ha plot divided into 4 (Plot 11, 4-H) or 13 (Plot 12,

96

13-H) paddocks (Figure 2.1, 2.2). Stocking rates were 15.8 steers/ha and corresponded
to the high SR of the grazing system study.

The alfalfa (variety Big Ten) was seeded in 1987. The pastures were managed as
described in Chapter 3. Occupation periods were 8 and 2 d for the first grazing cycle
and 12 and 3 d for the second and third cycle for the 4 (4-H) and 13 (13-H) paddock
GM, respectively.

As with the grazing system study, after 24 d of grazing, it was realized that the
pastures were overstocked. Also, photosensitivity was observed during this period as
was the case in the grazing system study. Therefore, 6 steers exhibiting photosensitivity
and 2 additional steers were removed from pasture on June 16 (d 27), reducing the SR
to 10.5 steers/ha. Steers in plot 11 (4-H) grazed from May 20 to June 25 (d 36)
completing 1 grazing cycle. Plot 12 (13-H) steers grazed from May 20 to June 16. In
both cases when steers were removed from their assigned experimental plots, the steers
were placed on supplemental alfalfa pasture.

On June 26, the 16'remaining steers were given free access to alfalfa hay (2.3 kg
DM/steer) and water until 1600. The next day, following a 16 h shrink, steers were
weighed. To decrease possibility of bloat, steers were fed alfalfa hay (2.3 kg DM/steer)
and placed into their assigned experimental plots. Two steers in each plot were replaced
by animals with esophageal and duodenal cannulas. This was done because protein flow
to the small intestine was to be measured. Due to complications with the duodenal
cannulas, this could not be completed.

The six non-cannulated steers in each plot were randomly assigned to one of three

grazing time allotments (2 steers/time). Grazing time allotments were varied to produce

97

differences in pasture intake and subsequent ADG. The grazing times were 6, 10 and
24 h. Steers grazing 10 h were placed on pasture at 0800 and the 6 h steers at 1200.
Both the 6 and 10 h grazers were removed from pasture at 1800 and placed in a
vegetation-free pen with ad libitum access to water and poloxalene-mineral mix. This
regime continued for the remainder of the grazing season (Aug. 25, d 97). Steers were

weighed every 12 d coinciding with the movement of the 4-paddock GM.

Forage sample collection and analysis

Forage samples from each paddock were randomly collected from three quadrants
(.5 x .5 m) prior to steer entry. At the same time, extended canopy heights were
determined from four random sites within the paddock. Forage samples from each
quadrant were composited and split into two subsamples. Both subsamples were
weighed. One subsample was frozen for CP analysis, the other dried at 55°C for 48 h
(AOAC, 1984) to determine forage DM and pasture yield. The dried sample was ground
through a 1 mm screen of a Wiley mill. In duplicate, l g of each ground sample was
placed in at 500°C muffle furnace for 12 h to determine ash content and OM (100 -
%Ash). In triplicate, 1 g of the ground sample, was used to determine IVDMD and
IVOMD utilizing the Tilley and Terry (1963) procedure with urea (.5 g/L) added to 1
part strained ruminal fluidzl part McDougall’s Buffer (McDougall, 1948) and a 24-h
acid-pepsin digestion phase (Mader and Horn (1986). Residual DM was collected in a
Buchner funnel fitted with a pre-weighed, oven-dried Whatrnan No. 541 filter paper.
The residual DM and filter paper were placed in a pre-weighed 50 ml beaker and dried

12 h in a 60°C oven. The beaker, containing the filter paper and residual DM, was

98

weighed and then placed in a 500°C muffle furnace for 12 h to determine residual ash
content.

The frozen sample was thawed at 4°C overnight, chopped with a Hobart chopper
and assayed for total nitrogen (CP = N x 6.25) by the Kjeldahl procedure using a

Technicon auto-analyzer system (AOAC, 1984).

Total fecal collection

A ruminal Cr203 bolus (Quad Five, Ryegate, MT) was given to each steer on July
22 (d 63, Figure 4.1). Chromium release was allowed to equilibrate for 7 d before total
fecal collection began. The average Cr203 release rate was 1641 mg/d (1116 mg Cr/d)
as determined by CSIRO Chiswich Research Station, Armidale, NSW, Australia. Fecal
collection bags (Cheyenne Awning Co., Cheyenne, WY) were placed on 6 animals in
each paddock on July 29 (d 70) at 0800. Accumulated feces were removed at 24 h
intervals for 3 d (July 30 to August 1). The collected feces were weighed each day and
a 500 g sample frozen. A second fecal collection period of 4 d was performed from
August 7 (d 79) to August 11 (d 83). Each fecal collection was made within a separate

12-d weigh period.

Fecal output and intake prediction

Fecal samples were allowed to thaw overnight at 4°C. Samples were analyzed for
total N by the Kjeldahl procedure using a Technicon auto-analyzer system (AOAC, 1984)
and converted to CP values. Fecal DM content was determined by placing a 250 g

sample in a weighed aluminum pan and dried at 55°C for 48 h (AOAC, 1984). Dried

99

bolus
administered

fecal collection periods

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IllllLlIlllIJJIllillIIlIII

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13-H 13-H 13-H
steers steers steers
weighed weighed weighed

Figure 4.1. Total fecal collection schedule. Days of study are given below time line.
Collection periods are represented as boxes above the time line. Rotation of paddocks
is indicated by treatment abbreviation below the time line.

samples were ground through a 1 mm screen of a Wiley mill and analyzed for OM
(AOAC, 1984). Chromium content was determined by wet-ash digestion of the sample
(Analytical Methods Committee, 1960) and subsequent analysis by atomic emission
spectrophotometry.

Fecal output was determined in two ways. First, total fecal collections were
averaged within a period, then across periods to determine an average daily DM and OM
fecal output for each animal. Second, the Cr content of the feces was used to estimate
DM and OM fecal output utilizing the following equation (Le Du and Penning, 1982):

Daily feces produced (g/d) = Weight of marker given (g/d) x Marker recovery (%)
Mean concentration of the marker in feces (g/g)

100

The weight of the marker given (Cr-bolus release rate) was 1.116 g/d, as determined by
the manufacturer. Marker recovery was assumed to be 100%, following the
characteristics of an ideal marker (Le Du and Penning 1982).

Intake was determined from daily fecal output and forage digestibility with the
following equation (Le Du and Penning, 1982):
Intake (kg) = Fecal output (kg)

1 - digestibility

Both IVDMD and IVOMD were used to estimate DM and OM intake, respectively.
Digestibility of alfalfa taken during each fecal collection period was used to predict
intake. Intake predicted from digestibility of esophageal extrusa samples gives a more
accurate prediction than digestibility from clipped samples (Greenhalgh, 1982).
Digestibility of DM and OM from the esophageal extrusa samples from the 4-H and 13-H
systems in the grazing system study (Chapter 3) were 15% greater than clipped samples
in that study (Table 3.4). Dry matter and OM intake were determined from the
following four procedures: 1) total fecal collection and forage digestibility (TC-D); 2)
total fecal collection and forage digestibility increased 15% to simulate esophageal
extrusa samples (TC-15D); 3) Cr predicted fecal output and forage digestibility (CR-D);

and 4) Cr predicted fecal output and forage digestibility increased 15% (CR-15D).

Development of regression equations and net energy values
Average daily gains, over the two 12-d weigh periods when fecal collections were

made, were regressed and correlated to fecal CP and intake. The GM were pooled to

101

provide 12 observations for each analysis. The regression and correlation procedures of
SAS ( 1987) were used. From the equations generated, the NEm and NEg of the alfalfa
could be estimated.

To determine N Em of alfalfa from the regression equations, the intake at y (ADG)
= 0 was calculated. Steers averaged 262 i 5.9 kg during the collection period would
require 5.01 Mcal/d NE", (NEm = .077BW'75; NRC, 1984). Net energy for maintenance
(Meal/kg) of alfalfa was then estimated by dividing NE", required (5.01 Meal/d) by
intake (kg/d).

Intakes at ADG of .25, .50, .75, and 1.00 kg/d were determined from the
regression equations. Net energy for gain of large-frame steer calves required to achieve
the live-weight gains (LWG) selected were .70, 1.50, 2.34, and 3.21 Meal/d (NE: =
.049BBW'7’(LWG)‘ 097; NRC, 1984). Intake determined for maintenance was subtracted
from the intake calculated for each rate of gain. The N E, (Meal/d) required for each rate
of gain was divided by the remaining intake (kg/d) to estimate the NE‘ (Meal/kg) of

alfalfa.

Statistical analysis

Steer ADG, fecal components (DM, OM, CP), fecal output and intake were
analyzed as a 2 x 3 factorial experiment utilizing the General Linear Model of SAS
(1987). The model consisted of GM (4 or 13 paddocks), grazing time allotments (6, 10,
or 24 h) and the interaction. The animal was used as the experimental unit. Mean
separation for grazing time utilized orthogonal polynomial contrasts to determine a linear

or quadratic response (Gill, 1987a). Coefficients used in the contrast correspond to

102
unequally spaced levels of 0, 2, 9 (Gill, 1987b). If a significant (P< .10) time x GM

interaction was present, means were separated using a Bonferroni t-test and significant
differences were indicated with superscripts.

Differences between total fecal collections and predicted fecal output were
analyzed using a pair-wise t-test of the Means procedure of SAS (1987). The average
value over both collection periods was used in the analysis with the animal as the

experimental unit.

RESULTS AND DISCUSSION

Forage production and nutritive quality

A summary of forage presentation, canopy height, and forage CP, IVDMD, and
IVOMD is presented in Table 4.1. Forage presentation from the intake pastures (plots
11 and 12) had numerically greater production than the corresponding plots (4-H and 13-
H) of the grazing system study (5041 and 5848 versus 4564 and 5476 kg/ha). This may
be explained by the age of the stand as this was the second harvest year as compared to
the first harvest year in the grazing systemsstudy. Canopy heights were also greater for I
plots 11 and 12 as compared to 4-H and 13-H (41.2 and 46.3 versus 34.3 and 35.0 cm).
Forage CP content and digestibility were similar between plots 11 and 12 and 4-H and

l3-H of the companion grazing system study.

Steer performance and fecal output
Prior to steers being assigned to grazing time allotments (d 0 to 37), steers in the

13-H system had greater (P= .002) ADG than 4-H steers (Table 4.2). The reason for

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104

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105

this difference is not apparent since there were no differences during this same period
between the 4 and 13 paddock GM of the companion. The 13-H plot had accumulated
approximately 300 kg more forage presentation at this point which could explain the
discrepancy. '

After grazing time allotments were initiated, steer ADG was similar among
allotments and GM, but drastically lower than the previous period. An increase in ADG
would be expected with increased grazing time. This was not observed, and the reverse
was true for the 13-H plot. During the period (d 70 to 73 and 79 to 83) when fecal
collections were made, there was a trend (P=.20) of increased ADG as grazing time
increased.

All steers had similar fecal DM, OM and CP content (Table 4.3). Likewise, there
were no differences in fecal. output among steers when determined with total collection
or predicted from Cr marker (Table 4.4). A trend (P= .12) for increased fecal DM and
OM output with increased grazing time was observed with total collections but not with

Cr-predicted fecal output.

Fecal output prediction procedures

Estimation of fecal output by Cr marker resulted in an increase (P< .001) of 39
and 38% for fecal DM and OM output, respectively, as compared to total fecal collection
(Figure 4.2). The difference was due to an over-prediction of Cr release rate. The
manufacturer’s rumen release rate was 1.116 g/d whereas the average amount of Cr
release determined from total collection and fecal Cr concentration was .85 g/d.

Brandyberry et al. (1991) also demonstrated a lower release rate than that reported by

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108

 

2.5
. SED=.08 *** seo=.07

2.0 - w .- -.
***

 

Fecal output, kg

 

 

 

 

 

 

 

 

DM output ' OM output

Figure 4.2. Effect of procedures for determining fecal output. Solid and open bars
represent total fecal collection and Cr—predicted fecal output, respectively. *** P < .001

109

the manufacturer (.876 g versus 1.123 g). In addition, Brandyberry et al. (1991) and
Buntinx et a1. (1992) determined the use of Cr203 bolus over-estimated fecal output,
although an earlier study by Momont et al. (1990) found a positive correlation between

actual and predicted output.

Predicted DM intake

Predicted DMI ranged from 2.96 kg for TC-D (Table 4.5) to 7.13 kg calculated
for the CR-lS procedure (Table 4.6). A similar range was observed for OMI. Grazing
allotment time tended to affect (P< .12) intake as measured by total fecal collection
(TC). The 24 h steers having the greatest intakes, 6 h intermediate and the 10 h steers
the lowest level of intake. Steers allotted to 10 h should have been able to consume their
daily energy and protein requirement. Visual observation from the system study (Table
3.16) suggest steers actively graze 9 to 11 hours each day. The 13-H steers had 28 and
39% greater (P< .05) OMI (TC-D and TC-ISD) than 4-1-1 steers but DMI was similar.
This may be related to the greater forage presentation of the 13-H plots during the period
of fecal collections. Organic matter intake also factors out possible differences in
mineral consumption from the poloxalene-mineral mix.

There were significant time x GM interactions for each of the CR predicted
intakes. Dry matter intake (CR-D) of l3-H steers at 6, 10, and 24 h was 13% greater
(P< .05) than 4-H steers grazing 10 or 24 h. The l3-H steers had 27% greater (P< .05)
OMI (CR-D) than 4-H steers. When intake was based on CR-lSD, 13-H steers allowed

to graze 24 h had 22% greater DMI than 4-H steers grazing 10 h. Organic matter intake

110

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112

for CR-ISD followed similar trends as observed with CR-D predictions. the 13-H steers
had 36% greater (P< .05) OMI than 4-H steers.

One may notice when digestibility was increased 15%, intake also increased.
Common sense would suggest that if a forage is more digestible intake would be less.
The reason for the discrepancy is that the equation to determine intake is based on the

indigestibility of the forage. Therefore. as indigestibility decreases, intake will increase.

Regression equations

Fecal CP and DMI from the 12 steers were regressed against ADG over the 24-d
collection period. A study by McCollum (1990) demonstrated a positive correlation
between fecal N (OM basis) with N intake and ADG. Coefficients of determination (r3)
for McCollum’s (1990) study were .74 and .78 for N intake and ADG, respectively.
These values are considerably larger than the determined r2 in this study (r2 = .21, Table
4.7). In addition, the slope for the equation of fecal N versus ADG was greater in the
McCollum study (1.23 versus .24). The greater slope demonstrates a stronger
relationship of fecal N and ADG of steers grazing tallgrass prairie. This does not
suggest that increased fecal N can increase ADG, but that greater N intake may increase
fecal N. This may be explained by the differences in N content between the two types
of forage. The CP content of tallgrass prairie ranged from 9 to 14% as compared 16 to
19% for alfalfa.

The r2 for ADG regressed against intake ranged from .34 to .74. A smaller
percentage of the variation in ADG could be accounted for by DMI and OMI with the

total collection than CR-prediction methods. In all cases, DMI had lower r2 values than

113

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114

OMI intake. As stated previously, this may be a result of removing the variation of
mineral intake. Increasing forage digestibility by 15% to simulate esophageal extrusa
digestibility increased the r2 for intakes based on TC but not for CR—methods. Equations
with r2 greater than .5 are presented graphically in Figures 4.3 to 4.5.

Intakes predicted from regressions with r2 greater than .5 (OMI, TC-D; OMI, TC-
15D; DMI, CR-D; OMI, CR-D; DMI, CR-lSD; and OMI, CR-15D), are presented in
Table 4.8. For steers weighing 262 kg and gaining between .25 to 1.0 kg/d, NRC
(1984) would predict DMI between 6.21 to 7.07 kg/d and OM] (based on 90% OM)
from 5.59 to 6.36 kg/d. Dry matter intake based on CR-D are below estimated intakes
(NRC, 1984), but intakes determined from CR-15D is within the range. Organic matter
intakes determined in this study from TC-D, TC-15D and CR-D are within this range,

but OMI determined from CR—15D is considerably greater.

Net energy of alfalfa

Estimated NE", for alfalfa ranged from .84 to 1.56 Meal/kg OM and .77 to .99

Meal/kg DM depending on intake prediction procedure (Table 4.9). Values for NE",

from NRC (1984) for midbloom alfalfa are 1.24 (DM basis) and 1.36 (OM basis)
Meal/kg. The NRC values are considerably higher than those estimated from this study.
Miller et al. (1991) demonstrated a decrease of NEm with increasing maturity (1.48 to
1.33 Mcal/kg for early and late cut alfalfa, respectively). Net energy for maintenance
predicted from OMI(TC-D) and OMI(TC-ISD) provided the best fit to NRC (1984)

values (1.56 and 1.18 versus 1.36 Mcal/kg OM).

ll

115

 

 

 

 

 

 

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c? 0.5 * '
'5
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"D
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a. b
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y = .28x - 1.19
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Figure 4.3. Relationship between average daily gain and organic matter intake as
determined by total fecal collection and two OM digestibilities a) IVOMD, b) IVOMD
increased 15 %. Solid line is the regression equation based on 12 steers from two grazing
methods (4-H, open points and 13-H closed points) and three grazing time allotments (6
h, Ell; 10 hOC; and 24 h, 0‘).

116

 

P
u.

 

Average daily gain, kg

 

 

 

 

Dry matter intake, kg (CR-D)

 

P
u.

 

Average daily gain, kg
.5

 

 

 

 

Dry matter intake, kg (CR-15D)

Figure 4.4. Relationship between average daily gain and dry matter intake as determined
by CR-predicted fecal output and two DM digestibilities a) IVDMD, b) IVDMD
increased 15%. Solid line is the regression equation based on 12 steers from two grazing
methods (4-H, open points and 13-H closed points) and three grazing time allotments (6
h, Ell; 10 h 0.; and 24 h, Os).

117

-O.5

 

Average daily gain, kg

y = .58x - 2.59

1 ___k. _- - __._.-. _ _ ._ . _ _ “A _. ---_ ___-. _ _.__ -_ __ __z _-_-..

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Organic matter intake, kg (CR-D)

 

.9
Ln
0

 

-O.5

Average daily gain, kg

 

 

 

 

3 4 5 6 7 8 9
Organic matter intake, kg (CR-15D)

Figure 4.5. Relationship between average daily gain and organic matter intake as
determined by Cr-predicted fecal output and two OM digestibilities a) IVOMD, b)
IVOMD increased 15%. Solid line is the regression equation based on 12 steers from
two grazing methods (4-H, open points and 13-H closed points) and three grazing time
allotments (6 h, Ell; 10 h 0.; and 24 h, Cu).

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Greater variability was seen in the prediction of NEY. National Research Council
(1984) lists NE‘ for midbloom alfalfa as .68 and .74 Mcal/kg for DM and OM,
respectively. All values of NE‘ determined in this study are considerably greater than
the NRC values and those determined by Welch et al. (1969) for alfalfa hay and Miller
et al. (1991) for alfalfa cubes. Net energy for gain greater than 1.75 Mcal/kg would
appear unrealistic because these values would be greater than the NE: for corn (NRC,
1984). Welch et al. (1969) determined the NE‘ of alfalfa with 20% CF to be .88
Mcal/kg whereas Miller et al. (1991) reported values of .55 to .68 Mcal/kg. The
differences between Welch et al. (1969) and Miller et al. (1991) and the present study
are that the energy values calculated would suggest the energy value of pasture is greater
than harvested forage. This observation would agree with those of Lofgreen et al. (1956)
who saw similar gains in steers grazing alfalfa pasture or consuming soilage but the
grazing steers had 22 to 43% lower intakes. This, therefore led Lofgreen et al. (1956)
to conclude that the alfalfa pasture had a greater NE value than did the soilage.

Grass in early vegetative stage have greater NEm and NE: values than midbloom
alfalfa (Table 4.10). As grass infiltrates the alfalfa pasture, the net energy value of the
pasture could increase if the pasture is grazed when the grasses are at the early vegetative
stage. If grasses are grazed at the midbloom to mature stage, the average of the pasture

will be lower than a monoculture alfalfa pasture.

121

Table 4.10. Net energy values for common grasses and alfalfa (NRC, 1984)

—
Species and maturity NEm (Meal/kg)l NEgMcal/kg)

Bluegrass, kentucky

 

fresh, early vegetative 1.70 1.08
fresh, mature 1.18 .61

Brome, smooth

fresh, early vegetative 1.73 1.11
fresh, mature 1.07 .52
Orchardgrass

fresh, early vegetative 1.70 1.08
fresh, midbloom 1.21 .64
Alfalfa

fresh, late vegetative ‘ 1.41 .83
fresh, early bloom 1.31 .74
fresh, midbloom 1.24 .68
fresh, full bloom 1.14 .58

—
‘DM basis

1 22
IMPLICATIONS

The use of a slow-release Cr bolus must be used with caution because marker recovery
was below 100% and Cr—release rates were below that reported by the manufacturer
which resulted in increased fecal output estimates. Allotting animals to restricted grazing
times did alter intakes and daily gains. Intakes of alfalfa pasture averaged 3.84 kg OM
and 4.28 kg DM based on total fecal collections. Net energy for maintenance of alfalfa
was estimated to be 1.18 to 1.56 Mcal/kg OM and NEg at .85 to 1.15 Mcal/ kg OM.

Therefore, NRC (1984) underestimates the net energy value of grazed alfalfa.

CHAPTER 5: CHARACTERIZATION OF PHOTOSENSITIVITY
OF CATTLE GRAZING ALFALF A PASTURES

SUMMARY

A study was conducted to characterize photosensitivity in cattle grazing a
predominantly alfalfa pasture. N inety-six Holstein steers (242 kg) were placed on an
alfalfa pasture on May 20, 1989. Seventeen days after the initiation of the study, the
first steer showed signs of hair loss and skin lesions. Twenty-one steers experiencing
photosensitivity plus 11 non-affected steers were removed from the alfalfa pasture (d 24).
The steers were placed in a feedlot with partially covered pens, and fed a corn silage—
high moisture corn diet. A numerical scale was devised to separate steers into 4 groups
based on severity of hair loss and lesion formation. Two blood samples were drawn
from each steer 32 and 75 d following the beginning of the grazing study. The blood .
was used to determine the extent of liver damage by evaluating the concentration of two
liver enzymes, aspartate transaminase (AST) and sorbitol dehydrogenase (SDH). Steers
were weighed at the initiation of the grazing study and on d 24, 32, and 75. In 1990,
a microbial assay was used to determined the potential of primary photosensitivity of the
pasture. Fresh alfalfa samples, frozen alfalfa samples from 1989, grasses, and weeds
found in the pasture were evaluated. All steers had similar weights over the period of

the study. Serum AST values were within normal levels during the photosensitive (d 0

123

124

to 32) and recovery (d 33 to 75) periods. All steers had SDH levels 3.7 times greater
than normal during the photosensitive period (68.75 IU/L) and 2.7 times greater during
the recovery period (5105 IU/L). No plants were found to have the potential to produce
primary photosensitivity with the microbial assay used. Elevated SDH levels, an
indication of liver damage, and the lack of a primary photosensitizer, may indicate

hepatogenous photosensitivity had occurred.

INTRODUCTION

Photosensitivity is the sensitization of the superficial layers of lightly pigmented
skin to sunlight. Photosensitivity is categorized into four groups; primary, hepatogenous,
aberrant pigment metabolism and photosensitization of unknown origin (Clare, 1955;
Johnson, 1986; Scott, 1988). Primary photosensitization is due to the ingestion of a
photodynamic compound that enters the blood unchanged and causes a reaction in the
skin. Buckwheat (Polygonium fagopyrum) and St. John’s wort (Hypericum perforatum)
are plants that cause primary photosensitivity in livestock (Evans, 1987).

Hepatogenous photosensitivity is a secondary condition caused by liver damage
from an ingested hepatoxin (Cornelius et al., 1965) or a genetic defect that occurs in
sheep (Hancock, 1950). The liver damage or genetic defect decreases the ability of the
liver to excrete phylloerythrin, which is the endproduct of the anaerobic breakdown of
chlorophyll by microorganisms in the rumen and lower gastrointestinal (Clare, 1955;
Scott, 1988). The accumulated phylloerythrin spills over into the serum and produces
photosensitivity in peripheral tissues. Hepatogenous photosensitivity can be caused by

plants, mycotoxins, infections, neoplasia, or chemicals (Scott, 1988).

 

125

Aberrant pigment metabolism results in photosensitization due to accumulation of
porphyrins in the blood and body tissues due to aberrant porphyrin synthesis (Scott,
1988). Bovine congenital protoporphyria and bovine erythropoietic porphyria are
examples of aberrant pigment metabolism due to autosomal recessive traits (Ruth et al.,
1977).

Reports of photosensitivity often occur when common plants are grazed. These
include alfalfa (Medicago saliva), clovers (T nfolium spp.), vetches (Vicia spp.) and oats
(Avena sariva; Clare, 1955; Johnson, 1986; Scott, 1988), but the origin of the phototoxin
is unknown.

The objective of this study was to characterize the photosensitive condition that
developed unexpectedly in Holstein steers grazing alfalfa pastures, and characterize the

origin of the photodynamic agent.

MATERIALS AND METHODS

Background

In 1989, 72 (239 kg) steers were randomly allocated to eight alfalfa (variety
WL225) pasture plots (.76 ha) and four grazing systems. The systems consisted of a 4-
paddock or a 13-paddock rotational grazing methods with SR of 7.9 and 15.8 steers/ha
(Chapter 3). Twenty-four additional steers (250 kg) were on an alfalfa intake study
grazing an adjacent pasture seeded to alfalfa (variety Big Ten) in 1987 (Chapter 4).

The first steer showed signs of erythema, hair loss, and necrosis of the lightly
pigmented skin within 17 d (June 5) from the onset of grazing alfalfa (Figure 5.1). By

d 24 (June 12), 21 steers showed varying degrees of hair loss. Hair loss ranged from

 

126

 

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127

loss on the top line of the animal to extensive losses over the shoulder. Twenty-one
steers (14 from the grazing system study, 7 from the intake study) with signs of
sensitivity and 11 additional steers (10 from the grazing system study, 1 from the intake
study) with normal appearance of the hair and skin were removed from the pasture study

to allow the animals to recuperate.

Photosensitivity characterization

This study was conducted under approval from the Michigan State University All-
University Committee on Animal Use and Care (AUF# 8/88-321-01). A system based
on visual observation was devised to classify the severity of hair loss and skin damage
in the 32 steers removed from pasture. The four point scoring system ranged from 0 to
3 with a score of 0 representing nohair loss; 1) hair loss only on the top line; 2) hair
loss on top line and top of shoulder; and 3) considerable hair loss on top line and over
the shoulders.

Cattle were grouped and housed according to hair loss score in five pens with
concrete floors and partial cover (6.4 to 10.2 mz/steer). There were two pens of steers
with a hair loss score of 0 and one pen for each of the other hair loss groups. Steers had
ad libitum access to feed and water. The diet consisted of 64% corn silage, 30% high
moisture corn, and 6% protein-mineral supplement (DM basis). Steers were weighed at
the initiation of the grazing experiment (d 0) and 24 d later when steers were removed
from the pasture. Eight days (d 32) and 51 d (d 75) after removal from pasture, steers
were weighed and blood samples collected by jugular venipuncture. Serum samples were

analyzed to determine extent of liver damage by evaluation of serum aspartate

 

128

transaminase (AST) and sorbitol dehydrogenase (SDH) concentrations. Aspartate
transaminase and SDH are liver enzymes that become concentrated in the blood due to
liver damage. The serum was analyzed by Veterinary Clinical Pathology Laboratory at
Michigan State University which utilized enzyme kits to quantify serum AST (Electro-
nucleonics, Fairfield, NJ) and SDH (Sigma Chemical Co., St. Louis, MO).

Variations in response between steers with different hair loss scores were
determined with the General Linear Model subroutine of SAS (1987). Least square
means were calculated and a Dunnett’s test was used to compare cattle with hair loss

scores 0 to 3 (Gill, 1978a).

Microbial assay

During the summer of 1990, pasture and weed specimens (Table 5.1) were
collected to determine the potential for primary photosensitivity of the pasture. In
addition, the photosensitivity potential of two alfalfa samples from the period when

photosensitivity occurred'in 1989 were analyzed. A microbial assay developed by

Daniels (1965) as modified by Rowe et al. (1987) was used. The method developed by.

Daniels (1965) was used for the identification of plants or plant materials with
photosensitizing properties of the psoralen type. Rowe et al. (1987) used the procedure
by Daniels (1965) to identify Cooperia pedunculata as the photosensitizing agent of cattle
in southwest Texas.

Fresh and frozen plant samples were placed on Sabouraud dextrose agar inoculated

with a Candida albicans culture. The C. albicans culture was grown for 48 h in

I V

129

Table 5.1. Plant specimens used to determine primary phototoxic potential of
alfalfa pasture

 

Plant name Plant part Zone of Inhibition
Parsley (Petroselinum crispum) stem positive .
leaf positive
Alfalfa (Medicago sativa) stem negative
leaf negative
1989 Alfalfa sample If 1 leaf negative
1989 Alfalfa sample #2 leaf negative
Wild carrot (Daucus carota) leaf negative
Alsike clover (Trifolium hybridum) leaf negative
Red clover (Trifolium pratense) leaf negative
White clover (T nfolium repens) leaf negative
White cockle (Lychm's alba Mill) leaf negative
Curly dock (Rumex crispus) flower negative
leaf negative
Dandelion (Taraxacum officinale Weber) leaf negative
Lambsquarter (Chenopodium album L.) leaf negative
Orchardgrass (Dactylis glomerata) leaf negative
Pennsylvania smartweed flower negative
(Polygonum pensylvanicum L.) leaf . negative
Quackgrass (Agropyran repens L. Beauv) leaf negative

V

130

Sabouraud broth before the assay began. Penicillin and streptomycin were added to the
agar (100 mg/L) to inhibit bacterial growth.

Eight plant particles per specie; leaves, stems or flowers, were placed on duplicate
plates inoculated with the culture (4 particles/plate). One plate was placed under an 8
watt-longwave UV light (Fisher Scientific, Pittsburgh, PA) and the second plate was non-
irradiated and placed in a dark box. The UV light was placed 22 cm above the plates.
Parsley (Petroselinum crispum), a known primary photosensitizer (Daniels, 1965) was
used as a positive control.

Forty-eight hours after initial UV irradiation, plates were observed for zones of
inhibition around the plant particles. Irradiated plant particles exhibiting a zone of
inhibition greater than the non-irradiated particles were considered to contain a primary

phototoxin.

RESULTS AND DISCUSSION

Hair loss score groups 1.2, and 3 had similar (P> .05) weights on d 24, 32, and
75 as the control group (Table 5.2). Average‘daily gains were not different from d 0 to
32, but groups 1 and 2 had lower (P< .05) ADG during the recovery period than group
0. The normal range for AST and SDH is 45.3 to 110.2 and 6.1 to 18.4 IU/L (Fraser,
1986), respectively. Serum AST levels were within the normal range during the
photosensitive (d 0 to 32) and recovery (d 33 to 75) periods (Table 5.3), and all steers
had similar AST levels. Steers had SDH levels approximately 3.7 times greater than
normal values during the photosensitive period and 2.7 times greater during the recovery

period. Serum SDH levels were similar for each hair loss group during the

131

 

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133

photosensitive period and AST levels were similar during the photosensitive, but group
2 had higher (P<.01) SDH levels than control (0 hair loss score group) during the
recovery period. Why this difference existed is not apparent.

All pasture plant specimens were negative, exhibiting no zone of inhibition.
Parsley, a positive control, did show a zone of inhibition around the plant particles when
irradiated with UV light. It is possible that plants present in 1989 were not present in
1990 or environmental conditions that caused the malady were different.

Development of similar symptoms has been reported from Oklahoma (Glenn et al. ,
1964; Putnam et al., 1986) in cattle fed water—damaged alfalfa hay. Clinical signs
described were very similar to those observed in this study. Environmental similarities
prior to the onset of the photosensitization were observed. In early June, 1989 East
Lansing, MI experienced 8 cm of rain over a 3 (1 period which may have influenced the
alfalfa plant in a similar fashion as in the Oklahoma study. Through histological liver
studies, Glenn et al. (1964) determined liver dysfunction had occurred but the causative
agent was not identified.

In the report by Putnam et al. (1986), two cows were fed the water-damaged alfalfa
hay to determine the effects on liver function and hepatic enzyme activities. After
feeding alfalfa, there was a rapid increase in AST (456%) and SDH (3500%) levels,
peaking 8 to 11 d after alfalfa consumption. Following the initial peak, enzyme levels
decreased but did not return to normal levels until the diet was changed. Cholestasis and
bile duct necrosis were indicated as serum 'y-glutamyl transferase was increased. Putnam

et al. (1986) believed the photosensitivity resembled facial eczema caused by the

134

hepatoxin sporidesmin. Sporidesmin is produced by the fungus Pithomyces chartarum.
Attempts were made to detect molds, but none could be found.

In another report, cattle experienced photosensitivity grazing cicer milkvetch
(Astragalus cicer) pastures (Marten et al,. 1987). In that study, hair loss and sloughing
of skin occurred only on white pigmented areas and a genetic predisposition to develop
the malady was observed. Results from this study would support the previous premise
of a genetic predisposition, in that not all the cattle developed hair loss even though
enzyme levels were elevated and only white pigmented areas were affected. Marten et
al. (1990) also observed photosensitivity in Hampshire sheep grazing alsike clover
(Tn'folium hybridum).

The actual cause of the photosensitivity observed has not been determined.
Elevated SDH levels, an indication of liver damage, and the lack of a primary
photosensitizer, may indicate hepatogenous photosensitivity had occurred. Steers
developed photosensitivity grazing alfalfa pastures seeded in different years with different
varieties. One field was infested with weeds whereas the other was not, which further
suggest that the alfalfa was the source of the photosensitivity. Further studies need to.
be completed to determine whether the causative agent was plant, fungal or
environmental and to define the relationship between these conditions and the
development of the phenomenon. Although, this would be difficult to accomplish until

a suitable model is developed.

1 35
IMPLICATIONS

This study cannot conclusively determine that the origin of the photosensitivity, but
the elevated liver enzyme concentrations and absence of a primary photosensitizer
suggests that hepatogenous photosensitivity was observed. In addition, the results from
this study would suggest that all steers do not react to a photodynamic agent in a similar
fashion as is evident by the increased SDH levels by steers in all hair loss score groups.
Through the understanding of how environmental factors interact, photosensitivity may

be prevented.

CHAPTER 6: CONCLUSIONS

The four year study described in this thesis determined that increasing paddock
number from 4 to 13, did not increase beef produced per hectare or forage presented.
Stocking rate impacted the grazing system to a far greater extent than did paddock
number. The optimum stocking rate was 5.3 to 7.9 steers/ha (1289 to 1922 kg/ha). To
further elucidate the stocking rate at which optimum per animal and per hectare gains are
achieved further studies utilizing stocking rates between 5.3 to 7.9 steers/ha should be
used.

As stated in the introduction of this thesis, a drawback to grazing experiments is
the uncontrollable environment. In the first year, excessive rain in May and June
resulted in trampling of the alfalfa and reduction of the stand. To alleviate this problem,
a grass pasture available to place cattle in to prevent this trampling would be beneficial.
Unfortunately, this strategy requires the removal and reintroduction of an alfalfa diet
increasing the risk of bloat.

In addition to trampling problems, alfalfa weevils and alfalfa leaf hopper infested
the pastures. Neither did extensive damage to the pasture, but the harvested plots turned
yellow from the leaf hopper. This may also explain the poor yields from the harvested
plots in year 1. Also in year 1, photosensitivity was observed. Before this condition

was observed the author knew very little about the malady, and by the time the subject

136

 

137

was understood, the condition disappeared and did not surface again, preventing a
complete analysis.

The importance of the electric fence cannot be overlooked, because without it, this
study would be difficult and very expensive to conduct. In future studies, adapting steers
to an electric fence prior to placement on pasture would be beneficial. This study did
not train steers and the co-mingling of animal groups occurred in the first two weeks.
In addition, paddocks to be grazed later in the grazing cycle were grazed before the
scheduled time. The fence charger should be fully charging the fence before animals are
placed on pasture.

As the study progressed, encroachment of grasses and weeds into the alfalfa
pasture occurred. Animal and plant productivity increased annually over the four year
study. This is likely the. result of better environmental conditions and improved
management skills by the author and the guidance committee. Alfalfa-grass pastures
have been shown to produced more beef per hectare than grasses alone (Van Keuren and
Heinemann, 1958; Van Keuren and Matches, 1988), but this author could not find
research which compared an alfalfa-grass pasture to a pure stand of alfalfa. The author
believes this would be a logical step in continuing research in the use of alfalfa for
pasture.

The use of esophageally cannulated animals is effective in determining what the
cattle consume. The animals require a great deal of post-operative care and the chance
of the esophageal fistula closing is always a concern. More animals than needed should
be fistulated to insure enough animals will be available for sample collection. Steers

should be trained to a halter to allow easy collection of samples. The author would not

 

138

suggest the collection of esophageal extrusa unless a well defined objective for these
samples is determined because the time required to collect such samples is great.

Answering objective two, comparing the forage productivity of a pasture system
to a mechanically harvested system, was not accomplished as well as the other objectives.
The main problem was the communication between the group conducting the research
and those in charge of cutting and harvesting the alfalfa. The fields did not get cut when
needed and the forage was not harvested in a timely fashion allowing increased field
losses. The easiest way to alleviate this problem would be to have equipment available
when needed. This is not always practical or possible. The other option is to use
smaller areas and use plot harvesters or hand clipped areas to simulate mechanical
harvest.

The feedlot phase (objective three) of the study did not demonstrate compensatory
gain following a summer grazing program. During the first two years, steers entering
the feedlot heavier were also slaughtered at heavier weights and tended to have greater
estimated yield grades. Further studies should slaughter steers at an equal weight end
point to determine if differences in carcass fat exist or if this observation was related to
steer weight. A common end weight would also allow analysis of the number of days
spent in the feedlot and the additional cost of light-weight steers entering the feedlot.

This thesis as well as other studies evaluated the use of a slow-release Cr bolus and
determined it was not effective for determination of fecal output. Total fecal collection
is time consuming and the animals should be trained to wear the harness and bag prior
to collection, but it is the most accurate method to determine fecal output. Animals were

not trained in this study and the animals were annoyed by the bags the first few hours.

139

The use of time allotments to alter intakes and ADG was effective (objective four).
During the period of fecal collection, steers from the intake study had similar ADG as
those steers used in evaluating grazing systems. Again, I stress the need for animals
which are halter trained to allow the removal of animals from pasture.

It is difficult to know how accurately intakes were estimated. Based on NRC
(1984), steers weighing 262 kg and gaining up to .45 kg/d should have a DMI at 2.4%
of BW as compared to 1.6% of BW observed in this study. This would explain the
increase in calculated net energy values (objective five). Estimation of intakes should
be determined over an entire grazing season not just at one time point. In addition,
digestible energy intake could be determined from gross energy values from forage
samples, collected feces, and if possible esophageal extrusa samples. The estimated
digestible energy intake could be used to check the accuracy of the calculated net energy
values.

This author as well as the members of the guidance committee learned a great deal
about conducting grazing experiments. Grazing experiments are expensive to initiate and
very time consuming. This project expanded the knowledge base on alfalfa grazing
systems in North America, and demonstrated the productive potential of such a system.
Further research needs to explore the differences between pure alfalfa and alfalfa-grass
pastures; the effect of grazing or mechanically harvesting alfalfa the summer following

a late summer seeding; and the interaction of stocking rate on steer production.

 

APPENDICES

APPENDIX A: TERMINOLOGY OF GRAZING LANDS AND
GRAZING ANIMALS

Defined by the Forage and Grazing Terminology Committee, 1991

Aftermath: Forage grown following a harvest.

Animal unit: One mature non-lactating bovine weighing 500 kg and fed at maintenance
level, or the equivalent, expressed as (weight)”, in other kinds of classes of animals
(Table A.1).

Animal unit day: The amount of dry forage consumed by one animal unit per 24-hour
period.

Browse: Leaf and twig growth of shrubs, woody vines, trees, cacti, and other non-
herbaceous vegetation available for animal consumption. To browse. The consumption
of browse by animals.

Carrying capacity: The maximum stocking rate that will achieve a target level of
animal performance in a specified grazing method, that can be applied over a defined
time period without deterioration of the ecosystem.

Continuous stocking: A method of grazing livestock on a specific unit of land where
animals have unrestricted and uninterrupted access throughout the time period when
grazing is allowed.

Creep grazing: The practice of allowing juvenile animals to graze areas that their dams
cannot access at the same time.

Extensive grazing management: Grazing management that utilizes relatively large land
areas per animal and a relatively low level of labor, resources or capital.

First-last grazing: A method of utilizing two or more groups of animals, usually with
different nutritional requirements, to graze sequentially on the same land area.

Forage: Edible parts of plants, other than separated grain that can provide feed for
grazing animals, or that can be harvested for feeding. To search for, or to consume
forage.

Forb: Any herbaceous broadleaf plant that is not a grass and is not grass-like.

140

141

Forward creep: (see First-last grazing)
Graze: The consumption of forage by animals.

Grazing cycle: The time elapsed between the beginning of one grazing period and the
beginning of the next grazing period in the same paddock where the forage is regularly
grazed and rested.

Grazing event: The length of time that an animal grazes without stopping.

Grazing land management: The manipulation of the soil-plant-animal complex of the
grazing land in pursuit of a desired result.

Grazing management: The manipulation of animal grazing in pursuit of a defined
objective.

Grazing management unit: The grazing land area used to support a group of grazing
animals for a grazing season. It may be a single area or it may have a number of
subdivisions.

Grazing method: A defined procedure or technique of grazing management designed
to achieve a specific objective(s).

Grazing period: The length of time that grazing livestock or wildlife occupy a specific
land area.

Grazing pressure: The relationship between the number of animal units and the weight
of forage dry matter per unit area at any one point in time; an animal-to-forage
relationship.

Grazing season: The time period during which grazing can normally be practiced each
year or portion of each year.

Grazing system: A defined, integrated combination of animal, plant, soil, and other
environmental components and the grazing method by which the system is managed to
achieve specific results or goals.

Herbaceous: Non-woody.
Intensive grazing management: Grazing management that attempts to increase
production or utilization per unit area or production per animal through a relative

increase in stocking rates, forage utilization, labor, resources, or capital.

Herbage: The biomass of herbaceous plants, other than separated grain, generally above
ground but including edible roots and tubers.

 

142

Intermittent grazing: A method that imposes grazing for indefinite periods at irregular
intervals.

Mixed grazing: Grazing by two or more species of grazing animals on the same land
unit, not necessarily at the same time but within the same grazing season. ’

Mob grazing: In the management of a grazing unit, grazing by a relatively large
number of animals at a high stocking density for a short time period.

Paddock: A grazing area that is a subdivision of a grazing management unit, and is
enclosed and separated from other areas by a fence or barrier.

Pasture: A type of grazing management unit enclosed and separated from other areas
by fencing or other barriers and devoted to the production of forage for harvest primarily
by grazing.

Period of occupation: The length of time that a specific land area is occupied whether
by one animal group, or by two or more animal groups in succession.

Period of stay: The length of time that a particular animal group occupies a specific
land area.

Put-and-take stocking: The use of variable animal numbers during a grazing period or
grazing season, with a periodic adjustment in animal numbers in an attempt to maintain
desired sward management criteria, i.e., a desired quantity of forage, degree of
defoliation or grazing pressure.

Residue: Forage remaining on the land as a consequence of harvest.

Ration grazing: Confining animals to an area of grazing land to provide the daily
allowance of forage per animal.

Rest: To leave an area of grazing land ungrazed or unharvested for a specific time, such
as a year, a growing season, or a specified period required within a particular
management practice.

Rotational stocking: A grazing method that utilizes recurring periods of grazing and
rest among two or more paddocks in a grazing management unit throughout the period
when grazing is allowed.

Sequence grazing: The grazing of two or more land units in succession that differ in
forage species composition.

Seasonal grazing: Grazing restricted to one or more specific seasons of the year.

143

Stocking density: The relationship between the number of animals and the specific unit
of land being grazed at any one point in time.

Stocking rate: The relationship between the number of animals and the grazing
management unit utilized over a specified time period.

Strip grazing: Confining animals to an area of grazing land to be grazed in a relatively
short period of time, where the paddock size is varied to allow access to a specific land
area.

Set Stocking: The practice of allowing a fixed number of animals on a fixed area of
land during the time when grazing is allowed.

Stockpiling forage: To allow forage to accumulate for grazing at a later period.
Sward: A population of herbaceous plants, characterized by a relatively short habit of

growth and relatively continuous ground cover, including both above and below-ground
parts.

Table A.1. Factors for converting the number of grazing animals of
different species and weight into standard livestock units (500 kg
non-lactating bovine)

 

 

Sheep Cattle
Live weight, Livestock units Live weight, Livestock units

kg kg

10 .038 100 .30
20 .063 200 .50
30 .086 300 .68
40 .106 400 .84
50 .126 500 1.00
60 .145 600 1.15
70 .163 700 1.29

APPENDIX B: COMMON AND SCIENTIFIC NAMES OF GRASSES AND
LEGUMES (Heath et al., 1985)

Alfalfa .................................... Medicago sativa L.
Bahiagrass ............................. Paspalum notatum Flugge
Berrnudagrass .......................... Cynodon daclylon (L.) Pers.
Bluegrass, kentucky ............... ' .............. Poa pratensis (L.)
Bromegrass, smooth ......................... Bromus inennis Leyss.
Clover, alsike ............................. T nfolium hybn’dum L.
Clover, red ................................ T rtfolium pratense L.
Clover, subterranean ....................... T nfolium subterraneum L.
Clover, white ................................ T nfolium repens L.
Corn ......................................... Zea mays L.
Crownvetch .................................. Coronilla varia L.
Fescue, red ................................... Festuca rubra L.
Fescue, tall ........................... Festuca arundinacea Schreb.
Lirnpograss ................ Hemarthria altissima (Poir.) Stapf and Hubbard
Lupines ..................................... Lupinus spp. L.
Milkvetch, cicer .............................. Astragalus cicer L.
Oats ....................................... Avena sativa L.
Orchardgrass ............................... Dacrylis glomerata L.
Quackgrass ........................... Agropyron repens (L.) Beauv.
Rye ....................................... Secale cereale L.
Ryegrass, perennial ............................. Lalium perenne L.
Sainfoin .............................. Onoblychis viciifolia Scop.
Sweetclover, yellow ........................ Melitotus ojficinalis Lam.
Trefoil, birdsfoot ............................ Lotus comiculatus L.
Wheatgrass, intermediate ................ Elym'gia intennedia (Host) Nevski

144

APPENDIX C: TEMPERATURE AND RAINFALL DATA FOR
1989 THROUGH 1992

 

 

 

 

 

 

 

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rainfall (solid bars) from May to September 1989 and 1990.

145

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rainfall (solid bars) from May to September 1991 and 1992.

APPENDIX D: RAW DATA FROM THE GRAZING SYSTEM
STUDY, INTAKE STUDY AND CHARACTERIZATION OF
PHOTOSENSITIVITY

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166

Table D5. Forage presentation per rotation and over the entire grazing season
(1989 to 1991)

 

 

Summer Fall
Rotation l Rotation 2 Rotation 3 Overall Rotation 4
Plot Year GS SR kg/ha kg/ha kg/ha kg/ha kg/ha
1 1989 4 L 3706 2631 572 6909 1491
2 1989 13 L 3340 3218 1395 7953 1650
3 1989 13 H 3403 2291 950 6643 1618
4 1989 4 H 2675 1493 424 4592 1618
5 1989 Haylage 1948 685 -- 2633 1015
6 1989 13 H 241 1 1 159 740 4309 1389
7 1989 4 L 2177 2689 614 5480 1357
8 1989 4 H 2570 1658 308 4536 1055 ~
9 1989 13 L 2084 2121 1182 5387 1300
10 1989 Haylage 1964 1131 -- 3095 1638
1 1990 4 L 2988 3482 1707 8177 --
2 1990 13 L 2830 3639 2920 9389 --
3 1990 13 H 2201 2583 2426 7210 --
4 1990 4 H 2201 2426 1213 5840 --
5 1990 Haylage 4762 3751 -- 8513 --
6 1990 13 H 2269 2493 1932 6694 --
7 1990 4 L 2449 4246 1483 8178 --
8 1990 4 H 21 12 3459 1505 7076 --
9 1990 13 L 2224 3482 2538 8244 --
10 1990 Haylage 3414 4650 -- 8064 ~-
1 1991 4 L 4972 3596 2573 l 1 140 --
2 1991 13 L 4608 3876 3050 1 1533 --
3 1991 13 H 4191 3808 3031 11029 --
4 1991 4 H 4416 4824 2545 11784 --
5 1 991 Hay 4093 1970 -- 6063 --
6 1991 13 H 4135 3666 2931 10733 --
7 1991 4 L 4724 3812 2720 11257 --
8 1991 4 H 4083 4454 2444 10981 --
9 1991 13 L 4073 3869 3761 1 1703 --
10 1991 Hay 4733 2285 -- 7018 --

 

 

167

Table D6 Nutrient composition of forage samples (1989)

 

 

CP, CP, IVDMD, IVOMD,
Plot Period DM, % Ash, % OM, % (% DM) (% OM) % %

1 A 16.76 9.33 90.67 17.99 19.84 74.37 74.79
1 B 16.85 11.21 88.79 19.54 22.01 61.94 62.38
1 C No sample

1 D 18.68 4.98 95.02 15.67 16.49 53.62 51.17
1 E 17.52 10.09 89.91 19.46 21.64 55.93 50.75
1 F 19.78 10.13 89.87 17.39 19.35 54.07 52.14
1 G 22.98 10.47 89.53 17.51 19.56 63.62 62.66
1 H 26.92 7.55 92.45 15.87 17.16 60.73 58.06
1 1 15.75 11.53 88.47 23.00 25.99 64.71 63.32 '
2 A 15.23 10.10 89.90 24.15 26.86 68.60 68.38
2 B 15.30 10.04 89.96 21.06 23.41 56.86 54.56
2 C 19. 06 9.12 90.88 17.56 19.32 61.93 62.31
2 D 18.16 8. 68 91.32 19.54 21.40 57.70 54.09
2 E 16.59 10.14 89.86 18.27 20.33 59.73 59.20
2 F 27.47 8.66 91.34 16.79 18.38 61.76 59.27
2 G 25.03 8.21 91.79 17.28 18.83 62.14 60.22
2 H 22. 80 8. 85 91.15 19.05 20.90 62.50 59.31
2 1 16.16 11 01 88.99 22.78 25.60 64.96 62.84
3 A 14.57 10. 39 89.61 23. 71 26. 46 67.46 66.75
3 B 16.46 10.06 89.94 18.10 20.13 55.07 53.94
3 C 19.86 8.97 91.03 18.23 20.03 55.50 56.01
3 D 20.08 8.83 91.17 17.92 19.65 57.39 54.94
3 E 17.47 10.71 89. 29 19.39 21. 71 64.46 60.52
3 F 20.40 8.72 91. 28 19. 84 21.74 60.90 60.09
3 G 34. 58 6. 94 93.06 14.21 15. 27 64.11 63. 73
3 H 21.14 10. 21 89.79 20.21 22.51 63.49 61.79
3 I 14.80 12.63 87.37 26.47 30.30 68.05 68.61
4 A 17. 39 9.46 90.54 19.77 21.83 71.63 74. 84
4 B 18.67 8.95 91.05 19.92 21.88 55.59 55.19
4 C No sample

4 D 20.94 11.27 88. 73 16.06 18.10 59.79 60.19
4 E 17.43 10. 42 89.58 19.49 21.75 66.15 63.45
4 F 24. 52 8. 69 91.31 16.09 17.62 57.90 56.47
4 G 24.29 17.45 82.55 16.68 20. 21 59.42 66.04
4 H 25.00 8. 64 91.36 19.06 20.87 66.69 67.58
4 I 17.36 11.98 88.02 21.78 24.75 69.30 69.59
6 A 15.70 10. 21 89. 79 24.00 26.73 66.62 67.17
6 B 9. 42 11.22 88.78 24.40 27.49 58.73 54.71
6 C 15.51 9.92 90.08 16.51 18.33 59.46 59.50
6 D 25.22 8.98 91.02 11.58 12.72 54.86 54.11
6 E 18.05 10.92 89.08 21.66 24.31 63.55 60.88
6 F 24.14 11.59 88.41 18.57 21.00 57.35 58.09
6 G 28.36 16.01 83. 99 18.28 21.77 55.44 61.95
6 H 20. 91 13.76 86. 24 19.57 22. 69 60.19 61.09
6 1 15.10 14.47 85.53 23.04 25.38 ' 65.15 64.80
7 A 14.98 9. 23 90.77 21.37 23.75 64.87 64.48
7 B 17.49 10. 04 89. 96 15.45 17.00 66.38 66.08

168
Table D.6. (Cont'd.)

 

 

 

 

CP, CP, IVDMD, IVOMD.
Plot Period DM, % Ash, % OM, % (% DM) (% OM) % %

7 C No sample

7 D 20.52 9.14 90.86 27.98 30.86 59.22 55.86
7 E 18.50 9.36 90.64 17.23 18.98 64.59 60.57
7 F 22.33 9.21 90.79 15.24 16.42 55.34 53.54
7 G 29.54 7.16 92.84 17.27 18.56 66.33 66.12
7 H 28.99 6.97 93.03 22.88 25.27 64.52 63.12
7 1 19.27 9.48 90.52 26.09 30.51 62. 76 60.27
8 A 14.81 10.12 89.88 25.52 28.39 70. 42 70.70
8 B 16.33 10. 66 89.34 21.33 23.88 65. 61 65.17
8 C No sample

8 D 18.45 8.33 91.67 21.11 23.03 58.26 58.88
8 E 14.65 12.18 87.82 27.66 31.50 67.04 63.94
8 F 18.92 8.93 91.07 16.81 18.46 56.66 56.85
8 G 30.48 6.65 93.35 16.88 18.09 72.00 72.27
8 H 28.09 7.57 92.43 17.50 18.94 63.67 62.17
8 1 20.68 10.84 89.16 22.07 24.75 68. 17 66. 40
9 A 16.22 11.32 88.68 23.04 25.99 71.04 70. 85
9 B 15.50 11.86 88.14 22.78 25.85 59.63 57. 72
9 C 21.96 12.91 87.09 16.47 18.92 57. 74 58.96
9 D 22.26 8.63 91.37 12.43 13.60 53.12 53.50
9 E 16.54 9.49 90.51 23.90 26.41 66.27 63.21
9 F 21.92 8.58 91.42 19.59 21.43 61. 22 59.48
9 G 28. 99 10.71 89.29 14.80 16.58 61.54 63.76
9 H 24.17 10. 27 89.73 16.92 18.86 57.13 55.57
9 1 13.59 10.14 89. 86 21.61 24.05 60. 62 58.97

Period Date

A 19-May

B 27-May

C 01-Jun

D 09-Jun

E 25-Jun

F 09-1111

G 21-Jul

H 02-Aug

1 l4-Aug

Table D7. Canopy heights (1989)

169

 

 

Plot 1 2 3 4 6 7 8 9
Date Day height, cm

05/19/89 0 37.75 38. 50 35.25 31.50 32.00 37.50 27.75 28.50
05/21/89 2 37.00 38.25 39.00 31.75
05/23/89 4 45. 50 45.50 42.00 22.50
05/25/89 6 45.75 48.50 . 38. 25 42.25
05/27/89 8 53.00 53.25 49.00 49.00 52. 75 46.75 44.00 43.00
05/29/89 10 49. 25 50. 25 51.00 44.75
05/31/89 12 49.50 45.00 49.75
06/01/89 13

06/03/89 15 55.75 51.00 45.50 37.00
06/04/89 16

06/05/89 17 50.25 54.50 40.33 45.25
06/07/89 19 53.25 56.75

06/09/89 21 62.25 59. 25 58.25 48.00 58.50 40.00
06/11/89 23 52.00 67.25

06/25/89 37 43.00 41.25 29.50 46.50 38. 75 48.25 39.00 43.75
06/30/89 42 40. 75 39.00 38. 75 39.25
07/03/89 45 45. 25 44.50 30. 25 39.00
07/06/89 48 52. 75 43.75 28. 50 55.25
07/09/89 51 52.75 53.75 46.50 38.25 31.50 54.25 50.25 58.50
07/12/89 54 53.25 48.00 25.75 52.00
07/15/89 57 47.25 25.00 25.00 50.50
07/18/89 60 55.50 38.50 28.00 52.50
07/21/89 63 38.75 42.00 20.00 15.25 28.25 39.25 27.50 36.75
07/24/89 66 55.00 31.00 13.75 27.50
07/27/89 69 51.75 47.00 11.50 48.75
07/30/89 72 54.25 48.25 20.00 28.00
08/02/89 75 52.00 54.00 42.75 22.25 14.50 32.25 23.50 17.00
08/05/89 78 25.50 15.75 17.50 26.75
08/08/89 81 27. 25 26.25 21.00 27.00
08/11/89 84 31.00 23.25 19.25 23. 50.
08/14/89 87 28.50 23.00 25.00 19.25 20. 75 24.75 24.00 25.50
08/17/89 90 32. 25 31. 50 23.75 30.50
08/20/89 93 40. 75 34.00 21. 00 28. 50
08/23/89 96 41.50 35.00 32.00 37.25

 

1 70
Table D8. Esophageal extrusa nutrient composition (1989)

 

 

 

1989 CP. IVOMD, Rumen Rumen
Plot Period OM, % (% of OM) (% of DM) DMD, % UDP
(% of CP)
1 E 90.36 25.83 69.23 76.95 16.53
1 F 93.08 23.93 93.00 87.13 11.54
1 G 93.51 20.58 77.24 78.67 14.61
1 H 91.09 14.73 76.99 81.69 14.07
1 1 89.18 23. 25 66.20 82.73 12.50
2 E 90.09 26.63 62.54 77.75 19.67
2 F 91.53 27.04 71.19 82.39 10.37
2 G 93.45 20. 41 75.63 77.97 15.47
2 H 92.85 15.22 74.42 79.37 16.14
2 1 91.58 27.76 75.95 81.00 11.29
3 E 91.46 26.88 75.22 79.62 14.88
3 F 89.59 26.06 83.58 11.85
3 G 92.82 18.89 73.98 73.94 20.95
3 H 92.87 13.83 73.80 78.03 19.89
3 1 91.08 27.34 73. 81 78. 28 16.75
4 E 90.64 27.25 64.98 73.18 18.99
4 F No sample
4 G 91.34 19.46 73.21 78.28 19.25
4 H 90.82 18.18 67.31 75.56 20.23
4 1 89.45 26.78 72.04 70.67 28.53
6 E 89.14 26.40 60.01 84.88 11.11
6 F 93.35 27.71 59.41 79.65 14.48
6 G 90.71 17.53 75.37 76.87 19.28
6 H 86.12 22.46 64.91 80. 52 13. 83
6 1 84.18 27.01 74.14 76. 52 17.90
7 E 90.70 31. 19 69.10 78.89 14. 81
7 F 90.70 26.00 68.72 86. 03 10.48
7 G 88.06 18.81 83.34 84. 44 11. 22
7 H 88.06 15.74 80.31- 79. 94 16.17
7 1 92. 53 73.17 81. 16
8 E 90.62 31.93 69.56 80.70 11.52
8 F 91.02 27.03 79.30 80.63 16.46
8 G 93.40 18.48 78.26 80.04 17.62
8 H 92.81 16.57 71. 92 79.66 15.83
8 1 91.66 28.58 75.53 83.62 12.60
9 E 91.19 25.94 75.87 86.40 10.45
9 F 91.67 26.30 74.34 80.56 12.75
9 G 93.56 18.32 75.84 76.58 16.45
9 H 92.45 17.17 65.65 68.79 24.13
9 1 87.78 25.18 65.83 73.74 20.20
Period Date

E 06/25/89
F 07/09/89
G 07/21/89
H 08/02/89
I 08/14/89

Table D9. Nutrient composition of forage samples (1990)

171

 

Plot Period DM, % Ash, % OM, % (% DM) (% OM) IVDMD, % IVOMD, %

1990

 

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11.17
13.41
19.65
21.70
22.38
22.17

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11.78
8.53
8.61

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88.22
91.47
91.39
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CP GP
21.46 24.00
28.13 31.88
23.22 25.38
21.97 24.04
20.64 22.24
17.15 18.64
18.04 19.59
19.62 21.34
18.47 20.42
22.27 24.48
27.32 30.35
24.37 27.01
21.72 23.92
20.99 23.14
20.83 22.88
18.60 20.18
17.01 18.48
18.23 19.98
17.79 19.41
21.97 24.05
25.85 28.79
24.88 27.67
21.93 24.49
21.29 23.53
22.92 25.24
20.27 22.26
18.81 20.45
18.22 20.14
21.09 23.21
22.41 24.82
23.12 25.56
24.16 26.79
20.08 22.64
22.18 24.54
20.49 22.68
23.25 25.80
17.89 19.73
22.23 24.36
22.11 24.39
19.71 21. 90
23.51 26.16
22.54 25.06
19.71 21.82
21.34 23.42
25.97 28.70
17.27 18. 81
21.01 22.89

77.46
71.13
69.62
69.86
49.74

63.88
68.69

76.84
70. 77
66.89
65.56
63.16
62.60
63.25

75.69
69.49
69.15
67.93
47.36
45.52
62.58
53.92
60.00
63.23
76.13
69.78
63.62
62.11

1.1"-

Table D9 (Cont'd.)

172

 

 

 

1990 CP CP
Plot Period DM, % Ash, % OM. % (% DM) (% OM) IVDMD, % IVOMD, %
6 H 18.28 9.47 90.53 22.12 24.44 61.26 57.42
6 1 18.70 9.08 90.92 21.16 23.27 63.27 61.47
6 1 17.40 10.01 89.99 21.99 24.43 63.46 60.83
7 A 16.96 9.76 90.24 25.35 28.10 80.84 81.43
7 B 11.58 10.51 89.49 26.28 29.37 74.60 72.87
7 C 11.24 10.83 89.17 29.32 32.88 71.39 68.84
7 D 17.72 8.90 91.10 23.13 25.38 70.73 68.40
7 E 19.46 8.61 91.39 22.21 24.30 58.67 55.67
7 F 20.76 7.99 92.01 18.59 20.21 54.70 51.00
7 G 26.52 6.96 93.04 16.60 17.84 55.54 54.46
7 H 26.34 7.04 92.96 17.83 19.18 54.39 51.91
7 1 18.34 8.77 91.23 22.77 24.96 65.75 63.57
7 I 20.42 7.05 92.95 22. 23 23.92 62.75 60.94
8 A 16.67 9.40 90.60 23.97 26.46 79.19 79.40
8 B 11.6 10.14 89.86 25.37 28.24 73.02 71.30
8 C 17.65 9.44 90.56 20.14 22.24 70.62 69.03
8 D 17.49 9.52 90.48 25.33 27.99 71.72 69.22
8 E 18.12 9.60 90.40 22.86 25.29 67.44 64.86
8 F 21.36 7.42 92.58 18.25 19.72 51.30 48.37
8 G 22.07 8.21 91.79 19.50 21.24 64.41 61.68
8 H 20.73 8.41 91.59 21.78 23.78 59.85 61.75
8 1 17.97 8.74 91.26 23.34 25.58 68.07 66.19
8 1 19.74 11.31 88.69 19.79 22.31 64.73 62.09
9 A 13.96 11.81 88.19 24. 48 27.75 77.10 78. 21
9 B 12.51 10.08 89.92 26.84 29.85 73.84 72. 38
9 C 17.70 9.26 90.74 20. 81 22.93 68.07 65.98
9 D 19.24 8.85 91.15 21.30 23.36 65.17 64.33
9 E 16.80 8.18 91.82 21.23 23. 12 57.26 54.61
9 F 22.24 7.83 92.17 18.10 19.64 57.72 52.82
9 G 22.03 7.29 92.71 17.98 19.39 57.47 54.63
9 H 22.88 8.24 91.76 18.43 20.09 58.24 56.21
9 1 20.90 8.29 91.71 20.19 22. 01 56.07 53. 00
9 I 18.87 9.22 90.78 21.91 24.13 58. 97 57. 56
Period Date

A 05/14/90

B 05/18/90

C 05/26/90

D 06/07/90

E 06/19/90

F 07/01/90

G 07/13/90

H 07/25/90

I 08/06/90

I 08/18/90

Table D. 10. Canopy heights (1990)

173

 

 

Plot 1 2 3 4 6 7 8 9
Date Day height, cm

05/14/90 0 42.50 39.25 38.75 38.75 40.25 41.50 40.00 38.75
05/16/90 2 44.25 46.25 46.75 31.50
05/18/90 4 42.25 45.25 44.25 40.75 42.75 43.75 44.75 38.75
05/20/90 6 45.50 44.75 50.00 43.75
05/22/90 8

05/24/90 10 52.75 46.00 46.00 47.75
05/26/90 12 53.50 53.25 34.75 33.75 41.50 48.00 52.00 54.75
05/29/90 15 56.75 41.25 42.50 56.50
06/01/90 18 72.50 54.00 49.25 52.25
06/04/90 21 68.25 65.25 53.00 59.00
06/07/90 24 71.00 77.00 45.25 41.50 45.50 55.00 49.75 56.00
06/10/90 27 54.75 47.25 43.25 51.00
06/13/90 30 54.25 49.25 50.25 48.25
06/16/90 33 54.25 49.25 46.50 49.50
06/19/90 36 51.00 54.00 51.25 52.75 50.00 53.50 52.25 52.75
06/22/90 39 56.75 47.50 47.25 46.50
06/25/90 42 48.50 44.25 48.50 61.25
06/28/90 45 66.50 60.50 69.75 74.25
07/01/90 48 65.00 74.75 65.00 47.75 59.00 57.75 49.00 64.00
07/04/90 51 60.25 53.25 44.50 60.75
07/07/90 54 62.50 56.25 69.75 74.25
07/10/90 57 59.25 59.25 49.75 56.00
07/13/90 60 64.75 64.75 59.50 60.25 55.25 65.25 63.25 51.50
07/16/90 63 66.00 60.00 49.75 64.25
07/19/90 66 73.50 53.25 35.50 48.50
07/22/90 69 57.25 50.75 52.50 60.00
07/25/90 72- 62.75 37.00 31.00 42.50 38.50 52.25 58.00 39.00
07/28/90 75 46.75 44.25 40.75 42.50
07/31/90 78 48.00 53.50 56.25 45.00
08/03/90 81 47.75 53.00 49.75 53.75
08/06/90 84 60.75 51.00 64.75 62.25 51.50 51.00 53.50 55.75
08/09/90 87 54.50 60.00 41.25 54.00
08/12/90 90 0.00
08/15/90 93 48.25 54.00 49.75 51.75
08/18/90 96 54.25 54.75 52.25 34.00 34.25 45.50 47.25 43.25
08/21/90 99 56.00 50.50 46.50 43.50
08/24/90 102 53.75 45.00 40.50 53.25
08/27/90 105 55.75 50.00 51.25 54.50

 

174

Table D. 11. Esophageal extrusa nutrient composition (1990)

 

 

1990 CP IVOMD Rumen Rumen
Plot Period OM, % (% of OM) (% of OM) DMD, % UDP
(% of CP)
1 D 89.86 25.91 74.18 78.99 13.99
1 E 90.34 25.27 68.44 87.45 15.88
1 F 92.01 25.97 69.72 77.50 12.70
1 G No sam le
1 H 91.8 23.73 77.84 83.13 9.60
l I 91.69 23.19 75.19 84.64 10.40
1 .1 90.49 25.05 76.37 81.11 15.55
2 D 88.40 28.26 72.86 80.56 18.00
2 E 90.17 29.03 71.86 81.63 12.85
2 F 91.70 24.23 65.45 76. 13 13.18
2 G No sam le
2 H 92.3 20.69 81.72 84.37 11.03
2 l 91.59 24.31 76.02 84.61 9. 83
2 1 90.92 26.00 75.86 78.64 17. 28
3 D 89.91 26.54 72.80 78.31 15.28
3 E 90.10 33.96 74.14
3 F 90.24 30. 08 73.89 85.28 6.89
3 G No sam le
3 H 91.9 23.43 78.54 79.96 16. 11
3 I 84.83 27.95 78.39 84. 25 8. 32
3 .1 91.62 25.42 82.06 85.19 10. 75
4 D No sample
4 E 90.54 29.07 72.04 93.67 9.70
4 F 87.99 26.01 69.06 78.61 15.33
4 G No sam le
4 H 92.1 24.90 79.48 87.51 6.30
4 I 90.72 27.54 79.51 87.74 7.51
4 .1 92.01 23.09 77.95 79.45 15.86
6 D 91.46 20.43 73.49 68.27 23.23
6 E 90.27 29. 95 76.43 86.49 9.12
6 F 90.43 28.12 73.33 82.70 9. 41
6 G No sam le
6 H 91.60p 22.08 80.79 90. 63 4.54
6 I 82.92 25.70 73.83 83.01 10.84
6 I 90.55 22.45 70.91 72.95 23.13
7 D No sample
7 E 89.23 29.94 70.24 83.65 11.53
7 F 91.47 29.08 74.70
7 G No sam le
7 H 91.60p 22.27 75.14 87.51 6.76
7 l 90.76 17.97 76.53 86.22 14.28
7 J 91.20 26.67 70.88 99.24
8 D 89.65 30.17 74.28 80.36 13. 75
8 E 90.41 24.25 74.98 87.17 8. 67
8 F 91.70 26.15 76.65 86. 02 13.43
8 G No sample

175
Table D. 11. (Cont'd.)

 

 

 

1990 CP IVOMD Rumen Rumen
Plot Period OM, % (% of OM) (% of OM) DMD, % UDP
(% of CP)

8 H 92.09 24.72 75.70 87.67 5.97

8 I 91.68 26.24 79.75 89.79 5.29

8 J 90.37 25.17 73.14 82.47 14.93

9 D 91.39 25.41 76.92 81.45 9.47

9 E 90.94 28.89 73.82 82.82 11.47

9 F 91.09 22.01 64.50 74.42 15.43

9 G No sam le

9 H 91.9 23.29 78.80 90.93 4.62

9 l 86.20 23.79 79.02 83.04 8.69

9 .1 90.31 26.05 72.83 82.64 13.51
Period Date

D 06/07/90

E 06/19/90

F 07/01/90

G 07/13/90

H 07/25/90

I 08/06/90

.1 08/18/90

176

Table D. 12. Forage sample fiber analysis (1989)

 

 

Plot GM SR Date NDF, % ADF, % Lignin, %
1 4 L 05/18/89 31.50 21.41 3.95
l 4 L 06/25/89 54.99 36.66 9.71
l 4 L O7/21.’89 46.74 31.73 8.67
1 4 L 08/14/89 39.53 25.32 7.48
2 13 L 05/18/89 29.73 18.86 3.27
2 13 L 06/03/89 49.80 33.33 7.38
2 13 L 06/30/89 42.96 27.53 6.71
2 13 L 07/21/89 40.16 24.46 7.03
2 13 L 08/14/89 40.88 25.98 7.67
2 13 L 10/29/89 54.01 36.64 9.42
3 13 H 08/14/89 33.26 20.49 5.85
3 13 H 05/18/89 31.30 21.16 4.11
3 13 H 06/03/89 49.67 34.30 8.05
3 13 H 06/30/89 42.28 25.95 6.45
3 13 H 07/21/89 51.00 32.96 9.14
4 4 H 05/18/89 29.57 19.74 3.83
4 4 H 06/25/89 44.24 27.44 7.33
4 4 H 07/21/89 44.95 22.23 5.14
4 4 H 08/14/89 34.72 21.10 6.29
4 4 H 10/26/89 28.88 17.90 7.09
5 Haylage 06/20/89 64.37 46.31 11.64
5 Haylage 08/21/89 62.65 39.29 12.64
5 Haylage 10/26/89 47.67 30.79 22.55
6 13 H 05/18/89 41.83 25.79 5.57
6 13 H 06/04/89 46.08 ' 32.43 7.07
6 13 H 06/30/89 49.73 31.33 8.33
6 13 H 07/21/89 41.73 23.92 7.00
6 13 H 08/14/89 33.29 20.24 6.05
6 13 H 10/27/89 31.26 18.83 5.15
7 4 L 05/18/89 39.56 26.20 6.06
7 4 L 06/25/89 47.20 31.36 8.01
7 4 L 07/21/89 38.77 24.59 6.44
7 4 L 08/14/89 43.55 26.57 8.44
7 4 L 10/29/89 44.57 29.01 8.16
8 4 H 05/18/89 34.89 21.17 4.40
8 4 H 06/25/89 44.90 29.36 7.39
8 4 H 07/21/89 38.93 21.78 6.18
8 4 11 08/14/89 35.04 20.24 5.57
8 4 H 10/26/89 28.59 16.29 5.05

177
Table D.12. (Cont'd.)

 

Plot GM SR Date NDF, % ADF, % Lignin, %

9 13 L 05/18/89 44.07 24.30 3.01
9 13 L 06/04/89 41.65 27.04 5.98
9 13 L 06/30/ 89 36.73 24.85 6.27
9 13 L 07/21/89 44.87 30.39 8.04
9 13 L 08/14/89 43.48 28.30 8.19
9 13 L 10/27/89 48.37 30.84 12.69
10 Haylage 06/20/ 89 60.54 41.19 9.27
10 Haylage 08/21/ 89 62.18 39.55 11.08
10 Haylage 10/26/ 89 47.76 28.66 7.33
11 4 06/25/89 43.21 29.53 6.77
12 13 06/25/89 45.39 28.76 6.75

 

178

 

 

Crude protein, % of OM

 

 

 

 

 

 

 

IVOMD, 96

 

 

 

 

Day of study

Figure D.1. Crude protein (a) and IVOMD (b) composition of forage (solid lines) and extrusa
(dashed lines) over the 1989 grazing season collected from 4 paddock (circles) and 13 paddock
(squares) systems at the low (open) and high (closed) stocking rates.

179

 

 

 

 

 

 

 

 

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30 40 50 60 70 80 90
Day ofstudy

Figure D.2. Rumen DMD (a) and UDP (b) of extrusa samples over the 1989 grazing season
collected from 4 paddock (circles) and 13 paddock (squares) systems at the low (open) and high
(closed) stocking rates. ‘

180

 

 

   

 

 

 

 

 

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0102030405060708090100
Dayofstudy

Figure D.3. Crude protein (a) and IV OMD (b) composition of forage (solid lines) and extrusa
(dashed lines) over the 1990 grazing season collected from 4 paddock (circles) and 13 paddock
(squares) systems at the low (open) and high (closed) stocking rates.

95

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Figure D.4. Rumen DMD (a) and UDP (b) of extrusa samples over the 1990 grazing season
collected from 4 paddock (circles) and 13 paddock (squares) systems at the low (open) and high

(closed) stocking rates.

182

 

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Table DIS.

1 87
Daily fecal output and fecal DM, OM, CP and Cr concentrations

 

Total

 

Sample Collection Anim. Feces Fecal Fecal OM, Fecal CP, Fecal Cr,
No. Date No. wt., lb DM, % % of DM % of DM ug/g DM
2000 7-30—89 35 10.9 17.23 83.62 13.30 907.97
2001 7-30—89 89 31.2 11.20 81.68 16.47 731.25
2002 7-30-89 91 25 .9 28.18 85.26 8.85 694.08
2003 7-30-89 102 4.3 19.30 82.88 10.49 974.38
2004 7-30—89 105 27.0 16.75 83.78 13.20 1046.81
2005 7-30—89 114 23.2 16.43 81.84 13.59 831.52
2008 7-30-89 39 15.4 17.08 86.45 11.73 645.12
2009 7-30-89 45 14.7 16.11 82.39 11.88 580.01
2010 7-30-89 75 31.3 14.80 86.86 11.45 484.45
2011 7-30-89 81 24.7 14.48 86.08 11.08 672.55
2012 7-30-89 109 33.4 14.16 86.24 10.45 651. 52
2013 7-30-89 117 24.7 12.17 87.05 11.49 569. 85
2016 7-31-89 35 16.8 15.95 86.10 15.62 N/A
2017 7-31-89 89 30.6 13.08 85.46 18.36 988.80
2018 7-31-89 91 29.7 14.36 84.75 16.64 705.37
2019 7-31-89 102 23.1 17.06 84.26 15.70 874. 22
2020 7-31-89 105 14.8 15.74 85.95 17.82 1085.12
2021 7-31-89 114 26.6 15.21 85.35 16.15 820.58
2024 7-31-89 39 24.3 16.39 85.42 11.71 657.04
2025 7-31-89 45 29.9 16.41 85.67 13.56 640. 72
2026 7—31-89 75 16.2 14.45 87.67 13.47 571.86
2027 7-31-89 81 21.7 15.59 83.36 13.78 606.08
2028 7-31-89 109 37.2 15.57 86.47 12.92 625.61
2029 7-31-89 117 13.1 13.24 86.75 12.83 388. 37
2032 8-1-89 35 4.6 19.88 83.26 14.58 784. 68
2033 8-1-89 89 19.8 13.27 84.48 13.04 703. 44
2034 8-1-89 91 9.1 16.11 79.49 13.17 701.87
2035 8-1-89 102 12.4 19.03 74.36 13.65 682.10
2036 8-1-89 105 9.7 18. 36 78.75 15.26 767.52
2037 8-1-89 114 15.6 16.59 83.27 13.91 507. 67
2040 8-1-89 39 22.1 15. 50 85.16 12. 83 444.89
2041 8-1-89 45 24. 7 14.60 85.99 15.58 479. 42
2042 8-1-89 75 31.5 11.69 86.73 16.82 437. 83
2043 8-1-89 81 No sample
2044 8-1-89 109 26.6 13.36 87.72 16.26 430.46
2045 8-1-89 117 13.5 11.13 87.19 13.24 535.30
2048 8-8-89 35 13.7 17.48 81.79 13.54 467.37
2049 8-8-89 89 41.9 13.61 83.21 13.05 296.48
2050 8-8-89 91 37.4 12.67 85.52 14.58 419. 66
2051 8-8-89 102 22.7 17.07 80.99 14.61 454. 92
2052 8-8-89 105 20.9 14.79 85.46 15.14 461.02
2053 8-8-89 114 31.3 15.38 82.72 13.79 366.08
2054 8-8-89 39 28.6 17. 40 81.06 12.36 521.07
2055 8-8-89 45 23.0 17. 28 78.33 13.84 528.57
2056 8-8-89 75 22.6 17.76 79. 02 14.09 475.24
2057 8-8-89 81 29.8 14.35 82.26 15.15 494.05

 

Table D. 15. (Cont'd)

188

 

Total

 

Sample Collection Anim. Feces Fecal Fecal OM, Fecal CP, Fecal Cr,
No. Date No. wt., lb DM, % % of DM % of DM ug/g DM
2058 8-8-89 109 21.3 16.40 81.76 15.01 387.33
2059 8-8-89 117 19.2 12.91 82.93 15.08 405.72
2060 8-9-89 35 9.2 17.50 83.34 13.23 475.91
2061 8-9-89 89 16.1 13.17 84.42 13.34 427.95
2062 8-9-89 91 12.1 14.06 89.27 15.78 330.10
2063 8-9-89 102 18.3 17.78 83.59 12.27 421.19
2064 8-9-89 105 19.1 14.59 80.62 13.45 475.31
2065 8-9-89 114 32.0 15.58 86.98 13.27 301.98
2066 8-9-89 39 23.6 16.34 83.08 13.45 479.08
2067 8-9-89 45 20.0 15.99 81.54 16.20 552.08
2068 8-9-89 75 28.6 15.32 81.24 15.81 529.01
2069 8-9-89 81 21.6 13.89 77.91 14.98 470.63
2070 8-9-89 109 33.4 15.20 82.26 16.32 344.13
2071 8-9-89 117 24.2 11.46 80.18 15.15 404.22
2072 8-10-89 35 19.3 18.56 83.64 11.26 500.02
2073 8-10-89 89 22.2 14.13 85.69 11.27 431.56
2074 810-89 91 20.8 14.88 89.53 13.51 333.85
2075 8-10-89 102 13.6 19.16 82.95 11.13 362.12
2076 810-89 105 9. 8 12.12 85.54 9.64 552.40
2077 8-10-89 114 25.4 14.94 87.15 11.86 315.93
2078 8-10-89 39 22.0 16.16 85.00 14.40 388.55
2079 8-10—89 45 11.1 18.16 81.47 13.44 511.26
2080 8-10-89 75 20.2 16.50 78.28 15.79 508.53
2081 8-10-89 81 13.2 14.08 80.64 13.91 472.35
2082 810-89 109 13.4 14.90 81.65 13.97 207.14
2083 810-89 117 ’ 17.1 14.12 82.22 12.36 495.44
2084 8-11-89 35 16.8 17.01 85.40 12.15 518.92
2085 8-11-89 89 14.5 15.27 86.43 11.75 483.87
2086 8-11-89 91 28.7 15.42 89.81 14.18 375.64
2087 8-11-89 102 14.0 18.29 84.71 11.12 423.54
2088 8-11-89 105 15.1 13.71 82.39 8.97 631.67
2089 8-11-89 114 20.0 15.89 88.10 18.05 298.64
2090 8-11-89 39 23.4 18. 18 80.57 13.90 480.46
2091 8-11-89 45 16.2 18.07 78.55 16.28 484.63
2092 8-11-89 75 20.5 17.38 78.89 14.40 576.54
2093 8-11-89 81 18.7 18.36 78.99 14.50 759.43
2094 8-11-89 109 23.4 18.06 80.77 17.79 171.25
2095 8-11-89 117 35.7 14.02 81.63 14.27 769.08

 

189

Table D. 16 Individual live-weight and enzyme levels of photosensitive steers

 

1989
Anim. Hair Initial Day 24 Day 32 Day 75 AST AST SDH SDH
No. Loss wt., lb wt., 1b wt., lb wt., lb IU/L IU/L IU/L IU/L
Score 05/20 06/14 06/22 08/04 06/22 08/04 06/22 08/04

513 520 545 725 66 59 7O 30 ‘

465 480 470 590 63 34 48 67
5 37 550 550 650 50 53 23 37
595 620 605 750 68 75 50 42

0
5 O 428 445 475 640 69 25 84 62
9 0 578 620 615 725 71 59 55 34
13 0 588 600 620 710 119 59 178 58
17 0 573 580 565 680 57 59 36 26
33 0 435 480 500 655 61 65 59 40
46 0 453 470 430 505 1340 43 37 62
51 0 548 555 530 685 61 52 50 43

O

0

0

15 1 518 530 555 625 58 58 6O 54
31 1 530 560 530 620 49 52 47 40
36 1 483 505 520 590 89 59 154 41
40 l 560 610 610 695 57 34 35 51
43 1 445 470 495 560 68 67 24 61
107 1 555 565 575 655 71 64 96 28
4 2 635 700 690 810 88 78 43 63
30 2 558 545 560 675 71 72 60 51
47 2 543 530 540 660 61 84 52 114
62 2 525 560 5 30 615 68 59 224 43
65 2 560 530 565 615 57 51 33 86
76 2 493 550 550 590 56 66 50 1 14
122 2 456 480 485 545 56 61 45 65
3 3 670 685 645 820 67 86 31 53
7 3 528 570 555 720 68 72 34 26
53 3 583 600 600 640 65 59 103 29
60 3 533 525 550 645 59 58 180 33
74 3 488 505 490 610 72 24 82 59
88 3 555 545 520 640 47 48 51 30
1 13 3 450 455 470 600 54 55 53 27
120 3 485 525 520 660 48 48 30 33

 

AST: Aspartate transaminase
SDI-1: Sorbitol dehydrogenase

APPENDIX E: EFFECT OF GRAZING NIETHOD AND
STOCKING METHOD ON HEIFERS GRAZING STOCK-FILED
ALFALFA PASTURES IN THE FALL

Forty-eight cross-bred heifers (371 kg) were utilized to study the effects of grazing
method. 4 or 13 paddocks, and stocking rate, 5.3 and 10.5 heifers/ha, on ADG and gain
per hectare stock-piled alfalfa forage. Alfalfa was stock-piled from September 1, 1989
until October. 12, 1989. On October 7, 1989, heifers were weighed and allowed ad
libitum access to alfalfa haylage and water for the next week prior to initiation of the
study. The heifers were divided into 2 weight blocks (354 kg, 388 kg) and randomly
assigned to 1 of 4 grazing treatment combinations. On October 12, 1989 heifers were
weighed full. and following 16 h without feed and water, a shrunk weight was
determined. On October 14, heifers were fed alfalfa haylage and transported .8 km to
the alfalfa pasture. On pasture, heifers had ad libitum access to water and a poloxalene
block. Heifers were rotated through 1 grazing cycle and were moved to the next
paddock based on forage availability. Forage samples were collected from each paddock
prior to heifer entry from 3 randomly placed quadrants (.5 x .5 m), and analyzed for DM
to determine forage presentation. When all paddocks had been grazed, heifers were
returned to the MSU Beef Cattle Research Center and withheld from feed and water for
16 h to determine a shrunk weight. Threedays later, a full weight was determined.
Average daily gain was determined from the difference between the 2 full or shrunk
weights. Gain per hectare was calculated by multiplying ADG x SR x Days on pasture.
Forage presentation is presented in Table D5 and animal performance and plot gains is

presented in Table D. 13.

190

 

Stocking rate nor GM influenced ADG primarily due to the large variation in
animal response. Unlike the grazing study over the summer, there was no clear
relationship among SR and ADG. Heifers from high SR plots spent 50% less (P< .05)
days on pasture than the low SR plots. This response would be expected with a fix
amount of forage but twice the number of animals. Live-weight gain per hectare and
forage present were similar for all plots. There was no clear trends in gains with the
amount of forage present. This would suggest that difference in forage quality may have
been produces the varied outcome. Although production from stock-piled alfalfa was
variable, the use of fall pasture can increase the amount of beef produced per hectare in

a given year.

Table 13.1. Effect of grazing method and stocking rate on live-weight gains and
forage presentation

 

Item 4-L 4-H 13-L 13-H SEM Effects‘
Average daily gain, kg .41 .56 .29 -.12 .54 - -
Days on pasture 34.5 18.0 35.0 17.0 .48 SR
Gain per hectare, kg 74.6 105.0 53.5 -12.3 96.3 - -

Forage presentation, kg/ha 1424 1337 1475 1504 93 - -
—

'Main effect statistical significance, (P< .05)

191

APPENDIX F: PROBLEMS ENCOUNTERED THROUGHOUT

THE 4 YEAR GRAZING STUDY

YEAR 1: 1989
5-19-89 Steers in plots 1-4 were placed on pasture.
5-20-89 Steers in plots 6-9 were placed on pasture.
The staggered start was done to save time but caused more work because
instead of sampling paddocks every 3 days, samples needed to be collected 2
out of every 3 days.
5-30—89 5.4 cm of rain
6-1-89 1100 Steers in plot 3 and 6 were moved to the alleys to prevent
trampling of paddocks. (1.4 cm of rain)
Afternoon Steers were moved to drier paddocks.
Plots 1—4, next paddock
Plots 6-9, last paddock, because central paddocks were
low lying
6—4-89 Moved cattle in plots 6 and 9 due to wet paddocks. (.9 cm rain)
6-5-89 Steer #113 was noticed with sunburn (photosensitivity).
6-6-89 Steer #3 (plot 11) observed with photosensitivity.
Noticed 4-1-1 plots low in forage (1“ indication that the paddocks were
overstocked).
6-7-89 Additional steers became photosensitive.
Hay field cut, but center part of plot 5 and west side of plot 10 were not due
to wet ground.
6—9-89 A11 paddocks previously grazed were sprayed with Sevin [Carbaryl (l-naphthyl

N-methyl carbamate)] to control alfalfa weevils.

192

 

193

Year 1 (Cont’d.)

6-13-89

6-15-89

6—21-89

6-25-89

6-26-89

6-27-89

7-9-89

7-11-89

7-26-89

8-2-89

8-18-89

8-20-89

One-third of the cattle were removed from the study to reduce the stocking
rate.

9 steers: not photosensitive

21 steers: showing photosensitivity
1 steer: with one testicle

1 steer: with an infected ear implant

Cattle from plots 2,3,6, and 9 were placed on supplemental pasture.

Duodenal cannulas came out of the duodenally fistulated steers, and re-
inserted. (cannulas were made of silastic tubing)

Steers in plots 4 and 12 were placed on supplemental pasture.

Steers in plots 1,7, and 8 were moved to supplemental pasture.

Steers in plot 11 were moved to supplemental pasture.

Steers were fed alfalfa hay (2.3 kg DM/steer) and allowed access to water and
poloxalene-mineral mix. At 1600 fed, water and poloxalene-mineral mix were

removed for a 16 h shrink.

A shrunk weight was determined on all steers, fed alfalfa hay as the day
before and placed back on assigned plots

Steer #91 looked bloated, administered a mixture of poloxalene-mineral mix
and water, and .9 L of mineral oil

Steer #2981 (esophageally fistulated) collapsed, because its esophageal cannula
fell out.Other steers which lost their cannulas had the fistulae grow shut, but
in the case of #2981, the fistulae did not close and the steer die of
dehydration.

Pump engine on mobile water tank broke, and cattle had to be water by
gravity (repaired next day).

Potato leaf hopper infested the alfalfa field. The hay fields were affected to
a greater extent than the pastures.

Steer #75 found dead of bloat (steer jumped fence and grazed lush alfalfa).

Esophageal steers #9 and #95 were bloated from jumping a fence into lush
pasture. Steers were given .5 to l L of mineral oil by stomach tube.

194
Year 1 (Cont’d.)

8-21-89 Plot 8 was out of forage, so steers received 4.5 kg alfalfa hay per steer to
maintain similar rate of growth.

Seven steers from plot 12 were bloated. Steers were given .5 to l L of
mineral oil.

8-22-89 Steers in plot 8 were given 4.5 kg alfalfa hay per steer.

8-23-89 Steers in plot 4 and 8 were moved to lush supplemental pasture and given 2.3
kg alfalfa hay per steer to try to reduce incidence of bloat.

8-24-90 Steers on supplemental pasture were moved to the next paddock.

825-89 0800 Steer #58 and #29 were found dead of bloat, but the remaining
steers were fine.

1500 Steer #68 was found dead, and #2 was severely bloated. After
attempts were made to relieve the bloat, steer #2 died. Seven
additional steers were bloated and were stomach tube to relieve the
bloat.

8-29-89 All steers removed from pasture.
10-12-89 Cross-bred heifers used for fall grazing study and not tame and will not stay
in their assigned paddocks. Also the fence charger is weak and not charging

the fence to its maximum potential

11-15-89 A few inches of snow fell prompting removing the heifers from pasture.

YEAR 2: 1990

5-14-90 Steers moved to pasture.

5-15-90 Steers did more walking around the paddocks as if they did not know what to
eat.

5-29-90 Low stocked plots infested with curly dock.
6-6-90 Canadian thistle started to infest pastures.

6-21-90 Five steers were treated for pink eye. Steer #42 was blind in one eye from
pink eye

195
Year 2 (Cont’d.)

6-29-90 Four steers treated for pink eye.
7-4-90 Two steers were treated for pink eye.

7-18-90 Three steers were treated for pink eye.

7-29-90 Two steers were treated for pink eye.

8-1-90 Two esophageally fistulated steers lost cannulas, although, the cannulas were
replaced.

8-3-90 Steer #42 contracted pink eye in the second eye and become totally blind, but
eating and doing well.

8-30-90 Steers removed from pasture.

YEAR 3: 1991

5-13-91 Steers placed on pasture.

6-5-91 Alley-ways were bush-hogged to increase fence voltage.
6-6-91 Four steers treated for pink eye.

7-15-91 One steer treated for pink eye.

9-2-91 Steers removed from pasture.

YEAR 4: 1992

5-13-92 Steers placed on pasture.
7-20-92 Steer #731 died of bloat.
8-9-92 Steer found with lacerated leg.

9-8-92 Steers removed from pasture.

 

 

 

196

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LIST OF REFERENCES

LIST OF REFERENCES

Amoroso, E.C., R.M. Loosmore, C. Remington, and BE. Tooth. 1957. Congenital
porphyria in bovines: First living cases in Britain. Nature. 1801230.

Anand, B.K., G.S. Chhina, K.N. Sharma, S. Dua, and B. Singh. 1964. Activity of
single neurons in the hypothalamic feeding centers: effect of glucose. Am. J.
Physiol. 207:1146.

Analytical Methods Committee. 1960. Methods for the destruction of organic matter.
Analyst. 85:643.

Anderson, S.J., T.J. Klopfenstein, and V.A. Wilkerson. 1988. Escape protein
supplementation of yearling steers grazing smooth brome pastures. J. Anirn. Sci.
66:237. -

AOAC. 1984. Official Methods of Analysis ( 14th Ed.). Association of Official Analytical
Chemists, Arlington, VA.

Aremu, B. , and H.W. Essig. 1992. Grazing management of newly established endophyte
free pasture. J. Anim. Sci. 70(Supp1. 1):187 (Abstr.).

Arnold, G.W. 1970. Regulation of food intake in grazing animals. In: A.T. Phillipson
(Ed.) Physiology and Metabolism in the Ruminant. p 264. Oriel Press Limited,
Newcastle, UK.

Baile, C.A., A.W. Mahoney, and J. Mayer. 1968. Induction of hypothalamic aphagia
and adipsia in goats. J. Dairy Sci. 51:1474.

Baile, CA. and J. Mayer. 1970. Hypothalamic centers: Feedbacks and receptor sites in
the short-term control of feed intake. In: A.T. Phillipson (Ed.) Physiology and
Metabolism in the Ruminant. p 254. Oriel Press Limited, Newcastle, UK.

Baile, CA. and J. Mayer. 1969. Depression of feed intake of goats by metabolites
injected during meals. Am. J. Physiol. 217:1830.

Baile, CA. and J. Mayer. 1968. Hypothalamic temperature and the regulation of feed
intake in goats. Am. J. Physiol. 214:677.

197

198

Baker, RD. 1982. Estimating herbage intake from animal performance. In: J .D. Leaver
(Ed.) Herbage Intake Handbook. p 77. Br. Grassl. Soc., Hurley, Maidenhead,
Berkshire, UK.

Balch, CG, and RC. Campling. 1962. Regulation of voluntary food intake in
ruminants. Nutr. Abstr. Rev. 32:669.

Barnes, D.K., and CC. Sheaffer. 1985. Alfalfa. In: M.E. Heath, R.F. Barnes, and D.S.
Metcalfe (Ed.) Forages, the Science of Grassland Agriculture. p 89. Iowa State
Univ. Press, Ames.

Bamhart, S., W.F. Wedin, M.A. Sanderson, and W. Fruehling. 1987. Alfalfa and
crownvetch as legumes for long-term pasture. Beef Cattle Res. Rep. Iowa State
Univ. p 95.

Bartley. E.E., T.G. Nagaraja, E.S. Pressman, A.D. Dayton, M.P. Katz, and LR. Fina.
1983. Effects of lasalocid or monensin on‘legume or grain (feedlot) bloat. J. Anim.
Sci. 56:1400.

Bateman, G.Q., and W. Keller. 1956. Grass-legume mixtures for irrigated pastures for
dairy cows. Utah Agric. Exp. Sta. Bull. No. 382.

Baylor, J.E. 1991. Hay Management in North America. In: K.K. Bolsen (Ed.) Field
Guide for Hay and Silage Management in North America. p 13. National Feed
Ingredients Association, Des Moines.

Blaser, RB. 1986. Forage-Animal Management Systems. Virginia Agricultural
Experiment Station. Bulletin 86-7. Virginia Polytechnic Institute and State Univ.,
Blacksburg.

Blood, D.C. , O.M. Radostits, and J .A. Henderson. 1983. Veterinary Medicine, Bailliere
Tindall, London, UK. '

Brandyberry, S.D., R.C. Cochran, E.S. Vanzant, and D.L. Harmon. 1991. Technical
Note: Effectiveness of different methods of continuous marker administration for
estimating fecal output. J. Anim. Sci. 69:4611.

Brownlee, H. 1973. Effects of four grazing management systems on the production and
persistence of dryland lucerne in central western New South Wales. Austr. J. Exp.
Ag. Anim. Husb. 13:259.

Brummer, EC, and J.H Bouton. 1992. Physiological traits associated with grazing-
tolerant alfalfa. Agron. J. 84:138.

199

Brummer, EC, and J.H Bouton. 1991. Plant traits associated with grazing-tolerant
alfalfa. Agron. J. 88:996.

Buntinx, S.E., K.R. Pond, D.S. Fisher, and J .C. Burns. 1992. Evaluation of the captec
chrome controlled-release device for the estimation of fecal output by grazing
sheep. J. Anim. Sci. 70:2243.

Burlison, A.J. , and J. Hodgson. 1985. The influence of sward structure on the mechanics
of the grazing process in sheep. Anim. Prod. 402530 (Abstr.). '

Bun'is, R., J. Randolph, N. Gay, M. Rasnake, and G. Lacefield. 1993. Univ. of
Kentucky Beef Cattle Res. Rep. p 17.

Campling, RC. 1970. Physical regulation of voluntary intake. In: A.T. Phillipson (Ed.)
Physiology and Metabolism in the Ruminant. p 226. Oriel Press Limited,
Newcastle, UK.

Campling, RC, and CC. Balch. 1961. Factors affecting the voluntary intake of food
by cows. 1. Preliminary observations on the effect, on the voluntary intake of hay,
of changes in the amount of the reticqu-ruminal contents. Br. J. Nutr. 15:523.

Cheeke. PR. 1971. Nutritional and physiological implications of saponins: A review.
Can. J. Anim. Sci. 51:621.

Christian, K.R. , D.B. Jones, and M. Freer. 1970. Digestibility and chemical composition
of fractions of lucerne during spring and summer. J. Agric. Sci. (Camb.) 75:213.

Clare, N.T. 1952. Photosensitization in diseases of domestic animals: A review.
Ruakura Anim. Res. Sta. Dept. Agric. No. 3, Hamilton, New Zealand.

Clare, N.T. 1955. Photosensitization in Animals. Adv. Vet. Med. 2:182.

Clarke. R.T.J., and C.S.W. Reid. 1974. Foamy bloat of cattle. A review. J. Dairy Sci.
57:753.

Clarke, R.T.J., and C.S.W. Reid. 1970. Legume Bloat. In: A.T. Phillipson (Ed.)
Physiology of Digestion and Metabolism in the Ruminant. p 599. Oriel Press
Limited, Newcastle, UK.

Cochran, R.C., E.S. Vanzant, K.A. Jacques, M.L. Galyean, D.C. Adams, and JD.
Wallace. 1987. Internal Markers. Proceedings, Grazing Livestock Nutrition
Conference. July 23-24, Jackson, Wyoming. p. 39.

Cooke, D.A., S.E. Beacem, and WK. Dawley. 1965. Pasture productivity of two grass-
alfalfa mixtures in northeastern Saskatchewan. Can. J. Plant Sci. 45:162.

 

200

Corah, L., and E.E. Bartley. Alfalfa grazing - the other alternative. Coop. Ext. Serv.
Great Plains States. No. GPE-1850.

Cornelius, C.E., I.M. Arias, and BI. Osbum. 1965. Hepatic pigmentation with
photosensitivity: A syndrome in Corriedale sheep resembling Dubin—Johnson
syndrome in man. J. Am. Vet. Med. Assoc. 146:709.

Daniels, F., Jr. 1965. A simple microbiological method for demonstrating phototoxic
compounds. J. Invest. Dermatol. 44:259.

Davis, AG. 1947. Luceme growing. Empire J. Exp. Agric. 15:113.

Dodds, D.L., W.T. Barker, and DR. Kirby. 1985. Grazing systems. North Dakota
Coop. Ext. Serv. No. R-559.

Dougherty, C.T., N.W. Bradley, L.M. Lauriault, P.L Cornelius, and M. Collins. 1990.
Alfalfa intake of grazing beef cattle. Univ. of Kentucky 1990 Beef Cattle Res.
Rep. Progress Rep. No. 326. p 19.

Douglas, J .A. 1986. The production and utilization of lucerne in New Zealand. Grass
Forage Sci. 1:81.

Douglas, J .A., and RC. Wilkinson. 1976. A preliminary trial on the spring grazing of
lucerne. Proc. N. Z. Grassl. Assoc. 37:248.

Ellis, D.J., R.H. Bamer, D. Madden, I. Melcer and J.M. Orten. 1958. Congenital
porphyria (pink tooth) in Michigan. M.S.U. Vet 18:89.

Ernst, P., Y.L.P. Le Du, and L. Carlier. 1980. Animal and sward production under
rotational and continuous grazing management - a critical appraisal. In: W.H. Prins
and G.H. Arnold (Ed.) The Role of Nitrogen in Intensive Grassl. Production. p
119. Pudoc, Wageningen, Netherlands.

Evans, M.A.B. 1987. Photosensitization: A case report. Bov. Pract. 22:209.

Fletcher, LR. 1976. Effect of season and regrowth period on the in vitro digestibility
of irrigated lucerne in Canterbury. N. Z. J. Exp. Agric. 4:469.

Forbes. T.D.A., and J. Hodgson. 1985. Comparative studies of the influence of sward
conditions on the ingestive behavior of cows and sheep. Grass Forage Sci. 40:69.

Fourie, P.J.J. 1936. The occurrence of congenital porphyrinuria (pink tooth) in cattle in
South Africa (Swaziland). Onderstepoort J. Vet. Sci. Anim. Indust. 7:536.

201

F raser, CM. 1986. The Merck Veterinary Manual: A Handbook of Diagnosis. Therapy,
and Disease Prevention and Control for the Veterinarian (6th Ed.). Merck and
Co., Inc. Rahway, NJ.

Gill J .L. 1978a. Design and Analysis of Experiments in the Animal and Medical Sciences
(Vol. 1). Iowa State Univ. Press, Ames.

Gill J .L. 1978a. Design and Analysis of Experiments in the Animal and Medical Sciences
(Vol. 3). Iowa State Univ. Press, Ames.

Glenn, B.L., A.W. Monlux, and R.J. Panciera. 1964. A hepatogenous photosensitivity
disease of cattle: 1. Experimental production and clinical aspects of the disease.
Path. Vet. 1:469.

Greenhalgh, J.F.D. 1982. An introduction to herbage intake measurements. In: J.D.
Leaver (Ed.) Herbage Intake Handbook. p 1. Br. Grassl. Soc., Hurley,
Maidenhead, Berkshire, UK.

Gronwall, R. 1970. Sulfobromophthalein sodium excretion and hepatic storage in
Corriedale and Southdown sheep with inherited hepatic dysfunction. Am. J. Vet.
Res. 13:2131.

Grovum, WI. 1988. Appetite, palatability and control of feed intake. In: DC. Church
(Ed.) The Ruminant Animal, Digestive Physiology and Nutrition. p 202. Prentice
Hall. Englewood Cliffs. NJ.

Hamilton, R.J., J.M. Scholl, and A.L. Pope. 1969. Performance of three grass species
grown along and with alfalfa under intensive pasture management: Animal and
plant response. Agron. J. 61:357.

Hancock, JJ. 1950. Congenital photosensitivity in Southdown sheep. N. Z. J. Sci.
Tech. A32216.

Harrison, C .M., C .L. Cole, and BC. Rather. 1941. Continuous and rotational grazing
of alfalfa-brome grass pasture with ewes and lambs. Soil. Sci. Soc. of Am. 6:303.

Harrison, J.H., and S.Fransen. 1991. Silage management in North America. In: K.K.
Bolsen (Ed.) Field Guide for Hay and Silage Management in North America. p 13.
National Feed Ingredients Association, Des Moines.

Heath, M.E., R.F. Barnes, and D.S. Metcalfe. 1985. Forages, the Science of Grassl.
Agriculture (4th Ed.). Iowa State Univ. Press, Ames.

Hetherington, A.W., and SW. Ranson. 1942. The spontaneous activity of food intake
of rats with hypothalamic lesions. Am. J. Physiol. 136:609.

202

Hintx. R.W. and K.A. Albrecht. 1991. Prediction of alfalfa chemical composition from
maturity and plant morphology. Crop Sci. 31:1561.

Hodgson. J. 1982. Influence of sward characteristics on diet selection and herbage intake
by the grazing animal. In: J.B. Hacker (Ed.) Nutritional limits to animal
production from pastures. p 153. Commonwealth Agric. Bureaux, ‘Farnham
Royal, UK.

Holmes, W. 1989. Grass: Its Production and Utilization (2nd Ed.). Blackwell Scientific
Publ. Boston.

Horn, F.P. , and GE. Miller. 1979. Bovine boots - a new research tool. Oklahoma State
University Animal Science Res. Rep. p 44.

Hoveland, C.S., N.S. Hill, R.S. Lowrey, Jr., S.L. Fales, M.E. McCormick, and AB.
Smith, Jr. 1988. Steer performance on birdsfoot trefoil and alfalfa pasture in
central Georgia. J. Prod. Agric. 1:343.

Howarth, RE. 1975. A review of bloat in cattle. Can. Vet J. 16:281.

Hubbard, W.A., and H.H. Nicholson. 1964. Irrigated grass-legume mixtures as summer
pasture for yearling steers. Can. J. Plant Sci. 44:332.

Ittner, N .R., G.L. Lofgreen, and J .H. Meyer. 1954. A study of pasturing and soiling
alfalfa with beef steers. J. Anim. Sci. 13:37.

Iverson, CE. 1967. Grazing management of lucerne. In: R.H.M. Langer (Ed.) The
Luceme Crop. p. 129. Reed, Wellington, New Zealand.

Jamieson, W.S., and J. Hodgson. 1979. The effect of daily herbage allowance and sward
characteristics upon the ingestive behavior and herbage intakes of calves under
strip—grazing management. Grass Forage Sci. 34:261.

Jason, CG. 1974. Lucerne management for the critical spring period under light land
grazing. Proc. N. Z. Grassl. Assoc. 36:66.

Jason, C.G. 1975a. Interaction of maturity stage and defoliation duration in the simulated
grazing of irrigated lucerne. N. Z. J. Exp. Agric. 3:63.

Jason, C.G. 1975b. Influence of autumn-winter lucerne management and overdrilled
’Grassl.s Tama’ or Spring herbage yields under irrigation and dry conditions. N.
Z. J. Exp. Ag. 3:229.

Johnson, AB. 1986. Derrnatotoxic Plants. In: J .L. Howard (Ed.) Current Veterinary
Therapy Food Animal Practice. p 406. W.B. Saunders Co., Philadelphia.

203

Jones, W.T., and J .W. Lyttleton. 1972. Bloat in cattle XXXVI. Further studies on the
foaming properties of soluble leaf proteins. N. Z. Agric. Res. 15:267.

Joyce, J .P. , and L.C.F. Brunswick. 1975a. Sodium supplementation of livestock grazing
lucerne. Proc. Ruakura Farmer’s Conference 27:35.

Joyce, J .P., and L.C.F. Brunswick. 1975b. Sodium supplementation of sheep and cattle
fed lucerne. N. Z. J. Exp. Agric. 3:299.

Joyce, J .P., and L.C.F. Brunswick. 1977. Beef Production from lucerne. Proc. N. Z.
Soc. of Anim. Prod. 37:67.

Jung, G.A., L.L. Wilson, P.J. LeVan, R.E. Kocher, and R.F. Todd. 1982. Herbage and
beef production from ryegrass alfalfa and orchard-grass-alfalfa. Agron. J. 74:937.

Karges, K.K., T.J. Klopfenstein, V.A. Wilkerson, and DC. Clanton. 1992. Effects of
ruminally degradable and escape protein supplements on steers grazing summer
native range. J. Anim. Sci. 70:1957.

Katz, M.P., T.G. Nagaraja, and LR. Fina. 1986. Ruminal changes in monensin- and
lasalocid-fed cattle grazing bloat-provocative alfalfa pasture. J. Anim. Sci.
63:1246. '

Le Du, Y.L.P. and PD. Penning. 1982. Animal based techniques for estimating herbage
intake. In: J.D. Leaver (Ed.) Herbage Intake Handbook. p 37. Br. Grassl. Soc.
Hurley, Maidenhead, Berkshire, UK.

Leach, G.J. 1978. The ecology of lucerne pastures. In: J .R. Wilson (Ed.) Plant Relations
in Pastures. p 290. Commonwealth Scientific and Industrial Research
Organization, East Melbourne, Australia,.

Leach, G.J. 1979. Regrowth characteristics of lucerne under different systems of grazing
management. Austr. J. Agric. Res. 30:445.

Leaver, JD. 1982. Herbage Intake Handbook. Br. Grassl. Soc. Hurley, Maidenhead,
Berkshire, UK.

Leng, R.A., and J .R. McWilliam. 1973. Bloat. Reviews in Rural Science No. 1. Univ.
of New England, Armidale, New South Wales, Australia.

Levin, E.V. 1968. Uroporphyrinogen III cosynthetase in bovine erythropoietic porphyria.
Science. 161 :907.

Lofgreen, G.P., J .H. Meyer, and ML. Peterson, 1956. Nutrient consumption and
utilization from alfalfa pasture, soilage, and hay. J. Anim. Sci. 1521158.

I-

 

204

Lofgreen, G.P., J .H. Meyer, and J .L. Hull. 1957. Behavior patterns of sheep and cattle
being fed pasture or soilage. J. Anim. Sci. 16:773.

Mader, TL, and G.W. Horn. 1986. Low quality roughages for steers grazing wheat
pasture. II Effect of wheat forage intake and utilization J. Anim. Sci. 62:1113.

Manning, TO. 1984. Noninfectious Skin Diseases of Cattle. Vet. Clin. North Am.
Large Anim. Pract. 6:175.

Marsh, R., and L.F.C. Brunswick. 1978. Beef production from lucerne and
luceme/prairie grass swards on the pumice soils of the Taupo region. Proc. N. Z.
Grassl. Assoc. 39:79.

Marten, G.C., and RM. Jordan. 1972. Put-and-take vs. fixed stocking for defining three
grazing levels by lambs on alfalfa-orchardgrass. Agron. J. 64:69.

Marten, G.C., F.R. Ehle, and EA. Ristaw. 1987. Performance and photosensitization
of cattle related to forage quality of four legumes. Crop Sci. 27:138.

Marten, G.C., R.M. Jordan, and EA. Ristau. 1990. Performance and adverse response
of sheep during grazing of four legumes. Crop Sci. 30:860.

Matches, AG, and J .C. Burns.1985. Systems of grazing management. In: M.E. Heath,
R.F. Barnes, and D.S. Metcalfe (Ed.) Forages: The Science of Grassland
Agriculture (4th Ed.). p 537. Iowa State Univ. Press, Ames.

Mayer, J., R.G. French. C.F. Zighera, and R.J. Barnett. 1955. Hypothalamic obesity
in the mouse. Am. J. Physiol. 182:75.

McClymont, G. L. 1967. Selectivity and intake in the grazing ruminant. In: C. F. Code
(Ed. ) Handbook of Physiology, Section 6. Alimentary Canal, Vol. 1, Food and
Water Intake. p 129. Am. Physiol. Soc., Washington, D. C.

McClymont, G.L. 1973. The ecology of bloat. In: R.A. Leng and J .R. McWilliam (Ed.)
Bloat. Reviews in Rural Science No. 1. p 3. Univ. of New England, Armidale,
New South Wales, Australia.

McCollum, F.T. 1990. Relationships among fecal nitrogen, diet nitrogen, and daily gain
of steers grazing tall grass prairie. 1990. Oklahoma State Univ. Animal Science
Res. Rep. p 232.

McDougall, El. 1948. Studies of ruminal saliva. I. The composition and output of
sheep’s saliva. Biochem. J. 43:49.

 

205

McGavin, M.D., C .E. Cornelius and R.R. Gronwall. 1972. Lesions in Southdown sheep
with hereditary hyperbilirubinemia. Vet. Path. 9:142.

McGiIl, L.D., D.L. Cross, B.W. Pinkerton, W.C. Stringer, G.C. Skelley, and CE.
Thompson. 1989. Comparison of continuous vs intensive grazing systems on
interseeded fescue-rye pastures. Clemson Univ. Animal Science Highlights. p 7.

McGraw, R. L. and G. C. Marten. 1986. Analysis of primary spring growth of four
pasture legume species. Agron. J. 78: 704.

McIntosh, J .T., and F.R.M. Cockrem. 1977. Genetics of the susceptibility of bloat in
cattle 11. Preliminary results from saliva samples from cows of high and low
susceptibility. N. Z. J. Agric. Res. 20:263.

McKinney, G.T., A. Axelsen, and F.H.W. Morley. 1970. The consumption of lucerne
by sheep at pasture. Proc. Aust. Soc. Anim. Prod. 8:466.

McKinney, GT. 1974. Management of lucerne for sheep grazing on the southern
tablelands of New South Wales. Austr. J. Exp. Agric. Anim. Husb. 14:726.

Meijs, J.A.C., R.J.K. Walters, and A. Keen. 1982. Sward Methods. In: J.D. Leaver
(Ed.) Herbage Intake Handbook. p 1. Br. Grassl. Soc. Hurley, Maidenhead,
Berkshire, UK.

Mendel, V.E., and J .M. Boda. 1961. Physiological studies of the rumen with emphasis
on the animal factors associated with bloat. J. Dairy Sci. 44:1881.

Meyer, J .H., G.P. Lofgreen, and N .R. Ittner. 1956. Further studies on the utilization
of alfalfa by beef steers. J. Anim. Sci. 15:64.

Michigan Agricultural Statistics Service. 1992. Michigan Agricultural Statistics.-
Michigan Dept. of Agric., Lansing.

Miller, P.S., W.N. Garret, and N. Hinman. 1991. Effects of alfalfa maturity on energy
utilization by cattle and nutrient digestibility by cattle and sheep. J. Anim. Sci.
6922591.

Miltimore, J.E., J.M. McArthur, J.L. Mason, and D.L. Ashby. 1970. Bloat
investigations. The threshold fraction 1 (18S) protein concentration for bloat and
relationships between bloat and lipid, tannin, Ca, Mg, Ni and Zn concentrations
in alfalfa. Can. J. Anim. Sci. 50:61.

Minson, DJ. 1990. Forage in Ruminant Nutrition. Academic Press, Inc., Boston.

206

Momont, P.A., R.J. Pruitt, R.J. Emerick, and RH. Pritchard. 1990. Evaluation of
controlled release chromic oxide boluses and alkaline peroxide lignin as marker
methods to determine forage intake of ruminants. J. Anim. Sci. 68 (Suppl. 1):562
(Abstr.).

Mooso. G.D., D.G. Morrison, and CC. Willis. 1990. Effect of short duration grazing
on forage availability and quality. J. Anim. Sci. 68(Suppl. 1):577 (Abstr.).

NRC. 1984. Nutrient Requirements of Beef Cattle (6th Ed.). National Academy Press,
Washington, DC.

Nestel, BL. 1958. Bovine congenital porphyria (pink tooth), with a note on five cases
observed in Jamaica. Cornell Vet. 48:430.

O’Connor, KR 1970. Influence of grazing management factors on herbage and animal
production from lucerne pastures. Proc. N. Z. Grassl. Assoc. 32:108.

O’Connor, K.F., and E.W. Vartha. 1968. Factors affecting weed incidence in lucerne.
Proc. N. Z. Weed and Pest Control Conf. 21:54.

Penning, P.D., G.L. Steel. and RH. Johnson. 1984. Further development and use of an
automatic recording system in sheep grazing studies. Grass Forage Sci. 39:345. -

Pond, K.R. , J .C . Burns, and D.S. Fisher. 1987. External markers - use and methodology
in grazing studies. p 49. Proc. Grazing Livestock Nutr. Conf. July 23-24, Jackson,
WY.

Putnam, M.R., C.W. Qualls, L.E. Rice, L.J. Dawson, and WC. Edwards. 1986.
Hepatic enzyme changes in bovine hepatogenous photosensitivity caused by water-
damaged alfalfa hay. J. Am. Vet. Med. Assoc. 189:77.

Railsback, LT. 1938. A case report presented by the Southwest Missouri Vet. Assoc.
Vet. Med. 34:102.

Rather, HQ and C .M. Harrison. 1944. Alfalfa and smooth bromegrass for pasture and
hay. Michigan State College Agric. Exp. Sta. Circ. Bull. No. 189.

Rawn, DJ. 1989. Biochemistry. p 621. Neil Patterson Publishers, Burlington, N .C.
Reardon, TE 1980. Level of lucerne allowance and performance of 15-month-old

steers. In: Agricultural Research Division Annual Report 1979/80. p 68. N. Z.
Ministry of Agric. and Fisheries, Wellington, New Zealand (Abstr.).

207

Reeve, J .L., and M.J. Sharkey. 1980. Effect of stocking rate, time of lambing and
inclusion of lucerne on prime lamb production in north-east Victoria. Austr. J.
Exp. Agric. Anim. Husb. 20:637.

Reid, C.S.W., and A.T. Johns. 1957. Bloat in cattle on red clover 3. Treatment and
prevention with anti-foaming agents. N. Z. J. Sci. and Tech. A38:908.

Rhode, E.A., and CE. Cornelius. 1958. Congenital porphyria (pink tooth) in Holstein-
Fresian calves in California. J. Am. Vet. Med. Assoc. 132:112.

Romeo, G., and E.V. Levin. 1969. Uroporphyrinogen III cosynthetase in human
congenital erythropoietic porphyria. Proc. Nat. Acad. Sci. 68:856.

Rowe, L.D., J.O. Norman, D.E. Corrier, S.W. Casteel, B.S. Rector, E.M. Bailey, J.L.
Schuster, and J .C. Reagor. 1987. Photosensitization of cattle in southwest Texas:
Identification of phototoxic activity associated with Cooperia pedunculata. Am. J.
Vet. Res. 48:1658.

Ruckebusch, Y. 1988. Motility of the gastro-intestinal tract. In: DC. Church (Ed.) The
Ruminant Animal, Digestive Physiology and Nutrition. p 64. Prentice Hall,
Englewood Cliffs, NJ.

Ruth, G.R., S. Schwartz, and B. Stephenson. 1977. Bovine protoporphyria: The first
nonhuman model of the hereditary photosensitizing disease. Science 198:199.

SAS. 1987. SAS/STAT" Guide for Personal Computers (Version 6 Ed.). SAS Inst. Inc.,
Cary, NC.

Sassa, S., S. Schwartz, and G. Ruth. 1981. Accumulation of protoporphyrin IX from -
aminolevulini acid in bovine skin fibroblasts with hereditary erythropoietic
protoporphyria. J. Exp. Med. 153:1094.

Schelecher, F., M. Delverdier, P. Bezille, P. Cabanie, and J. Espinasse. 1991.
Observation on bovine congenital e'rythrocytic protoporphyria in the blonde
d'Aquitaine breed. Vet. Record 1292403.

Schmidt, S.P., C.S. Hoveland. E.D. Donelly and RA. Moore. 1985. Beef steer
performance on alfalfa and sericea Iespedeza pastures. Proceedings of the 4lst
Southern Pasture and Forage Crop Improvement Conference, Raleigh, NC. , May
20-22, 1985, p. 21.

Schmitz, E.G., J.C. Whittier, J.C. Henning, G.B. Garner, and RE. Morrow. 1989.
Comparison of four grazing systems using various number of paddocks. J. Anim.
Sci. 67(Supp1. 1):286 (Abstr.).

208
Scott, D.W. 1988. Large Animal Dermatology. W.B. Sanders Company, Philadelphia.

Sheaffer, C.C., G.D. Lacefield, and VI. Marble. 1988. Cutting schedules and stands.
In: A.A. Hanson, D.K. Barnes and R.R. Hill, Jr. (Ed.) Alfalfa and Alfalfa
Improvement, p 411, ASA-CSSA-SSSA, Madison.

Smetham, M.L. 1990. Pasture management . In: R.H.M. Langer (Ed.) Pastures, their
Ecology and Management. p 191. Oxford University Press, New York.

Smith, D., R.J.- Bula and RP. Walgenbach. 1986. Forage Management (5th Ed.)
Kendal/Hunt Publishing Co., Dobuque.

Smith, M.V. 1970. Effects of stocking rate and grazing management on the persistence
and production of dryland lucerne on deep sands. p 624 In Proc 11th Int. Grassl.
Congr., Surfers Paradise, Queensland, Australia, April 13 to 23. Univ. of
Queensland Press, St. Lucia.

Sollenberger, L.E., C.S. Jones, Jr., J.E. Moore, and W.R. Ocumpaugh. 1989. Steer
gains on limpograss and bahiagrass pastures. Univ. of Florida, Florida Beef Cattle
Res. Rep. p 21.

Southwood, OR, and G.E.~ Robards. 1975. Luceme persistence and the productivity of
ewes and lambs grazed at two stocking rates within different management systems.
Austr. J. Exp. Agric. Anim. Husb. 15:747.

Tharel, L.M. 1988. Rotational grazing on three bermudagrass cultivars. University of
Arkansas Current Topics on Beef Cattle Research in Arkansas. p 16.

The Forage and Grazing Terminology Committee. 1991. Terminology for Grazing Lands
and Grazing Animals. Pocahontas Press, Inc. Blacksburg.

Thompson, J.A., K.P. Sheridan, and BA. Hamilton. 1976. The effects of rates of
stocking with rotational grazing on the productivity of dryland lucerne at
Tamworth, New South Wales. Austr. J. Exp. Agric. Anim. Husb. 16:845.

Thompson, R.W., H.A. Fribourg, J.C. Waller, W.L. Sanders, J.H. Reynolds, J.M.
Phillips, S.P. Schmidt, R.J. Crawford, Jr., V.G. Allen, D.B. Faulkner, C.S.
Hoveland, J .P. Fontenot, R.J. Carlisle, and PP Hunter. 1993. Combined analysis
of tall fescue steer grazing studies in the eastern United States. J. Anim. Sci.
7121940.

Tilley, J .M.A., and RA. Terry. 1963. A two-stage technique for in vitro digestion of
forage crops. J. Br. Grassl. Soc. 18:104.

USDA. 1979. Soil Survey of Ingham County, Michigan. USDA, Washington, DC.

 

209

Van Keuren, R.W., and W.W. Heinemann. 1958. A comparison of grass-legume
mixtures and grass under irrigation as pastures for yearling steers. Agron. J.
50:85.

Van Keuren, R.W. , and G.C. Marten. 1972. Pasture production and utilization. In: C.H.
Hanson (Ed.) Alfalfa Science and Technology. p 641. Agronomy Monograph No.
15. Am Soc. Agron., Madison.

Van Keuren, R.W. and AG. Matches. 1988. Pasture production and utilization. In:
A.A. Hanson, D.K. Barnes and R.R. Hill, Jr. (Ed.) Alfalfa and Alfalfa
Improvement. p 515., ASA-CSSA-SSSA, Madison.

Voisin, A. 1988. Grass Productivity. Island Press. Washington, DC.

Wachenheim, C. 1991. The economic viability of intensive stocker cattle grazing
systems. MS. Thesis. Michigan State Univ. East Lansing.

Waggoner, J.W., S.L. Applegate, and DH. Shain. 1988. Feedlot performance of
yearling steers summered under different grazing schemes. Univ. of Wyoming
Stockmen’s Homecoming Roundup. p 28.

Walker, J.W., and R.K. Heitschmidt. 1989. Some effects of a rotational grazing
treatment on cattle grazing behavior. J. Range Manage. 42:337.

Walton, P.D., R. Martinex, and AW. Bailey. 1981. A comparison of continuous and
rotational grazing. J. Range Manage. 34:19.

Wass, W.M., and H.H. Hoyt. 1965. Bovine congenital porphyria: Hematologic studies,
including porphyrin analyses. Am. J. Vet. Res. 26:659.

Wedin, W.F., R.L. Willham, M.A. Sanderson, and D. Maxwell. 1987. Legume-grass
pasture effects on performance of steers varying in frame size: A progress report.
Iowa State Univ. Beef Cattle Research Report. p 91.

Welch, J.G., M. Clancy, and G.W. Vander Noot. 1969. Net energy of alfalfa and
orchardgrass hays at varying stages of maturity. J. Anim. Sci. 28:263.

Welch, J.G., and AP. Hooper. 1988. Ingestion of feed and water. In: DC. Church
(Ed.) The Ruminant Animal Digestive Physiology and Nutrition. p 64. Prentice
Hall, Englewood Cliffs, NJ.

Whittier, J .C., and EG. Schmitz. 1990. Optimizing pasture utilization through intensive
beef cattle grazing management systems. A review. p 89. Low Input Sustainable
Agriculture Beef & Forage Conference, June 13 to 14. Omaha, NE.