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EFFECT OF ENERGY AND PROTEIN
LEVELS ON MILK PRODUCTLON'
DURING LATE LACTATION

Thesis for the Degree of M. S.
MICH!GAN STATE UNWERSITY
VERN EMERY ER!.CKSON
1971

 

 

 

ABSTRACT

EFFECT OF ENERGY AND PROTEIN LEVELS ON MILK PRODUCTION
DURING LATE LACTATION

By
Vern Emery Erickson

Two experiments were conducted to determine the ef-
fects of varying the protein and energy intake of dairy
cows during late lactation in the Andrews University Dairy
herd.

In Experiment I, 5 pounds of hay and ad libitum corn
silage were fed to both the control and experimental groups
(2# cows per group). To the control group, 9.0 pounds of
high moisture corn (HMO) and one pound of 55 percent pro-
tein concentrate (containing NPN) were mixed into the corn
silage at feeding time, and 0.? pound of soybean meal (SBM)
was fed in the parlor. The experimental group received
only corn silage and hay. Average dry matter intake and
milk production values for the control group were 29.9 and
29.9 pounds per day and for the experimental group were
26.5 and 22.9 pounds per day, respectively for a 30-day
period.

Data from EXperiment I indicate that feeding corn
silage ad libitum and 5.0 pounds of average quality alfalfa

hay was not sufficient to maintain normal production of

- 1 -

ABSTRACT 2

cows producing 30 pounds of milk daily. The calculated in-
take of both energy and protein exceeded National Research
Council (NRC, 1966) requirements by 10 to 13 percent in the
control group, whereas energy was equal but protein intake
was approximately 25 percent less than NRC in the experi-
mental group fed no concentrates or protein supplement.

At the end of the fourth week the experimental group pro-
duced 9.4 pounds less milk per cow daily than controls.
This resulted in a loss of 50 cents per cow daily in gross
income minus feed cost.

In Experiment II removal of 14.0 pounds of high
moisture shelled corn from the ration of cows producing 55
to 37 Pounds of milk daily and fed corn silage ad libitum,
5.0 pounds of alfalfa, and 0.5 pound of supplemental pro-
tein resulted in no significant difference in milk produc-
tion, milk fat production, or body weight over an eight-
week period. Calculated intake of energy was 53 percent
higher and protein 9 percent lower than NRC requirements
in the control group, whereas energy intake was equal to
NRC but protein intake 21 percent less than NRC requirements
in the experimental group. All cows followed a normal lac-
tation curve downward and gained weight in this experiment.
Removing the corn from the ration increased income above

feed cost 21 cents per cow daily.

ABSTRACT 3

From the results of these experiments it appears
that feeding 10 to 20 percent less protein than the NRC
standards during late lactation had no effect on perform-
ance; but feeding 25 percent less protein than the require-
ment significantly affected milk production. A ration con-
taining 11 percent crude protein on a dry matter basis was
adequate to maintain normal milk production whereas 10 per-
cent crude protein was too low under the conditions of this
experiment. Energy intake equivalent to the 1966 NRC al-
lowances for total digestible nutrients (TDN) maintained
milk production of cows in late lactation as well as a ra-
tion containing 55 percent more TDN, from shelled corn, when
adequate protein was fed under the practical farm conditions

of this experiment.

EFFECT OF ENERGY AND PROTEIN LEVELS ON MILK PRODUCTION
DURING LATE LACTATION

By

Vern Emery Erickson

A THESIS

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

MASTER OF SCIENCE

Department of Dairy

1971

ACKNOWLEDGEMENTS

The author expresses many thanks and sincere appre-
ciation to Dr. Donald Hillman, associate professor, for the
help, counsel, and hours spent in critically reading this
manuscript during its preparation.

Also many thanks for the counsel of Dr. J. T. Huber,
Dr. R. S. Emery, and Dr. J. W. Thomas of the Department of
Dairy Science and Dr. C. R. Hoglund of the Department of
Agricultural Economics as committee members.

Thanks and appreciation is also expressed to Dr.
Roger Neitzel for his help in statistical analyses of the
data.

The author is grateful to Mrs. Donald Hillman for
her fine work in typing the manuscript and is also thankful
to his loving wife, Sharon, for her hours of help and con-

stant encouragement.

ii

TABLE

ACKNOWLEDGEMENTS . . . . . .
LIST OF TABLES . . . . . . .
LIST OF FIGURES. . . . . . .
INTRODUCTION . . . . Q . . .
REVIEW OF LITERATURE . . . .
Nutrient Requirements . .
Effects of Energy on Milk
Effects of Energy on Body
Effects of Obesity on the
Milk Fat Test Depression.

OF CONTENTS

Production.
Weight. . .
Health. . .

Energy Effects on Reproduction. . . .

Nutrient Value of Corn Silage . . . .

Energy . . . . . . . .
Protein. . . . . . . .
Minerals . . . . . . .

Vitamins . . . . . . .

Urea in Rations of Lactating Dairy Cows

Urea in the Silage. . . .

High Moisture Corn as a Source of Energy.

Intake Regulation . . . .

Literature Resume . . . .

O O O O O O

Page

ii

vii

10
19
21
26
29
51
51
56
57
37
38
40
45
46
51

EXPERIMENTAL PROCEDURE

Experiment I .

Experiment II . . .

RESULTS AND DISCUSSION

Experiment I .
Experiment II .

SUMMARY AND CONCLUSIONS

LITERATURE CITED .

iv

Page

53
55
56
60
60
68
77
79

LIST OF TABLES

Table Page

1 Chemical Composition of Feeds Fed in Experi-
ment I. O O O O O O O O O O O O O O O O O 0 54

2 Daily Nutrient Requirements of Lactating Dairy
Cows in Experiment I to Maintain 50 Pounds
Of Milk 0 e e e e e e e e e e e e e e e e e 55

5 Chemical Composition of Feeds Fed in Experi-
ment II 0 O O O O O O O O O O O O O O O O O 58

4 Daily Nutrient Requirement of Lactating Cows
in Experiment II. . . . . . . . . . . . . . 59

5 Average Daily Milk Production by Weekly Peri-
ods for Control and Experimental Cows in
Experiment I. O O O O O O O O O O O O O O O 60

6 Average Daily Intake and Feed Costs for Cows
on Experiment I . . . . . . . . . . . . . . 62

7 Average Weekly Gross Income and Gross Income
Minus Feed Costs for Cows on Experiment I . 65

8 Analysis of Variance Table of Milk Production
for Experiment I. O O O O O O O O O O O O O 66

9 Daily Nutrient Intake of Dairy Cows in Experi-
ment I O O O O O O O O O O O O O O O O O O 0 67

10 Analysis of Variance of Change in Body Weight,
Experiment II . . . . . . . . . . . . . . . 68

11 Daily Milk Production for Control and Experi-
mental Cows for Three Preliminary Weeks
and Eight Weeks of Experiment II. . . . . . 69

12 Analysis of Variance in Milk Production for
Experiment II 0 O O O O O O 0 O O O O O O 0 7O

15 Daily Nutrient Intake of Dairy Cows in Experi-
ment II 0 O O O O O O O O O O O O O O O O O 72

Table Page

14 Average Daily Intake and Feed Costs for Cows
on Experiment II. . . . . . . . . . . . . . 74

15 Average Gross Income and Gross Income Minus
Feed Cost for Cows on Experiment II . . . . 74

vi

LIST OF FIGURES

Figure Page

I Milk Production Curves for Cows Fed No
Grain or Protein Supplement (Lot 2) Com-
pared to Controls (Lot 1) Experiment I . . 61

II Gross Income of Cows on Experimental and
Control Ration, Experiment I . . . . . . . 64

III Gross Income Minus Feed Cost from Cows on
Control and Experimental Ration, Experi-
ment I e e e e e e e e e e e e e e e e e e 65

IV Average Pounds of Milk Per Day for Cows on
Experiment II e e e e e e e e e e e e e e 71

V Average Daily Feed Costs, Gross Income, and

Gross Income Minus Feed Costs for Cows
on Experiment II . . . . . . . . . . . . . 75

vii

INTRODUCTION

Dairy farm management methods have been subjected to
dramatic changes in recent years in order to reduce costs
and maintain or improve profits.

The adoption of bulk methods for handling of feeds
and management of cattle requires careful attention to the
effects of such changes on the health and performance of
cattle and the efficiency of utilization of feed resources.
Thus, the management system must be sufficiently flexible
to allow providing a reasonably well-balanced diet for all
of the cattle in keeping with their productive requirements.

Among the most significant changes on Michigan farms
have been the trends toward larger herds and the feeding
and management of cattle in one or more groups. Increased
use of corn silage, or hay-cr0p silage, as the major source
of forage has commonly accompanied expanding herd size.

The advantages offered by a silage feeding system for mechan-
ical handling during harvesting, storing, and feeding of
forages produced on the farm have helped to reduce the cost
of dairy production compared to dry hay.

Methods of handling and feeding grain have also
changed substantially. On many of the larger dairy farms,

corn is stored in silos as high moisture (25-52%1moisture)

- 1 -

shelled corn or ground ear corn in order to expedite the
harvesting process, reduce field and storage losses, and
eliminate the cost of heat-drying and further processing.

The traditional practice of hand-feeding of concen-
trates to lactating cows according to their individual pro—
duction requirements was largely lost with the advent of
the milking parlor. While the use of milking parlors in-
creases labor efficiency in the milking process, individu-
a1 feeding is more difficult to accomplish and incompatible
with milking efficiency when high producing cows are al-
lowed enough time in the milking parlor to eat the amount
of concentrates required.

The combination of circumstances resulting from bulk
handling of feeds and group handling of cattle has prompted
some dairymen to feed a blended mixture of forages and con-
centrates to the milking herd thereby eliminating the prac-
tice of individual feeding. Sub-grouping of the herd ac-
cording to different levels of milk production, stage of
lactation, or age of the cattle is commonly practiced in an
attempt to feed concentrates according to requirements and
approximate the practice of individual feeding.

The Andrews University dairy herd at Berrien Springs,
Michigan, was recently expanded to include 240 milk cows
plus young stock. Feeding and management conditions

were similar to those typically found on modern mid—west

dairy farms of similar size. The feeding program consisted
of corn silage and high moisture shelled corn processed in
conventional silos, baled hay limited to five pounds per
cow daily,and sufficient protein supplement, minerals, and
vitamins to balance the ration.

Prior to these experiments the herd had been plagued
with health problems at calving tine typical of the so-
called "fat-cow syndrome." The incidence of milk fever,
ketosis, netritis, and mastitis was too frequent and re-
sulted in poor milk production. This condition largely
subsided after the dry cows were separated from the milking
herd and groups were fed concentrates according to milk
production.

In view of the tendency for cows in late lactation
to fatten excessively when fed a ration of corn silage ad
libitum and concentrates according to a thumb-rule, such as
one pound of concentrates per three pounds of milk, the re-
search reported herein was conducted to determine the ef-
fects on milk production and body weight when supplemental
energy as high moisture corn or both energy and protein sup-
plement were eliminated from the ration of cows in late lac-
tation.

Other research pertaining to these topics is also
discussed in the review of literature.

REVIEW OF LITERATURE

The nutrients provided dairy cattle are major fac-
tors in determining the level of milk production, health
condition, and profit from a dairy enterprise.

Nutrient requirements for dairy cattle have been
studied by numerous investigators over the years. The most
recent estimates of the nutrient requirements for dairy
cattle were published in 1966 by the National Academy of
Sciences, National Research Council (NRC) in publication

1549, Nutrient Requirements 9; Dairy Cattle (155).

Nutrient quuirements:

The National Research Council (155) states that for
a 1,210 pound cow 8.4 pounds of total digestible nutrients
(TDN) are required for maintenance of a lactating cow. Mor-
rison's (151) requirements for a 1200 pound lactating cow
are 9.5 for TDN or 7.4 therms (or megacalories) of net
energy.

Requirements for energy according to Rebhan (145)
differ for animals differing in body condition. The animal
that is the fattest requires the most energy per unit of
weight for maintenance. A maintenance ration is the amount
of feed required to support an animal which is doing no

work and yielding no product.

-4...

5

Rebhan referred to Haecker's (70) report that showed
that the cost of producing a pound of butter increased when
a cow carried an average of 80 pounds more flesh one year
than the previous year. Also maintenance requirements
change with more exposed body surface area.

The requirements for energy or total digestible nu-
trients vary widely depending upon the animal's activity,
the climatic condition, and the quality and the quantity of
feed fed. The variance among cows of similar size and
breed in maintenance requirements under controlled activity
is as much as 8 to 10 percent (177).

The maintenance value given in the NRC tables pro-
vides minimal energy to cover usual activity of cows fed in
confinement. Cows grazing may require from 25 to 100 per-
cent more energy for maintenance than for those confined
(100, 148, 180).

Reid (149) set the amount at 40 percent more total
digestible nutrients for cows grazing than cows in confine-
ment. He found that a 1000 pound cow required 11.5 pounds
of TDN per day to support maintenance, including expense
of grazing. The same cow when confined in the barn would
utilize only 7.9 pounds of TDN. Reid continues by saying
that the selection of grazing by cows will increase the
quality of the diet 10 to 25 percent more in total digesti-

ble nutrients than that harvested as a soiling crop. Thus,

for the same amount of dry matter consumed, cows will eat
two to five pounds more total digestible nutrients. How-
ever, when 75 percent of the forage available is consumed
by grazing, the advantage for selection would be less.

In addition to feeding a properly balanced ration
appetite, appearance, and health of cattle should be ob-
served to insure Optimum performance.

Energy is expressed in megacalories (or therms)
which is the amount of heat required to raise the tempera-
ture of 1,000 kilograms of water one degree centigrade.

In analyzing a feed for its useful purposes of main-
tenance, milk production,and reproduction, each feed will
supply a different quantity of metabolizable and net energy.
To find net energy one must take gross energy and subtract
the energy loss in the feces, urine, combustible gases and
heat increment. That which is left is used for milk produc-
tion, fattening, reproduction, growth, and maintenance (151).
Net energy values should be considered as averages because
of effects of varying levels of intake, animal species, and
combination of feeds fed on the resulting net energy value.

Due mainly to fiber content, feeds vary widely in
net energy. Morrison (151) believed that net energy values
are a better measure of the value of the feed than using

total digestible nutrients values.

Some studies (50, 117) have questioned the superi-
ority of the net energy systems over the total digestible
nutrient system. Other reports (158, 129) indicate that
the estimated net energy system is a more accurate system
for evaluating feeds for productive purposes.

Rene (107) states that the TDN system of feed evalu-
ation is subject to several sources of error. It over
evaluates forages, its analytical methods are empirical,
.and its energy value assignments to components are ques-
tionable. However, TDN values are still used because of
ease of determination. Net energy values are difficult to
obtain.

Moore (129) compared estimated net energy values of
Morrison, Forbes, and the productive energy values of
Fraps. He then plotted them graphically against the TDN
values. He found that net energy value of feeds decreased
at a faster rate than the TDN values. He concluded that
the energy value of a unit of TDN in concentrates is
greater than that of the same unit in roughages. Morrison
(152) agreed by saying that "There is no question but what
net energy values are theoretically more accurate than total
digestible nutrients for comparing the values of roughages
or low grade concentrates with values of grain and other

high grade concentratesfbr productive purposes."

Armstrong (5) and Becker (15) state that net energy
values of feeds vary greatly depending upon whether they
are utilized for maintenance or growth and probably also
for milk production.

Loosli et al (117) replaced part of the TDN from
hay with an equal amount of TDN from concentrates and con-
cluded that the TDN system overestimated the value of for-
ages when compared to concentrates.

In making conversions the National Research Council
(NBC) (57) assumed that 1.0 kg of TDN had 4,400 kilocalaries
of digestible energy and 5,740 kcal of metabolizable energy.

Net energy values should be used more than they are
especially for corn silage. The value of the grain cons
tained in corn silage is more accurately estimated with net
energy values than with TDN.

In calculating the nutritional requirements of dairy
cattle, the size of the animal, stage of gestation, and
quantity and quality of milk produced is usually taken into
account in order to estimate the requirements accurately.

Nutritional requirements for maintenance of lactat-
ing cows vary widely depending on their size, breed, type
of housing, and their ability to utilize nutrients. These
factors can vary from one animal to another as much as 8
to 10 percent (154). Grazing cattle may require as much as

25 to 100 percent more energy for maintenance than those in

confinement (148, 157).

Reproduction requirements vary among the different
breeds as much as 60 to 100 percent. The weight changes
according to the combined weight of the fetus, fluids, and
fetal membranes. This can increase a cow's weight up to
121 pounds more at time of parturition (15).

Fat is a highly concentrated energy product. As the
percent of fat in the milk increases, more nutrients are
required to maintain the energy balance of the animal.

In a paper recently presented at the American Dairy
Science Association, the National Research Council (154)
recommended a standard value for a given fat test regardless
of the level of production. Thus they concluded that recent
studies at the USDA and Norway did not support the need for
substantially higher intakes of protein, energy, and miner-
als per unit of milk for high milk yields.

Protein is required to maintain all body functions.
The values given in tables for the needs of protein are suf-
ficient to support the animal if adequate energy and other
required nutrients are supplied. A ration with a very wide
protein-to-energy ratio, where protein meets minimum require-
ments, depresses efficiency of ration utilization, growth
rates, and milk yields (154).

A deficiency of protein depresses milk yields and

may lower milk-protein content (155). Morrison (151)

10

recommends 1.52 pounds of crude protein for maintenance of
a 1200 pound cow and .045 pound of protein per pound of
milk testing 5.5 percent fat. The protein requirements
vary with body weight, milk production level, percent fat,
and reproductive status of the animal.

Minerals known to be required by dairy cattle are
calcium, phosphorus, magnesium, potassium, sodium, chloride,
sulfur, iodine, iron, capper, cobalt, manganese, zinc, and
selenium. These elements are needed for maintenance and
growth of body tissue, production of milk, fat metabolism,
and reproduction. They maintain osmotic pressures, acid-
base equilibria and the irritability of muscles and nerves,
and are required for the function of several enzyme systems'
(154).

In prevention of milk fever maintenance of proper
ratio of calcium to phosphorus is important when feeding
pregnant dry cows a calcium to phosphorus ratio of 2.5:1
will reduce the incidence of milk fever according to one

report (64).

Effect; of Energy on Milk Production
Several researchers (ll, 55, 52, 58, 46, 47, 45, 59,

 

150) increased the amount of concentrate in the ration and
milk production increased.
Irvin et al (101) specifically state that increased

ll

milk production was due to increasing the net energy intake
by increasing the amount of concentrates fed.

Jumah et al (105) used nine Holstein cows producing
an average of 19,171 pounds of milk. They found a high
correlation (r - 0.82) between the energy allowance and
milk production. In an earlier experiment Jensen et al
(102), using cows which produced 11,000 pounds of milk per
year, found that 0.5 pound of TDN was required per pound of
fat-corrected milk (FCM).

The National Research Council in 1966 (154) stated
that energy requirements for high levels of milk production
were greater than previously recognized. They increased
the standard required for milk production ten percent for
average levels and 25 percent for higher milk production
levels. This conclusion was based on observations that di-
gestibility of the ration declines as intake is increased
four to five times maintenance levels. Since the need for
higher energy intake per pound of milk at high levels of
milk production was not supported by metabolism studies at
Beltsville and in Norway, the NRC has returned to the ear-
lier standards for the 1971 revision (118).

Hooven and Plowman (85) experimented with two groups
of 19 cows. One group was fed ad libitum grain, hay, and
silage while the other group was fed 110 percent of Morri-

son's upper standard. They found no difference in FCM,

12

solids-not-fat, and persistency 0f production. However,
cows fed the ad libitum ration consumed more estimated net
energy and gained more body weight but produced only 1.51
pounds of milk per therm of net energy compared to 1.79
pounds of milk per therm for cows fed the controlled ration.

Elliot and Loosli (59) fed diets where the level of
estimated net energy intake above maintenance was held con-
stant. Production of FCM was not different on diets where
40, 60, or 80 percent of the estimated net energy came from
concentrates.

Reagendoorn and Grieve (84) reported results of
three levels of roughages containing 1.65, 5.50, and 5.50
pounds per 100 kg of body weight, each was supplemented
with concentrates providing 90, 100, and 120 percent Na-
tional Research Council requirements (154) for digestible
energy. Twenty-seven cows were used throughout one com-
plete lactation. When cows were offered 90 percent of the
National Research Council requirements a significant decrease
in milk production was obtained in the 16th week. Maximum
milk production could be obtained by providing 90 percent
energy requirement during peak production and 100 percent
during decline of production.

The 1971 NRC tables (118) list the amount of energy
required for milk production for various levels of milk fat.

For each .05 percent of increase in fat test above 5.0

15

percent, the extra energy required is from .05 to .05
megacalories of net energy per pound of milk.

Early research with lactating dairy cows by Huffman
and Duncan (95, 94, 95, 96, 97) fed an all-roughage ration
following parturition showed that milk production declined
steadily as body fat was depleted to a point that milk pro-
duction and body fat would be maintained by the amount of
roughage consumed. Supplying concentrates at this time gave
the cows the capability to increase milk production. It
was thought that energy alone was ineffective in increasing
milk production because feeding of purified starch or sugar
instead of corn grain did not increase milk production.
Burroughs et al (40) showed that starch lowered the digesti-
bility of the ration.

Huffman (99) in'later work reported that early out
hay and corn silage, containing ears, gave favorable re-
sults over mature hay plus corn stalks and leaves less the
ears.

Beach (14) found that digestible nutrients from corn
were more valuable for maintenance and for milk production
than digestible nutrients from roughages. Moore et al (129),
Sarrinen et al (158), and Irvin et al (101) concluded that
the increase of milk production when fed concentrates was
because the cows had an increased intake of net energy.

Putnam and Loosli (144) fed rations in which either

14

80, 60, or 40 percent of the dry matter content came from
forages and the balance from concentrates. They found a
slight difference in the amount of milk produced per pound
of TDN fed. The range was from 2.10 pounds of FCM milk to
1.95 pounds of FCM per pound of TDN for the 80 and 40 permmm
roughage rations, respectively.

Mather et al (120) reported that feeding grain at
one pound of grain to 5 pounds of milk depressed forage in-
takes but increased milk production. They found no evidence
of diminishing returns in the high potential cows and lit-
tle for the low-producing cows.

Huffman (92), in reviewing the literature, reported
increased milk yields of cows fed high levels of concen-
trates over those fed low levels of concentrates. Ninety-
five percent of the cows responded by increased milk pro-
duction from increased grain feeding. Approximately 40 per-
cent of these cows showed a profitable response.

Brown et a1 (56) reported that feeding grain at the
rate of one pound of grain per 2.5 pounds of milk and grain
ad libitum provided more milk than one pound of grain per
5.5 pounds of milk. The protein, fat, solids not fat con-
tent of the milk were not significantly effected by the dif-
ferent feeding regimes. Economically the cows which re-
ceived grain ad libitum and one pound of grain per 2.5

pounds of milk returned approximately 355 more over feed

15

cost during the 280-day trial than the cows which received
grain at the rate of one pound of grain per 5.5 pounds of
milk.

A review by Reid (146) indicated that cows produced
70 to 80 percent as much on all roughage diets as when con-
centrates were supplemented at a level of one pound of
grain to 6 pounds of milk. The extra 20 to 50 percent in-
crease in milk production could be extra net profit.

Wing (185) in Florida, using three different rations,
and the Morrison standards, concluded that liberal forage
systems supplemented with concentrates can support maximum
milk yields. This work agrees with work done by Huffman
(92) that no increase of milk production was noted over ad
libitum feed versus one pound of grain per 2.5 pounds of
milk.

Several workers (58, ll, 52, 58, 46, 47, 45, 150,
59) have substantiated Huffman's review that high level
grain feeding has resulted in increased milk yield. If the
cows have the potential, they will respond to the greater
energy intake. Ronning (95) agreed with this and added
that there were no definite health problems encountered
from 10 to 100 percent concentrate feeding. One animal had
a case of laminitis but it was not positively diagnosed.

Heglund (82) suggested a method for high level grain
feeding by starting to feed grain two weeks before calving

l6

and increasing the grain during lactation until maximum pro-
duction is obtained, keeping in perspective the law of di-
minishing returns.

Kesler and Spahr (106) reported observations made
on 41 cows fed to their maximum consumption, but with a
controlled percent of concentrates in the diet. They con-
cluded that most of the cows reached their maximum intake
of productive energy when concentrates made up 50 to 60 per-
cent of the ration (14 to 16 percent fiber). Unlimited
grain feeding did not always increase production and may
have been detrimental to the cow.

Schmidt and Schultz (159) divided 65 cows into 5
groups which received no grain, 6 pounds of grain, and 15
pounds of grain during the 8-week dry period. Each group
was fed 2 pounds of corn silage per 100 pounds of body
weight plus ad libitum good quality hay. After calving all
cows received grain according to production. No statisti-
cal differences in milk, butterfat, or 4 percent fat cor-
rected milk production were obtained.

Burt (59) cited Bonnier's (29) experiments where
monozygous twins were reared on different planes of nutri-
tion 65 to 70 and 120 to 155 Percent of the recommended
levels. The animals on the higher rate produced 654 to 570
pounds more milk in the first two lactations respectively

than the animals on the low plan of nutrition. This was

17

due to the fact that the poorer fed animals grew during
the first two lactations. Burt also cited Hansen (72) in
which heifers were fed at two nutritional planes. The
group fed adequately matured faster and produced more milk
than the under fed group.

Burt (59) reported that Woodward (187) using 10 cows
obtained no differences in milk production or live weight
gain when grain was fed at 12 pounds or 4 pounds per day for
two months before parturition. A second experiment (188)
was done with fat and thin cows. The fat cows consumed an
average of 1,016 pounds of grain more than the thin cows.
Most of the grain was fed during late lactation and the dry
period but two hundred pounds of this grain was fed after
calving. The additional grain before parturition produced
an extra 100 pounds of milk in late lactation and 485 pounds
more after parturition in the first 90 days. There was no
difference in milk production after 100 days from parturition
in which time the fat cows lost 24 pounds and the thin cows
gained 16 pounds in body weight, the later being 54 pounds
lighter.

Burt (58) suggested that very low levels of feeding
will have adverse effects on production and health during
the next lactation. He also added that high levels of feed
before calving will have adverse effects upon mammary gland
develOpment.

Greenhalgh and Gardner (66) cited Boutflour (50) that

18

heavy grain feeding 6 weeks before calving (steaming up) in-
creased to 75 percent of the estimated grain requirement for
early lactation, built up the cowh reserves and accustomed
her to a heavy grain ration resulting in higher milk produc-
tion in the subsequent lactation. Blaxter (27) reported
that feeding 6 pounds of concentrates 6 weeks before calv-
ing resulted in significantly greater milk yields over a
control ration of bulky feeds. In a third group the net
energy of the bulky feed matched the energy in the grain

and no increase in milk yield was obtained.

Greenhalgh and Gardner (66) fed more grain for 6 weeks
before parturition than was required for maintenance. No
increase in milk production was observed. These results are
different than those reported by Fountains (65). Blaxter (27),
Lees (114), and Boutflour (50). Greenhalgh and Gardner ex-
plained that this difference was because the control cows in
the other experiments actually lost weight or did not keep
up with the fetus increase in weight, meaning they were be-
ing under fed. Greenhalgh and Gardner (66) also reported no
increase in udder edema due to grain feeding while dry.

Swanson and Hinton (169) fed paired cows equal amounts
of extra concentrates either in late lactation or during the
dry period. Those cows fed grain during the dry period pro-
duced 502 pounds of milk more than those cows fed grain dur-

ing late lactation. Only 507 pounds of grain were used to

19

produce that increase. These results agree with Reid (146)
who stated that cows should be fed in such a way that most
of the necessary increase in body weight should be made dur-
ing the dry period.

Hemken (74) stated that a high producing cow can
utilize body fat for half of her energy needs during the
early phase of lactation, and failure to consume enough nu-
trients, especially energy, limited milk production for many
dairy cows.

Grain should be fed in such a way as to challenge
the cow by increasing the energy intake during the early
part of the lactation period. The preponderance of evidence
indicates that cattle fed energy according to published re-
quirement standards produce milk at or near their inherited
potential. Under farm conditions adjustments in concentrate
feeding rates may be necessary to compensate for variations

in the energy value of forages and other conditions.

Effects of Energy:on Body Weight

The amount of energy in a ration can directly affect
body condition. Reid (147) cited an experiment by Bines et
a1 (25) where three different rations were fed: 1) oat
straw, 2) rye grass fed ad libitum, and 5) 5 kg of rye grass
with ad libitum concentrates. By feeding one of these dif-

ferent rations he could change the condition of a lactating

2O

cow from fat to thin and vice versa. Essentially he was
varying the energy an animal received. These data agree
with other workers who concluded that high level grain feed-
ing increases milk production and body condition of lactat-
ing cows (11, 52, 58, 45, 46, 47, 59, 129).

Hoglund (82) pointed out that high level grain feed~
ing is not well defined. Hillman (79) stated that farmers
in Michigan have been continuing the high level of grain
feeding after peak production resulting in cows becoming
too fat at the end of lactation. The consequences were the
develOpment of many health problems.

Hemken (74) stated that limitation of milk production
often is the result of an animal's inability to consume
enough energy. So when an animal is in peak production she
is using body fat as well as consumed nutrients. He refer-
red to studies at Beltsville, Maryland, that indicated a
high producing cow can utilize body fat for half of her
energy needs during early lactation. If the ration is not
sufficient in the supply of energy for milk production, fat
stores are rapidly expended. When the excess body fat is
utilized, milk production will be reduced.

Moe et al (126) indicate that tissue energy used for
milk production during early lactation depends upon feed
intake, body condition, and genetic potential. Moe's work

indicates that milk may be produced from body tissue reserves

21

with an efficiency of 82 to 84 percent.

Besides the effect energy has on body condition, age
also affects body weight changes. Miller et al (125) re-
ported in a study of 1004 lactations of 477 cows in the
Beltsville herd that first calf heifers gained the most,

84 kg during lactation. Mature cows gained only 54 kg.

Cows in second and later lactations lost weight from the
first to the second month in lactation while first lactation
animals gained weight. The difference was due to mobiliza-
tion of fat reserve by the older cows and this increased milk
production.

After body fat has been mobilized for milk production,
sufficient energy must be fed after peak production to re-
establish the animal to the desired body condition (126).

Kesler, Spahr (105), and Jorgensen (105) reported
that feeding a diet too high in energy (concentrates) may
force the animal into a fattening type of metabolism which
may be antagonistic to a metabolism desirable for milk pro-
duction. The reason for this apparent shift in energy

utilization is not clear.

Effects of Obesity on the Health
Cattle that receive more energy than required tend
to become excessively fat and are prone to a higher incid-

ence of health problems.

Ketosis or hyperketonemia refers to ketone body

22

accumulation in the blood. Bergman (25) in his review
stated that ketosis may occur in all mammalion species and
can be brought forth by many factors such as starvation,

low carbohydrate and high fat diets, cold exposure, anesthe-
sia, impaired liver function, hypoglycemia, and endocrine
disorders such as diabetes or growth hormone as well as
other endocrine excesses (54, 179). The digestive tract,
liver, and mammary gland seem to be the major sites of ke—
tone body production in ruminants (25).

Some high moisture silages increase the amount of
butyrate (l, 162) produced which is then metabolized into
ketone bodies. During ketosis, hepatic ketogenesis accounts
for most of the ketone bodies, particularly if the animal is
starving. The major sources of these ketone bodies are from
the free fatty acids which are mobilized from fat in body
stores (25).

Depriving ruminants of food induces fat mobilization,
hepatic ketogenesis, and ketosis (109). This has been ob-
served in sheep as well as in cattle (150).

Spontaneous ketosis and hypoglycemia, a disease
called acetonemia, is usually found in cows that give high
milk yields and that are in excellent nutritional condition,
often too fat, and often in herds which are adequately fed
(164, 165). Spontaneous ketosis develOps initially in cows

whose feed consumption is equal to or greater than the

23

majority of cows. The cow which develOps ketosis is usually
the one which is well fed, healthy, and a highly productive
cow but may consume less feed than required for the high
level of production (109).

Schultz (165) concludes that management of the feed
is the only way to control ketosis. One should provide
feeds containing adequate nutrients according to feeding
standards. The feeds should be offered at the Optimum
level of the cow's ability to consume the feed without go-
ing "off feed." The management practices which maximize in-
take in early lactation and minimize prolonged mobilization
of body fat should be utilized. Schultz suggests that dur-
ing the latter part of the dry period grain should be fed
at the rate of one percent of body weight at calving. Then
grain should increase by one pound per day, limiting the
grain to 2 percent of body weight and at the same time sup-
plying at least one third of total dry matter intake as
forage (165).

Since there is no cure for ketosis, Schultz recom-
mends the following: 1) Avoid having excessive fattness at
calving, 2) Increase concentrate feeding slowly during the
later part of the dry period and rapidly after calving, us-
ing care so the animal doesn't go off feed, 5) Feed good
quality forage, 4) Do not make abrupt changes in the ration

especially to low quality materials, 5) Feed recommended

24

levels of protein, minerals, and vitamins, 6) Avoid hay
crop silage high in butyric acids, 7) Maximize intake by
providing comfort, exercise, and stress-free areas, 8) In
problem herds, test milk weekly for ketones, 9) If possible
select strong cows with good appetites.

The observation by Koropov et al (108) who reported
higher ketones when cows were fed a concentrate type ration
would appear to contradict these recommendations. The con-
ditions under which KorOpov's experiments were conducted.
were not defined and may account for the discrepancy.

No work has been reported on how obesity effects
mastitis and milk fever. Personal observation has been
that fat cows have more problems at time of calving which
often leave the animal in a weakened condition.

Emery et a1 (60) used 98 heifers and 50 cows in which
half of them received grain 21 days prepartum, while the
others received no grain. Each treated heifer received 220
kg of grain which resulted in 54 extra kg of milk during the
45-day milking period. The treated cows each received 295
kg of grain, which resulted in an increase of 56 kg of
milk. Feeding grain during late pregnancy to cows in good
condition was not economical. An increase in edema was noted
in the heifers. Metritis, retained placenta, and indigestion
were noted but were not significantly different between the

groups. Milk fever and mastitis were significantly greater

25

in the group fed extra grain. Similar increases in various
diseases have been previously noted in studies by Emery (61)
and Robertson (152).

Reid (146) concluded that if cows are thin and in
poor body condition after a lactation, they should be fed
in such a way that the necessary increase in body weight
would be made during the dry period.

The physical form of roughages fed may be important
to the health of cattle. Tyrrell et al reported a high in-
cidence of health problems and mortality among cows fed only
corn silage and liberal concentrates compared to cows fed
hay, silage, and a similar amount of concentrates over a
three-year period. Whether the effects were due to dif—
ferences in the energy concentrations of the two rations,
differences in physical form of the forages, or discrepan-
cies in other nutrients was not clear. The possibility
exists that the texture and acidity of the total diet in-
fluence rumen fermentation and rate of passage of feed nu-
trients. Therefore nutrient substrate and utilization should
be considered as possible contributors to health problems
in cattle.

The higher incidence of health problems commonly
found in herds fed excessive amounts of energy may be due
to obesity, or obesity may only be a symptom of other in-

balances in the ration. The evidence indicates that cat-

26

'tle fed balanced rations in relation to their nutrient re-
quirements, particularly during the dry period, are less
jprone to ketosis, metritis, and mastitis than when fed

excessively.

Milk Fat Test Depression

Balch et a1 (12) reported that diets low in hay and
high in concentrates given to lactating dairy cows were
important in determining the extent of milk fat depression.
They found a greater depression with steamed flaked maize
than with maize meal or oats and barley due to the effect
of heating the starch on the flora of the reticulo-rumen.

Jorgensen and Schultz (105) fed four different kinds
of concentrates to determine the effect of each on milk
percentage. Ranking them according to the most drastic
effect on milk fat was: 1) pelleted corn, 2) ground corn,
5) herd mix, and 4) corn and cob meal. These are ranked
according to the fiber content. A mixture of eight pounds
of hay plus twenty-eight pounds of grain would contain about
eight percent fiber when using either pelleted or ground
corn but up to 12 percent fiber when using corn and cob
meal.

Kesler (106) and Balch et a1 (12) suggested that fi-
ber levels below 15 to 14 percent of dietary proportions of
above 50 to 60 percent concentrate in the ration may be

detrimental to the lactating cow.

27

Brown et a1 (57) found no significant difference in
milk fat percentage within summer and winter lactation
trials for cows fed milo and barley at concentrate to
roughage ratios of 40 to 60 and 60 to 40. Their data in—
dicated that a higher ratio of concentrates would reduce
milk fat content.

Miller et al (124) found a reduction in milk fat
percentage of cows fed corn silage that was chOpped a
second time through a re-cutting machine compared to the
original normal cut. They concluded that a chOpper knife
setting of .59 to .51 inch is necessary to avoid fat depres—
sion in cows consuming corn silage as the sole roughage
when feeding concentrates to meet the milk production needs
of high producing cows.

Thomas et al (172) reported that addition of 0.70
percent of sodium bicarbonate plus 0.55 percent of magnesium
oxide (MgO) or twice or three times that level added to the
grain increased fat production in cows fed a high grain ra-
tion. The effects were the same when large quantities of
sodium bicarbonate and MgO were administered into the rumen
via a fistula or mixed with the grain. High levels of these
minerals fed to cows on a normal ration did not change
Inilk fat secretion since milk production was reduced and

nailk fat percentage increased but grain consumption was

28

reduced.

In other work, Thomas (171) administered 272 or 565
grams per day of sodium bicarbonate and 156 or 181 grams
per day of MgO. Fed alone or separate, MgO and sodium bi-
carbonate increased fat test and rumen pH but decreased
molar proportion of valerate and prOpionate in the rumen
of cows on a low-roughage high-concentrate ration. Daily
milk and fat production was increased by addition of sodium
bicarbonate, but addition of MgO caused a slight decrease.

Hillman (79) stated that feeding mineral supplements
to increase test has not routinely increased the fat test
on farms where the test has already decreased. Maintaining
a normal fat test or raising a low fat test can be accomp-
lished by feeding a balanced ration of good quality forage
and concentrates.

The evidence indicates that the percent of milk fat
can be depressed by feeding excessive amounts of concentrate
in relation to forage, by feeding a ration too low in fiber
content, and by finely chopping, grinding, or pelleting of
the ration. The fat test depression may be returned to
normal by correcting these conditions. Cattle fed milk fat
depressing rations frequently become excessively fat and

are susceptible to health problems.

29

Energy Effects on Reproduction

Several workers have demonstrated the importance of
adequate nutrient levels for fertility in calves and heifers
(5, 149, 168). Tuff (175) found that normal estrous cycles
did not take place when mature cows were under-fed.

Zimmerman et al (190), McGillivray et al (125), and
Rigor et al (151) reported that additions of a high-energy
source to a basal ration for a short period of time enhanced
ovulation rate in the gilt. In working with ewes, Howland
et a1 (86) reported that the nutritional level of the diet
is important for normal reproductive performance.

Wiltbank et al (185) reported that onset of post-partum
estrus was delayed when TDN intake was limited to one-half
of the recommended allowance by the National Research Coun-
oil in 1958 (154) and that the interval from first breeding
to conception was longer when the TDN allowance was reduced.

Wiltbank (185, 184) indicated that a low level of
energy before calving delayed the onset of estrus following
parturition and decreased conception rate for the following
.parturition. In contrast cows fed adequately after parturi-
tion.had a high conception rate.

Dunn (57) fed 8.7 MCal (low) and 17.5 MCal (high) of
calculated digestible energy per head daily to 240 two-year
old heifers 60 days before their first parturition. At

calving time prepartum energy groups were subdivided into

50

three groups fed 14.2, 27.5, or 48.2 MCal of digestible
energy daily postpartum. The results indicated that the
level of energy intake can alter reproductive performance.
Percent pregnant at 120 days after calving was directly
related to post-calving energy level. Eighty-seven per-
cent of the cows fed the high energy level after calving
were pregnant as compared to seventy-two percent of those
on the moderate level and sixty-four percent of those fed
the low energy level. The onset of estrus was delayed

in the cows which received the low level of energy before
calving. In this group thirty percent of the Hereford
cows and nine percent of the Angus cows failed to show
estrus.

Reproductive performance was further studied by Hol-
lon and Branton (85) when 1172 pregnancies from 2057 services
were analyzed for the effect of early post partum weight
changes. Of the animals gaining weight during the month of
service, 1477 services resulted in 907 pregnancies or 61 per-
cent conceived and required 1.65 services per cow. Among
those animals losing weight, 580 services resulted in 257
pregnancies or 41 percent conceived and 2.45 services were
required per cow. For animals which gained during the 50
to 90 day post partum period, 814 first services resulted

in 519 pregnancies or a 64 percent conception rate. Those

51

cows losing weight had 558 first services resulted in 165
pregnancies or a 46 percent conception rate. Body weight
changes during the 50 to 90 day post partum period had no
significant effect on conception rate of later services.
Adequate energy levels must be maintained to expect high
reproductive efficiency.

Moe et al (125) using 50 cows for 5 complete lac-
tations reported that liberal grain feeding increased the
interval between first and second calving by 26 to 46 days
over moderate levels of grain feeding. Services per con-
ception increased from 1.55 to 1.78 services per cow as a,
result of liberal amounts of grain feeding.

An Optimum level of feeding grain apparently depends
on many factors such as the condition of the cow post and
prepartum, the rate at which the animal will mobilize her
body reserves after parturition, and the animal's potential
for consuming high levels of energy. For high productive
efficiency an animal must be in good nutritional health.

nutrient Value of Corn Silage

Energy 1

An all-silage forage program is becoming increasingly
popular stated Hemken and Vanersall (75) because of areas
where hay curing is difficult and field curing losses are
high, silage offers a method of circumventing this problem.

Silage feeding is easier to automate and in most areas offers

52

more potential of maximizing production of energy per acre.

Some early reports on use of corn silage seemed to
conflict with recent research. Waugh (181) reported that
cows performed better when fed one-half pound of hay per
100 pounds of body weight with corn silage than when corn
silage was fed as the only roughage. The dry matter in the
corn silage was from 19.8 to 25.0 percent. The low dry
matter in the corn silage could have been the reason for
that poor result. Pratt (145) also reported in 1950 that
heavy corn silage feeding resulted in slightly greater dry
matter consumption and in slightly greater milk production.
The group fed less silage produced more milk and also lost
more weight.

Coppock (51) cited an Iowa Study (141) in which 22
heifers were paired at birth and fed either corn silage or
corn silage and hay from birth through two lactations.

Both groups were on pasture during the summer after one year
of age. Production of milk, butterfat, and breeding effi-
ciency were similar for both groups.

Research by Hammes (71) showed that use Of corn si-
lage for fattening steers gave gains similar to those Of a
high grain ration and lowered the cost of fattening.

Corn silage was compared to alfalfa hay using differ-
ent combinations by Brown (54). Five groups of lactating

cows were fed either corn silage ad libitum, corn silage

55

plus 10 pounds of hay, corn silage plus twenty pounds of
hay, corn silage plus thirty pounds of hay or ad libitum
hay. The average daily milk production was 56.1, 58.2,
54.7, 56.0, and 54.8 pounds of milk, respectively. The
differences among ration groups in persistency of milk pro-
duction were not statistically significant. With increas-
ing amount of hay in the ration, dry matter consumption in-
creased, so that dry matter from corn silage was used more
efficiently for milk production than dry matter from hay.
Body weight changes followed a similar trend to that of
dry matter consumption.

Vandersall (176) also found dry matter intake was in-
creased slightly by addition of hay to cows consuming corn
silage ad libitum but milk production was lowered.

In investigations, Thomas et al (170) and Rumsey
(155) used cows at a higher level of milk production than
the ones previously cited. The difference in milk produc-
tion of cows producing 50 pounds of milk was not signifi-
cant between groups fed different ratios Of corn silage and
hay. Brown (55) concluded that corn silage can adequately
support high milk production.

Hillman (80), in reviewing the literature, stated
that the roughage portion of corn silage (stalks and leaves)
is equivalent in milk production value to clover hay. Also

the grain in the corn silage is as valuable for milk

34.

production as corn fed as dry corn and cob meal. The grain
in the silage increased the TDN value over silage with the
grain removed, the difference being from 59 to 69 percent.
Supplementation of corn silage with urea can reduce the
cost of corn silage even lower than the value for hay.

Hemken et a1 (75) reported that differences in the
grain to stalk ratio of two varieties of corn failed to
significantly affect digestibility or milk production.
However, the differences may have been masked in their
experiment since the silage having low grain content was
supplemented with additional grain to compensate for this
difference. The data seem to indicate that cows fed well-
eared corn silage produced an equal amount of milk and
gained more weight when fed 2.4 kg less grain than cows fed
silage with a low grain content.

Iintering brood cows fed all Pro-Sil treated corn
silage (a proprietary mixture of anhydrous ammonia, molas-
ses, minerals, and water) versus an all-hay ration in
Michigan (68) resulted in three pregnant beef cows wintered
per acre on the corn silage ration versus one pregnant beef
cow wintered per acre on the all-hay ration. Dry matter
consumption was 19.5 pounds per head daily for those fed
all hay versus 15.1 for those fed corn silage. There was
no difference in the average weight gain.

In another experiment, (69) wintering pregnant

35

heifers were fed an all silage versus a silage plus hay
ration and similar results were Obtained. Pro-Sil treated
corn silage performed just as well as when hay was added to
the ration.

In an experiment done the following year (67) win-
tering brood cows were fed either an all corn silage or an
all alfalfa grass silage ration. The animals ate 10.0
pounds of dry matter of Pro-Sil corn silage per head per day
versus 25.1 pounds of dry matter of alfalfa grass silage
per head per day. At the end of the experiment the cows
on corn silage gained 81 pounds whereas the cows on alfalfa-
grass silage lost 59 pounds.

These studies show that Pro-Sil treated corn silage
may successfully support pregnant beef cows as the sole
source of energy.

The value of corn silage has been under-rated.
Over-wintering of beef cattle on 90 percent of NRC require-
ments was successful in at least maintaining body condi-
tion. This was a savings of 1.8 pounds of TDN per head
daily.

Tyrrell et al (175) reported that feeding an all
corn silage and liberal grain ration for 5 complete lacta-
tions resulted in lower survival rates of lactating dairy
cows compared to cows receiving corn silage plus hay and

grain. Tyrrell concluded that liberal grain feeding had

56

no significant effect on the high cow losses. The cows re-
ceiving only corn silage and grain, however, produced more
milk than the other cows receiving some hay during the
first and second lactation.

The influence of feeding forages that are finely
chapped, high in moisture content, and fermented on.micro-
bial synthesis in the rumen and interactions with level of
grain feeding has not been adequately studied. More con-
clusive work needs to be done on what effect an all corn
silage ration has on longevity and health Of the dairy cow.

Corn silage is a rich source of energy. The TDN
content ranges from about 60 to 70 percent on a dry basis
and averages about 68 percent. This is higher than most
other forages and is equivalent to excellent quality hay.

The estimated net energy value of dent stage corn
silage is 71.2 megacalories per 100 pounds of dry matter ac-
cording to Morrison (151). ENE values for corn silage con-
taining more than 28.5 percent dry matter are not listed in
Morrison. Typical corn silage in the midwest contains
about 52 to 55 Percent dry matter, therefore is more mature,
contains a higher preportion of grain, and may be higher in

net energy value than shown in Morrison's tables.

Protein
Protein content of corn silage is relatively low com-

pared tO legume hay or silage. Michigan corn silage normally

37

contains 7 to 10 percent protein on a dry basis. Nitrogen
fertilization has increased the crude protein content of
corn silage as well as crOp yields (2, 156). However, if
fertilization rate is held constant and plant pOpulation
is increased the protein content of the silage will decrease.
Protein levels in corn silages also vary as the amount of
available moisture and other environmental conditions dif-
fer from year to year (80).

The addition Of urea, non-protein nitrogen (dis—
cussed in a later section), is one way to increase the nitro-
gen content of ensiled corn silage with very little added

cost.

Minerals

Corn silage is low in calcium and sodium and often
low in phosphorus, cobalt, and iodine. Sulfur may be low
in high silage rations particularly if urea is added and
natural protein withdrawn. Supplementation of these min-
erals may vary for different moisture conditions, soil
types, stages of harvest, and the types of drinking water
supplied to the animals (80).

Vitamins
The quantity of carotene (pre—Vitamin A) in corn
silage is usually sufficient for lactating cows unless the

harvested corn forage was too mature, had few leaves, had

58

severe frost damage, or was overheated during storage.
Vitamin D supplementation to a high corn silage diet usually
is not necessary unless the silage is made from immature

green corn (80).

Urea in Rations of Lactating Dairy Cows

Early work with urea in dairy cattle rations was
with low producing cows which had low dry matter intakes.
The high producing cow of today requires different feeding
practices (89).

Willett et al (182) experimented with feeding 1.25
and 2.5 percent urea in the ration. The main roughage was
chopped napier grass. They found that when urea replaced
SBOM in.the concentrates, milk yields were depressed.

Lassiter et al (115) reported no detrimental effect
on lactating cows fed from 25 to 55 percent of their total
ration nitrogen concentrate as urea. The cows' milk pro-
duction was from 24.2 to 59.6 pounds daily.

Rupel et al (156) in 1945 recommended that urea
should not be fed at a greater rate than one percent of the
total dry matter of the ration (5 percent of the concentrate)
The rate Of feeding grain was 1:5.5 pounds of milk. These
cows were only producing at an average of 27.9 pounds of
milk, so total urea consumption was low.

Conrad and Hibbs (50) discovered that one percent

39

(20 percent of total protein equivalent) urea in the grain
ration fed to cows producing from 29.9 to 75.0 pounds of
milk per day caused no depression of milk production. When
2.75 percent (60 percent of total protein equivalent) urea
was added to the grain ration, feed intake, milk production,
and body weights were depressed. They more recently found
that cows fed a pelleted alfalfa meal and urea combination
did not have depressed milk production.

Bates et a1 (15) reported that animals were able to
grow, mature, and produce milk when fed rations in which
essentially all the digestible protein equivalent was sup-
plied by urea. NO toxic effect was observed.

Huber et al (87) concluded that when urea was added
to the concentrate and furnished from 22 to 25 percent of
the total dietary nitrOgen fed to lactating cows with corn
silage as their principle ration the milk yield was de-
pressed. This would amount to one to 1.25 percent of urea
in the concentrate. When urea was increased to 2 percent,
then palatability of the concentrates was decreased.

Colovos (49) found in cows fed a low fiber concen-
trate that 2 percent urea improved digestibility of the
fiber, but the Opposite effect resulted when fed with a
high fiber concentrate. They fed a fair quality timothy

hay.

4O

Urea in the Silaggg

Woodward and Shephard (189) did early work with en-
siled corn silage and .5 percent urea which was fed along
with low protein concentrates and hay. Another group had
the urea mixed with the concentrates. Both groups main-
tained their production of milk with no differences.

In an experiment by Huber and Thomas (90) cows were
fed 6 different rations adding 0 percent urea, 0.5 percent
urea, 0.75 percent urea and CaSO4 to corn silage in conjunc-
tion with 8 percent, 12 percent, and 18 percent protein in
the concentrates. The cows fed untreated control corn si-
lage with 8 percent concentrate produced less milk than
those cows fed urea. The highest milk yields were Obtained
from the cows receiving 50 percent of the supplemental ni-
trogen from urea added to the corn silage and the balance
from soybean Oil meal. The authors concluded that a 10 per-
cent increase Of income over feed cost was obtained from
those cows which received their nitrogen from urea in corn
silage and soybean oil meal in grain rather than just from
soybean oil meal in grain. These facts emphasized the bene-
fits of adding urea to corn silage at harvest time.

In research done by Schmutz (161) a decrease in si-
lage intake was Observed but not a decrease in milk produc-
tion from cows fed 0.75 percent urea in the corn silage.

However, Huber (87) found no significant decrease in milk

41

production of cows fed silage containing 0.75 percent urea.
The difference in dry matter intake may have been due to a
higher dry matter content of silage in the latter study (87).

Hillman et a1 (77) suggest that corn silage should
contain a minimum of 50 percent dry matter to prevent stor-
age losses of nitrogen from seepage in urea—treated silages.

Huber et al (91) reported that silage dry matter in-
take increased with the addition Of 10 pounds of urea per
ton to 50 and 56 percent dry matter corn silage compared to
untreated control silages. Milk yields were not affected
by urea-treated silage but corn silage yields did decrease
with increasing maturity of the forage. As dry matter of
the silage increased to 44 percent, there was a high loss
of dry matter (15.1 percent) in the silo, and milk per-
sistency was lower than for the 50 and 56 percent dry mat-
ter silages. The highest intakes occurred with the urea-
treated (56 percent) dry matter silages. Cows fed the un-
treated corn silage ate less of the lower and higher dry
matter corn silage and more of the medium dry matter silage.
In these experiments cows fed urea-treated silage (50 and
56% dry matter) and a grain ration containing 15.8 percent
protein produced as well as those fed untreated silage and
a grain ration containing 18.7 percent protein composed of
all natural protein.

More urea can be tolerated in the presence of high

42

carbohydrate feeds such as cereal grains. Urea may produce
harmful effects under unusual conditions, such as starved
animals, rapid consumption of urea containing feed or in
animals that have not adjusted to the urea supplement (116).

No detrimental effect is apparent if the total non-
protein nitrogen (NPN) of the diet does not exceed 0.45 kg
of urea per 1000 kg body weight. Considering the wide NPN
content of forages one should not add more than 0.27 kg per
1000 kg body weight. The recommended level of urea is 0.5
percent when added to the corn forage as ensiled (80). How-
ever, favorable results were Obtained in one short—term
study from adding 0.85 percent urea (87).

Fletcher et a1 (64) and Campbell et a1 (42) demon-
strated that rumen ammonia levels were more constant when
urea-treated corn silage was fed more frequently. This
reduced the amount of urea consumed at one time and ammonia
concentrations were not as great as when the animal was fed
more often. Estimated pounds of TDN required per pound of
gain was significantly greater for animals fed silage two
times daily than for those fed urea-treated silage four
times. This agrees with data of Packett and Groves (159)
in relating energy and ammonia utilization.

When urea is correctly used, supplementing dairy cat-
tle rations with urea or non-protein nitrogen can be of fi-

nancial benefit.

43

High Moisture Corg_as a Source of Energy

There have been some conflicting reports on the use
of high moisture corn. Hansen et al (75) in 1959 using 24
(Holstein) heifers and 27 (Holstein and Brown Swiss) cows
reported that high moisture corn was not superior to dry
corn. The dry corn was ground and the high moisture corn
was not because they assumed that moisture made the kernels
soft enough to be disintegrated during digestive processes.

Zogg et al (191) in 1961 using 27 cows reported that
the efficiency of utilization of dry matter of high-moisture
corn increased as the moisture content increased from 22 to
52 percent. This corresponds with work done by Beesen et
al (l6, 17, 18, 19, 20) and Colbertson et a1 (55) where
corn stored at 51 to 52 percent mOisture gave increased
feed efficiency for fattening beef cattle over corn stored
at 10 to 15 percent moisture.

McCaffree and Merrill (122) compared high moisture
corn, dry corn, and a commercial grain mixture. Milk pro-
duction was not significantly different for cows fed high
moisture corn or dry corn but both groups produced more
milk than those fed the commercial grain mixture. In
another trial (122) high moisture ear corn was compared to
high moisture shelled corn. They found no significant dif-
ference in milk or butterfat production, or total dry matter
intake.

44

Pratt and Rogers (142) reported that ear corn silage
fed to heifers was a satisfactory source of energy for
growth and also for preparation for freshening. Milk pro-
duction could also be sustained by ear corn silage and
ear corn silage was ssgood a source of energy as a mixed
dairy ration when adequate protein supplement was provided.

McCaffree and Merrill (17) found no difference in
digestibility of shelled high-moisture corn compared to
dry corn.

Hillman (78) concluded in a review that carnage
(high-moisture corn) is equivalent in feed value to dry
corn for milk production and for fattening beef cattle and
that cornage is more efficient than dry corn. Cornage
should be ground before feeding. Ground ear carnage can
support high milk production and at the same time provide
15 percent more nutrients per acre than shelled cornage.

Schmutz (160) et a1 studied the fermentation and
preservation of corn containing various levels of moisture
and processed in silos. The lactic acid content of the
products was directly related to their moisture content.
Consumption of corn dry matter was negatively correlated
with the lactic acid content when fed ad libitum to dairy
heifers. These findings suggest the possibility Of cone
siderable variation in the feeding qualities of high mois-

ture corn and the need for further research to define

45

optimum.conditions for storing high moisture corn.

Lassiter et al (111) stored ground high moisture
shelled corn at 26, 52, and 40 percent moisture and ground
ear corn at 52 and 56 percent moisture and unground high
moisture shelled corn at 52 percent moisture. Dried corn,
used as a control, was stored at 14 percent moisture. Those
cows which received 40 percent ground shelled corn produced
4 percent less milk than cows fed 26 percent ground shelled
or 56 percent ground ear corn. When moisture was controlled
at 52 percent for ground ear, ground shelled, or unground
shelled corn the cows which were receiving the unground
shelled corn lost the most weight. This was probably due
to the passage of whole kernels into the feces. The high
moisture corn in all cases performed equal to if not greater
than that of dry corn, based on dry matter content. High
moisture shelled corn should be ground before it is fed,
this will increase its value.

Schmutz (160) reported that with the exception of one
growth study there was no significant difference in weight
gain of heifers when fed ground ear corn (24 to 25 percent
moisture) or when fed ground dry corn. In two studies ani-
mals fed the wetter silages (54 to 55 percent moisture) 1
required less dry matter per pound of gain and they consumed

less dry matter.

46

The use of high moisture corn is becoming more pOpu-
lar in.Michigan due to ease of handling and its equal if
not better nutritional value when compared to dry corn. In
areas where the growing season is short and labor is in
short supply the use of high moisture corn should be recom-
mended.

Igtake Regglation
The goal for feeding lactating dairy cows is to in-

crease dry matter consumption to the highest possible level
in order to maintain high milk production. Some have rea-
soned that if the cow has a high genetic potential for milk
production.more frequent feeding of fresh food would in-
crease the animal's consumption. 1

Marts et al (119) studied the effects of frequency
Of feeding a blended corn silage concentrate ration contain-
ing a pelleted urea-alfalfa combination during a l20-day
continual study. Twenty cows were divided into two groups.
The first group was fed twice a day and the other group was
fed four times a day. At the end Of the study the average
daily fat-corrected milk, milk fat, solids-not-fat, milk
protein, body weight, and dry matter intake was not signifi-
cantly different. These results indicated that frequency
of feeding of a blended corn silage concentrate ration con-

taining pelleted-urea supplement had no effect on performance.

47

Campbell and Fletcher (42) demonstrated that fre-
quent feeding Of a urea-ration four or six times compared
to two times daily increased growth and feed efficiency of
sheep. Martz (119) suggested these favorable results may
have been due to small quantities of urea administered at
frequent intervals, theoretically resulted in a more sus-
tained ammonia release. Thus the ruminal microflora may
have been able to utilize the ammonia nitrogen to a greater
extent for protein synthesis. Huber (89) found that higher
levels of urea in the silage did reduce dry matter consump-
tion.

Blaxter et a1 (28) postulated that animals on a
diet made up of long forages regulated voluntary intake so
that the gastrointestinal tract fill among rations is con-
stant at the end of the meal. In 1962 Balch and Campling
(10) agreed that food intake of ruminants receiving rations
of primarily roughages was regulated by the amount of di-
gests in the reticulorumen.

Balch and Campling (9) in another review stated that
palatability is an important factor in the voluntary intake
of individual feeds, showing that ruminants have perceptive
faculties. Differences in intake in a variety of roughages
can be related to that rate at which the undigested resi-
dues are removed from the reticulorumen. Montgomery (128)

questioned this theory and stated that the gastrO-intestinal

48

tract fill increased as dry matter intake increased, and a
more accurate system to verify the fill of food intake was
needed. Campling (45) stated that meal size in diets of
low digestibility may be a controlling factor in rations
that have a low fiber and high digestible energy content
and that ruminal distention is not a feedback signal in
control of meal size.

Bhattacharya and Warner (24) conducted experiments
with rumen-fistulated Holstein heifers. Hourly infusions
of cold or warm water effected slight changes in rectal and
tympanic temperature but had no affect on hay intake. When
the infusion of water was increased to every hour a marked
change in rectal and tympanic temperature was Observed, and
rumen temperature remained altered for a long period of
time. Compared to a control (50° C) infusion of cold (5° 0)
water increased (P c.01) consumption of an all-pellet diet
by 24 percent while a warm (49° C) infusion depressed intake
nonsignificantly by 9 percent. This experiment suggested
that physiological conditions causing a decline in body tem-
perature could be an important signal for controlling feed
consumption in ruminants.

Bails et al (7) found little evidence in their re-
search for hypothalamic temperature changes as a direct
feedback signal. They continued by writing that palata-
bility offers little evidence of its importance in deter-

49

mining meal size.

In an experiment by McCaffree and Merrill (121) trials
were conducted in which concentrates were increased after
calving to essentially ad libitum levels and adjusted weekly
to stabilize body weight to postpartum level. Lead feeding
was utilized prior to parturition, with daily concentrate
increases of 0.45 kg per day until 9.1 kg per day was
achieved or parturition occurred. After calving the concen-
trates were increased to 0.45 kg per day until the cows be-
gan to increase beyond the postpartum body weight. Then
the grain allowance was reduced. As grain was reduced
based on body weight increases, the cows compensated for
the energy formerly supplied from the grain by increasing
their forage consumption.

Montgomery et al (127) found in ruminants that volun-
tary intake decreased as proportions of concentrates in-
creased in the diet so the available energy consumption was
relatively constant. Cowsert et al (52) also found that ru-
minants while being fed isonitrogenous rations varying in
energy concentrations adjust voluntary feed intake in rela-
tion to physiolOgical energy demands if rumen load does not
limit their energy consumption.

Donefer (56), Woods and Rhodes (28), and Brent et a1
(51) while working with sheep found that as the proportion

of concentrate was increased in the diet voluntary dry

50

matter intake decreased, so that the available energy con-
sumption was about constant. Cohn and Joseph (48) force-fed
rate above their normal diet or intake and the body weight
increased by fat deposition. When forced feeding was ter-
minated the rats ate less and body weight decreased by loss
of fat. As normal body fat levels were attained voluntary
intake was resumed. During Obesity, activity of an animal
will be reduced by the energy balance signal and the mobili-
zation potential will be reduced (110, 140). Fasting of a
normal animal will cause the Opposite responses. Reid and
Robb (147) stated that accumulation of fat in the abdominal
cavity might restrict gastrointestinal capacity and curtail
appetite especially in high-forage diets.

Dinius and Baumgardt (55) experimented with voluntary
feed and energy intake of rations varying in digestibility
and density. When the ration was low in energy density
rumen fill limited the intake but as energy density in-
creased then total energy intake remained constant.

Heat stress (4), inadequate protein-digestible energy
balance (44, 58) and dehydration (22) may all effect total
intake. Bails (6) stated these limiting factors of intake
may be put under more stress by very high milk production
or a disease.

Feeding high levels of corn silage depresses dry mat-

ter intake compared to all hay rations according to Brown

51

et a1 (55). Similar results have been shown with high
moisture grass silages. The causes for this appetite de-
pression are not known.

The above studies indicate that feed intake may be
affected by the quality of the ration, energy density of
the ration, energy-protein balance, and requirements of the

animal.

Literature Resume

In.resumé one concludes that lactating cows must be
provided a ration that provides adequately levels of energy,
protein, fiber, and the various minerals and vitamins in
order to maintain high level milk production. The published
NRC nutrient requirement tables appear to be sufficiently
accurate to allow optimum performance of cattle when fed
according to these standards.

Feeding excessive amounts of energy may result in
milk fat depression, excessive fatness of cattle and in-
crease the incidence of health problems at parturition.

Corn silage is a satisfactory forage for lactating
and pregnant dry cows when prOperly balanced with protein,
minerals, and vitamins. The maturity, fineness of chopping,
and moisture content may affect the nutritive value Of corn
silage and under some conditions feeding 10 to 20 percent

of the ration dry matter as hay may be desirable because of

52

the variation in corn silage. High moisture corn processed
through silos is comparable to dry corn in feed value but

may be more variable in composition and keeping quality un-

der farm conditions.

Nonpprotein nitrogen sources such as urea and ammonia
can replace 25 to 50 percent of the nitrogen from natural
protein sources in the ration of lactating and pregnant

dry cows and substantially reduce feed costs.

EXPERIMENTAL PROCEDURE

These experiments took place at the Andrews Univer-
sity Dairy in Berrien Springs, Michigan. The cows were kept
in open lot free-stall housing and fed mechanically using
tube feeders. Each cow was placed in one of three or four
lots according to her daily production soon after the monthly
Dairy Herd Improvement Association (DHIA) tests were taken.

The main roughage was corn silage stored in cement
stave silos. Minimum quantities of hay were fed in stalls
at the end of each barn. High moisture corn was stored in
a Herd-King sealed silo, rolled, and weighed at the time
of feeding. Feeds were analyzed for protein and dry matter
content and these values are reported in Table l which also
shows the estimated TDN and net energy values calculated
from Morrison (151).

A 55 Percent pelleted concentrate containing 26.2
percent proteinpequivalent from nonprotein nitrogen was
stored in a metal bin. As corn silage was being fed, high
moisture corn and the 55 Percent concentrate were metered
into the tube feeders with the corn silage. The quantity
of concentrates fed was regulated according to the nutri-
tional requirements of each lot. Thorough mixing occurred

as these feeds traveled to the bunks. Soybean meal (SBM)

- 53 -

Table 1

Chemical Composition of Feeds Fed in Experiment I

 

 

 

Forage or Digestible a Dry
Concentrate Protein Protein TDNa NE Matter
95 96 % MCal %
per lb.
High Moisture Corn 7.75 5.9 72 .85 76.77
55% Concentrate 55 46.6 65 .91 90.00
Alfalfa Hay 15.19 10.8 51 .49 88.40
SBM 45.70 42.0 78 .91 90.0
Corn Silage 5.79 1.7 52 .54 46.0

 

aTDN, NE, and Digestible Protein values were calculated
from references 62, 151, 154, and 155.

was fed in the milking parlor to each individual cow based
on requirement.

Prior to treatment, daily milk weights were taken on
all cows in the herd. Only those cows which were below 50
pounds of milk daily were chosen for the experiment. The
milk was recorded daily by reading the quantities from
weigh jars.

The calculated requirements for protein and energy
Of the cows used in Experiment I are shown in Table 2.

Fat test values used were taken directly from the DHIA
monthly reports in Experiment II. Feed samples were analyzed

by the Department of Biochemistry, Michigan State University.

55

Table 2

Daily Nutrient Requirements of Lactating Dairy Cows in
Experiment I to Maintain 50 Pounds of Milk

   

Digestible

 

 

Protein Protein TDN1 NE2
1b. lb. lb. MCal
Maintenance for
1100 pound ma-
ture cow 1.40 .66 8.10 9.0
50 Lbs. of Milk 2.10 1.55 9.15 9.5
Total Requirement 5.50 2.01 17.25 18.5

 

INational Research Council, Publication 1549, Nutrient fig:

guirements 2; Dairy Cattle, National Academy of ScIences,
be

F. B. Morrison, Feeds and Feedin , 22nd ed., 1956.

 

2

Body weights were taken for Experiment II on a port-
able platform scale as the cows walked from the parlor after
the afternoon milking. Dry matter consumption of corn si-
lage was estimated from the data reported by Brown (54) who
measured dry matter intake of cows in late lactation when
fed corn silage ad libitum with and without grain. Actual

silage intake was not measured in these trials.

Eyperiment I

The first experiment was conducted to determine the
effect of eliminating all concentrates and protein supple-

ment from the ration of cows fed corn silage and limited

56

hay in the late part of lactation.

Forty-eight cows were paired according to age and
daily level of milk production (not exceeding thirty pounds
of milk per day) from the herd of 180 milking cows. Pre-
liminary milk weights within groups varied not more than
two pounds from the average and the age of cows varied not
more than three months from the average. Most of the ani-
mals were heifers in their first lactation with an average
age of thirty-five months.

The paired cows were separated with each cow going
into either the control or the experimental lot. Days in
lactation for each lot were assumed to be equal due to the
dividing of pairs at random. The experimental group went
into the dry cow lot (Lot III) and were separated out at
milking time. These cows received only free choice corn
silage and five pounds of hay per day. Another lot was used
to house the cows producing less than thirty pounds of milk
per day. Twentybfour of these cows served as the control
group. The control group was fed 9 pounds of high moisture
corn, free choice corn silage, one pound of 55 Percent con-
centrate, 5 pounds of hay, and 0.75 pound of soybean meal.

The concentrates were mixed with the corn silage.

Eyperflnent II
Experiment two was designed to determine the effect

of reducing the energy intake while maintaining adequate

57

protein in the ration of cows in late lactation.

Before Experiment II was started there was a two-
week preliminary testing for allocation of cows to groups.
This period of time was set aside to observe all cows in
the Andrews University herd. Milk weights were taken twice
each week to determine which cows would be used. At the
end of the preliminary testing period a 60-day experiment
was begun.

Thirty cows were selected which ranged in milk produc-
tion from 55.5 to 57.5 pounds daily. The cows were placed
alternately in one of the two chosen lots. The cows used
for the research were milked and fed the same as the other
cows in their respective lots. Cows on test were identified
by a red ink mark on their udder.

Lot 11 (control group) received 14 pounds of high
moisture shelled corn, 5 pounds of hay,‘% pound of 55 percent
concentrate, % pound Of soybean meal and free choice corn
silage.

The experimental group (low energy) received the same
ration as the controls except that the 14 pounds of high
moisture corn was eliminated. Fat tests were taken directly
from the monthly DHIA report. Milk was weighed five days
per week during the eight-week experiment. Body weights
were taken at the beginning and end of the experiment, the

cows were weighed on a platform scale as they came from the

58

parlor. The concentrates were group-fed by weighing and
metering into the tube auger slowly while the corn silage
was being fed to each lot. The soybean meal was fed indi-
vidually in the milking parlor. Table 5 gives the chemical
composition Of feed and Table 4 gives the daily requirements

of a lactating cow producing 55 pounds of milk.

Table 5

Chemical Composition of Feeds Fed in Experiment II

 

 

 

 

 

Forage or Digestibge a a Dry
Concentrate Protein Protein TDN NE Matter
% % % MCaI %
per 1b.
High Moisture 6.81 4.70 67 .80 71.15
Corn
Alfalfa Hay 18.00 12.78 50 .48 85.55
Corn Silage 5.25 1.54 50 .52 45.05
SBM 45.70 42.0 78 .91 90.0
55% Concentrate 55 46.6 65 .91 90.0

 

aDigestible Protein, TDN, and NE were calculated from re-
ferences 62, 151, 154, and 155.

59

Table 4

Daily Nutrient Requirement
of Lactating Cows in Experiment II

 

 

 

 

Digestible 1 2
Protein Protein TDN NE
1b. 1b. 1b. MCal
Maintenance for
1200 pound ma-
ture cow 1.52 .72 8.8 9.6
55 Lbs. of Milk 2.50 1.57 11.6 10.9
Total Requirement 4.02 2.29 20.4 20.5

 

INational Research Council, Publication 1549, Nutrient Eg-

quirements g; Dairy Cattle, National Academy of Sciences,
1966.

 

2F. B. Morrison, Feeds and Feeding, 22nd ed., 1956.

RESULTS AND DISCUSSION

Eyperiment I

The experimental lot (no additional concentrates)
started with a weekly average of 0.9 pounds above the con-
trol group of cows. At the end of the first week the aver-
age daily production had drOpped to 25.2 as compared to the
control weekly average of 50.1 pounds of milk. The average
daily production of the control group remained between 29.4
and 50.1 pounds per day during the first, second, third,
and fourth weeks of the experiment as shown in Table 5 and

Figure 1. They did not decline as normally expected. One

Table 5

Average Daily Milk Production by Weekly Periods
for Control and Experimental Cows in Experiment I

 

 

 

Control Experimental
lb. lb.

Pre-Egperimental 28.7 29.6
Egperimental--by week

1 50.1 25.2

2 50.0 25.0

5 29.4 22.7

4 50.1 20.7
Egpgrimental M332, 29.9 22.9

 

 

- 60 -

.Asasoce mass seas commas: sassv .H
pqoafinomxm AH ponv maonpaoo on donwmaoo Am ponv pmosoammsm

 

 

“m namponm no mango oz com @300 Mon mobhso noaposdoym MHaSIIH essmam
mass:
3 m N H
o
L
whoa i 2
1 n
ma
m.
g s
.1..: a: .u om m.
i- '5’
I is! l m
still 1. mm 1.
x.
I
i 7Q
0m m
G
I. 8
mm .A
1 cs
1 me
I on

 

62

might conclude that these cows were being over-fed which
retarded the normal decline in daily milk production.

The weekly average for the experimental group, at
the end of the second, third, and fourth week was 25.0, 22.7,
and 20.7 pounds of milk per cow daily, respectively. These
values were 7.0, 6.6, and 9.4 pounds of milk below the con-
trol group which produced 50.0, 29.4, and 50.1 pounds the
second, third, and fourth week, respectively.

Feed costs for the experimental group (Table 6) were

51.5 cents per head per day compared to 55.5 cents per head

Table 6
Average Daily Intake and Feed Costs for Cows on Experiment I

 

 

Control Eyperimental
Concentrates No Concentrates

Amount Total Amount Total

 

Cost/lb. Fed Costs Fed Costs

cents lb. cents lb. cents

Corn Silage 0.5 57.0 18.5 48 24.0
Alfalfa Hay 1.5 5.0 7.5 5 7.5
High Moisture Corn 2.0 9.0 18.0 -- --
55%1Concentrates 6.0 1.0 6.0 -- --

- SBM 5.0 0.7 5.5 -- --

 

Total Intake 52.07 55.5 55 51.5

 

65

per day for the control lot. An investment of an extra
22.5 cents per day for concentrates yielded 9.4 pounds of
milk above the experimental group which at 35.50 per hun-
dred pounds amounted to 50 cents more return above feed cost
at the end of the fourth week (See Figures II and III and

Table 7).

Table 7

Average Weekly Gross Income and Gross Income
Minus Feed Costs for Cows on Experiment I

 

Control

 

 

 

 

erimental

Received Concentrates Receive NO Concentrates
1 Income 1 Income

Ave. lb. Gross Minus Ave. lb. Gross Minus

Milk Income Feed Milk Income Feed

Period Produced Dollars Costs Produced Dollars Costs
x2 28.7 1.58 1.04 29.6 1.62 1.50
1 50.1 1.65 1.11 25.2 1.52 1.07
2 50.0 1.65 1.11 25.2 1.27 0.95
5 50.0 1.62 1.08 22.7 1.25 0.95
4 50.1 1.66 1.12 20.7 1.14 0.82

 

IMilk value at $5.50 per hundred pounds.
2X . Preliminary period.

Assuming the value of 100 pounds of milk at $6, the

extra return above feed cost for feeding grain and protein

supplements was 8.55 or 152 percent return on the investment

for extra feed.

.Aaaaa Ho menses sandman nan om.m¢ .MHHa Ho osaa>v .H
psmaanmmwm .noapwm Honpaoo and Hupnoaflnmnwm no msoo Ho oaoonH mmonwllHH ondwwm

 

 

 

6x063
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— J
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mopwnpnooqoo oz amaanonwm all _
,mpwnpnooooo umbwooomnlaonpnoohrll " 1
_ om.a

 

65

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Inna Hon om.mw .MHwa mo ofiad>v .H unoaanomxm .noapwm prnma

Iwnomxm and aonpqoo no mBoo scum pmoo doom mnafia oaoonH mmontIHHH onswam

 

 

axooa
é m N H
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mmpmanoonoo oz do>aooomllaupqmaanmgnu||

mo guano onoo cobaooomunaonpnoo II

 

ow.

om.

OO.H

OH.H

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4 .3

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saettoq

sqsoo pee; snurm emoouI ssoas

66

The difference in milk production between supple-
mented and unsupplemented groups was highly significant

(P «.01). (Table 8).

Table 8

Analysis of Variance Table of Milk Production
for Experiment I

   

 

Source d.f. Sum of Squares Mean Square F. F 01
Total 47

Treatments 1 471.25 471.25 11.79‘ 7.21
Error 46 1858.55 59.97

 

 

rS‘i—gnificantly different (15": .01).

Dry matter consumption was assumed to be 2.7 and 2.4
pounds per hundred pounds of body weight for the control and
experimental cows, respectively, based on the data of Brown
(34).

The control ration contained 12.5 percent crude pro-
tein and the experimental ration 10.0 percent crude protein
on a dry matter basis as calculated from chemical analysis
and estimated intakes.

The cows which received grain were given sufficient
feed to exceed NRC requirements (Table 9) for total digesti-
ble nutrients, net energy, digestible protein, and total pro-

tein. The group which received no grain received an adequate

67

.hame Mass ammonom m.m no mUQSOA om oosconm op mpnmsoawauon omz consanoamo.

 

 

 

 

 

 

mm.m o.m m.ma m.ua mm.m o.m m.ma m.aa omz .smnasaom.
nm.m o¢.H mm.ma Hm.ua om.mm ms.m o¢.m mm.¢m mo.mm sm.mm sun was Boo
Ham asaqu Hapoa
om. mm. so. mm. no. as»: amonsom
mm. 5%. am. mm. om. mopwnpaoonoo &mm
on. mm. u.s m¢.m om.o anoo .mfioa swam
ma. 4m. m.m mm.m m¢.¢ ms. am. ¢.m mm.m m¢.¢ ham uuaama<
mm.a om. mm.ma mm.ma mo.mm os.H mm. m.~H aw.aa mo.ma omaaam anon
.nH .na (Hams .na .na .pH .pH. Haas .HH1 .na
Hmpom .mmn as zna asaan Hapoa .mmn an age oawan
dampohm Hoppms nwoponm 909982
hum ham
Anne 02 cobaooomv Anson cobdooomv

 

prnoafino

donpnou

 

 

 

.H puoaanomufi ad @300 haddn Ho ouwan unownppzphdddn

m canda

68

amount of energy; however, their protein intake was approxi-
mately 25 percent below the NRC requirement.

Theoretically if the 55 percent concentrate and soy-
bean meal were left in the ration and the corn was omitted
all calculated nutrients would have been supplied except
total protein. This established the basis for designing
Experiment II in which only the corn was removed from the
ration and the soybean meal and 55 percent concentrate were

left in the ration.

Egpggiment II
Before starting the experiment the previous weekly

 

average production was 55.5 and 55.1 pounds of milk per cow
per day for the control and experimental groups, respectively;
Cows in the control group (fed corn) averaged eleven pounds
more per head in body weight than those in the experimental
group. Change in body weight was not Significantly differ-

ent between groups due to treatment (Table 10).

Table 10
Analysis of Variance of Change in Body Weight, Experiment II

 

 

 

Source d.f. Sum of Squares Mean Square F
Treatments 1 2005 2005 5.54 n.s.
Error 27 15265 565

Total 28

 

69

From the beginning to the end of the experiment both groups
had a significant (P <.10) increase in body weight. The
experimental group gained an average of 28 pounds as the
control group gained 44 pounds but this difference was not
significant.

Average daily milk production for the control and
experimental groups throughout the length of the trial
was 50.4 and 51.6 pounds, respectively (Table 11).

Table 11

Daily Milk Production for Control and Experimental Cows
For Three Preliminary Weeks and Eight Weeks of Experiment II

 

 

Control
Received Corn

Experimental
Received No

 

 

 

Periods Milk-Pigduction Milk Pigductiog
Preliminary Weeks
1 57.1 35.8
2 57.9 35.6
5 55.5 55.1
Experimental Weeks
1 32.9 55.5
2 31.4 52.7
5 51.5 31.9
4 51.0 55.5
5 31.3 50.7
6 28.6 29.7
7 28.1 29.2
8 28.5 29.4
Average 50.4 51.6

 

70
The difference in milk production between the two groups dur-

ing the 8 weeks was not significant (Table 12).

Table 12

Analysis of Variance in Milk Production for Experiment II

 

 

 

 

Source d.f. Sum of Squares Mean Square F
Treatments 1 51 51 1.402 N.S.
Period 7 1016 145.1 7.262
T x P 7 84 12.0 .600
Cows Per

Treatment 28 619 22.1 1.106
Error 186 5716 ‘ 19.97
Total 229 5466 .

 

Current NRC nutritional standards for protein appear
to be higher than required. Total protein intake of the
control group was 0.57 Pounds below the calculated need or
91 percent of the NRC allowance as indicated in Table 15.
Digestible protein, however, was in excess. Part of this
discrepancy may be due to erroneous assumption in the cal-
culation of digestible protein.

The calculated protein intake of the experimental
group was 0.85 pounds less than the NRC allowance. This
represents 79.5 percent of the NRC allowance as shown in

Table 15.

71

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ma canes

75

It can be concluded that the amount of protein sup-
plied, according to recommendations, was marginal. The
control ration contained 11.5 percent crude protein and the
experimental ration 11.0 percent on a dry matter basis.

The experimental group was fed essentially the same
as the control group except.that 14 pounds of high moisture
corn was omitted from the ration. This did not produce any
significant difference in milk production or change in body
weight, although the cows fed no corn tended to gain less
weight. Protein intake was actually below the NRC allow-
ance for the no corn group.

Huber et a1 (90) and Lassiter et al (112) found that
low protein rations can give a reduction in milk flow. Ap-
parently the protein content of rations fed in this experi-
ment was not sufficiently low to depress milk production or
elicit a difference in reSponse.

The cost of the two rations differed by 15 cents per
cow daily as shown in Table 14. The experimental lot which
received no corn produced an equal amount of milk at a lower
cost with an increased net return of 21 cents per cow per
day (Table 15, Figures IV & V). Theoretically, if 50 cows
in late lactation were fed the ration without corn for 5
months, the extra income over feed costs would be 8945.

During the next lactation, when all cows re-

ceived normal herd treatment, milk and fat production

74

Table 14

Average Daily Intake and Feed Costs for Cows
on Experiment II

 

 

 

 

 

 

 

 

Control Experimental

Corn No Corn
Amount Total Amount Total
Cost/lb. Fed Costs Fed Costs
cents lb. cents lb. cents
Corn Silage 0.5 40 20.0 55 27.5
Alfalfa Hay 1.5 5 7.5 5 7.5
High Moisture Corn 2.0 14 28.0 -- ---
55% Concentrates 6.0 .5 5.0 .5 5.0
Soybean M88]. 5.0 05 205 05 205
Total 60.0 61.0 61.0 40.5

Table 15

Average Gross Income and Gross Income Minus Feed Cost
for Cows on Experiment II

M

 

 

 

 

 

 

 

Control
Received Grain

Milk Income
Per Minus
Cow Gross Feed Feed
Daily Income Costs Costs
1b. 3 3 3
50.4 1.74 .61 1.15

Experimental
Received No Grain
Milk Income
Per Minus
Cow Gross Feed Feed
Daily Income Costs Costs
1b. 5 3 5
51.6 1.82 .48 1.54

 

75

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mamas
osoonH mwoam maoonH amonm

 

 

 

 

 

 

 

 

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O®.H

 

76

records were not completed to determine the effect of feed-
ing high corn compared to no corn during the last two months
of the previous lactation.

Investigation into these records revealed that 11 of
15 cows in the control group (fed corn) were removed from
the herd before completing the next lactation. In contrast
only two cows in the experimental group (fed no corn during
late lactation) had been removed from the herd at the time
the records were inspected 15 months after completing the
experiment.

The reasons for this difference in rate of removal
from the herd are unknown and may or may not be related to

the level of feeding during the previous lactation.

SUMMARY AND CONCLUSIONS

Two experiments were conducted to determine the ef-
fects of varying the protein and energy intake of dairy
cows during late lactation in the Andrews University Dairy
herd.

Data from Experiment I indicate that feeding corn
silage ad libitum and 5.0 pounds of average quality alfalfa
hay was not sufficient to maintain normal production of
cows producing 50 pounds of milk daily. The calculated in-
take of both energy and protein exceeded NRC recommended
allowances by 10 to 15 percent in the control group, whereas
energy was equal but protein intake was approximately 25
percent less than NRC recommended allowances in the experi-
mental group fed no concentrates orprotein supplement. At
the end of the fourth week the experimental group produced
9.4 pounds less milk per cow daily than controls. This re-
sulted in a loss of 50 cents per cow daily in gross income
minus feed cost.

In Experiment II removal of 14.0 pounds of high mois-
ture shelled corn from the ration of cows producing 55 to
57 pounds of milk daily and fed corn silage ad libitum,

5.0 pounds of alfalfa, and 0.5 pound of supplemental pro—
tein, resulted in no significant difference in milk produc-

tion or body weight. Calculated intake of energy was 55

- 77 _

78

percent higher and protein 9 percent lower than NRC allow-
ances in the control group, whereas energy intake was equal
to NRC but protein intake 21 percent less than NRC recom—
mended allowances in the experimental group. All cows fol-
lowed a normal lactation curve and gained weight in this
experiment. Removing the corn from the ration increased
income above feed cost 21 cents per cow daily based on
observed milk production, feed intake assumptions, and
prices under practical farm conditions.

These results indicate that feeding 9 to 21 percent
less protein than the NRC standards had no effect on per-
formance; but feeding 25 percent less protein than these
allowances in late lactation significantly reduced milk
production. A ration containing 11 percent crude protein
on a dry matter basis was adequate to maintain normal milk
production of cows producing 55 pounds per day whereas 10
percent crude protein was too low under the conditions of

this experiment.

5.

6.

7.

8.

9.

10.

11.

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