' ‘Ilulllllllllllll‘
(\ m3) ,

This is to certify that the
thesis entitled

AFFECT 0F DIETS VARYING IN FORAGE CONTENT
ON NUTRIENT DIGESTIBILITY, FEEDLOT

PERFORMANCE AND CARCASS CHARACTERISTICS
OF LAMBS

presented by

MATTHEW THOMAS SHANE

has been accepted towards fulfillment
of the requirements for

M.S. degree in ANIMAL SCIENCE

 

A

diam/égwgw

L
/ Major professor

Datefi/ /?X

0-7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

 

 

 

LIBRARY

Michigan State

University

 

 

PLACE lN RETURN BOX
to remove this checkout from your record.
TO AVOID FINES return on or before date due.

 

DATE DUE

DATE DUE

DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ma mam-p.14

AFFECT OF DIETS VARYING IN FORAGE CONTENT ON NUTRIENT
DIGESTIBILITY, FEEDLOT PERFORMANCE AND CARCASS
CHARACTERISTICS OF LAMBS
By

Matthew Thomas Shane

A THESIS
Submitted to
Michigan State University
in partial fiilfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Animal Science

1997

ABSTRACT

AFFECT OF DIETS VARYING IN FORAGE CONTENT ON NUTRIENT
DIGESTIBILITY, F EEDLOT PERFORMANCE AND CARCASS
CHARACTERISTICS OF LAIVIBS

By

Matthew Thomas Shane

A series of trials was conducted to determine nutrient digestibility, lamb performance
and carcass characteristics by lambs fed pelleted diets containing 25, 62.5 or 100%
forage. In the digestibility trial, dietary ME values and apparent digestibilities of
DM, OM, NDF and ADF decreased as dietary forage level increased. In performance
trial 1, lambs were fed either 25 or 100% forage diets at ad libitum or 85% of ad
libitum levels of intake. Lambs fed diets at ad libitum levels of intake had greater
ADG. Lambs fed 100% forage diets had lighter carcasses and less 12th rib fat. In
performance trial 2, lambs were fed a 62.5% forage diet at ad libitum or 85% of ad
libitum levels of intake. Lambs fed at ad libitum levels of intake had greater ADG,
heavier carcasses and more 12th rib fat. In performance trial 3, lambs were fed
25,625 or 100% forage diets at ad libitum levels of intake. Lambs fed the 62.5%
forage diet had the greatest ADG. As dietary forage level increased fat and carcass
weight tended to decrease. An economic analysis indicated that cost of gain could be
decreased by decreasing dietary forage level and(or) restricting feed intake to 85% of

ad libitum levels.

DEDICATION

I would like to dedicate this manuscript to the many individuals
who have touched my life.
To my parents Rona and Tom who have given me their love and
have always encouraged me to pursue my dreams.
To my sister, Laura, whose love of family has inspired me.
And to Jackie who has shown me that laughter is the secret of life

and continues to share my dreams.

ACKNOWLEDGMENTS

I would like to express my deepest appreciation and gratitude to Dr. Margaret
Benson for her valuable counsel throughout my graduate program. In addition, I am
deeply grateful to my committee members, Dr. Dennis Banks, Dr. Joe Rook and Dr. Herb
Bucholtz for their advice and review of this manuscript.

Appreciation is expressed to the Michigan State University sheep crew for the use
of facilities and research animals and their unfaltering friendship and support throughout
my graduate program. Acknowledgment is extended to Dr. Matt Doumit for his support
and for giving me the opportunity to develop skills in the meat science area.

Appreciation is expressed to Bob Burnett, Dave Main and Jane Link for
laboratory assistance, Tom Forton for his support and assistance and to other personnel
involved in this research project.

Special thanks are extended to Karen Waite for her friendship and support. My
deepest gratitude is extended to Mr. George Good who served as my Mentor throughout
my time at Michigan State University. I am deeply thankful to God for providing me

with both the opportunity and strength to complete this work.

iv

TABLE OF CONTENTS

Rage
LIST OF TABLES .................................................................................... vii
LIST OF FIGURE ........................................................................................ x
INTRODUCTION ....................................................................................... 1
Hypothesis ............................................................................................ 2
Objectives ............................................................................................ 2
CHAPTER 1 ................................................................................................ 3
LITERATURE REVIEW ......................................................................... 3
Feedlot Lamb Performance .................................................................. 3
Factors Affecting Intake and Digestibility of Diets
Varying in Forage Content ................................................................ 9
Nitrogen Balance of Diets Varying in Forage Content ...................... 17
Energy Balance of Diets Varying in Forage Content ........................ 24
Economic Analysis of Feeder Lamb Production ............................... 30
CHAPTER 2 .............................................................................................. 36
MATERIALS AND METHODS ............................................................ 36
Digestibility Trial ............................................................................... 36
Performance Trial 1 ........................................................................... 41
Performance Trial 2 ........................................................................... 43
Performance Trial 3 ........................................................................... 44
CHAPTER 3 .............................................................................................. 47
RESULTS AND DISCUSSION ............................................................. 47
Diet Digestibility ................................................................................ 47
Nitrogen Balance ............................................................................... 56
Energy Balance .................................................................................. 61
Feedlot Performance and Carcass Characteristics ............................. 69
Performance Trial 1 ......................................................................... 70
Performance Trial 2 ......................................................................... 73
Performance Trial 3 ......................................................................... 75
Economic Analysis ............................................................................ 77
CHAPTER 4 .............................................................................................. 81
SUMMARY ............................................................................................ 81

V

APPENDICES ........................................................................................... 83

APPENDIX A - ANOVA Tables - Digestibility Trial ......................... 83
APPENDIX B - ANOVA Tables - Performance Trial 1 ...................... 90
APPENDIX C - ANOVA Tables - Performance Trial 2 ...................... 92
APPENDIX D - ANOVA Tables - Performance Trial 3 ...................... 94
APPENDIX E - Volatile fatty acid production and methane
calculation - Digestibility Trial ........................................................ 96
LITERATURE CITED .............................................................................. 97

vi

LIST OF TABLES
Page
Table 1. Review of lamb performance on pelleted diets .............................. 4
Table 2. Review of performance as forage content of the diet increases ..... 7

Table 3. Review of the effect of forage to concentrate ratio (F :C)
on diet digestibility ................................................................................. 11

Table 4. Review of the influence of dietary particle size
on diet digestibility ................................................................................. 15

Table 5. Review of the effect of forage source on nitrogen (N) balance ...18

Table 6. Review of the effect of forage to concentrate ratio (F :C)

on nitrogen (N) balance ........................................................................... 20
Table 7. Review of the effect of feeding supplemental nitrogen (N)

on N balance ........................................................................................... 22
Table 8. Review of the effect of forage type on energy balance ................ 27
Table 9. Review of the effect of forage to concentrate ratio (F :C)

on energy balance .................................................................................... 29
Table 10. Non-feed costs associated with lamb production ....................... 32

Table 11. Lamb performance and cost of gain - computer simulation ..... 33

Table 12. Lamb performance and cost of gain - feedlot trial .................... 34
Table 13. Fat thickness requirements of the yield grading system ............ 35
Table 14. Diet composition (DM basis) - digestibility trial ....................... 37

Table 15. Diet chemical composition (DM basis),
digestibility trial - lightweight lambs ...................................................... 37

vii

LIST OF TABLES (cont’d)

Ease
Table 16. Diet chemical composition (DM basis),
digestibility trial - heavyweight lambs .................................................... 38

Table 17. Diet composition (DM basis)- performance trials 1,2, and 3 ....42

Table 18. Diet chemical composition (DM basis)
performance trials 1 and 2 ....................................................................... 43

Table 19. Diet chemical composition (DM basis) performance- trial 3 ....45
Table 20. Feed costs of dietary ingredients ................................................ 46

Table 21. Daily nutrient requirements for 40 and 50 kg
lambs gaining 345 and 300 g/d ............................................................... 47

Table 22. Feed intake prior to and during the
digestibility trial - lightweight lambs ...................................................... 49

Table 23. Feed intake prior to and during the
digestibility trial - heavyweight lambs .................................................... 49

Table 24. Least square means for dry matter,
organic matter, and fiber digestibility - lightweight lambs ..................... 51

Table 25. Least square means for CP, ME, NDF and ADF intakes-
lightweight lambs .................................................................................... 52

Table 26. Least square means for dry matter, organic matter,
and fiber digestibility - heavyweight lambs ............................................. 54

Table 27. Least square means for CP, ME, NDF and ADF intakes-
heavyweight lambs .................................................................................. 55

Table 28. Least square means for nitrogen balance -
lightweight lambs .................................................................................... 59

Table 29. Least square means for nitrogen balance -
heavyweight lambs .................................................................................. 60

Table 30. Least square means for energy balance -
lightweight lambs .................................................................................... 62

viii

LIST OF TABLES (cont’d)

P18:
Table 31. Least squrare means for energy balance -
heavyweight lambs .................................................................................. 62
Table 32. Least square means for fermentation balance
and ME estimation - lightweight lambs .................................................. 65
Table 33. Least square means for fermentation balance
and ME estimation - heavyweight lambs ................................................ 66

Table 34. Estimation of the ME values of the diets - lightweight lambs...68

Table 35. Estimation of the ME values of the diets —
heavyweight lambs .................................................................................. 68

Table 36. Least square means for lamb feed intakes, ADG, feed
conversions (GzF), HCW, LEA, FAT and DRESS values -
performance trial 1 ................................................................................... 72

Table 37. Least square means for lamb feed intakes, ADG, feed
conversions (GzF), HCW, FAT and DRESS values -
performance trial 2 ................................................................................... 74

Table 38. Least square means for lamb feed intakes, ADG, feed
conversions (GzF), HCW, LEA, FAT and DRESS values -
performance trial 3 ................................................................................... 76
Table 39. ADG and feed intake before and after day 56 ........................... 76

Table 40. Economic analysis of feedlot lamb production -
performance trials 1, 2 and 3 ................................................................... 79

ix

LIST OF FIGURE

283:

Figure 1. Scheme of energy metabolism (NRC, 1966)
with expected losses (NRC, 1985) ............................................. ' ............. 2 5

INTRODUCTION

Beef and lamb producers traditionally feed their livestock a concentrate based diet
to finish them for market. Rising grain prices, resulting in increased feed costs, have forced
producers to look at alternative feeding strategies and ingredients. Not only do producers
want to decrease their costs of production, they also want to maximize profits by receiving a
premium price for their livestock. Producing lean carcasses with adequate muscling is one
way producers can achieve optimum market prices. Diets with increased forage content
may have the potential to reduce feed costs, and produce leaner animals at slaughter.

A unique advantage of ruminants, compared to monogastrics, is their ability to
utilize forage to yield high quality carcasses (Bidner et al., 1986). In general, animals
finished on lower-energy diets have a smaller proportion of carcass fat than comparable
animals finished on higher energy diets (Bidner et al., 1986). Feeding practices that
maximize forage and minimize cereal grain usage could be the most desirable feeding
strategies, especially when the prices for feed grains are high.

Pelleting finely ground, dehydrated alfalfa may be a solution for producing leaner
lambs while decreasing feed costs. Some researchers have fed pelleted hay or chopped hay
in loose form to determine the effects on performance and carcass characteristics (Meyer et

al., 1959 and Weir et al., 1959). Others have tested feeding pelleted alfalfa with or without

2
concentrate supplementation to detemrine the effects on performance and carcass
characteristics (Cate et al., 1959). Another theory that was developed was that feeding the
animals at less than ad libitum levels of intake would improve performance and carcass

characteristics (Murphy et al., 1994).

Hypothesis
Increasing forage content of lamb diets from 25 to 100% will decrease nutrient

digestibility, decrease lamb performance, decrease carcass quality and increase cost of gain.

Objectives
A digestibility trial and three performance trials were designed to test the hypothesis
that the level of pelleted alfalfa in the diet would influence nutrient digestibility, lamb
performance and carcass characteristics. The objectives of these trials were:
1. To determine nutrient digestibility by lambs fed pelleted diets ranging from 25 to
100% forage.
2. To determine performance and carcass characteristics of lambs fed pelleted diets
ranging from 25 to 100% forage, fed at ad libitum or 85% of ad libitum levels of

intake.

CHAPTER 1

Literature Review

Feedlot Lamb Performance

Optimizing lamb performance means getting a lamb to market weight in the
shortest time possible with the lowest input costs. The key to increasing performance is
to feed diets that result in increased average daily gains (ADG), feed efficiency and
decreased days on feed. This can be accomplished by several methods: pelleting,
adjusting the foragezconcentrate ratio and supplementing low quality forages.
Lamb Performance on Pelleted Diets

Increased lamb gain and improved feed efficiency resulting from pelleting feed
have been reported by several authors (Cate et al., 1955; Weir et al., 1959 and Meyer et
al., 1959) (Table 1). In these studies, improved performance in pellet-fed animals was
due to increased feed consumption. When equal amounts of pelleted or ground feed were
fed, no differences in performance were obtained.

The results of studies conducted by Cate et al., 1955; Weir et a1, 1959 and Meyer
et al., 1959 are shown in Table 1. In their studies feed intake was improved an average of

11.3% when lambs were fed diets in pelleted rather than chopped or meal form.

Table 1. Review of lamb performance on pelleted diets

 

Study Diet* Intake ADG GainzFeed Carcass fat DP
kg/d kg/d % %
Cate et al., 1955 Pelleted' 1.31 0.20 0.15 51.6
Meal‘ 1.35 0.18 0.13 52.2
Pelletedz 1.70 0.23 0.14 52.0
Mealz 1.57 0.17 0.11 49.9
Pelleted3 1.59 0.20 0.13 50.6
Meal’ 1.40 0.13 0.09 49.0
Meyer et al., 1959 Pelleted“ 1.48 0.18 0.12 28.4
pelleted - 13‘ 1.14 0.12 0.10 30.8
Chopped‘ 1.14 0.12 0.11 30.8
Weir et al., 1959 Pelleteds 1.68 0.18 0.11 53.1
Choppeds 1.41 0.14 0.10 49.8
Pelleted6 1.45 0.16 0.1 1 55.2
Choppedé 1.27 0.14 0.11 52.4

 

*Diets fed at ad libitum levels of feed intake unless noted otherwise

' Pelleted - alfalfa and corn; Chopped - alfalfa and corn

2Pelleted - timothy, corn, molasses, soybean meal; Chopped - timothy, corn, molasses, soybean meal
3Pelleted - timothy and corn; Chopped - timothy and corn

‘Pelleted - alfalfa hay; Pelleted - B - alfalfa hay fed at level of chOpped hay consumption;
Chopped - alfalfa hay

5Pelleted - alfalfa hay; Chopped — alfalfa hay
6Pelleted - alfalfa hay plus 30% barley; Chopped - alfalfa hay plus 30% barley

5
However in the Cate et al. (1955) study, the lambs fed the higher quality alfalfa and corn

pellets consumed 3% less feed than the lambs fed the same diet in meal form. As a result
of the increased feed intake, lambs consuming pelleted diets also had increased ADG. In
the Meyer et a1. (1959) study a group of pellet fed lambs was fed at the same intake level
as the chopped hay fed lambs. In this case there was no increase in ADG or any other
performance characteristics. All three authors reported little or no effect on feed
efficiency by altering the form of the diet. Both Cate et al. (1955) and Weir et a1. (1959)
reported a 2% increase in dressing percent (DP) when pelleted diets were fed. However,
no difference in DP was reported by Cate et a1. (1955) when the high quality alfalfa and
corn diet was fed. Similarly, Meyer et a1. (1959) reported a 2.4% decrease in carcass fat
when the pelleted diet was fed at ad libitum levels of intake.

Feeding alfalfa and corn in pelleted form did not result in significant changes in
performance, therefore the increased cost of pelleting would not be justified. However,
pelleting lower quality timothy did show an improvement in lamb performance. Lambs
consuming these diets in pelleted form had increased feed intake resulting in increased
ADG. However, gain to feed ratios were not affected by pelleting diets. Cate et a1.
(1955) suggested that increased feed intake of pellets was a result of increased palatability
of the diet. Increased feed intake could be attributed to a decreased consumption time
and increased rate of passage from the rumen when pelleted diets were fed (Cate et al.,

1955; Weir et al., 1959 and Meyer et al., 1959).

6

Performance on Diets Varying in Forage Content

Several studies have shown an effect on feeder lamb performance based on the ratio
of forage to concentrate in the diet (Table 2). The caloric content of the diet increases with
increased level of concentrate, which causes an increase in energy retention and ultimately
an increase in performance (Kromann et al., 1975). However, increasing concentrate levels
too much can result in decreased feed intake and performance. High concentrate diets have
been shown to increase lactic acid content and lower pH values in the rumen (Meyer et al.,
1959). These authors suggest that an accumulation of lactic acid in the rumen tends to
lower appetite.

In the studies conducted by Oltjen et al. (1971), Kromann et al. (1975), Thomas et
al. (1984) and Glimp et al. (1989), increased forage levels caused an average of a 30%
increase in feed intake. Decreased feed intake of the high concentrate diets was attributed to
an excessive caloric content of these diets. These studies also showed a decrease in ADG as
forage level in the diet increased. However, Kromann et al. (1975) and Glimp et al. (1989)
did report a decrease in ADG when concentrate was increased above 85% and 72.5% of the
diets, respectively. The increase in performance was described by a curvilinear relationship
between energy gain and diet composition, which resulted from a decreased intake in high
(65 — 100%) com diets. The decreased intake was due to an increase in net energy (NE)
retention as corn increased in the diet, since more NE was available for production
(Kromarm et al., 1975). Days on feed increased as forage level increased in the Oltjen et al.
(1971) and Thomas et al. (1984) studies. However, days on feed were increased in the
Glimp et al. (1989) study when forage level was decreased to 10% of the diet. Thomas et al.
(1983) found no differences in intake, ADG or days on feed with increased forage content

of the diet.

0.58 8.3588 8 owes.“ 5 898:0 5:5 :08 38.—0&6 Ego—haw; oz 2....
93m 55 558 2:8 55 vogue—Eco beam .1.

09¢ ougeooeoo 8 owfiom e

 

 

oqam ES 0.: w©~ KN.— WNS cog Ho
ovfim 58 v6 MON no; amdfi 98— nega~ in “0 nob—O
neamz .8..st we mo; wNA cano—
ssemz .8..st mm HMN $6.— WNBHWHN
seamz 2..st an v—N No; mmumv owe in an 95—0
goodm OWNN mo“ :6 owd 8— Ho
o\ao_.vm cvdm ma: cfio 2V.— mwuwm
AXE—6N ofiom no“ o~d 2; omnow
o\oON.hN OMAN mo— cfio VMA 99: 3.2 a? «0 goa—
UDmNQHOOU UDWNDHOOU COMMOHODU “039—05 OWQDHUDU H60“: Omfluhua Hava— Cw OH ON VW@H F—fl HO goat—r
seamz seamz anmz saamz asamz . assimiz 00 8 ON mwo— in we 8895.
so we 33 can a.
Amn— HMM mmfluso .E mmflnvhdo “gunk GO m~ANQ 0% OMNHQH {Unnm %mvam

 

83803 3% 05 no 5880 amigo.“ we nuggetom .«o 32.6% .N oEaH

8
These studies suggest that pelleted diets containing less than 15% forage and greater than

75% forage may result in lower ADG compared to when forage is included at more
intermediate levels in the diets.

These same authors studied the significance of increasing forage content in the diet
on carcass composition (Table 2). Studies conducted by Thomas et al. (1983) and Glimp et
al. (1989) reported no differences in carcass weight, fat content or DP with increased dietary
forage content. Thomas et al. (1984) found carcass weight, fat content and DP were
decreased when forage content of the diet was increased. Kromann et al. (1975) reported a
linear increase in carcass weight and linear decrease in carcass fat as forage content
increased from 0 to 100%. Similarly, Oltjen et al. (1971) found steers fed 100% forage
diets had 44.7% less fat and 4.5% lower DP than steers fed 100% concentrate diets. The
decreased DP was attributed to decreased carcass fat. However, the decreases in DP
reported by Oltjen et al. (1971) and Thomas et al. (1984) were likely a result of increased
gut fill in animals fed high forage diets. Desired ADG and days on feed to produce
properly finished animals must be considered when selecting dietary feed ingredients.

The results of these studies indicate that varying foragezconcentrate ratio in diets fed
to lambs and steers can impact performance. Increasing forage level in the diet tends to
increase daily feed intake and reduce ADG resulting in increased days on feed. However,
increasing the amount of concentrate in the diet to 90% and above had a negative affect on
ADG and days on feed. This decrease in performance was likely a result of increased lactic
acid production in the rumen causing a decrease in appetite (Meyer et al., 1959). Altering
the foragezconcentrate ratio produced inconsistent effects on carcass weights and DP, but

animals fed high concentrate diets tended to have higher percentages of carcass fat. The

9

increase in carcass fat can be attributed to the increased caloric content of the high

concentrate diets, resulting in excess energy available for growth (Kromann et al., 197 5).

Factors Affecting Intake and Digestibility of Diets Varying in Forage Content

The objective of this section is to show that the improvements in feed intake and
performance shown previously are related to changes in the digestibility of the different
feed components. There are several factors that afl‘ect the intake and digestibility of diets
fed to ruminants. These factors include particle size of dietary components, pelleting of
feed ingredients and the frequency of feeding. In addition, one of the most important
factors is the amount of forage (vs. concentrate) in the diet. High forage diets contain more
cell wall components than high concentrate diets. The primary cell wall components are
cellulose, hemicellulose and lignin. Of these, cellulose and hemicellulose are potentially
digested and the extent to which they are digested is important in determining the nutritive
value of a diet. The lignin within the cell wall is indigestible and is thought to protect the
cellulose from digestion (Van Soest and Wine, 1967). Cereal grains may reduce roughage
intake due to the rapid fermentation of starch which lowers ruminal pH and, reduces or
retards the digestion of cellulose (ARC, 1980).

Digestion trials are usefirl because indigestibility accounts for the largest single loss
in nutrient utilization by ruminants (Colucci et al., 1989). Much of the digestibility data has
been collected from trials with sheep and assumes that cattle and sheep are equal in their
digestive capacity. The assumption is also made that variations in intake and type of diet
produce similar changes in digestibility of energy and other feed fractions in both species.
To validate the use of sheep as models for cattle in digestibility trials, Colucci et al. (1989)

conducted a study in which both species were compared at 2 levels of feed intake (ad

10
libitum and maintenance). At high dry matter intakes (DMI), Holstein cows digested less

organic matter (OM), energy, crude protein (CP), starch and soluble detergent matter than
wether lambs. When diets contained low, intermediate or high levels of concentrate (20,
45, and 70%, respectively) the digestibility of DM, OM and energy were positively and
linearly related to the proportion of concentrate in the diet for both cows and lambs fed at
maintenance and ad libitum levels of intake. Cell wall digestibility by both species
exhibited a positive relationship with proportion of concentrate at low intakes. At high
intakes, cell wall digestibility by lambs was not affected by forage level, whereas a negative
relationship was seen in cattle. Although concentrates are usually more digestible than
forages, and diet digestibility generally increases with increased concentrate in the diet; a
positive relationship between, OM digestibility or energy and amount of concentrate in the
diet does not always occur. When forages are replaced by concentrates in the diet, there is a
change in type and amount of fiber, which can change ruminal environment and retention
time of the feedstuffs (Colucci et al., 1989). The depression of digestibility of different feed
fractions with increasing intake was greater for cows than for sheep. For this reason, sheep
may not be accurate models for predicting digestibility in cattle, particularly at high intakes.
The impact of foragezconcentrate ratio on dietary intake and digestibility was
examined in several studies (Table 3). In general, decreased forage content in the diet
decreased digestibilities of neutral detergent fiber (NDF), acid detergent fiber (ADF) and
increased organic matter digestibility (OMD). In studies conducted by Weir et al. (1959),

Kromann et al. (1975), Reynolds et al. (1991) and Murphy et al. (1994), increased forage

content of the diets resulted in increases in DMI.

11

Table 3. Review of the effect of forage to concentrate ratio (F:C) on diet digestibility

Apparent digestibility, %

 

 

Study DMI F:C Intake" DMD” OMD*“"" NDF ADF
kg/d %
Reynolds et al., 1991a 5.1 25:75 100 77.0 77.6 49.2 42.1
6.3 75:25 100 65.2 66.4 39.7 34.2
Kromann et al., 1975 0.8 to 1.36 0 to 1002 100 decreased decreased
Lambert et al., 1987 NS1 0:100 90 82.8 73.8 81.5
NS1 60:40 90 64.5 56.2 55.0
198' 30:70 90 72.6 59.1 63.1
NS1 1000 90 61.5 63.8 60.6
Murphy et al., 1994 1.14 78:22 100 44.1 44.9 31.5 29.4
1.01 61:39 95 52.7 53.6 32.4 30.3
0.90 39:61 80 62.7 63.8 35.5 32.4
0.78 8:92 70 80.3 82.2 45.8 51.6
Merchen et al., 1986 0.72 100:0 2.7% BW 59.1 46.7 47.9
0.79 50:50 2.7% 13w 72.3 45.4 40.3
Weir et al., 1959 1.68 10003 100 47.0
1.41 70:303 100 42.0
1.45 1000 100 51.0
1.27 70:30“ 100 53.0

* Percent of ad libitum

"DMD - Dry matter digestibility

”*OMD - Organic matter digestibility
lNS - No significant difference in DMI among dietary treatments (P < .05)

25% increments from 0 to 100
3Pelleted diet

4Chopped diet

‘Cattle study

12
Differences in DMI of these diets could affect their rate of passage, which may explain the

decreased digestibility of the higher forage diets. It was also suggested by Kromann et al.
(1975), that as concentrate level increased above 85%, the fiber content of the diet
decreased to a level at which normal rumen function was likely impaired, resulting in
decreased DMI. In contrast to these studies, Merchen et al. (1986) and Lambert et al.
(1987) reported no differences in DMI with increasing dietary forage content.

As expected, dry matter digestibility (DMD) of the diets decreased with decreasing
proportions of concentrate, since concentrates generally contain more highly digestible cell
solubles than do forages (Merchen et al., 1986; Lambert et al., 1987; Reynolds et al., 1991
and Murphy et al., 1994). However Lambert et al. (1987), reported that the DMD of their
two intermediate forage diets were 6.5% lower than would be expected if the response were
linear. This non-linearity may be explained by increased DMI and DMD associated with
reduced dietary NDF content. A similar trend was reported by Reynolds et al. (1991) and
Murphy et al. (1994) for organic matter digestibility (OMD) which was attributed to
increased OM content of the high concentrate diets. It has been estimated that two-thirds of
OM digestion can occur in the rumen (F aichney and Gherardi, 1986) and a negative
relationship was reported between OMD and DMI. In addition, as intake increased towards
ad libitum levels, mean ruminal retention time in sheep fed luceme hay decreased more
rapidly when the hay was ground and pelleted than when it was chopped (F aichney and
Gherardi, 1986). Beardsley et al. (1959) also reported that elevated intakes on pelleted diets
were associated with increased rates of passage and decreased digestibility of finely ground

and pelleted feedstuffs.

13
Due to increased fiber content and increased DMI of high forage diets, fiber

digestibility was expected to decrease due to increased rates of passage Earn the rumen
(Kromann et al. (1975). In studies conducted by Kromann et al. (1975), Lambert et al.
(1987), Reynolds et al. (1991) and Murphy et al. (1994), there was an average decrease of
11.3% NDF digestibility and 17% ADF digestibility as dietary forage level increased. In
contrast to their work, Weir et al. (1959) reported a 3.5% increase in crude fiber digestibility
and Merchen et al. (1986) reported no difference in NDF digestibility and a 7.6% increase
in ADF digestibility as dietary forage level increased. These differences in NDF and ADF
digestibilities were attributed to decreased intake in corn supplemented lambs (Merchen et
al., 1986).

The physical characteristics of the roughage component of a ruminant diet are
important criteria in the animal's ability to utilize feedstuffs (Kerley et al., 1985). Pelleting
prevents selectivity of the more palatable dietary ingredients by sheep. Paladines et al.
(1964) found that pelleting of finely ground feeds increased feed intake of lambs as much as
22.6% compared to feeding the same diets in meal form. Similarly, Nocek and Kesler
(1980) found that calves fed a pelleted hay and concentrate diet consumed 20% more DM
than calves fed a similar conventional loose hay and concentrate diet. Pelleting increases
palatability of fine dusty feeds. Meyer et al. (1959) demonstrated that increased gains fi‘om
lambs fed a pelleted alfalfa hay diet compared to a chopped alfalfa hay diet was due to
increased feed intake. This increased intake appeared to be caused by an increased rate of
passage from the reticulorurnen of the finely ground feedstuff. In addition, OMD of
pelleted alfalfa hay did not differ fiom that of the chopped alfalfa hay.

Not only does pelleting or ch0pping affect intake and digestibility, but particle size

of the chopped forage may also influence intake and digestibility (Table 4). A study to

l4
evaluate the influence of particle size of diets fed to cattle, conducted by J aster and Murphy

(1983), determined DMD decreased with increased DMI resulting in increased rate of
passage. Dry matter intakes were greater when coarse and fine chopped hays were offered
compared to hay fed in long stem form. Digestibilities of DM and NDF were decreased
when comparing chopped hay to long hay. A trend for decreased fiber and DM
digestibilities was also apparent as particle size decreased. A similar increase in DMI was
seen in lambs fed ground alfalfa hay (1.9lcm) which consumed 6.4% less DM than lambs
fed low-moisture silage (0.64cm) (Merchen and Satter, 1983). However, they found that
OMD was unaffected by diet. Lambs fed alfalfa hay consumed more ADF than lambs fed
low-moisture silage (249 vs. 214 g/d), while ADF digestibility was identical for the two
forages. These results showed that feeding dry ground alfalfa hay or chopped low-moisture
alfalfa silage had no affect on OMD or ADF digestibilities due to the increased rate of
passage associated with the 0.64cm forage.

Other studies, where pelleted lambs were fed comcob and concentrate diets varying
in comcob particle size, found that DM, starch and NDF digestibilities did not differ
(Kerley et al., 1985 and Kinser et al., 1985). However, ADF digestibilities varied with
changes in particle size. Fecal DM excretion was highest for adult sheep fed the two diets
containing the smallest (.8-mm) comcob particles, when fed at 90% of ad libitum intake
levels (Kerley et al., 1985). Apparent total tract DM and NDF digestion varied little among

diets.

15

Table 4. Review of the influence of dietary particle size on diet digestibility

Apparent digestibility, %

 

 

Study Particle size DMI“ DMD" OMD*""" NDF ADF
kg/d

Merchen and Satter, 1983 1.91cm 0.575 62.8 54.0
0.64cm 0.614 64.3 54.0
Jaster and Murphy, 1983‘l Long hay 8.0 62.6 59.3 54.1
Coarse chop 8.4 61.3 58.6 55.1
Fine chop 8.5 56.3 57.6 52.8
Kinser et al., 1985b 6.5mm 0.513 69.9 31.5 23.3
5.4mm 0.524 68.6 31.1 13.0
1.4mm 0.520 69.4 45.1 36.3
0.8mm 0.523 66.5 33.4 32.7

Kerley et al., 1985 Same as Kinser NSl NSl NSl

etaL,l985
aCattle study

bAverage values of two experiments

cCoarse chop = >10.2cm particles; Fine chop = <10.2cm particles
*Ad libitum levels of intake

”DMD - Dry matter digestibility

*"OMD - Organic matter digestibility

'Ns - Not significant (P < .05)

16
The lack of a difference in fiber digestibility in this study indicated a possible interaction

between animal size and fiber digestibility. Since, in two experiments conducted by Kinser
et al. (1985), lambs consuming diets with 1.4-mm comcob particles digested 45.1% of
dietary NDF compared to lambs with similar intakes of diets containing 6.5, 5.4 or .8—mm
comcob particles with NDF digestibilities of 32.0%. Acid detergent fiber digestibilities did
not differ between lambs consuming .8 and 1.4-mm comcob particles. However, ADF
digestibilities were higher for the .8 and 1.4-mm comcob diets compared to the larger
particle size diets. In general, decreasing the particle size of the diet will tend to increase
ADF digestibilities by increasing the surface area of the feedstuff being digested.

Feeding frequency is another contributing factor affecting the digestibility of forage
diets. Ruiz and Mowat (1987) concluded that eating patterns observed when feed was
available at all times did not differ fiom patterns seen from animals fed once daily.
Increasing feeding fiequency from 1 to 4 times per day, had no affect on fiber digestion
when steers had ad libitum access to feed, regardless of feeding frequency. Similarly,
Bunting et al. (1987) found that apparent and total tract digestibility of DM, OM, and cell
wall constituents were not affected by feeding 2, 4, 8, or 16 times daily. Gibson (1981)
summarized data from 25 trials and concluded that animals fed more than 4 times daily,
out-performed animals fed once or twice daily. Weight gain increased 16%, which was
attributed to a 19% increase in feed efficiency. Therefore, increasing fi'equency of feeding
to greater than once or twice daily may increase weight gain. However, these
improvements are not attributed to an increase in fiber or DM digestibility, but are likely a
result of increased feed efficiency when animals are fed at intake levels less than ad libitum.

Optimizing digestibility of diets fed to lambs appears to be dependent on several

factors. Maintaining the level of forage in the diet between 25 and 50% had the most

17
positive results on DM and fiber digestibilities. Feeding these pelleted diets at ad libitum

levels of intake resulted in greater DMI. However, fiber digestibility was usually decreased
due to an increased rate of passage from the rumen of the smaller particle sizes. This

decrease was compensated for by increased DMI resulting in greater feed efficiency.

Nitrogen Balance of Diets Varying in Forage Content

The digestibility of nitrogen in lamb diets can be affected by some of the same
factors that affect DM and fiber digestibility. Thirty-kg lambs of moderate growth potential
require 191 grams of protein to gain 300 grams of body weight (BW) per day (NRC, 1985).
Due to degradation of dietary protein in the rumen, a high dietary protein intake does not
guarantee that animals have an adequate supply of needed amino acids at the small intestine
(Church, 1988). Type of protein and the level at which it is fed has a profound impact on
nitrogen (N) digestibility and N retention. Determining how different types of feeds
(concentrates vs. forage) and levels of CP intakes affect N digestibility and N retention
make N balance trials useful.

The source of forage can have a profound effect on N digestibility due to differences
in CP levels. For example, alfalfa hay may have 17% CP, where as comcobs contain only
3.2% CP. Both are typical feed ingredients used as fiber sources in lamb diets. Several
studies were conducted to determine if forage source affected N digestibility and
metabolism (Kinser et al., 1988; Forster et al., 1991 and Gordon et al., 1995) (Table 5).
Kinser et a1. (1988) found that lambs consuming diets containing comcobs as a fiber source

had 8% higher N intakes than lambs consuming diets containing cottonseed hulls.

18

835 Z me e\.. a 8 5.588“ comets/f...
835 Zuo ..\e a an bamnwmowa 5322...

535 new 33 page. new $39an age 5 SEN
ESE new :3 enema can benzene enema an S6,:

 

 

beam 0:30.

3% 2: ma NBS SE
9% 3 Se .829 33 .32 ea a 828

ed 2 .H EN SN 3 Sena
2: n: 2: Q: E £§< 32 :3 a deed”.

m. E 8a ”.9. «.2 “=2 ennaeeoo
men an own NE 3888 £2 .a an 85
8e 3e 23 En .x.

tn: 2 he z 95 pass 2 do 8658 emcee seam

 

8:33 c6 coweba no 858 owfiem mo Bebe 05 .«e BuSom .m 053.

l9
Nitrogen digestion as a percent of N intake, was 5.2% higher for lambs consuming diets

containing comcobs compared to cottonseed hulls. The decrease in N digestibility for
lambs consuming diets containing cottonseed hulls as a fiber source was attributed to the
increase in N intake. However, in the Forster et al. (1991) study feeding different ratios of
alfalfa hay to flatpea hay, N intake of lambs on 100% flatpea hay was 23.7% higher than
that of lambs fed 100% alfalfa. This difference was due to the difference in N content of the
hays. No differences were found in N retention among the diets, since there was an excess
of N in all diets. Similarly, Gordon et al. (1995) reported no differences in N digestibility in
lactating dairy cows that showed a 16.1% increase in N intake when high DMD grass silage
was compared to low DMD grass silage. Results of these studies indicate that when high
quality forages (alfalfa hay) were fed at ad libitum levels of intake N retention was not
affected because N intake was in excess of the required N levels.

As with forage source, differences in the forage to concentrate ratio influences N
digestibility due to differences in N content of the forages compared to concentrates (Table
6). Nitrogen intakes were lower when lambs were fed a 75% concentrate compared to a
75% alfalfa diet (Reynolds et al., 1991). Lambs consuming the 75% alfalfa diet at low and
high levels of intake digested less N, as a percent of N intake, than lambs consuming the
75% concentrate diet at the same intake levels. Also, lambs fed the 75% concentrate diet
excreted an average of 31% less fecal N and 20% less urinary N. As a result, N retention
was higher for lambs fed the 75% concentrate diet at low and high levels of intake.
Similarly, Susin et al. (1995) fed ewe lambs either 80% alfalfa (high forage) diet or 10%
alfalfa (high concentrate) diet at intakes to maintain similar growth rates. Lambs on the

high forage diet consumed 9.6% more N and excreted 48.7% more fecal N.

20

Table 6. Review of the effect of forage to concentrate ratio (F:C) on nitrogen (N) balance

 

 

Study F2C Intake“ N intake DMI N dig" N ret***
g/d kg/d % %
Reynolds et al., 1991' 75:25 Maint‘ 133.4 4.75 69.8 15.7
25:75 Maintl 97.8 3.60 74.3 14.6
72:25 2x math 208.6 7.78 66.7 8.8
25:75 2x nnrint2 173.9 6.61 70.4 13.9
Susin et al., 1995 80:20 100 52.7 1.99 60.8 10.8
10:90 Rest3 47.6 1.58 77.7 21.2
Murphy et al., 1994 78:22 100 23.4 1.14 57.0 4.7
61:39 95 23.0 1.01 65.5 15.9
39:61 80 20.9 0.90 65.8 16.4
8:92 70 18.9 0.78 73.8 19.8
'Cattle study

lCattle fed at maintenance

2Cattle fed at two times maintenance

3Rest= restricted intake, sheep fed to gain the same as 80:20 group
*Intake level as a % of ad libitum unless otherwise noted
"Nitrogen digestibility as a % of N intake

""Nitrogen retention as a % of N intake

21
Urinary N did not differ between diets. As seen in the Reynolds et al. (1991) study feeding

high concentrate diets resulted in increased N digestibility and retention. Murphy et al.
(1994) also found a decrease in N intake as concentrate in the diet increased from 22 to 92%
and feeding level was decreased fiom 100% to 70% of ad libitum. Apparent N digestibility
and N retention increased linearly as the amount of dietary concentrate increased and
feeding level decreased. The results of these studies indicate that increasing the forage
content of the diet can increase N intake, however increases in fecal and/or urinary N losses
resulted in decreased N digestibility and retention. However, these authors attributed
variability in dietary N digestion to differences in dietary crude protein content.

Feeding supplemental N when diets contain low quality forages (less than 4% CP)
improves N retention (Table 7). Supplementation of 0, 5 and 10 g N/d increased total daily
N intake from 2.8 to 8.9 and 13.4 grams, respectively which is considerably below the 30.6
g/d of N required for 300 g/d BW gain (Martin et al., 1981). Total N retained was lower at
the 0 and 5 g levels of N supplementation than at the 10 g level, due to the low N intakes.
Similarly, Hill et al. (1996) reported that steers consurrring com-soybean (C-SBM) grain
sorghum-com (GSC) or pearl millet-com (PMC) had similar N intakes. Nitrogen
digestibility and N retention did not differ among dietary treatments. Petit and Veira (1994)
found that feeding 15% canola meal (15C) with timothy silage compared to 7.5% canola
meal (7C) with timothy silage increased N intake. Canola meal supplementation resulted in
higher N intake than molasses supplementation or feeding silage alone. However, when
timothy silage was supplemented with molasses, there was no difference in N intake when
compared to steers fed unsupplemented silage. This affect on N intake would be expected

when comparing a protein supplement to an energy supplement.

22

Table 7. Review of the effect of feeding supplemental nitrogen (N) on N balance

 

Study CP N intake DMI N dig“ N ret"
% g/d kg/d % g/d
Martin et al., 1981 3.6 2.8 0.0 -1.88
8.3 8.2 50.9 -040
12.8 13.4 69.9 0.79
Hill et al., 1996' 9.2 77.8 58.8 23.9
12.5 82.1 54.2 21.7
14.1 80.8 55.4 20.6
Diet
Petit and Veira et al., 1994' Silagel 149 6.67 65.9 33.8
7M2 152 6.97 64.6 32.8
15M3 163 7.54 64.8 37.8
7C‘ 180 6.89 68.9 48.0
15C5 203 6.87 72.4 40.4

 

llCattle study
ITimothy silage

LTimothy silage plus 7.5% molasses supplementation

3Timothy silage plus 15% molasses supplementation

“Timothy silage plus 7.5% canola supplementation

sTirnothy silage plus 15% canola supplementation
*Nitrogen digestibility as a % of N intake

"Nitrogen retention

23
Nitrogen digestibility and N retention were similar among treatments. Results of these

studies demonstrated that protein supplementation of low-quality, forage-based diets
increased N retention. However, when diets contained adequate levels of N,
supplementation had little effect.

The size of forage particles in the diet may affect N digestibility. Kerley et al.
(1985) reported that DM (1,623 g/d) and N (36 g/d) intakes were similar in lambs fed
comcobs ranging fi'om .8-mm to 6.5-mm particle size. However, lambs consuming pelleted
comcobs, which had 1.4-mm particle size had 7.6% lower apparent total tract N digestion
(70.1 vs. 77.7%) when compared to the other treatments. This decrease was attributed to
shorter remastication time of the smaller particle size diets resulting in a faster rate of
passage from the rumen and lower N digestion. Diets containing the .8-mm particle sizes
passed more quickly from the rumen, but increased surface area for bacterial attachment
allowed for increased N digestion. In contrast with Kerley et al. (1985), N metabolism was
unaffected by particle size of the roughage component of pelleted concentrate : comcob
diets when particle sizes ranged from .8 to 6.5-mm (Kinser et al., 1985). These results
indicate that varying roughage particle size has little effect on N digestibility.

The frequency of feeding forage-based diets may affect N excretion and ultimately
N retention (Ruiz and Mowat, 1987). In this work, cattle were fed alfalfa hay or corn silage
diets and feeding frequency increased from one to four times per day. Nitrogen retention
was not improved when expressed on a g/ 100 kg BW basis, however, when expressed as a
proportion of N intake, N retention was improved with more fi'equent feedings (32.2 to
34.7%). This increase was primarily due to a decrease in fecal nitrogen excretion. Urinary
N excretion was 17.1 g/ 100 kg BW/d for all cattle. In contrast, Bunting et al. (1987) found

that when feeding tall fescue hay, fecal N increased linearly (5.7 to 6.3 g/d) as feeding

15"

24
frequency increased from 2 to 16 times per day. The increase in fecal N observed with

increased frequency of feeding may have reflected the washout of potentially digestible feed
organic matter from the rumen. Neither urinary N nor N retention was effected by meal
frequency. The results of these studies indicate that increased feeding frequency had little
effect on N retention. However, when feeding frequency was increased fi'om 4 to 16 times
per day an increase in fecal N was observed. When feeding frequency was less than 4 times
per day, fecal N was decreased.
Energy Balance of Diets Varying in Forage Content

Differences in dietary digestible and metabolizable energy utilization can be
influenced by forage type, forage vs. concentrate level and energy supplementation levels.
The need for energy balance studies, which determine how efficiently dietary energy is
utilized, has been based on three points (Church, 1988). First, supplying energy to an
animal is more costly both biologically and economically than supplying any other nutrient.
Second, the primary factors that determine the efficiency of utilization of feed energy are
the energy losses in feces and heat production. Finally, the efficiency of converting feed
energy to products for human consumption is low. For example, a 30 kg early-weaned
lamb must consume 4,400 kcal of digestible energy/d or 3,600 kcal of metabolizable
energy/d to support 300 g average daily gain (NRC, 1985). These requirements are high
when compared to a monogastric animal. A pig of similar BW, gains 300 g/d with
digestible energy or metabolizable energy intake of 2,769 or 2,657 kcal/d, respectively
(NRC, 198 8).

The conventional scheme of energy metabolism is illustrated in Figure 1 (NRC,
1966 and NRC, 1985). Gross energy (GE) intake is the heat of combustion of the feed

ingested (ARC, 1980).

25
GROSS ENERGY OF FEED

_ _ _ p FECAL ENERGY (20 60%)
1. FEED ORIGIN
2. METABOLIC ORIGIN

 

DIGESTIBLE ENERGY (DE)

_ _ _ I, A. GAS PRODUCTION (310%)
B. URINARY ENERGY (3-5%)
1. FEED ORIGIN
2. ENDOGENOUS ORIGIN

 

METABOLIZABLE ENERGY (ME)

— — — -> HEAT INCREMENT (10-90%)

1. HEAT OF FERMENTATION
2. HEAT OF NUTRIENT

  

METABOLISM
NET ENERGY (NElrp)
MAINTENANCE ENERGY (NEM) PRODUCTION ENERGY (NE?)
1. BASAL METABOLISM 1. GROWTH
2. VOLUNTARY ACTIVITY 2. FATTENING
3. HEATING AND COOLING 3. MILK
OF THE BODY 4. WOOL
5. REPRODUCTION
6. WORK

Figure 1. Scheme of energy metabolism (NRC, 1966) with expected losses (NRC, 1985)

26
Digestible energy (DE) is the GE content of the feed minus the energy content of the feces.

Metabolizable energy (MB) is the DB of the feed minus the energy content of urine and
combustible gases, of which methane is quantitatively most important. Net energy
represents the amount of energy actually available to the animal for maintenance (NEm)
and productive processes (NEp) and is calculated by subtracting the heat increment, fi'om
ME. The heat increment is the increase in heat produced as a result of digestive and
metabolic processes in response to increased ME intake (NRC, 1985).

The rate and extent of digestion of a feedstuff is primarily influenced by its
chemical and physical nature (Church, 1988). Feedlot lambs are fed a wide variety of diets
ranging from 100% concentrate to 100% forage. The energy density of these diets will also
vary greatly. A 100% concentrate diet may contain approximately 3.8 kcal/ g DM DE while
100% forage may contain 2.5 kcal/ g DM DE. Therefore, knowing the energy values of
dietary components is important in identifying the nutritive value of a feedlot diet.

The DE content of a diet varies with different forage sources. Several studies were
conducted to determine the nutrient utilization of diets containing different forage sources
(Kinser et al., 1988; Forster et al., 1991 and Gordon et al., 1995) (Table 8). Forster et al.,
1991 reported that as the percentage of flatpea hay in the diet increased from 0 to 100%, DE
decreased linearly and ranged from 58.1% to 53.3%. Since all diets were formulated to
contain 4.5 kcal/g GE, the decrease in DE values was attributed to a 4.3% decrease in
DMD. Similarly, Kinser et al. (1988) found lambs consuming comcobs, compared to
cottonseed hulls, as a fiber source had 8.3% greater GE intakes, excreted 34% less fecal
energy which resulted in 10.7% higher DE values. However, Gordon et al. (1995) reported
that feeding a low digestibility grass silage to lactating dairy cattle had no effect on GE

intake, fecal energy or DE values compared to feeding a high digestibility grass silage.

27

Enema? Seas be -935...
amaze. mmfiw bancmowme c838 be 32.:

owmmm mmfim ram—Eamownu .6sz be Boa.

 

 

been 350.
new as. a? 32 8 3:2 43 ~93 an:
93 Re. NNN. 3:2 mm 322 2 m 295 264 .32 a? .o .8300
9mm 0mm ea Benz
3% fiwm >3 «babes 33 a? no Deacon
0N5 Que 38x mom.m 238. #436 £15 388on
5Q. Nmb gaux own; gaox 856 38800 32 in 8 Bang
o\o .x. mm
.843 >925 mwcoem Room 0x85 m0 855.“ owfiom 33m
ban—amowmu “5393‘

 

3:23 >928 no as omega we “cube 05 we 3030M .w via.

28
The results of these studies indicate that some correlation exists between DMD and energy

utilization of diets containing different forages. The results of the Gordon et al. (1995)
study indicate that during different stages of production which require more energy, for
example lactation, energy utilization of a diet is virtually unaffected by DMD.

Adding concentrate to forage-based diets increases the dietary energy content. The
effect of altering foragezconcentrate ratio on energy utilization was determined by several
authors (Wainman et al., 1970 & 1975; Kromann et al., 1975 and Reynolds et al., 1991)
(Table 9). These authors found that as the forage to concentrate ratio increased there was an
increase in DE values due to an increase in GE intakes. Kromann et al. (1975) reported DE
values for dehydrated alfalfa and corn were 2.67 and 4.07 kcal/ g, respectively. This
compares to current NRC (1985) values for these same feedstuffs 2.65 and 3.84 kcal/g,
respectively. Based on the Kromann et al. (1975) curvilinear equation, the maximum
energy retention (96.7 Mcal/d) occurred when a diet consisting of 80% com and 20% alfalfa
was fed. These studies also indicated that as forage to concentrate ratio increased there was
an increase in ME value, except in the Reynolds et al. (1991) work, which reported no
differences in ME value. As reported by studies comparing forage sources, these authors
found that there was a direct correlation between DMD and energy utilization. These
results would be expected since an increase in forage content of the diet tends to decrease
DMD and lowers the energy value of the diet being consumed.

The affects of feeding comcobs of varying particle sizes on digestive and metabolic
characteristics of GE were studied using early-weaned lambs (15.3 kg and 61 : 5d of age)

fed a pelleted 74.9% concentrate and 25.1% comcob diet (Kinser et al., 1985). The particle

29

Diana one: be -929.
an 38 3 8w Eon oxen Co Bose Na
Em whom 9 Rm Soc poo—SE we £32 v.
o2 8 o Sea $58205 o\omn

oogoufiafi 88a 23 “a vow oE~U~

06:80:59: “a vow ova—«U.

 

 

beam 330.
"US$83 c8882. @8883 38203 3.8205 “£26— m 2.5m 2.2 a? no 58355
3328a @8880“. CHESS @8885 ©8855 $.35— ». 85v 2.2 in «o 5:633
@8383 @8885 883: e< n2: 9 o 3.2 in no qua—hog

New Qt. cede Gem 2:: was: XN mnnmm

men 03 3.2. 3.3 3.3; «BEE XN mmumn

SK QR N034 Show mode .332 puma
mac #3 3.34 Ram 3.5 1:32 mm”: .32 a.“ no 335nm

o\o o\o 322 “5.2 334 BB—
...sz 33cm 03? m2 2:? mm 835 mo 833 UN"— beam
benzene Honour.

 

8:23 .358 so 6””: eta 8.55280 8 owfiom we Cube 2: :8 335% .e 05mg.

30

sizes of the comcobs in the diet were either 6.5, 5.4, 1.4 or .8 mm. No differences were
reported in GE intake, DB or urinary energy excretion based on particle sizes when fed at
90% of ad libitum levels of intake. Later, the same lambs (16.8 kg and 82 3; 5d of age) were
fed the same four diets. The 6.5-mm particle size resulted in the highest digestible energy
values. The larger particle size of the fibrous foodstuffs is thought to have stimulated
salivation and resulted in greater buffering capacity in the rumen. It has been postulated
that there was an increase in energy efficiency when the proportion of ruminal propionate to
acetate was increased. However, older lambs fed the 6.5 and 5.4-mm diets had the highest
molar proportion of acetic acid (59.4 and 56.4 mol/100 mol, respectively) and lowest
proportion propionic acid (26.2 and 29.2 mol/100 mol, respectively). For younger lambs no
differences were found in molar proportions of acetic or propionic acid. No differences
were found in molar proportions of butyric acid for either age group.

Altering the forage to concentrate ratio has been shown to affect energy retention in
both heifers and lambs (Reynolds et al., 1991 and Kromann et al., 1975; Wainman et al.,
1970 & 1975, respectively). Although ME responses differed between the two studies both
authors concluded that increasing the level of concentrate in the diet improved DMD which
increased energy utilization.

Economic Analysis of Feeder Lamb Production

The United States sheep industry is in a state of decline (Purcell, 1995). Inventory
numbers that exceeded 50 million in the 1940s have declined to less than 9 million in 1997.
For many sheep producers sales of slaughter lambs constitute much of the revenue flow.
When adjusted for inflation, slaughter lamb prices have declined over 60% from 1978 to the
early 19908. A major problem effecting slaughter lamb prices is a low and static demand

for lamb. Per capita consumption over the last several decades was estimated at .68 kg/year

31
(Purcell, 1995). Another factor that continues to affect lamb prices is the seasonality of

lamb availability. Prices are typically highest in the spring and lowest in the summer and
fall months, which corresponds with the seasons in which lamb supply is lowest and
highest, respectively (Ward and Hildebrand, 1993).

According to the SID Sheep Production Handbook (1992), 68% of the variable
costs associated with sheep production are feed costs followed by: labor-13%;
transportation, utilities and veterinary costs-9%; and shearing, bedding and miscellaneous
costs-10%. With farm production expenses rising, it is imperative that component
strategies of a fanning system that utilize resources most efficiently be selected. Packer
demand for leaner meat and market resistance to lambs that are too heavy and/or too fat are
key incentives for producers to develop new production systems. Therefore, it is important
that producers identify feed ingredient combinations that will allow lambs to attain
optimum performance and carcass potential, while minimizing production costs.
Historically, production, storage and feeding of forages has been a topic of considerable
analysis by animal scientists and agricultural economists (Knoblauch et al., 1981). In
today's economic environment, selection of a forage-based system for a sheep operation
may be even more critical to farm productivity. However, utilization of processed forages,
such as alfalfa pellets may increase feed costs. Utilization of pasture may be an effective
way to decrease feed costs. Feeding different foragezconcentrate ratios has a profound
effect on performance and carcass traits of feeder lambs (Oltjen et al., 1971; Glimp et al.,
1989 and Blackburn et al. 1991). The performance factors with the most economic impact
on lamb production include: days on feed, gain to feed ratios and ADG.

Minimizing the days that a lamb is on feed is one way to increase profitability. To

decrease days on feed and increase profitability, an increase in lamb performance must

32

occur. The average costs to maintain a lamb in a feedlot or on pasture were $0.12/d, not
including feed cost (Blackburn et a1. 1991) as shown in Table 10. Yardage cost included
utilities, equipment repairs and labor expenses. Pasture expense covered comparable

expenses for pasture production.

Table 10. Non - feed cost associated with lamb production“

 

 

Feedlot $/hd/d Pasture $lhd/d
Yardage 0.05 Yardage 0.05
Veterinary 0.06 Veterinary 0.06
Mineral 0.01 Mineral 0.01
Total 0. 12 Total 0. 12

 

l'Adapted from Blackburn et al. (1991)

Using these values in a computer simulation, Blackburn et al. (1991) estimated lamb
performance and feeding costs (Table 11). Average days on feed for lambs fed a standard
feedlot ration (F eedlot) was 94d, for lambs on alfalfa pasture 30d followed by Feedlot was
102d and for lambs on alfalfa 60d followed by Feedlot was 116d. This difference in days
on feed was a result of a 30 g/d decrease in ADG as days on alfalfa pasture increased from 0
to 60 days. The key to increasing ADG is to choose feed ingredient combinations that
maximize BW gain per unit of feed consumed. Blackburn et al. (1991) found lambs
averaged .160, .153 and .142 kg gain/ kg DMI for Feedlot, alfalfa 30d/Feedlot, and alfalfa
60d/Feedlot, resulting in costs of gain of $0.68, $0.72, and $0.77/kg gain, respectively when
the cost of Feedlot was $.11/kg. Feeding lambs on alfalfa pasture for 0 to 60 days increased

total daily costs from $0.23 to $0.46/hd/d due to the increased days on feed.

33

Table 11. Lamb performance and cost of gain - computer simulation

 

 

Diet
Feedlot' alfalfa 30d/Feedlot2 alfalfa 60d/Feedlot3
Trait
Days on feed 94 102 116
ADG, kg 0.160 0.153 0.142
Cost of gain, $ 0.68 0.72 0.77

 

Data from Blackburn et al. (1991)

|Feedlot - Standard commercial feedlot diet
2Alfalfa pasture for 30d then finished on Feedlot
3Alfalfa pasture for 60d then finished on Feedlot

In a feedlot trial, lambs consumed 1.3, 1.5 and 1.6 kg/d when fed diets containing
90, 72.5 and 55% concentrate with alfalfa hay, respectively (Table 12; Glimp et al. 1989).
Days on feed were least for lambs fed the 72.5 and 55% concentrate diets (58 and 59d,
respectively) and were greatest for lambs fed the 90% concentrate diet (68d). Average daily
gain was greatest (231 g/d) in lambs fed a 72.5% concentrate diet compared to 199 and 214
g/d for lambs consuming 90 and 55% concentrate diets, respectively. Lambs consuming
72.5 and 90% concentrate diets gained .16 kg/ kg DM consumed, where as lambs
consuming 55% concentrate diets gained .13 kg/ kg DM consumed. When applying a feed
cost of $0.1 l/kg from Blackburn et al. (1991), calculated cost of gain was $0.85, $0.69 and
$0.69/ kg BW gain for 55, 72.5 and 90% concentrate diets, respectively. Oltjen et al.
(1971) found feeding all forage diets increased days on feed (203 vs. 168d) compared to
feeding an all concentrate diet to beef cattle to gain 213 kg BW. Similarly, they reported
that steers consunring all concentrate diets gained .17 kg/ kg feed consumed compared to
.10 kg/ kg feed consumed for steers fed all forage diets. When using a feed cost of $0.1 1/kg

from Blackburn et a1. (1991) calculated cost of gain was $0.65 and $1.10/ kg BW gain for

34
all concentrate compared to all forage diets, respectively. Feeding diets with forage levels

greater than 50% have been shown to increase feed intake, decrease gain : feed ratios and

decrease ADG, which increased days on feed.

Table 12. Lamb performance and cost of gain - feedlot trial

Concentration level, %

 

 

 

55 72.5 90
Trait
Days on Feed 59 58 68
ADG, g/d 214 231 199
Feed Intake, kg/d 1.6 1.5 1.3
Cost of Gain, $' 0.79 0.71 0.72

 

Adapted from Glimp et al. (1989)
' Based on Blackburn et a1. (1991) feed costs

Overly fat lamb carcasses and inconsistent, low-quality, non-uniform lamb are cited
as major marketing/merchandising problems for the US sheep industry (Umberger, 1994).
Pricing lambs "on the average" has led to numerous production and marketing
inefficiencies, because all lambs are marketed by an average market price regardless of
potential yield grade. Lambs marketed on the basis of measurable differences in quality and
composition send more accurate signals from the marketing sector back to the producer. A
move towards value-based marketing has occurred in some segments of the lamb industry.
Carcass characteristics have become a more important factor in selling live lamb since the
establishment of a mandatory yield grading rule issued by the USDA in 1992. The yield
grading system is based on the percentage of boneless closely trimmed retail cuts and is
determined solely by fat thickness taken at the 12th and 13th rib as shown in Table 13

(American Lamb Council, 1994).

35
Table 13. Fat thickness requirements of the yield grading system"

Yield Grade Fat Thickness (cm)

 

1 0- .06
2 .06-.10
3 .10-.14
4 .l4-.18
5 .18+

 

I"Adapted from The American Lamb Council (1994)

Implementation of value-based marketing is found in the mid-Atlantic region of the
US where a value-based marketing system was developed to provide differential payments
for a product based on a set of economically important measurements: carcass weight,
quality grade and yield grade (Umberger, 1994). With two years data collected from this
program it was found that dressing percent had a greater impact on income than lamb
cutability. In the value-based marketing system lambs are sold electronically. The base
price is set for yield grade 1 to 3 carcasses, 18 kg and up. Carcasses which fall in the yield
grade 4 or 5 range are discounted $-0.05 and $-0.20/cwt., respectively. Carcasses that fall
below 18 kg or fail to grade choice are also discounted ($-0.05 and $-0.15/ cwt.,
respectively). Umberger (1994) also reported that although over-finished carcasses were a
national issue, the primary concern identified in this program was the marketing of lambs
that were too lean. With a shift towards value-based marketing systems, producers may
have an incentive to produce lambs that will produce yield grade 2 or 3 carcasses.

Since feed costs constitute 68% of lamb production it is necessary to develop
feeding systems that optimize productivity to maximize profits. In general, feeding 50% to
75% concentrate in the diet reduced days on feed, increased ADG, and decreased the cost of
gain (Glimp et al., 1989 and Blackburn et al., 1991). The goal of producers is to select a

feeding system that will maximize profits.

CHAPTER 2
Materials and Methods
This research was conducted under the approval of the Michigan State University

All-University Committee on Animal Use and Care (AUF # 07/96-086-00).

Digestibility Trial

To test the hypothesis that the level of pelleted alfalfa in the diet would influence
nutrient digestibility in lambs, a digestibility trial was conducted. Twenty-four crossbred
(Suffolk x Dorset x Rambouillet) wether lambs were blocked by weight into two
replications (40.1 and 45.6 kg) and randomly assigned to 3 dietary treatments: 3 pelleted
alfalfa diet, which contained 100% forage (ALFA), a pelleted concentrate-based diet, which
contained 25% forage (CONC) and a 1:1 mixture of these two diets, which contained
62.5% forage (SO/50). The composition of these diets is shown in Tables 14, 15 and 16.
Diets were formulated to meet or exceed NRC (1985) requirements for 40-50 kg lambs to
support gains of 300 - 345 g/d. Prior to placement in metabolism stalls, lambs were fed
their respective diets for a minimum of 14d and ad libitum levels of feed intake were
determined for each lamb. Lambs were then moved and housed in elevated, aluminum
metabolism stalls (1.5 x .45 m), which allowed separate total collection of feces and urine.
Lambs were given a 7d adaptation period in the stalls prior to the sampling period, during
which time intake was adjusted to 90% of their ad libitum intake levels. Lambs had access
to water throughout the study. Lambs were fed twice daily at 0800 and 1600. Feed
samples were collected on the first day of each collection period for compositional analysis.

36

-r

37

During the 7d collection period, total feces and urine were collected daily, 2 hrs after the
0800 feeding.

Table 14. Diet composition (DM basis) - digestibility trial

 

 

 

Diet
ALF A' 50/502 CONC3

Ingredient % DM

Alfalfa 100.0 63.0 25.0
Corn 0.0 25.5 51.6
Soybean meal 0.0 5.8 l 1.8
Molasses 0.0 3.5 7.0
Supplement‘ 0.0 2.3 4.6

 

' Supplement included: soy hulls, binder, limestone, salt,
Ammonium chloride, dical, vitamin premix and lasalocid sodium
'ALFA - Pelleted, 100% dehydrated alfalfa

250/50 - 1:1 mixture of ALFA and CONC

3CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

Table 15. Diet chemical composition (DM basis), digestibility trial - lightweight lambs

 

 

 

Diet
Ingredient ALFA' 50/502 CONC}
DM, % 90.7 90.1 89.5
CP, °/o 16.9 15.9 14.8
GB, kcal/g 4.09 4.16 4.22
MB, kcal/g' 2.04 2.20 2.36
NDF, % 46.5 36.3 26.0
ADF, % 32.0 22.1 12.1
ADL, °/o 7.6 5.0 2.3

 

'ME - calculated from tabular values (NRC, 1985)

'ALFA - Pelleted, 100% dehydrated alfalfa

250/50 - 1:1 mixture of ALFA and CONC

3CONC — Pelleted, 75% concentrate: 25% dehydrated alfalfa

38

Table 16. Diet chemical composition (DM basis), digestibility trial - heavyweight lambs

 

 

Diet

Ingredient ALFA1 50/50r CONC’
DM, % 92.2 90.7 89.3
CP, % 18.3 16.9 15.6
GB, kcal/g 4.20 4.17 4.14
MB, kcal/g‘ 2.04 2.20 2.36
NDF, % 43.2 33.3 23.3
ADF, % 29.2 20.4 11.6
ADL, % 7.2 4.7 2.1

 

'ME - calculated from tabular values (NRC, 1985)

‘ALFA - Pelleted, 100% dehydrated alfalfa

250/50 - 1:1 mixture of ALFA and CONC

3CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

Urine was acidified with 6 N HCl to maintain a pH < 3 and thereby preventing N losses due
to volatilization. Collected feces and urine were weighed and a subsample (10% of total
weight) weighed and fiozen. Daily subsamples of feces and urine were each pooled over
the 7d collection period. After the 7d collection period, lambs were removed from the
metabolism stalls and a 10 rrrl ruminal fluid sample was collected using Tygon tubing fitted
with a sieve attached to a 60-cc catheter tip syringe. The 10 ml sample was acidified using
.2 ml 6 N HCl and stored fi'ozen until analyzed Pooled feces and feed samples were dried
in a forced air oven at 55° C for 48 hrs and ground through a Wiley mill (l-mm screen) for
storage and subsequent compositional analysis. Duplicate samples of the feed and feces (2
g each) were used to detemrine DM by drying in a forced air oven at 105° C (AOAC, 1990).
Urine DM was determined with triplicate samples of urine (4 g each) added to .4g of cotton
in the bomb capsules and freeze dried. Samples were freeze-dried in a Virtis shelf type

freeze-drier. Samples were placed in the freeze-drier, frozen at -15° C and the temperature

39

was increased under vacuum, 15° C at 12 hour intervals to a final temperature of 30° C.

Total time in the freeze-drier was approximately 96 hours. Triplicate samples of the diet
and feces (1 g each) were also analyzed for NDF, according to Goering and Van Soest
(1970), modified by the addition of 4ml of a 2% or-amylase solution (Sigma A - 3306,
Sigma Chemical Co., St. Louis, Mo.) to each sample, substitution of triethylene glycol for 2
ethoxyethanol, and omission of decahydronaphthalene and sodium sulfite (Van Soest et a1.
1991). The NDF residues were sequentially analyzed for ADF and acid detergent lignin
(ADL) according to Goering and Van Soest (1970). Ash was determined following sample
ignition at 500°C for 6hr (Goering and Van Soest, 1970). Organic matter content of the
diets and feces was detennined by subtracting the ash values from the respective diet and
fecal sample weights. Duplicate samples were used to detemrine the N content of the diets
(1 g each), feces (l g each) and urine (3 g each) using the Kjeldahl N method (AOAC
1984). Triplicate samples of diets and feces were pelleted (1 g each) and triplicate freeze
dried urine samples (.5 g each) were used to determine the GE content using a 1241 Parr
adiabatic bomb calorimeter (Parr Instrument Co. Moline, IL). A standard curve for cotton,
with the freeze-dried urine samples, was determined using duplicate cotton samples from
.1 g to 1 g in the Parr bomb calorimeter. The GB of the cotton was determined from this
standard curve and then subtracted from the GB of the entire urine and cotton sample to
determine the GE of the urine. Rurnen fluid samples were thawed, decanted into plastic
centrifuge tubes and centrifuged at 26,000 x gravity for 30 minutes. A 1 ml sample of the
supernatant was analyzed for acetate, propionate and butyrate concentrations using a water
high performance liquid chromatography (HPLC) system with a Bio-rad HPX-87H organic

acid column (Waters Associates Inc., Milford, Mass.) following the general procedures of

4O

Canale et al. (1984). The analysis was replicated and the results were quantified using PC
Nelson turbochrornic HPLC software (T. E. Nelson, Cupertino, CA).

Digestible energy intakes (kcal/d) were determined by subtracting fecal energy from
GE intake. Metabolizable energy was determined by subtracting urinary energy and CH4
losses from DE intake. Methane loss was estimated using two methods, (W olin, 1960 and
Johnson et al., 1991). The Wolin (1960) method uses relative proportions of acetate,
propionate and butyrate to estimate methane while the Johnson et al. (1991) method is
based on DE intake levels. The ME values were compared to estimates fi'om NRC (1985)
which were calculated using DE * .82.

Wolin (1960) Equation:
Methane (M) = 0.5A + 0.53 - 0.25P

Where: A= Relative proportion of ruminal acetate
B= Relative proportion of ruminal butyrate
P= Relative proportion of ruminal propionate

Energy lost as methane:
(M * .2108) * 1000 = kcal lost

Johnson et al. (1991) equation:
Methane as % of GE = 5.5 + .06 (DE) - 2.25 (level of intake)

Where: DE=%DEinthediet
level of intake = multiple of maintenance

Energy lost as methane:
GE intake (kcal) * methane as % of GE = kcal lost

Data were analyzed using General Linear Model (GLM) procedures of SAS0
(1989). ANOVA tables are shown in Appendix A. Digestibility, N metabolism and GE

metabolism data were analyzed separately using the model statements which included

41

weight (block), dietary treatment and weight x treatment interactions as class variables.
Differences in digestibility were determined using DMI, fecal DM, DMD, OM intake, fecal
OM, OMD, NDF digestibility and ADF digestibility as dependent variables in the model
statement. Differences in N balance were determined using DMI, fecal N, urinary N, N
intake, N digestibility (g/d and % of intake) and N retention (g/d, % N digestibility and % N
intake) as dependent variables in the model statement. Differences in GE balance were
determined using DMI, GE intake, fecal E, DE, urinary E, CH4 estimates and ME estimates
as dependent variables in the model statement.
Performance Trial 1

The objective of performance trial 1 was to determine performance and carcass
composition of lambs fed diets containing 25% or 100% forage at ad libitum or 85% of ad
libitum levels of feed intake. In trial 1, 79 crossbred (Suffolk x Dorset x Rarnbouillet) ewe
and wether lambs (31.3 kg) were housed in 8 pens (4.3 x 18.3 m), in a 2 x 2 factorial design.
Lambs were blocked by weight and sex (10 lambs / pen) and randomly assigned to 2 diets:
a pelleted concentrate-based diet, which contained 25% forage (CONC) and a pelleted
alfalfa diet, which contained 100% forage (ALF A) fed at 2 levels of intake: ad libitum (A)
and 85% of ad libitum (R). The ingredient and chemical composition of these diets are
shown in Tables 17 and 18. Lambs were fed twice daily at 0700 and 1500 and orts were
measured prior to each 0700 feeding. The R intakes were adjusted daily as determined by
the previous days' consmnption by lambs fed at A levels of intake. Water and trace
mineralized salt were available to all lambs throughout the trial. Diets were sampled every
14d for compositional analysis. Samples were dried in a forced air oven-at 55° C for 48 hrs

and ground through a Wiley mill (l-mm screen). Analyses were conducted as in the

42

digestibility trial and included: 105° C DM (AOAC, 1990), Kjeldahl N (AOAC, 1984),
modified NDF, ADF, ADL and ash (Goering and Van Soest, 1970). Lamb weights were
recorded every 7d. Lamb were removed from the study when an average pen off-test final
weight (FW) of 52.3 kg was attained. Lambs were on feed for 63d. Lambs were
transported fi'om campus to Manchester, MI where they were sold through commercial
channels and processed the following day at Wolverine Packing, Inc., Detroit MI. Carcass
data were collected at the plant and included: hot carcass weight (HCW), loineye area
(LEA) and 12th rib fat thickness (FAT). In addition, HCW expressed as a percent of FW
was calculated (DRESS). One lamb on the ALFA diet, heavyweight block died of urinary
calculi on the last day of the trial, therefore carcass data averages were based on 1 less lamb

for that pen.

 

Table 17. Diet composition (DM basis) — performance trials 1, 2 and 3

 

 

 

Diet
ALFAI 50/502 CONC3

Ingredient % DM

Alfalfa 100.0 63.0 25.0
Corn 0.0 25 .5 51.6
Soybean meal 0.0 5.8 11.8
Molasses 0.0 3.5 7.0
Supplement‘ 0.0 2.3 4.6

 

' Supplement includes: soy hulls, binder, limestone, salt,
Ammonium chloride, dical, vitamin premix and lasalocid sodium
‘ALFA — Pelleted, 100% dehydrated alfalfa
250/50 - 1:1 mixture of ALFA and CONC, Not used in performance trial 1
3CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

43

Table 18. Diet chemical composition (DM basis), performance - trials 1 and 2

 

 

Diet
Ingredient ALFAl 50/507 CONC3
DM, % 95.0 94.0 93.0
CP, % 13.5 14.2 14.8
TDN, % 57.0 62.9 68.8
ME, kcal/g‘I 2.04 2.20 2.36
Calcium, %‘ 1.37 1.11 0.85
Phosphorus ,%' 0.24 0.27 0.30

 

”Tabular values (NRC, 1985)

‘ALFA — Pelleted, 100% dehydrated alfalfa

250/50 — 1:1 mixture of ALFA and CONC, Not used in performance trial 1
3CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

Performance Trial 2

The objective of performance trial 2 was to detemrine performance and carcass
characteristics when lambs were fed diets containing 62.5% forage at ad libitum or 85% of
ad libitum levels of intake. In trial 2, 42 crossbred (Suffolk x Dorset x Rarnbouillet) wether
lambs (30.9 kg) were housed in 4 pens (4.3 x 18.3 m), blocked by weight (11 lambs / pen,
lightweight pens and 10 lambs / pen, heavyweight pens) and randomly assigned to 2 dietary
treatments. Dietary treatments consisted of a 1:1 mixture of CONC and ALFA pellets,
which contained 62.5% forage (SO/50) fed at A or R intakes. Ingredient and chemical
composition of the diets is shown in Tables 17 and 18. Lambs were fed twice daily at 0700
and 1500 and orts were measured once daily prior to the 0700 feeding. The R intakes were
adjusted weekly as determined by the previous weeks' consumption by lambs fed at A
levels of intake. Water and trace mineralized salt were available to all lambs throughout the
trial. Diets were sampled every 14d for compositional analysis. Compositional analyses

followed the same procedures as defined in performance trial 1. Lamb weights were

44

measured and recorded every 7d. Lambs were removed fi'om the study when each pen
attained an average FW of 63.6 kg Lambs were on feed for 96d. Lambs were commercially
processed at Wolverine Packing Inc. Marketing procedures and carcass data collection
were the same as in performance trial 1.
Performance Trial 3

The objective of performance trial 3 was to determine performance and carcass
characteristics when lambs were fed diets containing 25, 62.5 or 100% forage at ad libitum
levels of intake. In performance trial 3, 42 crossbred (Suffolk x Dorset x Rambouillet) ewe
and wether lambs (33.0 kg) were housed in 6 pens (2.5 x 2.5 m), blocked by weight (7
lambs / pen) and randomly assigned to 3 dietary treatments: ALFA, CONC and 50/50 (25,
100 and 62.5% forage, respectively). Ingredient and chemical composition of the diets is
shown in Tables 17 and 19. Lambs were fed twice daily at 0700 and 1500 and orts were
measured once daily prior to the 0700 feeding. Diets were sampled every 14d for
compositional analysis. Compositional analyses followed the same procedures as defined
in performance trial 1. Lamb weights were measured and recorded every 14d. Lambs were
removed fi'om the study when each pen attained an average FW of 56.0 kg. Lambs were on
feed for 70 to 84d depending on dietary treatment. Lambs were commercially processed at
Wolverine Packing Inc. Marketing procedures and carcass data collection were the same as

in performance trial 1.

45

Table 19. Diet chemical conrposition (DM basis) , performance - trial 3

 

 

Diet
Ingredient ALF AI 50/502 CONCr
DM, % 91.5 90.4 89.4
CP, % 17.6 16.4 15.2
TDN, % 57.0 62.9 68.8
MB, kcal/gll 2.04 2.20 2.36
Calcium, %' 1.37 1.11 0.85
Phosphorus ,%' 0.24 0.27 0.30

 

'1“ abular values (NRC, 1985)

'ALF A - Pelleted, 100% dehydrated alfalfa

250/50 - 1:1 mixture of ALFA and CONC

3CONC —- Pelleted, 75% concentrate: 25% dehydrated alfalfa

A feed cost analysis was conducted using dietary ingredients valued at average feed
costs as shown in Table 20. These feed costs were then divided by the average feed : gain
ratio to determine the average cost of gain for an individual lamb on each dietary treatment.

Data from the three performance trials were analyzed using GLM procedures of
SAS" (1989). ANOVA tables are shown in Appendices B - D. To identify differences in
feed intake, the model included dietary treatment as a class variable and pen intake and
daily lamb intake as the dependent variables. To detemrine differences in performance and
carcass characteristics, the model included weight (block) and dietary treatment as class
variables with HCW, LEA, FAT, initial weight, FW, ADG and DRESS as dependent
variables. Where significant (P < .05) weight x treatment interactions were found, weight x

treatment was used as a class variable.

46

Table 20. Feed costs of dietary ingredients

 

 

 

I: . . . l: .
ingredient % Mfg

Alfalfa meal 100.0 62.5 25.0 0.165 0.103 0.041
Corn 0.0 32.5 65.0 0.043 0.085
Soybean meal 0.0 5.0 10.0 0.017 0.035
Wt 0.022 0.022 0.022
Total 100.0 100.0 100.0 0.187 04mm

 

'ALFA - Pelleted, 100% dehydrated alfalfa
250/50 - 1:1 mixture of ALFA and CONC
3CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

CHAPTER 3

Results and Discussion

Diet Digestibility

A digestibility trial was conducted to determine nutrient digestibility and utilization
by lambs fed diets ranging from 25 to 100% forage fed at ad libitum levels of intake. Data
fi‘orn one lightweight lamb fed ALF A was removed from the analyses due to errors in
sample collection. All diets were pelleted and met or exceeded the nutrient requirements of
40 - 50 kg lambs to support weight gains of 300 to 345 g/d according to NRC (1985) (Table
21). The ALF A diet contained 100% alfalfa and the CP content of the diet fed to

lightweight lambs was 16.9% and 18.3% CP fed to the heavyweight lambs.

Table 21. Daily nutrient requirements for 40 and 50 kg lambs gaining 345 and 300 g/d'

 

 

Weight ADG, g/d DMI, g/d DE, kcal/d ME, kcal/d CP, g/d
40 kg 345 1,500 5,100 4,200 202
50 kg 300 1,500 5,100 4,200 181
NRC, 1985

 

This range in CP is typical when purchasing large quantities of alfalfa pellets from a
commercial feed mill. The CONC diet contained 25% alfalfa, 52% com and 12% soybean
meal with molasses and supplement making up the balance of the diet. The CP content of
the CONC diet fed to the lightweight lambs was 14.8% and 15.6% when fed to the
heavyweight lambs. This diet is a typical com-soybean meal diet used commercially to

produce market lambs.

47

48
The 50/50 diet was a 1:1 mixture by weight, of the ALFA and CONC diets. The ME values

were calculated from NRC (1985) values and as expected the ME value for the CONC diet
(2.36 kcal/g) was higher than the ALFA diet (2.04 kcal/g). Fiber content of the diets
decreased as level of concentrate in the diets increased as shown with NDF, ADF and ADL
values (Tables 15 and 16). ALFA values of NDF (43.2 and 46.5) and ADF (32.0 and 29.2)
are representative of book values for 17% CP dehydrated alfalfa (SID Sheep Production
Handbook, 1992).

Lambs weights at the beginning of the digestion trial replicates were 40.1 kg and
45.6 kg for the lightweight and heavyweight blocks, respectively (Tables 22 and 23).
Average ad libitum intakes by lambs immediately prior to the adaptation period in the
metabolism stalls were 1,307, 1,727 and 1,380 g/d for the lightweight lambs consuming
ALFA, 50/50 and CONC diets, respectively (Table 22). This is equivalent to 3.3, 4.3 and
3.4% of BW, respectively. Average ad libitum intakes were 2,434, 2,233 and 1,576 g/d for
heavyweight lambs consuming ALFA, 50/50 and CONC, respectively (Table 23). This is
equivalent to 5.3, 4.9 and 3.5 % BW, respectively. The corresponding intakes of light- and
heavyweight lambs during the digestion study (90% of ad libitum) are shown in Tables 22
and 23, respectively. When feeding 31 kg lambs a 100% alfalfa pellet or an alfalfa pellet
that contained 30% barley, Weir et al. (1959) found that lambs consumed the diets at 5.5
and 4.8% of BW, respectively. Other studies (Cate et al., 1955 and Meyer et al., 1959) have
also shown that lambs consumed pelleted alfalfa diets at 4.3% BW when diets were offered

at ad libitum levels of intake.

 

49

Table 22. Feed intake prior to and during the digestibility trial — lightweight lambs

 

 

 

 

Diet
ALFA' 50/502 CONC3
N 3 4 4
Initial weight, kg 38.8 40.9 40.6
Intake:
ad libitum, g/d 1,307 1,727 1,380
90% ad libitum, g/d 1,176 1,554 1,242

 

lALFA - Pelleted, 100% dehydrated alfalfa
250/50 - 1:1 mixture of ALFA and CONC
3CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

Table 23. Feed intake prior to and during the digestibility trial — heavyweight lambs

 

 

 

Diet
ALFA‘ 50/502 CONC3
N 4 4 4
Initial weight, kg 42.9 46.5 47.5
Intake:
ad libitum, g/d 2,434 2,233 1,576
90% ad libitum, g/d 2,191 2,010 1,418

 

IALFA - Pelleted, 100% dehydrated alfalfa
250/50 - 1:1 mixture of ALFA and CONC
3CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

Among the lightweight lambs, DMI was highest (P < .01) for lambs consuming the

50/50 diet (1,554 g/d) compared to ALFA (1,176 g/d) and CONC (1,242 g/d) (Table 24).

Although DMI of lambs consuming ALFA and CONC were lower than 1,500 g/d suggested

by NRC requirements, for lambs gaining 345 g/d (Table 20), lambs fed those diets still

consumed amounts of CP (219 and 206 g/d, respectively) to meet or exceed those

requirements based on diet compositional analysis (Table 25). Results of the performance

trials (discussed in a later section) indicated that these lambs had moderate grth potential

according to NRC (1985) requirements (345 g/d).

50

Based on DMI requirements (NRC, 1985), lambs fed ALF A and CONC consumed enough
feed to support 270 and 285 g/d gain, respectively. The ME intakes, using DE * .82 (NRC,
1985) were 2,350, 3,351 and 3,318 kcal/d for ALFA, 50/50 and CONC, respectively. All
lambs had ME intakes lower than the 4,200 kcal/d suggested by NRC (1985). Lambs fed
ALFA excreted 480 g/d of fecal DM, the 50/50 lambs excreted 575 g/d and lowest (P < .01)
fecal DM excretion was seen with CONC fed lambs (281 g/d). Digestibilities of DM, OM,
NDF and ADF fractions of the diets are presented in Table 24. Apparent DM digestibilities
(DMD) ranged from 59.4% to 77.0% for ALFA to CONC fed lambs, respectively and
increased as level of alfalfa in the diet decreased. A similar response was seen with organic
matter (OM) where apparent OM digestibility (OMD) ranged from 61.1% to 79.0%. These
data agree with Kromann et al. (1975), Lambert et al. (1987) and Reynolds et a1. (1991)
who reported increased DMD and OMD with increased proportions of concentrate in the
diet, which was attributed to increased digestibility of cell solubles with added concentrate.

Lightweight lambs consuming ALFA diets consumed 547 g of NDF/d (Table 25) with an
apparent NDF digestibility of 43.3% (Table 24). Lambs consuming the CONC diet had a
higher (P < .01) apparent NDF digestibility (53.5%) while consuming approximately 1/2 as
much NDF (323 g NDF/d). Acid detergent fiber digestibility was also higher (P < .05) for

CONC fed lambs (44.3%) compared to 50/50 fed lambs (30.8%).

 

51

banumowme Bum:— oEnEO - Q20n

32586 .838 be - 955.

«babe @086»on $3 "88:80:06 $2. 680:3 - U750n

0200 28 (45¢. mo 03:3: fi— - oflomu
«barn 625.396 oboe 608:0.“ - «£45

been 05 89a 3582 83 £52 3.“ <93. 25 a.

so. v a see 88:36 as? 882....

 

 

 

WM n03 QM BWMW NA no.2. w; gosh. Won nHwN 9mm. .NVNJ v nUZOU
m.m awdm QM uwfim Nu— .oéo w.— .049. mém .mbm 9%. Bme.— V NOQOW
0.? send? v6. .m.mv ON L . ~© ~.N «Yam ~.Nv cow». wda achfim m _<..m.H<
Gm: emv 65
3mm ”ma Ema "H92 2mm “Q20 sum vQEQ Sim 2n— ?oom EMW ~29 :
o\o .banumowE Enema”?

 

 

amaze: ~an95an— .. bun—5&6 Hope 98 .533: enema £838 be .8.“ 338 Egg 3.qu .vm oBE.

52

Table 25. Least square means for CP, ME, NDF and ADF intakes,

 

 

lightweight lambs“
n DMI CPI' MEI2 NDFI3 ADFI‘
Diet (g/d) (g/d) (kcal/d) (g/d) (g/d)
ALFA’ 3 1,176 219 2,350 547 377
50/506 4 1,554 275 3,351 563 343
CONC7 4 1,242 206 3,318 323 151

 

°One ALFA fed lamb removed from the study

lCPI - Crude protein intake

2MEI - ME intake (NRC, 1985)

3NDFI - NDF intake

‘ADFI - ADF intake

SALFA - Pelleted, 100% dehydrated alfalfa diet

650/50 - 1:1 mixture of ALFA and CONC

7CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

53

In the heavyweight block (Table 26), lambs consuming the ALFA and 50/50 diets
had higher (P < .0001) DMI (2,191 and 2,010 g/d, respectively) than lambs consuming the
CONC diet (1,418 g/d). Crude protein intakes were 438, 375 and 250 g/d for ALFA, 50/50
and CONC fed lambs, respectively (Table 27). Using DE * .82 to estimate ME intake only
the 50/50 fed lambs (4,238 kcal/d) met the 4,200 kcal/d ME intake requirement (NRC,
1985) compared to ALFA (4,011 kcal/d) and CONC (3,641 kcal/d). Lambs fed the ALFA
diet had the highest (P < .0001) fecal DM excretion (1,036 g/d) compared to lambs fed
50/50 (764 g/d) and CONC (335 g/d) diets. Digestibility of DM, OM, NDF and ADF
fiactions of the diets are presented in Table 26. As alfalfa content of the diet decreased,
DMD increased (P < .01) from 52.7% to 62.0% to 76.4% for ALFA, 50/50 and CONC
diets, respectively. Lambs consuming ALFA diets consumed 947 g of NDF/d with an
apparent NDF digestibility of 26.7% (Table 27). Lambs consuming the CONC diet had a
higher (P < .001) apparent NDF digestibility (44.1%) while consuming approximately 1/3
as much NDF (331 g NDF/d). Apparent ADF digestibility by lambs on the all forage

ALFA diet (20.7%) was also lower (P < .01) than by lambs on the CONC diet (39.0%).

54

3.35%... seas eaawno - 920.

baggage gene be - 8,5.

are; 3.33% :3 seasoned $2 .82.... - 028.
028 nan <5... .3 23...... E - 85m.

agar... 353% $2: .828 - $3....

A3. v a came 8.38 as? 832......

 

 

0m .93 3 .3... S .35 3 ave» 3m .92 3K 3:} a .028
n... .2: 3 NR 2 .08 5 3% 3m .3; 3K .23 e .38
3 .SN 3 .SN 2 a? M: .Zm 3m .98.. 3: .83 a 2.3...
new 83 35

2mm .5... 2mm "52 2mm .38 2mm .95 2mm 29 zoom 2mm :8 e

 

.x. .bzseanme Bead?

 

3:5 “swag—won - gfiumomnu can: 98 £888 35MB #838 be 8m 2808 98:3 384 .cm 03.?

55

Table 27. Least square means for CP, ME, NDF and ADF intakes,

 

 

heavyweight lambs
n DMI CPI‘ MEIZ NDFI’ ADFI‘
Diet (g/d) (g/d) (kcal/d) (g/d) (g/d)
ALFA’ 4 2,191 438 4,01 1 947 640
50/50‘5 4 2,010 375 4,238 669 410
CONC7 4 1,418 250 3,641 331 164

 

lCPI - Crude protein intake
2MEI - ME intake (NRC, 1985)

’NDFI - NDF intake
‘ADFI - ADF intake
SALFA - Pelleted, 100% dehydrated alfalfa diet

650/50 - 1:1 mixture of ALFA and CONC

7CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

56

Regardless of weight, apparent DMD and OMD increased as the level of alfalfa in
the diet decreased fiorn 100% to 25%. With the lightweight lambs, the lowered DMD seen
with ALFA fed lambs compared to CONC may be attributed to more highly digestible feed
components in the CONC diet as similar intakes were attained on both diets. Intakes by
heavyweight lambs however, were higher (P < .05) on ALF A fed lambs than on CONC and
therefore it is reasonable to expect the rate of passage may also play a role in limiting DMD
of these high forage fed lambs. These results agree with data from Reynolds et al. (1991)
who found that DM, OM, NDF and ADF digestibilities decreased as level of alfalfa in the
diet increased.

Lightweight lambs consuming ALFA diets consumed 1,176 g DM/d (2.9% BW)
and had DMD of 59%, whereas heavyweight lambs consumed 2,190 g DM/d (4.8% BW)
and had DMD of 52%. These results suggest that DMI may explain differences in DMD by
lambs consuming the ALF A diet. A similar study by Lambert et al. (1987) found that 40 kg
lambs fed rape supplemented, orchardgrass hay had increased DMD (65 to 73%) as the
proportion of rape supplemented in the diet was increased from 40 to 70% when consuming
feed at 3.5% BW. The work by Lambert et al. (1987) suggests that DMD may also be

attributed to differences in concentrate level of the diet.

Nitrogen Balance

Nitrogen balance data are shown in Tables 28 and 29. Lightweight lambs fed the
50/50 diet had the highest (P < .05) N intake (44 g/d) compared to lambs fed ALFA and
CONC at 35 and 33 g/d, respectively. These intakes meet the CP requirements of 202 g/d
for a 40 kg lamb gaining 345 g/d, which is equivalent to 32 g N/d (NRC, 1985). Nitrogen

digestibilities (g/d) did not differ among dietary treatments, and ranged from 25 g/d for

57

ALFA and CONC diets to 30 g/d for 50/50 diets. When expressed as a percent of N intake,
digestibility of the 50/50 diet (67.6%) was lower (P < .05) than the CONC lambs (74.4%)
and was a result of a 37.3% greater (P < .05) fecal N excretion by the 50/50 lambs. Lambs
fed ALFA diets had similar N digestibilities to lambs fed the other two diets (72.4%) when
expressed as a percent of N intake. Lambs retained an average of 7 g of N/d regardless of
dietary treatment. Nitrogen retention, when expressed as a percent of N intake or N
digestibility did not differ among dietary treatments. Although lambs consuming the 50/50
diet had the highest (P< .05) DM intakes, increased fecal and urinary excretions resulted in
lower N digestibilities and similar N retentions to lambs consuming the CONC diet. For
the lightweight lambs, forage content of the diet had little effect on N digestibility or N
retention. This was probably a result of all diets meeting or exceeding the N requirements
of the lambs and therefore N was not a limiting factor in nutrient utilization by these lambs.

The high CP content of the alfalfa pellets combined with high dietary feed intake,
resulted in the heavyweight ALFA fed lambs having the highest (P < .05) N intake (70 g/d)
followed by 50/50 (60 g/d) and CONC (40 g/d). Digested N (g/d) was also highest (P <
.01) for lambs fed the ALFA diet (50 g/d) followed by 50/50 (41 g/d) and CONC (30 g/d).
However, when expressed as a percent of N intake, N digestibilities did not differ among
dietary treatments. This differs from data of Susin et al. (1995) who found that as
concentrate level in the diet increased from 20 to 90%, N intake decreased from 53 g/d to 48
g/d and N digestibility (% of N intake) increased fi'om 61 to 78%, respectively when lambs
were fed to a similar level of gain. Retained N was higher (P < .05) in lambs fed the ALFA
diet (17 g/d) compared to lambs fed the CONC diet (9 g/d) and as with N digestibility when

expressed as a percent of N digested or percent of N intake, there were no differences in N

58

retention among dietary treatments. The differences in N digestibility and retention appear
to be related to increased N intake rather than any change in efficiency of N utilization.

These results differ from other studies, which have shown N retention to increase
for animals fed high concentrate diets (Susin et al., 1995). Susin et al. (1995) showed that
lambs consuming 80% (16.2% CF) or 10% (22.8% CF) forage diets retained 18% and 27%
N as a percent of N intake. Even though the other studies showed decreases in fecal and
urinary N losses as forage content of the diet decreased, the changes in N retention were

attributed to differences in dietary CP levels rather than any N digestibility differences.

59

are: 82.8.38 82 u....8......2§ $8 .323 - ozoo.
028 8. <5... we e888. 3 - 3%.

88.. 8.8.88 52 .322 - <82.

238 8882 - E.

.358 05 Sch c9688 33 9:8— Uou 53¢. 25 _..

A8. v a see 8828 85.3 882....

 

 

 

 

 

5m Ndm Ev m.m~ Nd w flu even e._ mm v; E 2 .w Nd .mm 9%. kg; v. 40200
Nam 93 he 9: «N m _.N .93 e4 om v4 .mm 2 e3 ~.N e3. v.3. sewn; v nemBm
we we— ed 3: m.~ m YN page m.~ mm c; .78 m; .3 9N .mm mde .02; m ”55¢.
Acme 8m: GE 53 35
2mm ma. e\e 2mm 7x. 2mm 3» 2mm H e\.. 2mm 3w 2mm 2 EEO 2mm 2 zoom 2mm .2 2mm an a
86:82 cowobmz banumommo some: Z

 

«BEE Emmoafiwz - 88:3 camera 8m 8808 03:3 3.qu .wm vine.

60

2.2.. 38.38 28 88888 $2 .83... - 028.
028 8.. <5... 8.. 23...... E - .58..

2.2.. 8.528 .88. 88:... - <5...

.88. 8882 - E.

.8. v a 82:. 8828 as... 882...

 

5m m.wN 5v c._~
5m fivm 5v 9mm
56 nNm Ev QNN

_.N NE «o.— eon
~.~ ode a; a;
mm 0.2. a; .0m

5 ..~ 2 .2 2 .2. e8 .2} v .260
I .2 2 .2 2 .8 3K .23 e .38
E .2 I .8 2 .2 e8 .83 8 .Eq...

 

2% we: 2% 2..

N... .e
3 e:
3 .2
2% 2w

2% 3. 2% 2w

 

concave new“: Z

33:818.. 8882

.23 some 63 ewe 85
2% 2885 2mm 28.... 2mm .2 2mm :8 n

 

382 “$83.98; - 8:23 nowobE 8.“ 838 826... $.qu .3 053.

6 1
Energy Balance

Energy balance data are shown in Tables 30 and 31. According to NRC (1985), 40
- 50 kg early-weaned lambs require 5,100 kcal/d DE and 4,200 kcal/d ME to attain 300 to
350 g/d weight gain. Gross energy content of the diets in this trial, fed to lightweight lambs
ranged from 4.09 kcal/g for ALFA to 4.22 kcal/g for CONC diets (Table 15). Gross energy
content of the diets fed to heavyweight lambs ranged from 4.20 kcal/g for ALFA to 4.14
kcal/g for CONC diets (Table 16). Based on these dietary compositions and feed intakes,
among lightweight lambs, GE intakes were lower (P < .05) for lambs fed ALF A (4,815
kcal/d) and CONC (5,244 kcal/d) diets compared to lambs fed the 50/50 (6,460 kcal/d) diet
when consuming 1,176 and 1,242 g DM/d, compared to 1,554 g DM/d, respectively. With
similar GE densities of the diets, this increase in GE intake is the result of higher (P < .01)
DMI of lambs fed the 50/50 diet. After accounting for fecal energy losses, DE intakes were
greater (P < .01) for lambs fed CONC (4,046 kcal/d) and the 50/50 (4,087 kcal/d) diets
compared to 2866 kcal/d for lambs fed ALFA. Lambs consuming the CONC diet had 45%
lower fecal energy losses, compared to lambs consuming ALFA or 50/50 diets. These DE
intakes were less than the 5,100 kcal/d requirement to support the desired gains. In the
digestion study, lambs were restricted in feed intake to 90% of ad libitum levels, but even
accounting for this would not bring DE intakes up to the recommended levels.

The effects of dietary forage content on energy balance in heavyweight lambs is
shown in Table 31. Heavyweight lambs fed ALFA (9,193 kcal/d) and 50/50 (8,379 kcal/d)

diets had higher (P < .0001) GE intakes compared to CONC fed lambs (5,871 kcal/d).

62

Table 30. Least square means for energy balance - lightweight lambs"

 

 

 

 

n DMI SEM GEI‘ SEM Fecal E SEM 131312 SEM
Diet (g/d) (kcal/d) (kcal/d) (kcal/d)
ALFA’ 3 1,176' 90.8 4,815' 379.5 1,949' 169.8 2,866' 310.5
50/50‘ 4 1,554" 78.6 6,460” 328.6 2,373' 147.1 4,087” 268.9
CONC’ 4 1,242' 78.6 5,244' 328.6 1,198b 147.1 4,046b 268.9
”Means within columns differ (P < .05)
* One ALFA fed lamb was removed from the study
lGEI - Gross energy intake
2DEI - Digestible energy intake
3ALFA - Pelleted, 100% dehydrated alfalfa
‘50/50 - 1:1 mixture of ALFA and CONC
SCONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa
Table 31. Least square means for energ_y balance - heavyweight lambs

n DMI SEM GEI‘ SEM Fecal E SEM 131312 SEM
Diet (g/d) (kcal/d) (kcal/d) (kcal/d)
ALFA’ 4 2,191' 78.6 9,193' 328.6 4,302' 147.1 4,892 268.9
50/50‘ 4 2,010‘ 78.6 8,379‘ 328.6 3,211" 147.1 5,168 268.9
CONC’ 4 1,418b 78.6 5,871b 328.6 1,431° 147.1 4,440 268.9

 

all”Means within columns differ (P < .05)

lGEI - Gross energy intake

2DEI - Digestible energy intake

3ALFA - Pelleted, 100% dehydrated alfalfa
‘50/50 - 1:1 mixture of ALFA and CONC
SCONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

63

The increase in GE intake on the 100% forage diet was due to a 33% increase (P < .01) in
DMI for ALF A and 50/50 fed lambs compared to CONC fed lambs. There was, no
difference in DE intakes (4,833 kcal/d) among dietary treatments due to the 62% increase in
fecal energy losses for ALF A and 50/50 fed lambs, compared to CONC fed lambs.

Metabolizable energy determinations require the accounting of urinary and gaseous
losses. For lightweight lambs, urinary energy losses (Table 32) were higher (P < .05) for
lambs fed the 50/50 diet (294 kcal/d) compared to lambs fed the CONC diet (215 kcal/d).
Methane was used to represent gaseous losses and estimated using two equations. The
Wolin (1960) equation uses VFA concentrations in the rumen to estimate methane.
Volatile fatty acid concentrations are shown in Appendix E. Using this method, lambs fed
the ALFA diet were found to have 48% higher (P < .0001) methane production (599 kcal/d)
than lambs consuming the 50/50 (322 kcal/d) or CONC (300 kcal/d) diets. This was
expected since feeding high forage diets results in increased ruminal acetate ratios relative
to propionate while high concentrate diets results in increased propionate concentrations
and the equation associates greatest methane production with higher acetate and(or)
butyrate concentrations relative to propionate concentrations. Using this method, ME
intakes were lower (P < .01) for lambs consuming the ALFA diet (1,995 kcal/d) compared
to 3,471 kcal/d and 3,530 kcal/d for 50/50 and CONC fed lambs, respectively (Table 32).
Using another method to estimate methane based on DE intake (Johnson et al., 1991),
methane production by lambs fed the ALF A diet (204 kcal/d) did not differ from the lambs
fed the 50/50 diet (187 kcal/d), but was 25% higher (P < .0001) than for lambs consuming
the CONC diet (153 kcal/d). Using these methane losses to calculate ME intake, ALF A
lambs had lower (P < .01) ME intakes (2,390 kcal/d) than 50/50 lambs (3,606 kcal/d) and

CONC lambs (3,678 kcal/d). Metabolizable energy can also be estimated by using the

64

equation DE*0.82 (NRC 1985). Using this method, ALFA fed lambs again had lowest (P <
.01) ME intakes (2,350 kcal/d) compared to 50/50 fed lambs (3,351 kcal/d) and CONC fed
lambs (3318 kcal/d). The lower DE and ME intakes by ALFA fed lambs agrees with data
from Kromann et al. (1975) who determined that as the proportion of alfalfa in the diet
increased from 0 to 100% there was a decrease in both DE (5360 to 2160 kcal/d) and ME
(4690 to 1920 kcal/d) intakes. Regardless of method of estimation, ME intake of lambs
consuming ALFA was at least 30% lower than the other diets.

Fewer differences were found in ME intakes among dietary treatments for
heavyweight lambs. Using the Wolin (1960) equation, ALFA fed lambs had higher (P <
.0001) methane production (677 kcal/d), followed by 50/50 (387 kcal/d) and were lowest
for lambs fed CONC (261 kcal/d) diets (Table 33). However, ME intake did not differ
among dietary treatments and averaged 4,048 kcal/d. Using the Johnson equation (1991),
no differences among diets were found in estimated methane losses or ME intakes, which
averaged 209 kcal/d and 4,351 kcal/d, respectively. The average ME intake when
calculated as a multiple of DE (NRC 1985) was 3,963 kcal/d, and did not differ among
dietary treatments.

Since there was no differences in DMI between light and heavyweight lambs fed
CONC, gross energy intake (kcal/d) did not increase when feeding heavy compared to
lightweight lambs. Heavyweight lambs, fed ALFA and 50/50 diets, averaged a 36%
increase (P < .0001) in GE intake but DE and ME intakes did not differ among dietary
treatment. At lighter weights however, DE and ME intakes were increased (P < .05) by
feeding CONC or 50/50 diets, compared to ALFA. Data from the lightweight lamb trial
differ with data from Reynolds et al. (1991) who reported increased DE (90.8 to 86.6 MJ/d)

in heifers fed 7 5% alfalfa compared to 75% concentrate diets.

65

aha—a 8.8.33. $3 ”88588 €62. 630:9. - 0200..

0200 v8 <n3< .«0 8858 1. - 35m.

88.... .8538 .88. 886...... - <8...

53. .82. a... _. ma 8 .88.. 28...... - .8...
88...... :8: ..a .6 83...... 8 .88.. 8.8... m2 .6 28...... - . - .8...
82.83 See: .3 .o 88.8.. no 38.. 832 08.508 .3 0.8mm . nimmoq £0.
88...... 8...... 8...? 8 88.. 8.8... ms. .6 88...... - 3 - .8...
80:83 333 83>) no woman 832 28598 mo 88mm - 3-83 50.
83m 05 8c... @9688 83 £82 3.. «54¢. 80 _..

Ame. v A. 8&6 8828 85.3 832....

 

 

nos .28 2.: .83. ..~. .2. 88 .23. New .8... SN .3 .. .028
28. .23 3.2 .83. ..N. .2. 82 .EA Nam .NNM SN .48 e .88
3.2 .88 on: .83 3.. .8 we: .38.. 2.... 8% 38 an: m 2......

6.8... .88... .38... 9.8.8... 6.8... .88... .65
2mm .8 .52 2mm .75: .28 88380 28 .3 .52 Sum .3838”. 2mm wheat: a

 

 

 

 

I
I!

.882 Emmonfinwz - 80:98.8 m2 8.. 38:3 8288088.. .8 838 88.3. .83 .Nm nigh

66

«.3... 3.8.38 o\.mN H38.583 $3 889:0“. - 0200.
0200 8a .33.. ..o 2.88. .H. - 85m.
«3...... 8.8.38 $8. 689:“... - $3....

a... .82. a... ._ ma .5 8...... 3.8.... - .82.
8.3:... :2... ... s 8.5... 8 8...... 9.5... m2 .8 28...... - . - .8...
83.83 :33 .3 .o 808...... no .58.. 830. 88.08 .8 8.8qu - 7.8.. ion
82.83 83: 8.03 no woman 8.8... m2... o2.8....m. - 3 - ES.
83.83 83: 833 no 883 8.8. 88.08 .8 0.8.5”. - 3&8.— £0.
.8. v m. .8... 8.5.8 5...... 8.2....

 

 

 

32 .3. 32 .8... ..N. o... .32 .2... 3m .3. m... .8. .. .028
2.2 .2... ER 8.... ..N. R. 32 3.... 3m .2: SN .N... v .35.
32 .8... 2... .8... ..~. 3. .32 ME... N... .5 SN .. a. .. .8...
8.8... 8.8... 3.8... 38.8... .38... .38.... .8

2mm .8 - .ms. 23 L - is. 2mm .28.. .5 2% N3 - is. 2% 3.8.. .5 .28 m .55... a
n 88... .nmmoénon - 82.888 m2 v.8 8.8—um... 80.588280. .8 838 88...... .804 .mm 2%...

67

The calculated ME values of the diets were compared to NRC (1985) table values
and are shown in Tables 34 and 35. These values were determined by dividing ME intake
by DMI for lambs fed each diet. These values, for each diet were compared to NRC (1985)
values for the same feedstuffs to determine if ME table values of the diets were similar to
ME values of the diets consumed by the lambs. For lightweight lambs, the NIE values of
the diets were 1.70, 2.23 and 2.84 kcal/g when using ME intake estimated fi'om the Wolin
(1960) equation for ALF A, 50/50 and CONC diets, respectively. Using ME intake
estimates from the Johnson et al. (1991) equation the ME values were 2.03, 2.32 and 2.96
kcal/g for ALFA, 50/50 and CONC diets, respectively. Using DE * 0.82 (NRC, 1985) the
ME values were 2.00, 2.16 and 2.67 kcal/g for ALFA, 50/50 and CONC diets, respectively.
For heavyweight lambs, ME values were 1.72, 2.21 and 2.78 kcal/g, using ME intake
estimates fi'om the Wolin (1960) equation for ALFA, 50/50 and CONC diets, respectively.
Using ME estimates from the Johnson equation (1991) the ME values were 1.96, 2.34 and
2.86 kcal/g for ALFA, 50/50 and CONC diets, respectively. Using DE * 0.82 (NRC, 1985)
the ME values were 1.83, 2.11 and 2.57 for ALFA, 50/50 and CONC diets, respectively.
For light and heavyweight lambs these data indicate that the NRC (1985) table values may

underestimate the ME value of the CONC diet.

 

68

Table 34. Estimation of the ME values of the diets - lightweight lambs

 

 

 

 

ME - WI ME - J2 ME - DE3 NRC, (1985)‘
Diet . kcal/g
ALFAT 1.70 2.03 2.00 2.04
50/506 2.23 2.32 2.16 2.20
CONC, 2.84 2.96 2.67 2.36
lME — W - Estimation of ME values of the diets using the Wolin (1960) equation
2ME - J — Estimation of ME values of the diets using the Johnson et al. (1991)
equation
3ME - DE — Estimation of ME values of the diets using 082* DE (NRC, 1985)
‘NRC, (1985) - Calculated ME from tabular values
’ALFA - Pelleted, 100% dehydrated alfalfa
650/50 - 1:1 mixture of ALFA and CONC
7CONC — Pelleted, 75% concentrate: 25% dehydrated alfalfa
Table 35. Estimation of the ME values of the diets — heavyweight lambs

ME - Wl ME - J2 ME - DE3 NRC, (1985)‘
Diet kcal/g
ALFAS 1.72 1.96 1.83 2.04
50/50‘5 2.21 2.34 2.11 2.20
CONC, 2.78 2.86 2.57 2.36

 

iMB — W - Estimation of ME values of the diets using the Wolin (1960) equation
2ME - J - Estimation of ME values of the diets using the Johnson et al. (1991)
equation

3ME - DE - Estimation of ME values of the diets using 082" DE (NRC, 1985)
‘NRC, (1985) - Calculated ME from tabular values

5ALFA — Pelleted, 100% dehydrated alfalfa

650/50 - 1:1 mixture of ALFA and CONC

7CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa

69

These results suggest that the diets are used with similar efficiencies of energy
utilization by both lightweight and heavyweight lambs. This is indicated by similar ME
values of the diets for both weight classes within a given method of estimation. It would
also appear that using the Wolin (1960) equation for estimating methane losses, tends to
underestimate the ME value of the diets compared to other methods. Using the Johnson et
al. (1991) equation for estimating methane losses, ME values of the diets were similar to
NRC estimates for the ALFA and 50/50 and also closely associated with NRC estimates for
the CONC diet. This is not unexpected as the Johnson et al. (1991) equation used to
determine methane loss was derived fi'om high forage diets and less appropriate for use with
high concentrate diets.
Feedlot Performance and Carcass Characteristics

The purpose of a performance trial is to gain applied data based on the information
obtained in digestibility trials. Performance trials are beneficial, since they provide
information on how a group of animals respond to a given feedstuff or level of feeding.
Producers want data that shows improved performance at a reduced cost. Traditionally,
producers feed their livestock a concentrate-based diet. Some studies have shown that
increasing the level of forage in a finishing diet will reduce carcass fat (Kromann et al.,
1975 and Thomas et al., 1984). These authors also reported increased feed intakes on the
high forage diets. Others have also reported decreased DP lambs fed high forage diets due
to increased gut fill (Thomas et al., 1984). In some studies feeding forage diets with
concentrate supplementation, lambs had similar or greater performance than lambs fed high
concentrate diets due to increased feed intake (Cate et al., 1955, Meyer et al., 1959 and Weir
et al., 1959). How these factors effect the producer’s cost of gain is the true measure of how

successful a feeding strategy will be.

70

Performance Trial 1

The objective of performance trial 1 was to determine the effects on performance
and carcass characteristics of lambs fed ALFA or CONC diets (100 or 25% forage) at A or
R levels of intake (Table 36). Lambs fed the ALFA diet consumed 22% more (P < .01)
feed (2.48 kg/d) than lambs fed the CONC diet (1.84 kg/d) at A intakes. By design lambs
fed at A levels of intake consumed 15% more feed than lambs fed at R levels of intake.
Average daily gains were higher (P < .01) for lambs consuming ALFA (.35 kg/d) and
CONC (.36 kg/d) at A intakes compared to lambs consuming the same diets at R intakes
(.30 and .31 kg/d, respectively). Intake level had no significant effect on gain to feed (GzF)
ratios (.20 vs. .15) for lambs fed the CONC diet compared to lambs fed the other diet.
Afier 63 days on feed, FW were higher (P < .01) for lambs fed at A intakes (54.3 kg)
compared to 50.3 kg for lambs fed at R intakes. Lambs fed at A levels of intake out-
performed lambs fed at R levels of intake. However, lambs fed ALFA diets at A or R levels
of intake had similar ADG when compared to their CONC fed counterparts. These results
agree with data from Weir et al. (1959) who found that lambs consuming alfalfa pellets or
alfalfa pellets plus 30% barley had similar ADG (.18 and .16 kg/d, respectively) and lambs
fed alfalfa pellets consumed 14% more feed/d. Although feeding at R levels of intake
reduced feed intake by 15%, the practicality of implementing this in a large-scale feedlot is
low due to an increased labor cost. Carcass weights were heavier (P < .01) for lambs fed
CONC at A intakes (26.2 kg) followed by CONC at R intakes (24.4 kg) and ALFA at A
intakes (23.2 kg) and were lowest (P < .0005) for lambs fed ALFA at R intakes. CONC
lambs at A intakes had more (P < .05) FAT (.47 cm) than did lambs on the other dietary
treatments. Lambs fed ALFA at A intakes and CONC at R intakes had similar FAT (.31

and .37 cm, respectively). Lambs fed ALFA at R intakes had the least (P < .05) FAT (.21

71
cm). Lambs fed ALFA at R intakes also had the smallest (P < .01) LEA (13.1 cmz)
compared to the other dietary treatments (15.6 cmz). The differences in FAT and LEA
would account for the differences in carcass weight. DRESS values were determined by
dividing HCW by the off test weight. This calculation is not intended to reflect standard DP
used by the industry, where the live weight would be determined immediately prior to
slaughter. DRESS values were higher (P < .0001) for lambs fed CONC at A and R intakes
(48.1%) compared to lambs fed ALFA at A and R intakes (42.1%). A contributing factor to
the differences in DRESS values was the difference in FAT. However, the differences in
DRESS values were primarily attributed to an increase in gut fill in lambs on the ALFA

diets.

72

Table 36. Least square means for lamb feed intakes, ADG and feed conversions (GzF) HCW, LEA, FAT and

DRESS values — performance trial 1

 

 

Diet

ALF A2 ALFA’ CONC’ CONC3 SEM‘
Intake level‘ A R A R
Lambs 19 20 20 20
Pens/tn 2 2 2 2
Initial wt., kg 31.9 31.2 31.6 31.2 0.57 (0.60)
Final wt., kg 53.9a 49.9b 54.2' 50.8" 0.93 (0.99)
Days on feed 63 63 63 63
Lamb intake, kg/d 2.48‘ 2.00“ 1.84b 1.56" 0.15 (0.15)
ADG, kg/d 0.35‘ 0.30" 0.36' 0.31" 0.02 (0.02)
GzF 0.14 0.15 0.20 0.20
HCW‘, kg 23.0" 20.7' 26.2c 24.4‘“c 0.47 (0.50)
LEA‘, cm2 15.1' 13.1” 16.0‘ 15.5' 0.55 (0.58)
FA'I‘, cm 0.30lLb 0.21' 0.47‘ 0.37" 0.03 (0.04)
DRESS’, % 42.5' 41.6‘ 48.3" 48.0" 0.004 (0.005)

 

flMeans within rows differ (P<.05)

'SEM where n = 20, where n = 19 SEM value in ( )
'Intake level - A = ad libitum, R = 85% of ad libitum
2ALFA — Pelleted, 100% dehydrated alfalfa

3CONC — Pelleted, 75% concentrate: 25% dehydrated alfalfa

‘HCW — Hot carcass weight

’LEA - Loineye area

6FAT - 12'“ rib fat

7DRESS — HCW as a percent of off test weight

73

Performance Trial 2

The objective of performance trial 2 was to determine the effects on performance
and carcass characteristics of lambs fed 50/50 diets (62.5% forage) at A or R levels of
intake. In performance trial 2, 31 kg lambs were fed the 50/50 diet at A and R levels of
intake for 96 days (Table 37). With level of intake adjusted weekly, rather than daily as in
trial 1, lambs fed at the A level of intake consumed 11% more feed per day than lambs fed
at the R intake level. Average daily gains were higher (P < .05) for lambs fed at A intakes
compared to lambs fed at R intakes (.35 kg/d and .33 kg/d, respectively). This meant that
lambs fed at the A level of intake gained 5.7% faster than lambs fed at the R level of intake.
Although lambs consumed 11% more feed at A levels of intake, the 5.7% increase in gain
may justify feeding at this level since it would result in less days on feed and the ease of
feeding at A levels compared to feeding at R levels. Gain to feed ratios were similar (.15)
for lambs fed at both levels of intake. After 96 days on feed, FW did not differ by intake
level although after 96 days on feed ad libitum fed lambs weighed 2.4 kg more (64.7 and
62.3 kg) for A and R intakes, respectively. However lambs fed at A intakes had larger (P <
.001) HCW (29.4 kg) compared to 27.1 kg for lambs fed at R intakes. As a result of
increased carcass weights lambs fed at A intakes had greater (P < .001) DRESS values than
lambs fed at R intakes (45.4 vs. 43.4%, respectively). This increase in HCW and DRESS
was attributed to the increased (P < .01) FAT for lambs fed at A vs. R intakes (.63 vs. .43
cm, respectively). In a study by Kromann et al. (1975), lambs offered diets that contained
80% alfalfa and 20% com at ad libitum levels of intake had a lower carcass fat percentage
(25.1%) compared to lambs offered diets that contained 15% alfalfa and 85% com at ad

libitum levels of intake (34.1%).

74

Table 37. Least square means for lamb feed intake, ADG and feed conversions (G:F), HCW, FAT and Dress
values - performance trial 2

 

 

Diet

50/502 50/50’ SEM
Intake level1 A R
Lambs 21 21
Pens/trt 2 2
Initial wt., kg 30.8 30.9 0.46
Final wt., kg 64.7 62.3 0.89
Days on feed 96 96
Lamb intake, kg/d 2.40 2.14 0.06
ADG, kg/d 0.35‘ 0.33” 0.01
G:F 0.15 0.15
HCW’, kg 29.4‘ 27.1" 0.44
FAT“, cm 0.62' 0.43” 0.04
DRESS’, % 45.5‘ 43.5b 0.004

 

M’Means within rows differ (P<.05)

'Intake level - A = ad libitum, R = 85% of ad libitum
250/50 - 1:1 mixture of ALFA and CONC used in trial 1
3HCW - Hot carcass weight

4FAT - 12'h rib fat

’DRESS — HCW as a percent of off test weight

75

Performance Trial 3

The objective of performance trial 3 was to determine the effects on performance
and carcass characteristics of lambs fed ALFA, 50/50 or CONC diets (100, 62.5 or 25%
forage) at A levels of intake. In performance trial 3, all lambs were fed until an average pen
FW of 56.2 kg was reached (Tables 38). Lambs fed the ALFA diet consumed 30% more
feed than lambs fed the CONC diet before attaining that FW, which required 7d longer on
feed. Lambs fed 50/50 required fewer days on feed (70d) to attain FW. This was
accomplished since 50/50 lambs had higher ADG (.35 kg/d) than lambs fed the ALF A and
CONC diets (.30 kg/d and .28 kg/d, respectively). The ADG for lambs fed the CONC diet
was lower than seen in the previous two trials and was lower than expected. The CONC
diet was delivered in two separate batches from a commercial feed mill. On day 56 of the
trial, lambs began consuming feed from the second batch. Due to an error at the mill, a
dairy supplement was mixed with the lamb diet. The two pellets were similar in size and
color and were fed to the lambs over a 3d period before feed intake began to fall drastically
and the error was recognized. The high fat content of the dairy supplement was believed to
have caused the lambs to go off feed. The feed intake and ADG of lambs on the CONC diet
before and after the feeding of the tainted feed is shown in Table 39. After day 56, lambs
consumed 18.6% less feed and gained .14 kg/d less than before day 56 of the trial. Lambs
fed the CONC and 50/50 diets had greater gain to feed ratios (.16) than lambs fed the ALFA
diet (.12). All lambs were taken to a similar FW (56.2 kg). Lambs fed the CONC and
50/50 diets had greater (P < .001) carcass weights (27.6 and 27.2 kg, respectively)
compared to lambs fed the ALFA diet (25.2 kg). Lambs fed ALFA diets had less (P < .05)

FAT (.43 cm) than lambs fed CONC (.56 cm). CONC fed lambs also had a higher (P <

76

.0001) DRESS value (51.1%) compared to ALFA fed lambs (44.1%). The decreased

DRESS value was probably a result of increased gut fill and decreased FAT seen in ALFA

fed lambs.

Table 38. Least square means for lamb feed intakes, ADG and feed conversions (G:F), HCW, LEA, FAT

and DRESS values - performance trial 3

 

 

 

 

 

Diet

ALFA2 50/50I CONC‘ SEM
Intake levell A A A
Lambs 14 14 14
Pens/tn 2 2 2
Initial Wt., kg 32.0‘ 32.4' 33.4" 0.47
Final Wt, kg 57.0 56.7 54.9 0.83
Days on feed 84 70 77
Lamb intake, kg/d 2.43' 2.18“ 1.71” 0.12
ADG, kg/d 0.30- 0.35” 0.28‘ 0.01
G:F 0.12 0.16 0.16
ch‘, kg 25.2” 27.2- 27.6‘ 0.7
LEAS, cm’ 14.8b 16.7'| 17.8' 0.88
FATS, cm 0.43' 0.52“ 0.56” 0.05
DRESS7, % 44.1' 48.0b 51 .1‘= 0.007
‘b Means within rows differ (P<.05)
'Intake level - A = ad libitum
2ALFA - Pelleted, 100% dehydrated alfalfa
350/50 - 1:1 mixture of ALFA and CONC
‘CONC - Pelleted, 75% concentrate: 25% dehydrated alfalfa
‘HCW - Hot carcass weight
’LEA — Loineye area
GFAT — 12'” rib fat
7DRESS - HCW as a percent of off test weight
Table 39. ADG and feed intake before and after day 56

ADG Feed Intake
Day (kg/d) (kg/d)
0 - 56 0.35

57 + 0.21

 

77
Although lambs fed the CONC diet had lower performance in this trial, due to the
feed mixing error, the carcass data was similar to the other two trials. Also, the feed intake
and performance by lambs consuming the ALFA and 50/50 diets was similar to the other
two trials. In this trial, lambs consuming the 50/50 diet had the highest ADG probably due
to increased feed conversion since they consmned 250 g/d less and gained 500 g/d more
than ALFA fed lambs. Although ALFA fed lambs had .090m less fat than 50/50 fed lambs

they also had lighter carcasses and smaller DRESS values resulting in lower overall yields.

Economic Analysis

An economic analysis was conducted for each of the 3 performance trials (T able
40). An average feed cost was determined for each of the 3 pelleted diets, and was based on
bulk delivery of 5,455 kg (6 tons). The price determined for ALFA ($0.187/kg) and CONC
($0.183/kg), and were averaged to obtain the 50/50 price ($0.185/kg).

In performance trial 1, lambs fed ALF A at A and R intakes had feed : gain ratios of
7.08 and 6.67, which resulted in $1.32 and $1.25/ kg gain, respectively. Lambs fed CONC
at A and R intakes had more efficient feed : gain ratios (5.10 and 5.03, respectively), which
resulted in decreased cost of gain ($0.93 and $0.92/ kg gain) for CONC lambs fed at A and
R intakes compared to lambs fed ALFA at A and R intakes. Although lambs consuming
ALFA at A intakes had similar ADG to lambs consuming CONC at A intakes and had 11%
higher ADG than lambs consuming CONC at R intakes, the increased feed intake by ALFA
fed lambs, resulted in a 29.2% increase in cost of gain, when compared to lambs fed CONC
at A and R levels of intake. Implementing a management plan to feed diets at 85% of ad
libitum levels would cause a significant increase in labor costs. This type of feeding system

requires that lamb feeding level be monitored more precisely. However, the cost of gain

78
versus ADG benefits combined with labor costs would be key in determining the most
beneficial feeding strategy.

In performance trial 2, lambs fed the 50/50 diet at A intakes had a feed : gain ratio of
6.87 compared to 6.48 for lambs fed at R intakes. This resulted in a 5.5% increase in cost
of gain for lambs fed at A vs. R intakes ($1.27 / kg vs. $1.20 / kg).

In performance trial 3, lambs fed ALFA had the highest feed : gain ratio (8.10)
followed by lambs fed 50/50 (6.22) and CONC (6.10). Lambs fed ALFA also had 24.8%
higher cost of gain ($1.51/ kg) compared to lambs fed 5050 ($1.15/ kg) and CONC ($1.12/
kg).

Overall, feeding lambs at R intakes lowered cost of gain 5.4% for lambs fed ALFA
and 50/50 and 1.1% for lambs fed CONC, however increased labor cost and management
inputs associated with limit feeding lambs makes this method seem impractical in a large
feedlot setting. Feeding the CONC diet resulted in the most economical gains compared to
feeding ALFA or 50/50 diets. Based on the results of these three trials it was determined
that the price of the ALFA diet must be $0.05/kg less than the CONC diet to obtain an
equivalent cost of gain. This was calculated using the feed: gain ratios, diet costs and costs
of gain from performance trials 1 and 2 for ALFA and CONC diets at A levels of intake.
The average cost of gain for CONC was $1.01/kg gain, with a feed cost of $0.183 /kg and
the average feed: gain ratio was 5.61. The average feed: gain ratio for ALFA lambs was
7.60. Setting the costs of gain equal ($1.01/kg gain), the ALFA diet would have to cost

$0.133 /kg to meet this cost of gain.

79

833: 2 co $3 n a 53: B u < - :32 £55.

e3... Beige can ”333250 a? .323 - ozone.M
028 as <5< co 0558 E - 25m

are: Boeing $2: 322 - <55

 

 

 

 

 

 

 

 

 

 

3o N3 3° woo woo
N: 2._ En ON; NN._
$3 33 $3 33 £3
_ 3 Ne 2 .N was :3
a: N2 3N EN EN
NNd m3 one mac and
N N N N N
E 3 z N _N
< < < m <
nuzou ~38 33.. ~38 ~38
35 55
m E: N RE.

N; NE. N3 85 a; .56 co .80
N3 :3 m3 m2 mg .36 co e8
83 $3 $3 $3 9% .80 RE
8.“ :a Se 8N 5668a
02 3: SN NaN 2? .335 pg
:8 one one and can .09.
N N N N Beam
ON ON 8 2 ages
m < a < L22 335
nozoo bzoo _<..:< 2.3...
35
_ an...

 

m e5 N 4 $3.: commencing - 952689 252 868m .3 max—«5 ugoeoom .ov 03$.

80

Although costs of gain were increased in these trials where lambs were fed primarily
pelleted alfalfa diets, there is still producer interest. An advantage to feeding lambs on
alfalfa pellets is lamb health. Lambs are not likely to develop acidosis when consuming
alfalfa pellets. Lambs fed ALF A diets yielded leaner carcasses than their CONC fed
counterparts. However, increased feed consrunption and increased fecal output are
important factors to consider before implementing a feeding system based solely on alfalfa
pellets. Feeding lambs the 50/50 diets resulted in lamb performance and carcass
characteristics equal to or above that seen by lambs on the other dietary treatments. The
50/50 feeding strategy may be the most beneficial in terms of optimizing production,

minimizing costs and decreasing potential health problems.

CHAPTER 4

SUMMARY

A digestibility trial and three performance trials were conducted to determine
nutrient digestibility, lamb performance and carcass characteristics of lambs fed pelleted
diets containing 25, 62.5 or 100% forage (CONC, 50/50 and ALFA, respectively). In the
digestibility trial, apparent digestibility of DM, OM and NDF decreased as dietary forage
level increased. At lighter weights, lambs fed ALFA and 50/50 had similar apparent
digestibilities, which were lower than seen from CONC fed lambs. Lightweight lambs fed
ALF A and CONC had similar N intakes, whereas heavyweight lambs showed an increase
in N intake as dietary forage level increased. The percent of nitrogen retained was
unaffected by dietary forage level. Using three methods to estimate ME, ME intake for
lightweight lambs was lowest in lambs fed ALFA. In heavyweight lambs ME intake was
unaffected by dietary forage level. The ME values of the diets increased as dietary forage
level decreased. Using the Wolin (1960) equation seemed to underestimate methane losses,
resulting in decreased ME intakes compared to ME intakes when using the other two
methods of estimation.

In performance trial 1, lambs were fed either CONC or ALFA diets at ad libitum or

85% or ad libitum levels of intake. Lambs fed diets at ad libitum levels of intake had larger

81

82

FW and greater ADG. Lambs fed ALFA had lower G:F ratios, lighter HCW, less FAT and
lower DRESS values.

In performance trial 2, lambs were fed the 50/50 diet at ad libitum or 85% of ad
libitum levels of intake. Lambs fed at ad libitum levels of intake had greater ADG, heavier
HCW, more FAT and higher DRESS values, but had similar G:F ratios compared to lambs
fed at 85% of ad libitum levels of intake.

In performance trial 3, lambs were fed CONC, 50/50 or ALFA diets at ad libitum
levels of intake. Lambs fed the 50/50 diet had greatest ADG. Lambs fed ALFA consumed
the most feed and had the lowest G:F ratio. As dietary forage level increased FAT, HCW
and DRESS values tended to decrease.

An economic analysis of the three performance trials indicated that cost of gain
could be decreased by decreasing dietary forage level to 62.5 or 25% when compared to
100% forage. Cost of gain could also be decreased by feeding lambs at 85% of ad libitum

levels of intake.

APPENDICIES

APPENDIX - A

AN OVA Tables - Digestibility Trial

Dependent Variable: DMI

Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 3255073370 651014.674 26.33 0.0001
Error 17 420279.500 24722.324
Corrected Total 22 3675352870
R-Square C.V. Root MSE DMI Mean
0.885649 9.725599 157.2333 1616.696
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 1712186684 1712186684 69.26 0.0001
TRT 2 894870.581 447435.291 18.10 0.0001
REP'TRT 2 665213.081 332606.541 13.45 0.0001
Dependent Variable: FECAL DM
Sum of Mean
Source DF Squares Square F Value Pr > F
Model 5 1594917928 318983.586 59.97 0.0001
Error 17 90431255 5319.486
Corrected Total 22 1685349182
R-Square C.V. Root MSE FECDM Mean
0.946343 12.51 183 72.93480 582.9270
Source DF Type 111 SS Mean Square F Value Pr>F
REP 1 401767.0723 401767.0723 75.53 0.0001
TRT 2 871813.7764 435906.8882 81.95 0.0001
REP‘TRT 2 245283.5476 122641.7738 23.06 0.0001
Dependent Variable: DMD
Sum of Mean
Source DF Squares Square FValue Pr> F
Model 5 1844.339595 368.867919 28.49 0.0001
Error 17 220.098892 12.946994
Corrected Total 22 2064.438487
R-Square C.V. Root MSE DMDIG Mean
0.893386 5.508819 3.598193 65.31696
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 42.614232 42.614232 3.29 0.0873
TRT 2 1689.001646 844.500823 65.23 0.0001
REP‘TRT 2 41.783203 20.891602 1.61 0.2282
Dependent Variable: OM INTAKE
Sum of Mean
Source DF Squares Square F Value Pr > F
Model 5 2883335174 576667.035 27.55 0.0001
Error 17 355800.260 20929.427
Corrected Total 22 3239135433
R-Square C.V. Root MSE FEEDASH Mean
0.890156 9.755501 144.6701 1482.959
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 1427762217 1427762217 68.22 0.0001
TRT 2 766315.226 383157.613 18.31 0.0001
REP‘TRT 2 704578.250 352289.125 16.83 0.0001

83

84
APPENDIX - A

AN OVA Tables - Digestibility Trial (cont’d)

Dependent Variable: FECAL OM

Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 1223570941 244714.188 60.12 0.0001
Error 17 69199.305 4070.547
Corrected Total 22 1292770247
R-Square C.V. Root MSE F ECASH Mean
0.946472 12.57923 63.80084 507.1919
Source DF Type 111 88 Mean Square FValue Pr>F
REP 1 318342.4283 318342.4283 78.21 0.0001
TRT 2 665580.0761 332790.0380 81.76 0.0001
REP‘TRT 2 182805.7241 91402.8621 22.45 0.0001
Dependent Variable: OM DIGESTIBILITY
Sumof Mean
Source DF Squares Square F Value Pr> F
Model 5 1647.991001 329.598200 28.86 0.0001
Error 17 194.161893 11.421288
Corrected Total 22 1842.152894
R-Square C.V. Root MSE OMDIG Mean
0.894601 5.034628 3.379540 67.12590
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 48.172632 48.172632 4.22 0.0557
TRT 2 1528.712343 764.356171 66.92 0.0001
REP‘TRT 2 16.106205 8.053102 0.71 0.5079
Dependent Variable: NDF DIGESTIBILITY
Sumof Mean
Source DF Squares Square F Value Pr> F
Model 5 2219.026095 443.805219 12.50 0.0001
Error 17 603.660392 35.509435
Corrected Total 22 2822.686487
R-Square C.V. Root MSE NDFDIG Mean
0.786140 15.48714 5.958979 38.47696
Source DF Type 111 SS Mean Square FValue Pr>F
REP l 875.218527 875218527 24.65 0.0001
TRT 2 1228.823801 614.411900 17.30 0.0001
REP‘TRT 2 62.801108 31.400554 0.88 0.431
Dependent Variable: ADF DIGESTIBILITY
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 2180617695 436.123539 9.16 0.0002
Error 17 809.031592 47.590094
Corrected Total 22 2989.649287
R-Square C .V. Root MSE ADFDIG Mean
0.729389 21.53575 6.898557 32.03304
Source DF Type 111 SS Mean Square FValue Pr>F
REP l 846.307600 846.307600 17.78 0.0006
TRT 2 1142.433066 571216533 12.00 0.0006

REP‘TRT 2 190.256566 95.128283 2.00 0.1661

. 85
APPENDIX - A

AN OVA Tables - Digestibility Trial (cont’d)

Dependent Variable: FECAL N

Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 497.3343500 99.4668700 20.54 0.0001
Error 17 82.3084500 4.8416735
Corrected Total 22 579.6428000
R-Square C.V. Root MSE FECN Mean
0.858001 16.03776 2.200380 13.72000
Source DF Type 111 SS Mean Square F Value Pr>F
REP 1 188.5884632 188.5884632 38.95 0.0001
TRT 2 233.0366331 116.5183166 24.07 0.0001
REP‘TRT 2 70.7664981 353832491 7.31 0.0051
Dependent Variable: URINARY N
Sum of Mean
Source DF Squares Square FValue Pr> F
Model 5 681.9478054 136.3895611 16.99 0.0001
Error 17 136.4451250 8.0261838
Corrected Total 22 818.3929304
R-Square C .V. Root MSE URIN Mean
0.833277 12.05643 2.833052 23.49826
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 318.5300882 318.5300882 39.69 0.0001
TRT 2 257.1775000 128.5887500 16.02 0.0001
REP‘TRT 2 75.3544000 37.6772000 4.69 0.0238
Dependent Variable: N INTAKE
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 4183.236952 836.647390 41.71 0.0001
Error 17 341.017692 20.059864
Corrected Total 22 4524254643
R-Square C.V. Root MSE NINT Mean
0.924625 9.460450 4.478824 47.34261
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 2086.645011 2086.645011 104.02 0.0001
TRT 2 1311.614501 655.807250 32.69 0.0001
REP'TRT 2 706.517028 353258514 17.61 0.0001
Dependent Variable: N DIGESTIBILITY (g/d)
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 1854248595 370.849719 24.52 0.0001
Error 17 257.076692 15.122158
Corrected Total 22 2111.325287
R-Square C.V. Root MSE NDIG Mean
0.878239 11.56565 3.888722 33.62304
Source DF Type 111 SS Mean Square FValue Pr>F
REP l 1020.191421 1020.191421 67.46 0.0001
TRT 2 459.391703 229.695852 15.19 0.0002

REP’TRT 2 331.461266 165.730633 10.96 0.0009

86
APPENDIX - A

AN OVA Tables - Digestibility Trial (cont’d)

Dependent Variable: N DIGESTIBILITY (% N INTAKE)

Sum of Mean
Source DF Squares Square FValue Pr>F
Model 5 160.8014703 32.1602941 1.91 0.1460
Error 17 286.6560167 168621186
Corrected Total 22 447.4574870
R-Square C.V. Root MSE NDIGP Mean
0.359367 5.751437 4.106351 71.39696
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 0.4743860 0.4743860 0.03 0.8688
TRT 2 1512207883 75.6103942 4.48 0.0273
REP‘TRT 2 9.3649883 4.6824942 0.28 0.7609
Dependent Variable: N RETENTION (g/d)
Sumof Mean
Source DF Squares Square FValue Pr>F
Model 5 333.8025551 667605110 3.56 0.0219
Error 17 318.4355667 18.7315039
Corrected Total 22 652.2381217
R-Square C .V. Root MSE NRET Mean
0.511780 42.75201 4.327991 10.12348
Source DF Type 111 88 Mean Square FValue Pr>F
REP 1 198.8000439 198.8000439 10.61 0.0046
TRT 2 33.9541165 169770582 0.91 0.4227
REP'TRT 2 1069481165 53.4740582 2.85 0.0853
Dependent Variable: N RETENTION (% N DIGESTED)
Sum of Mean
Source DF Squares Square FValue Pr> F
Model 5 4962434703 992486941 0.78 05790
Error 17 2168.6608167 127.5682833
Corrected Total 22 2664.9042870
R-Square C.V. Root MSE NRETP Mean
0.186214 39.39941 11.29461 28.66696
Source DF Type IIISS Mean Square FValue Pr>F
REP 1 258.6459018 258.6459018 2.03 0.1726
TRT 2 57.6913883 28.8456942 0.23 0.8000
REP‘TRT 2 2285911008 114.2955504 0.90 0.4266
Dependent Variable: N RETENTION (% N INTAKE)
Sumof Mean
Source DF Squares Square FValue Pr>F
Model 5 248.4748562 49.6949712 0.57 0.7241
Error 17 1489.7076917 87.6298642
Corrected Total 22 17381825478
R-Square C.V. Root MSE NRETPI Mean
0.142951 45.23592 9.361082 20.69391
Source DF Type 111 SS Mean Square FValue Pr>F
REF 1 99.6470741 99.6470741 1.14 0.3012
TRT 2 487616915 24.380845? 0.28 0.7605

REP‘TRT 2 125.5533415 62.7766707 0.72 0.5027

87

APPENDIX - A

AN OVA Tables - Digestibility Trial (cont’d)

Dependent Variable: GE INTAKE

Sum of Mean
Source DF Squares Square FValue Pr> F
Model 5 5823723805 1164744761 26.96 0.0001
Error 17 734441142 432024.20
Corrected Total 22 6558164946
R-Square C.V. Root MSE GEI Mean
0.888011 9.751082 657.2855 6740.641
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 3029536940 3029536940 70.12 0.0001
TRT 2 1514573378 757286689 17.53 0.0001
REP‘TRT 2 1324097373 662048686 15.32 0.0002
Dependent Variable: F ECAL ENERGY
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 2723087063 544617413 62.95 0.0001
Error 17 147074961 86514.68
Corrected Total 22 2870162025
R-Square C.V. Root MSE FECE Mean
0.948757 12.10061 294.1338 2430.735
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 740625202 740625202 85.61 0.0001
TRT 2 1425323379 712661689 82.37 0.0001
REP‘TRT 2 432900251 216450125 25.02 0.0001
Dependent Variable: DE INTAKE
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 5 1110285231 222057046 7.68 0.0006
Error 17 491702918 289237.01
Corrected Total 22 1601988149
R-Square C.V. Root MSE DE Mean
0.693067 12.47841 537.8076 4309.906
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 7743307771 7743307.771 26.77 0.0001
TRT 2 2078976485 1039488242 3.59 0.0499
REP’TRT 2 2462909695 1231454.847 4.26 0.0317
Dependent Variable: URINARY ENERGY
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 5 145181.4552 290362910 16.07 0.0001
Error 17 30710.3673 18064922
Corrected Total 22 175891.8225
R—Square C.V. Root MSE URINE Mean
0.825402 14.00224 42.50285 303.5432
Source DF Type 111 88 Mean Square FValue Pr>F
REP 1 3938389743 39383.89743 21.80 0.0002
TRT 2 7210849315 3605424657 19.96 0.0001

REP‘TRT 2 25402.32593 12701.16297 7.03 0.0060

88
APPENDIX - A

AN OVA Tables - Digestibility Trial (cont’d)

Dependent Variable: METHANE ESTIMATION (WOLIN, 1960)

Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 561275.8950 112255.1790 23.95 0.0001
Error 17 796700770 46864751
Corrected Total 22 640945.972]
R-Square C.V. Root MSE CH4W Mean
0.875699 16.42870 68.45783 416.6965
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 6901.7308 6901.7308 1.47 0.2415
TRT 2 514382.9512 257191.4756 54.88 0.0001
REP‘TRT 2 15987.7725 79938862 1.71 0.2113
Dependent Variable: METHANE ESTIMATION (JOHNSON ET AL., 1991)
Sum of Mean
Source DF Squares Square FValue Pr> F
Model 5 1504913370 300982674 5.11 0.0048
Error 17 10014.14377 58906728
Corrected Total 22 2506327747
R-Square C.V. Root MSE CH4J Mean
0.600446 15.34959 24.27071 158.1196
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 10077.71011 10077.71011 17.11 0.0007
TRT 2 152927249 764.63625 1.30 0.2988
REP‘TRT 2 455683020 2278.41510 3.87 0.0413
Dependent Variable: ME ESTIMATION (JOHNSON ET AL., 1991)
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 1061097270 212219454 7.10 0.0009
Error 17 507865485 298744.40
Corrected Total 22 1568962755
R-Square C.V. Root MSE MEJ Mean
0.676305 14.20324 546.5752 3848.244
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 7207152420 7207152420 24.12 0.0001
TRT 2 2443051060 1221525530 4.09 0.0355
REP‘TRT 2 2179712641 1089856321 3.65 0.0489
Dependent Variable: ME ESTIMATE (WOLIN 1960)
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 5 1120416707 224083341 7.47 0.0007
Error 17 509875040 299926.49
Corrected Total 22 1630291746
R—Square C.V. Root MSE MEW Mean
0.687249 15.25644 547.6555 3589.667
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 6255749436 6255749436 20.86 0.0003
TRT 2 4678535671 2339267.835 7.80 0.0039

REP‘TRT 2 1707130427 853565.214 2.85 0.0859

89
APPENDIX - A

AN OVA Tables - Digestibility Trial (cont’d)

Dependent Variable: ME = DE " .82 (NRC, 1985)

Sum of Mean

Source DF Squares Square FValue Pr>F
Model 5 7465557966 1493111.593 7.68 0.0006
Error 17 3306210400 194482.965
Corrected Total 22 10771768366

R-Square C.V. Root MSE MEDE Mean

0.693067 12.47841 441.0022 3534.123
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 5206600049 5206600049 26.77 0.0001
TRT 2 1397903896 698951948 3.59 0.0499

REP‘TRT 2 1656060566 828030.283 4.26 0.0317

APPENDIX - B

ANOVA Tables - Performance Trial 1

Dependent Variable: PEN INTAKE

Sum of Mean
Source DF Squares Square FValue Pr>F
Model 3 262164.7826 873882609 8.04 0.0361
Error 4 434502477 108625619
Corrected Total 7 305615.0303
R-Square C.V. Root MSE PENINT Mean
0.857827 8.539367 104.2236 1220.508
Source DF Type 111 SS Mean Square FValue Pr>F
TRT 3 262164.7827 87388.2609 8.04 0.0361
Dependent Variable: DAILY LAMB INTAKE
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 3 090223750 0.30074583 6.76 0.0480
Error 4 0.17805000 004451250
Corrected Total 7 108028750
R-Square C.V. Root MSE DLAMINT Mean
0.835183 10.70285 0.210980 1.971250
Source DF Type 111 SS Mean Square FValue Pr>F
TRT 3 0.90223750 0.30074583 6.76 0.0480
Dependent Variable: ADG
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 7 008066865 001152409 4.94 0.0001
Error 70 0.16332750 000233325
Corrected Total 77 0.24399615
R-Square C.V. Root MSE ADG Mean
0.330614 14.68885 0.048304 0.328846
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 000221523 0.00221523 0.95 0.3332
TRT 3 005634621 001878207 8.05 0.0001
REP‘TRT 3 002375250 000791750 3.39 0.0226
Dependent Variable: CARCASS WEIGHT
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 7 7549085297 107.8440757 24.35 0.0001
Error 70 3099757575 4.4282251
Corrected Total 77 1064.8842872
R-Square C.V. Root MSE CARCWT Mean
0.708911 8.922684 2.104335 23.58410
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 4149718273 414.9718273 93.71 0.0001
TRT 3 3239516674 1079838891 24.39 0.0001
REP‘TRT 3 9.4077954 3.1359318 0.71 0.5504
Dependent Variable: LOINEYE AREA
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 7 2030935779 29.0133683 4.88 0.0002
Error 70 4161481400 5.9449734
Corrected Total 77 619.2417179
R-Square C.V. Root MSE LOINEYE Mean
0.327971 16.35412 2.438232 14.90897

90

9 1
APPENDIX - B

AN OVA Tables - Performance Trial 1 (cont’d)

Source DF Type 111 SS Mean Square F Value Pr > F
REP 1 8889951030 8889951030 14.95 0.0002
TRT 3 9818296943 3272765648 5.51 0.0019
REP‘TRT 3 1639210771 546403590 0.92 0.4362
Dependent Variable: 12TH RIB FAT
Sum of Mean
Source DF Squares Square F Value Pr > F
Model 7 096173538 0.13739077 5.81 0.0001
Error 70 1.65563000 002365186
Corrected Total 77 261736538
R-Square C.V. Root MSE FAT Mean
0.367444 45.69808 0.153792 0.336538
Source DF Type III SS Mean Square F Value Pr > F
REP 1 023041939 0.23041939 9.74 0.0026
TRT 3 0.69342486 0.23114162 9.77 0.0001
REP‘TRT 3 0.03530086 0.01176695 0.50 0.6852
Dependent Variable: INITIAL WEIGHT
Sum of Mean
Source DF Squares Square F Value Pr > F
Model 7 1141.766211 163.109459 25.18 0.0001
Error 70 453.516538 6.478808
Corrected Total 77 1595282749
R-Squarc C.V. Root MSE INIT Mean
0.715714 8.094577 2.545350 31.44513
Source DF Type 111 SS Mean Square F Value Pr > F
REP 1 1122461267 1122.461267 173.25 0.0001
TRT 3 14.381130 4.793710 0.74 0.5318
REP‘TRT 3 5.416423 1.805474 0.28 0.8406
Dependent Variable: FINAL WEIGHT
Sum of Mean
Source DF Squares Square F Value Pr > F
Model 7 1730.123395 247.160485 14.29 0.0001
Error 70 1210480740 17.292582
Corrected Total 77 2940.604135
R-Square C.V. Root MSE FINAL Mean
0.588356 7.976636 4.158435 52.13269
Source DF Type 111 SS Mean Square F Value Pr > F
REP 1 1364000691 1364.000691 78.88 0.0001
TRT 3 315135323 105045108 6.07 0.0010
REP‘TRT 3 92.164703 30.721568 1.78 0.1596
Dependent Variable: DRESS
Sum of Mean
Source DF Squares Square F Value Pr > F
Model 7 008129333 0.01161333 31.52 0.0001
Error 70 002579000 0.00036843
Corrected Total 77 0.10708333
R-Square C.V. Root MSE DRESS Mean
0.759160 4.249703 0.019194 0.451667
Source DF Type 111 SS Mean Square F Value Pr > F
REP 1 000512121 0.0051212] 13.90 0.0004
TRT 3 007330286 002443429 66.32 0.0001

REP’TRT 3 000209371 000069790 1.89 0.1385

APPENDIX - C

ANOVA Tables - Performance Trial 2

Dependent Variable: PEN INTAKE

Sum of Mean
Source DF Squares Square F Value Pr> F
Model 1 7204392810 72043.92810 17.85 0.0517
Error 2 8073.55250 403677625
Corrected Total 3 80117.48060
R-Square C.V. Root MSE PENINT Mean
0.899229 2.774894 63.53563 2289.660
Source DF Type 111 SS Mean Square FValue Pr>F
TRT 1 72043.92810 72043.92810 17.85 0.0517
Dependent Variable: DAILY LAMB INTAKE
Sum of Mean
Source DF Squares Square FValue Pr> F
Model 1 007022500 0.07022500 8.86 0.0968
Error 2 001585000 000792500
Corrected Total 3 008607500
R-Square C.V. Root MSE DLAMINT Mean
0.815858 3.908780 0.089022 2.277500
Source DF Type 111 SS Mean Square FValue Pr>F
TRT 1 0.07022500 0.07022500 8.86 0.0968
Dependent Variable: CARCASS WEIGHT
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 3 9422176385 3140725462 7.81 0.0004
Error 38 15280619131 402121556
Corrected Total 41 24702795516
R-Square C.V. Root MSE CARCWT Mean
0.381421 7.104655 2.005297 28.22511
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 3834679601 38.34679601 9.54 0.0038
TRT 1 5569789464 55.69789464 13.85 0.0006
REP‘TRT 1 0.60172463 0.60172463 0.15 0.7010
Dependent Variable: 12TH RIB FAT
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 3 0.49541166 0.16513722 4.50 0.0085
Error 38 1.39398548 003668383
Corrected Total 41 1.88939714
R-Square C.V. Root MSE FAT Mean
0.262206 36.40270 0.191530 0.526143
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 0.10208400 0.10208400 2.78 0.1035
TRT l 0.39179156 0.39179156 10.68 0.0023
REP‘TRT 1 000008728 000008728 0.00 0.9614

92

93
APPENDIX - C

AN OVA Tables - Performance Trial 2 (cont’d)

Dependent Variable: INITIAL WEIGHT

Sum of Mean
Source DF Squares Square FValue Pr>F
Model 3 3452504436 1150834812 26.52 0.0001
Error 38 164.8872601 4.3391384
Corrected Total 41 510.1377037
R-Square C.V. Root MSE INIT Mean
0.676779 6.760616 2.083060 30.81 169
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 3451246079 345.1246079 79.54 0.0001
TRT 1 0.1209109 0.1209109 0.03 0.8683
REP‘TRT 1 0.0028665 0.0028665 0.00 0.9796
Dependent Variable: FINAL WEIGHT
Sum of Mean
Source DF Squares Square FValue Pr> F
Model 3 2066386496 688795499 4.16 0.0121
Error 38 6294271332 165638719
Corrected Total 41 8360657828
R-Square C.V. Root MSE FINAL Mean
0.247156 6.408595 4.069874 63.50649
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 1448953215 144.8953215 8.75 0.0053
TRT 1 61.4284506 614284506 3.71 0.0616
REP‘TRT 1 0.0350747 0.0350747 0.00 0.9635
Dependent Variable: ADG
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 3 001195162 000398387 3.04 0.0407
Error 38 004982991 000131131
Corrected Total 41 006178153
R-Square C.V. Root MSE ADG Mean
0.193450 10.63281 0.036212 0.340569
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 000464022 0.00464022 3.54 0.0676
TRT 1 000726758 0.00726758 5.54 0.0238
REP‘TRT 1 000000652 000000652 0.00 0.9442
Dependent Variable: DRESS
Sum of Mean
Source DF Squares Square FValue Pr> F
Model 3 000436960 000145653 4.56 0.0080
Error 38 001214394 000031958
Corrected Total 41 001651354
R-Square C.V. Root MSE DRESS Mean
0.264607 4.023162 0.017877 0.444345
Source DF Type 111 SS Mean Square FValue Pr>F
REP 1 000016042 000016042 0.50 0.4830
TRT 1 000413637 0.0041363? 12.94 0.0009
REP‘TRT 1 000013423 000013423 0.42 0.5208

APPENDIX - D

AN OVA Tables - Performance Trial 3

Dependent Variable: PEN INTAKE

Sum of Mean
Source DF Squares Square FValue Pr>F
Model 2 2727298096 1363649048 7.17 0.0720
Error 3 57090.7785 190302595
Corrected Total 5 329820.5881
R-Square C.V. Root MSE PENINT Mean
0.826904 12.10725 137.9502 1 139.402
Source DF Typel SS Mean Square FValue Pr>F
TRT 2 2727298096 136364.9048 7.17 0.0720
Dependent Variable: DAILY LAMB INTAKE
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 2 0.49990000 024995000 8.73 0.0562
Error 3 008590000 002863333
Corrected Total 5 0.58580000
R-Square C.V. Root MSE DLAMINT Mean
0.853363 7.981786 0.169214 2.120000
Source DF TypeISS Mean Square FValue Pr>F
TRT 2 0.49990000 0.24995000 8.73 0.0562
Dependent Variable: CARCASS WEIGHT
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 5 77.78279048 1555655810 4.50 0.0027
Error 36 124.37074286 3.45474286
Corrected Total 41 20215353333
R-Square C.V. Root MSE CARCWT Mean
0.384771 6.972717 1.858694 26.65667
Source DF TypeISS Mean Square FValue Pr>F
REP 1 308343810 3.08343810 0.89 0.3511
TRT 2 47.59693333 23.79846667 6.89 0.0029
REP‘TRT 2 27.10241905 13.55120952 3.92 0.0288
Dependent Variable: LOINEYE AREA
Sum of Mean
Source DF Squares Square F Value Pr>F
Model 5 1152179262 230435852 4.22 0.0040
Error 36 1965660571 5.4601683
Corrected Total 41 311.7839833
R-Square C.V. Root MSE LOINEYE Mean
0.369544 14.22937 2.336700 16.42167
Source DF TypeISS Mean Square FValue Pr>F
REP 1 0.60720238 0.60720238 0.11 0.7407
TRT 2 6210923333 3105461667 5.69 0.0071
REP‘TRT 2 5250149048 2625074524 4.81 0.0141
Dependent Variable: DRESS
Sum of Mean
Source DF Squares Square F Value Pr> F
Model 5 003074286 000614857 18.02 0.0001
Error 36 001228571 000034127
Corrected Total 41 004302857
R-Square C.V. Root MSE DRESS Mean
0.714475 3.895013 0.018473 0.474286

94

95
APPENDIX - D

AN OVA Tables - Performance Trial 3 (cont’d)

Source DF Type 1 SS Mean Square F Value Pr > F
REP 1 000015238 000015238 0.45 0.5083
TRT 2 002588571 001294286 37.93 0.0001
REP‘TRT 2 000470476 000235238 6.89 0.0029

Dependent Variable: INITIAL WEIGHT

Sum of Mean

Source DF Squares Square F Value Pr>F
Model 5 2451015619 490203124 16.04 0.0001
Error 36 1099960000 3.0554444
Corrected Total 41 3550975619

R-Square C.V. Root MSE INIT Mean

0.690237 5.362303 1.747983 32.59762
Source DF TypelSS Mean Square FValue Pr>F
REP l 221.1691524 221.1691524 72.39 0.0001
TRT 2 155008905 7.7504452 2.54 0.0932
REP‘TRT 2 8.4315190 4.2157595 1.38 0.2646

Dependent Variable: FINAL WEIGHT

Sum of Mean
Source DF Squares Square FValue Pr>F
Model 5 7444181905 1488836381 1.56 0.1967
Error 36 34390722857 955297857
Corrected Total 41 418.34904762
R-Square C.V. Root MSE FINAL Mean
0.177942 5.498460 3.090789 56.21 190
Source DF TypelSS Mean Square FValue Pr>F
REP 1 1890743810 1890743810 1.98 0.1680
TRT 2 3494453333 17.47226667 1.83 0.1752
REP‘TRT 2 20.58984762 1029492381 1.08 0.3511
Dependent Variable: 12TH RIB FAT
Sumof Mean
Source DF Squares Square FValue Pr>F
Model 5 0.14576190 002915238 0.97 0.4512
Error 36 108588571 003016349
Corrected Total 41 123164762
R-Square C.V. Root MSE FAT Mean
0.118347 34.40759 0.173676 0.504762
Source DF TypelSS Mean Square FValue Pr>F
REP 1 000915238 0.00915238 0.30 0.5851
TRT 2 0.12779048 006389524 2.12 0.1350
REP‘TRT 2 000881905 000440952 0.15 0.8645
Dependent Variable: ADG
Sum of Mean
Source DF Squares Square FValue Pr>F
Model 5 005009762 001001952 9.54 0.0001
Error 36 003780000 000105000
Corrected Total 41 008789762
R-Square C.V. Root MSE ADG Mean
0.569954 10.46084 0.032404 0.309762
Source DF TypelSS Mean Square FValue Pr>F
REP 1 001339286 0.01339286 12.76 0.0010
TRT 2 003190476 001595238 15.19 0.0001
REP‘TRT 2 000480000 000240000 2.29 0.1163

APPENDIX E

Average volatile fatty acid production - Digestibility Trial

Lightweight lambs

Lamb # Treatment Acetic Acid Propionic Acid Butyric Acid

% % %
599 ALFA 50.52 22.08 7.96
609 ALFA 54.86 24.35 10.20
615 ALFA 53.13 18.56 9.26
606 50/50 39.37 21.91 15.40
617 50/50 33.62 14.78 10.58
623 50/50 43.06 21.41 15.47
640 50/50 32.54 11.98 14.84
613 CONC 19.62 22.97 9.91
636 CONC 27.71 18.21 6.79
653 CONC 16.21 17.68 4.01
674 CONC 13.88 12.10 15.14
Heavyweight lambs
Lamb # Treatment Acetic Acid Propionic Acid Butyric Acid
% % %
635 ALFA 56.59 20.36 7.89
645 ALFA 53.12 23.82 7.38
646 ALFA 37.57 16.76 5.57
661 ALFA 49.22 19.02 7.99
598 50/50 41.39 18.88 8.28
664 50/50 42.01 16.36 15.69
682 50/50 43.64 18.48 12.68
683 50/50 37.09 21.38 13.58
597 CONC 17.18 18.01 5.79
626 CONC 19.73 9.80 10.53
632 CONC . 15.10 17.50 3.17
637 CONC 31.42 11.09 10.08

96

LITERATURE CITED

LITERATURE CITED

AOAC. 1984. Official Methods of Analysis (12th Ed.). Association of Official
Analytical Chemists, Washington, D. C.

AOAC. 1990. Official Methods of Analysis (15th Ed.). Association of Official
Analytical Chemists, Washington, D. C.

ARC. 1980. IheNutrienLRequirementmfRuminamhxestnck Technical Review
by an Agricultural Research Council Working Party. Farnham Royal, England:

Commonwealth Agricultural Bureau.

American Lamb Council. 1994. Retail Merchandising Guide. Colorado: American
Sheep Industry Council.

Beardsley, D. W., W. C. McCormick, and B. L. Southwell. 1959. Steer
performance on and rumen effects of different concentrate: roughage ratios in pelleted and
unpelleted mixed fattening rations. J. Anim. Sci. 18:1507 (Abstr.)

Bidner, T. D., A. R. Schupp, A. B. Mohamad, N. C. Rumore, R. E. Montgomery, C.
P. Bagley and K. W. McMillin. 1986. Acceptability of beef fi‘om Angus-Hereford or
Angus-Hereford-Brahman steers finished on all-forage or a high-energy diet. J. Anim. Sci.
62:381-387.

Blackburn, H. D., G. D. Snowder, and H. Glimp. 1991. Simulation of lean lamb
production systems. J. Anim. Sci. 69:1 15-124.

Bunting, L. D., M. D. Howard, R. B. Muntifering, K. A. Dawson, and J. A. Boling.
1987. Effect of feeding frequency on forage fiber and nitrogen utilization in sheep. J. Anim.
Sci. 64:1170-1177.

Canale, A., M. E. Valente, and A. Ciotti. 1984. Determination of volatile carboxylic
acids (C1-C5i) and lactic acid in aqueous extracts of silage by high performance liquid
chromatography. J. Sci. Food Agric. 35:1178.

Cate, H. A., J. M. Lewis, R. J. Webb, M. E. Mansfield, and U. S. Garrigus. 1955.

The effect of pelleting rations of varied quality on feed utilization by lambs. J. Anim. Sci.
14:137-142.

97

98

Church, D. C. 1988.
Illinois: Waveland Press, Inc.

 

Colucci, P. E., G. K. Macleod, W. L. Grovum, L. W. Cahill, and I. McMillan. 1989.
Comparative digestion in sheep and cattle fed different forage to concentrate ratios at high
and low intakes. J. Dairy. Sci. 72:1774—1785.

F aichney, G. J ., and S. G. Gherardi. 1986. Relationships between organic-matter

digestibility, dry-matter intake and solute mean retention times in sheep given a ground and
pelleted diet. J. Agric. Sci., Camb. 106:219-222.

Forster, L. A., Jr., J. P. Fontenot, H. D. Perry, J. G. Foster, and V. G. Allen. 1991.
Apparent digestibility and nutrient balance in lambs fed different levels of flatpea hay. J.
Anim. Sci. 69:1719-1725.

Gibson, J. P. 1981. The effects of feeding frequency on the growth and efficiency of
food utilization of ruminants: an analysis of published results. Anim. Prod. 32:275-283.

Glimp, H. A., S. P. Hart, and D. VonTungeln. 1989. Effect of altering nutrient
density (concentrate to roughage ratio) and restricting energy intake on rate, efficiency and
composition of growing lambs. J. Anim. Sci. 67:865-871.

Goering, H. K., P. J. Van Soest. 1970. Forage fiber analysis (apparatus, reagents,
procedures, and some applications). Agric. Handbook No. 379. ARS—USDA. Washington,
D. C.

Gordon, F. J ., M. G. Porter, C. S. Mayne, E. F. Unsworth, and D. J. Kilpatrick.
1995. Effect of forage digestibility and type of concentrate on nutrient utilization by
lactating dairy cattle. J. Dairy. Research. 62:15-27.

Hill, G. M., G. L. Newton, M. N. Streeter, W. W. Hanna, P. R. Utley, and M. J.
Mathis. 1996. Digestibility and utilization of pearl millet diets fed to finishing beef cattle.
J. Anim. Sci. 74:1728-1735.

Jaster, E. H., and M. R. Murphy. 1983. Effects of varying particle size of forage on
digestion and chewing behavior of dairy heifers. J. Dairy. Sci. 66:802-810.

Johnson, D. E., T. M. Hill, B. R. Carmean, M. C. Branine and G. M. Ward. 1991.
New perspectives on ruminant methane emissions. C. Wenk and M. Boessinger eds.
Proceedings of the 12th symposium on energy metabolism of farm animals. Kartause
Ittingen, Switzerland. EAAP Publ. 58: 376-379.

99

Kerley, M. S., A. R. Kinser, J. L. Firkins, G. C. Fahey, Jr., and L. L. Berger. 1985.
Effects of roughage particle size on site of nutrient digestion and digesta flow through the
gastrointestinal tract of sheep fed comcob-concentrate diets. J. Anim. Sci. 61 :504-513.

Kinser, A. R., M. S. Kerley, G. C. Fahey, Jr., and L. L. Berger. 1985. Effect of
roughage particle size on rurrrinal, digestive and metabolic characteristics of early-weaned
lambs fed pelleted comcob-concentrate diets. J. Anim. Sci. 61:514-524.

Kinser, A. R., G.C. Fahey, Jr., L. L. Berger, and N. R. Merchen. 1988. Low-quality
roughages in high-concentrate pelleted diets for sheep: digestion and metabolism of
nitrogen and energy as affected by dietary fiber concentration. J. Anim. Sci. 66:487-500.

Knoblauch, W. A., R. A. Milligan, D. G. Fox and M. L. Woodell. 1981. Economic
utilization of forages in production of milk and beef in the northern united states. J Dairy
Sci. 64:2059-2070.

Kromann, R. P., E. T. Clemens, and E. E. Ray. 1975. Digestible, Metabolizable and
net energy values of corn grain and dehydrated alfalfa in sheep. J. Anim. Sci. 42: 1752-1758.

Lambert, M. G., S. M. Abrams, H. W. Harpster, and G. A. Jung. 1987. Effect of hay
substitution on intake and digestibility of forage rape (Brassica Napus) fed to lambs. J.
Anim. Sci. 65:1639-1646.

Martin, L. C., C. B. Ammerrnan, P. R. Henry, and P. E. Loggins. 1981. Effect of
level and form of supplemental energy and nitrogen on utilization of low quality roughage
by sheep. J. Anim. Sci. 53:479-487.

Merchen, N. R., L. L. Berger, and G. C. Fahey, Jr. 1986. Comparison of the effects
of three methods of harvesting and storing alfalfa on nutrient digestibility by lambs and
feedlot performance of steers. J. Anim. Sci. 63:1026-1035.

Merchen, N. R., and L. D. Satter. 1983. Digestion of nitrogen by lambs fed alfalfa
conserved as baled hay or as low moisture silage. J. Anim. Sci. 56:943-951.

Meyer, J. H., R. L. Gaskill, G. S. Stoewsand, and W. C. Weir. 1959. Influence of
pelleting on the utilization of alfalfa. J. Anim. Sci. 18:336-346.

Murphy, T. A., S. C. Loerch, and F. E. Smith. 1994. Effects of feeding high-
concentrate diets at restricted intakes on digestibility and nitrogen metabolism in growing
lambs. J. Anim. Sci. 72:1583-1590.

Nocek, J. E., and E. M. Kesler. 1980. Growth and rumen characteristics of Holstein
steers fed pelleted or conventional diets. J. Dairy. Sci. 63:249-254.

100

NRC. 1966. Biological Energy Interrelationships and Glossary of Energy Terms.
National Research Council, Washington, D. C.

NRC. 1985. Nutrient Requirements of Sheep, No. 6. National Academy of
Science.National Research Council, Washington, DC.

NRC. 1988. Nutrient Requirements of Swine No. 9. National Academy of Science.
National Research Council, Washington, D. C.

Oltjen, R. R., T. S. Rmnsey, and P. A. Putnam. 1971. All-forage diets for finishing
beef cattle. J. Anim. Sci. 32:327-333.

Paladines, O. L., J. T. Reid, B. D. Van Niekerk, and A. Bensadoun. 1964. Energy
utilization by sheep as influenced by the physical form, composition and level of intake of
diet. J. Nutrition. 83:49-59.

Petit, H. V., and D. M. Veira. 1994. Digestion characteristics of beef steers fed

silage and different levels of energy with or without protein supplementation. J. Anim. Sci.
72:3213-3220.

Purcell, W. D. 1995. Economic issues and potentials in lamb marketing: Keys to
the firture of the sheep industry. Sheep and Goat Research Journal, 11:92-110.

Reynolds, C. K., H. F. Tyrrell, and P. J. Reynolds. 1991. Effects of diet forage-
to-concentrate ratio and intake on energy metabolism in growmg beef heifers: whole body
energy and nitrogen balance and visceral heat production. J. Nut.121:994-1003.

Ruiz, A., and D. N. Mowat. 1987. Effect of feeding fiequency on the utilization of
high-forage diets by cattle. Can. J. Anim. Sci. 67: 1067-1074.

SAS". 1989. SAS" User‘s Guide: Statistics. SAS" Inst. Inc., Cary, NC.

SID Sheep Production Handbook. 1992. Colorado: American Sheep Industry
Association, Production Education and Research Council.

Susin, I., S. C. Loerch, K. E. McClure and M. L. Day. 1995. Effects of limit feeding
a high-grain diet on puberty and reproductive performance of ewes. J. Anim. Sci. 73:3206-
3215.

Thomas, J. D., T. T. Ross, and M. L. Galyean. 1983. Carcass characteristics of
lambs fed alternating high and low concentrate rations. WSASAS. Proceedings. 34:123-
124.

101

Thomas, V. M., and J. J. Dahmen, and L. M. Kelly. 1984. Performance and carcass
characteristics of lambs self-fed four ratios of alfalfa hay and barley grain in a complete
pelleted diet. WSASAS. Proceedings. 35:291-292.

Umberger, S. H. 1994. Management and marketing practices altered through a
value-based marketing program for slaughter lambs. Sheep and Goat Research Journal.
10:148-152.

Van Soest, P. J ., and R. H. Wine. 1967. Use of detergents in the analysis of fibrous
feeds. IV. Determination of plant cell-wall constituents. J. Assoc. Off. Analytical Chem.
50:50.

Van Soest, P. J ., J. B. Robertson, and B. A. Lewis. 1991. Methods for dietary fiber,
neutral fiber, non-starch polysaccharide in relation to animal nutrition. J. Dairy Sci.
74:3583-3597.

Wainman, F. W., K. L. Blaxter, and J. D. Pullar. 1970. The nutritive value for
ruminants of a complete processed diet based on barley straw. J. Agric. Sci. 74:311-314.

Wainman, F. W., J. S. Smith, and P. J. S. Dewey. 1975. The nutritive value for
sheep of ruminant Diet AA6, a complete cobbed diet containing 30% barley straw. J. Agric.
Sci. 84:109-111.

Ward, C. E., and J. L. Hildebrand. 1993. An analysis of price differences for
slaughter lambs. Sheep Research Journal, 9:45-50.

Weir, W. C., J. H. Meyer, W. N. Garrett, G. P. Lofgreen, and N. R. Ittner. 1959.
Pelleted rations compared to similar rations fed chopped or ground for steers and lambs. J.
Anim. Sci. 18:805-814.

Wolin, M. J., 1960. A theoretical rumen fermentation balance. J. Dairy. Sci.
43:1452-1459.

"11111111111111111111111“