THE NU?MTWE VALUE OF CGRN SILAGES
CONTAINENG CHEMlCAL 'ADDITIVES AS MEASURED
E‘I’ CERQWTH AND MiLK PRODUCTEON OF
DMRY ANIMALS

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thesis entitled
The Nutritive Value of Corn Silages
Containing Chemical Additives as Measured

By Growth And Milk Production Of
Dairy Animals

presented by

William G. Schmutz

has been accepted towards fulfillment
of the requirements for

Doctor degree in Dairy

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ajor professor

m.m May 4, 1966

0-169

ABSTRACT

THE NUTRITIVE VALUE OF CORN SILAGES CONTAINING
CHEMICAL ADDITIVES AS MEASURED BY GROWTH AND
MILK PRODUCTION OF DAIRY ANIMALS

by William G. Schmutz

The nutritive value of corn silage containing urea, diammonium
phosPhate, calcium carbonate and dicalcium phoSphate additives was
studied over a two year period. The fermentation pattern and feeding
value of thirteen silages were determined.

The initial and final pH values for two untreated silages were
5.1, 3.6; and 5.4, 3.6, reSpectively. There was a slight increase in
these values for a single additive regardless of whether the additive
was urea, diammonium phosPhate or calcium carbonate. Additive
combinations increased the pH more than single additives (P < 0.01).

No significant differences in pH were observed among silages containing
either urea or calcium carbonate.

Urea and diammonium phOSphate additions increased the crude
protein equivalent of the treated silages (P-< 0.01 and P«< 0.05 for
both additives). In general, the crude protein equivalent of the
treated silages increased in proportion to the level of urea added
to the silages. The percent of the theoretical crude protein recovered
ranged from 85 to 89 percent, while the percent of N.P.N. (non-protein

nitrogen) lost ranged from 32 to 45 percent.

William G. Schmutz

A11 additives resulted in increased organic acid production
compared to the control silage. The range of acetate and lactate
production expressed on a dry matter basis was 1.08 to 2.28 and 8.42
to 13.06 percent, respectively. Chemical combinations increased
lactate production in both years (probability 0.05 and 0.10) and
acetate production in the 1964-65 silages (P < 0.05), while silages
with added calcium contained greater amounts of acetate and lactate
in the 1964-65 silages (probability of 0.05 and 0.10) and lactate
in the 1963-64 silages (P 2 0.10).

Calcium carbonate or diammonium phosphate additions increased
the ash content, while added N.P.N. compounds increased the crude
protein equivalent of the treated silages.

In growth trials, heifers made adequate live body weight gains
when fed treated corn silages. In the first trial, differences between
two 0.5 percent urea silages with different calcium compounds were not
significant. In a second trial, heifers receiving the silages con-
taining 0.5 percent calcium carbonate either alone or in combination
with 0.5 or 0.75 percent urea made lower gains per day than heifers
receiving either the untreated control silage or the 0.5 or 0.75 percent
urea silages. This difference was significant (probability range of
0.05 to 0.01) for the 0.5 percent calcium carbonate and the 0.5 percent
calcium carbonate plus 0.75 percent urea silages. Those heifers
receiving the silages with urea serving as the only chemical additive
made slightly better gains (probability range of 0.05 to 0.01) as the

levels of urea increased.

William G. Schmutz

In lactation studies, animals receiving the silages containing
1.0 percent diammonium phosPhate consumed less (probability range of
0.05 to 0.01) silage dry matter per day, dry matter per hundred pounds
of body weight, total dry matter, and total digestible nutrients
(T.D.N.) per day and produced less 4.0 percent fat corrected milk
(F.C.M,) per day. This depression in intake did not occur when 0.5
percent calcium carbonate was used either alone or in combination with
diammonium phOSphate. In a second lactation study, silage containing
0.75 percent urea followed a similar pattern as the 1.0 percent diam-
monium phOSphate silage in the previous study except that 0.5 percent
calcium carbonate did not improve performance when added in combination
with 0.75 percent urea. In this study, cows consuming the 0.5 percent
urea silages produced the most 4.0 percent F.C.M. per day.

In digestibility studies, there was a slight, but non-significant
depression in apparent digestibility of dry matter, ash, and protein
in the silages containing urea. No definite trends were noted in the
biological values of silage proteins and definite conclusions could not
be formed. The loss of silage dry matter during storage averaged 8.6

to 11.0 percent.

THE NUTRITIVE VALUE OF CORN SILAGES CONTAINING
CHEMICAL ADDITIVES AS MEASURED BY GROWTH AND

MILK PRODUCTION OF DAIRY ANIMALS

BY

William G. Schmutz

A THESIS

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

DOCTOR OF PHILOSOPHY
Department of Dairy

1966

ACKNOWLEDGEMENTS

The author expresses his sincere appreciation to the following
members of the Dairy Department Staff: Dr. L. D. Brown, for his
valuable counsel during the course of this study and for his aid in
preparing this thesis; Dr. R. S. Emery and Dr. J. W. Thomas, for their
effective assistance in initiating the study; Mr. G. N. Blank, for
aiding with the chemical analyses; and Mr. Dennis Armstrong, for
managing the experimental animals.

He wishes also to thank Dr. E. J. Benne and his associates in
the Biochemistry Department for helping to analyze the silage samples.

Especially grateful thanks are extended to his wife, Betty,

for her help and encouragement during the entire duration of the

study.

ii

TABLE OF CONTENTS

Page
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 1
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . . . . . 3
Nutritive value of Corn Silage . . . . . . . . . . . . . . . 3
Relative Feeding Value for Growth and Fattening . . . . . 3
Relative Feeding Value for Lactation . . . . . . . . . . . 6
Digestibility of Corn Silage . . . . . . . . . . . . . . . 16
The Use of Chemical Compounds to Improve the Nutritive
value of Corn Silage . . . . . . . . . . . . . . . . . . . l7
Urea and Other Non-Protein-Nitrogen Compounds . . . . . . 17
Hydrogen Ion Concentration and Acid Production in
Urea Treated Silages . . . . . . . . . . . . . . . . . 19
Relative Feeding Value . . . . . . . . . . . . . . . . . 21
Digestibility and Balance Studies . . . . . . . . . . . 29
Diammonium Phosphate . . . . . . . . . . . . . . . . . . . 37
Mflneral Additives . . . . . . . . . . . . . . . . . . 40
Hydrogen Ion Concentration and Acid Production in
Corn Silage Treated with Mineral Additives . . . . . . 40
Feeding Trials with Silages Treated with Mineral.
Additives . . . . . . . . . . . . . . . . . . . . . . 42
Digestibility Studies with Mineral Additive Silages . . 44
Limestone Urea Combinations . . . . . . . . . . . . . . . 46
Hydrogen Ion Concentration, Acid Production and
Crude Protein Changes . . . . . . . . . . . . . . . . 46
Feeding Studies with Limestone-Urea Combinations . . . . 47
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 48
EXPERIMENTAL PROCEDURE . . . . . . . . . . . . . . . . . . . . 51
Experiment I . . . . . . . . . . . . . . . . . . . . . . . . 51
Heifer Growth Trial . . . . . . . . . . . . . . . . . . . 53
Lactation Study . . . . . . . . . . . . . . . . . . . . . 54
Experiment II . . . . . . . . . . . . . . . . . . . . . . . 56
HeiferGrowthTrial................... 57
Lactation Study . . . . . . . . . . . . . . . . . . . 57
Digestibility and Nitrogen Balance Study . . . . . . . . . 59
Computation of Data--Production Trials . . . . . . . . . . . 61
Chemical Analysis . . . . . . . . . . . . . . . . . . . . . 62
Moisture, pH, Crude Protein . . . . . . . . . . . . . . . 62
Volatile Fatty Acids . . . . . . . . . . . . . . . . . . . 62

AnalySis Of Data 0 O O O O O O O O O O O O O O I O O O O O 63

iii

RESULTS 0 O O O O O O O O O O O O O 0

Chemical Data . . . . . . . . . . .
pH . . . . . . . . . . . . . . . .
Crude Protein Equivalent . . . . .
Organic Acid Production . . . . .
Chemical Composition of Silages .

Animal Performance . . . . . . . . .
Heifer Growth Trials . . . . . . .
Lactation Studies . . . . . . . .
Digestibility and Nitrogen Balance
Silage Input-Output Data . . . . .

DISCUSSION 0 O O O O O O O O O O O O 0
SUMMARY AND CONCLUSIONS . . . . . . .

LITERATURE CITED . . . . . . . . . . .

iv

Studies

Page
64

64
64
67
70
74
74
74
79
83
87

89
104

108

11.

12.

13.

LIST OF TABLES

Effect of Chemical Additives on pH of Corn Silage . .

Crude Protein Equivalent of Experimental Corn
Silages (Dry Matter Basis) . . . . . . . . . . . .

Effect of Urea and Diammonium Phosphate Additions
on Silage Crude Protein Content (Dry Matter Basis).

Organic Acid Production in Experimental Corn
SilageSooooooooooocoococoa...

Chemical Composition of Experimental Silages . . . .

Growth of Dairy Heifers Fed Treated Corn Silages
(1963-648113895)00000000cocoa-coo

Growth of Dairy Heifers Fed Treated Corn Silages
(1964‘6SSi-lages)...oooooooooooooo

Lactation Trial (1963-64 Silages) . . . . . . .p. . .
Lactation Trial (1964-65 Silages) . . . . . . . . . .
Coefficients of Digestibility and Nitrogen Balance
of Experimental Corn Silages Fed to Lambs
(1964-65 Silages) . C C O O C O O O O O O C O O O 0

Effect of urea on Apparent Digestibility of
Treated Corn Silages . . . . . . . . . . . . . . .

Biological values of Experimental Corn Silage

Pratein O O O O C O O O O O O O O O O O O O O O O O

Silage Input-Output Data . . . . . . . . . . . . . .

Page

65

68

70

71

75

77

78

80

82

84

85

86

88

INTRODUCTION

Moir (1965) compared the physiology of ruminant-like animals
and concluded that because of their type of digestion, plant evolution
has favored those animal species which are able to consume and utilize
forages, and specifically the plant constituent, cellulose. Because
of this advantage which ruminants have over other animal species, the
development of methods to improve the utilization of forages has become
of predominant interest. While the use of pasture represents the most
economical forage for ruminant animals, its use as a year-around crop
is limited by climate. Green forage crops preserved as silage provide
a source of highly nutritious roughage during the times when pasture is
either not available or of poor quality. Of all silage crops, the corn
plant represents the most nutritious forage from the standpoint of
expected total digestible nutrients harvested per acre.

While the corn plant is highly nutritious, it is low in such
constituents as protein and calcium. In recent years much research
has been devoted to increasing these constituents in corn silage in
efforts to improve its feeding value. Such non-protein-nitrogen
compounds as urea, biuret, and diammonium phosphate have been ensiled
or fed with corn silage to supplement the total nitrogen content,
while limestone or calcium carbonate have been used to increase the
calcium content as well as to permit increased chemical fermentation.
Research, thus far, has shown considerable feeding value from the

1

addition of urea to corn silage, while results from other added com-
pounds, either non-protein-nitrogen or mineral, are still questionable.
If one considers that, in the year 1964, 3,685,000 tons of corn silage
were produced in the state of Michigan, this represents a potential
market for 36,850,000 pounds (10 lbs. per ton) of urea which could be
added to this silage to improve the total nitrogen content (Michigan
Agricultural Statistics, 1965). However, the most desirable level of
urea to be added to corn silage is still an unanswered question.

The purpose of the investigation described in this thesis was
to more accurately determine the optimal urea level in corn silage,
and explore the use of other compounds. Data are presented on the
chemical and nutritive value of corn silages ensiled with additions of
calcium carbonate, urea and diammonium phosphate, both separately and

in different combinations.

REVIEW OF LITERATURE

Much of the recent research dealing with corn silage has been
devoted to means of improving its nutritive qualities as a feed for
livestock. The question of using chemical additives as a means of
improving total nitrogen content or prolonging fermentation processes

has been of predominant interest.
Nutritive value of Corn Silage

Corn silage has been used as a roughage source for most domesti-
cated ruminants for maintenance, growth or lactation. The potential
value of corn silage must be considered depending upon whether it forms
the complete or partial roughage source in these rations.

Relative Feeding value for Growth
and Fattening

 

Stadler (1930) stated the following about corn silage: "Corn
is the preeminent silage crop, because of its heavy yield of nutritious
and palatable forage, because when it is ensiled it undergoes changes
of the most desirable kind, and because it is a standard and adapted
crop over a large part of the country." Nevens (1936) also emphasized
that corn preserved as silage had more feeding value than corn crops
utilized in other ways.

Corn silage has been extensively used as a source of roughage
for growth, fattening, and wintering rations. Eckles (1918) over a

3

period of several years examined various rations for wintering dairy
heifers. Legume hay, grass hay, grain mixtures and corn silage were
tested alone or in combination. The data show that only fair results
could be expected from feeding silage alone and generally about two
pounds of concentrates per head should be fed, of which one-half was
a high-protein feed. The range of corn silage intakes was from 17 to
21.4 pounds per day with an average daily gain of 0.71 pound compared
with 0.77 pound for normal growth. Eckles cited the low protein con-
tent of corn silage and the inability of the animal to consume enough
feed as lhmiting factors. Converse and Wiseman (1952) grew normal
dairy heifers from birth through at least one lactation on milk (to 6
months of age), and a 25 percent crude protein grain mixture and corn
silage as indicated by body weights and wither heights.

Corn silage has been and is now extensively used in beef fat-
tening rations. Livesay e£_§l, (1940) studied the value of stover
silage (ears removed), normal silage, and ear silage when fed to
yearling steers and young bred cows. Sixteen yearling steers divided
into two lots were fed as follows: Lot (1): For the first 70 days
of the 126 day experimental period: 20 pounds of normal corn silage,
4.0 pounds mixed hay, and 1.5 pounds cottonseed meal. For the re-
maining 56 days, 20 pounds of ear silage replaced the normal silage.
In the second lot, an identical ration was fed for the full 126 day
period, except stover silage replaced ear and normal silage on an
equal dry matter basis. The results of this experiment indicated that
the normal silage dry matter was only slightly superior to stover

silage dry matter; however, when the dry matter in 20 pounds of ear

silage was compared with an equal amount of stover silage dry matter,
the ear silage produced marked increases in gains. In a second experi-
ment, similar results were obtained with young bred cows except that the
normal silage dry matter was superior to the stover silage dry matter.
Hammes §£_§l, (1964) have also reported good gains for fattening beef
cattle with corn silage rations. The gains were not significantly
depressed when steers were fed limited cottonseed meal plus corn silage
as 80 to 100 percent of the forage dry matter intake compared with
steers fed a conventional high grain fattening ration.

In the growth of dairy heifers, Camburn e£_§l, (1942) conducted
two 120 day trials in which the following treatments were used: (a)
sun cured timothy hay, (b) corn silage, and (c) timothy molasses
silage and (d) artificially dried timothy hay. Some grain mixtures
were fed, but not over 3.0 pounds daily. In the second trial corn
silage was the superior roughage; however, the authors concluded that
poor quality silage prevented this effect in the first trial. Miller
and Morrison (1950) wintered beef cows on mixed hay fed alone (U.S.
No. 2 mixed legume and timothy hay, 30-50 percent legumes) or a ration
of mixed hay and corn silage. The average daily gains for four trials
for the mixed hay and the mixed hay plus corn silage treatments were
0.34 and 0.35 pound, respectively. However, Martz e£_§l, (1964) used
four groups of ten Guernsey heifers to study the comparative value of
corn silage, oat hay and orchardgrass hay when supplemented with
energy, protein, minerals and vitamins in a 118 day feeding period.
In this trial, the group receiving free choice corn silage consumed

more energy and gained significantly faster than the remaining three

groups. The average daily gains for the groups receiving free choice
corn silage, corn silage plus free choice oat hay, free choice oat
hay, and free choice orchardgrass hay were 1.34, 0.84, 0.69, and 0.93
pounds, respectively, while the total digestible nutrients per animal
per day for the same groups were 10.92, 10.25, 10.73, and 10.63 pounds,
respectively. All groups received between two and four pounds of
either a special supplement or a herd ration. Branaman and Davis
(1942) reported that a molasses treated legume silage produced better
gains than either corn silage or legume hay when these roughages were
full fed as part of a fattening ration. However, the quality of the
corn silage used in this study was thought to be inferior because of
insect infestation and drought.

Harshbarger §£_§l. (1956) compared rye silage in the pre-bloom
and early dough stage of development with corn silage in a heifer
growth trial. The silage consumed per animal for the early dough rye
silage (28.1 percent dry matter), corn silage (29.9 percent dry matter),
and the pre-bloom rye silage (19.5 percent dry matter) was 20.9, 25.0,
and 27.2 pounds, respectively, while the average daily gains for the
112 day period were 1.02, 1.70 and 1.21 pounds per day, respectively.
A grain mixture at a level of three to four pounds per day was fed at

different periods during the trial.

Relative Feeding value for Lactation

 

While the feeding value of corn silage has been recognized for
many years, an extensive amount of research pertains to its value when

added to control rations or when used to partially replace another

roughage. Carroll (1924) studied the effects of adding corn silage

to a basal ration of ad libitum alfalfa hay and a low rate of grain
feeding. Grain and ad libitum hay were fed as the control ration. The
reversal method of feeding was used with four experimental periods and
two lots of seven cows. The actual silage consumption for both years
of the experiment was only 24.6 pounds per day. However, 1.9 percent
more milk and 3.9 percent more butterfat were produced on the silage
ration than on the non-silage ration, while the weight gains on these
same rations were 11.5 and 9.5 pounds per cow, respectively. In this
study 2.49 to 2.95 tons of corn silage replaced one ton of alfalfa
hay. Huffman and Duncan (1954b) indicated that 100 pounds of corn
silage was equal to 22 to 27 pounds of hay and contained 13 to 17.4
pounds of grain. Similar results to those of Carroll (1924) had been
reported from the Indiana Experiment Station by Fairchild and Wilbur
(1925). These workers found that milk production of cows receiving no
silage decreased an average of 16.3 percent in each 28 day period of
the experiment, whereas the production of those receiving silage re-
mained approximately the same or increased slightly. Greater weight
gains were also made on the silage ration. Converse (1928) fed nine
cows on similar rations to the two previously mentioned studies at
approximately 106 percent of the Savage Total Digestible Nutrient
Requirement and reported that 2.8 percent more milk and 4.2 percent
more butterfat were produced on the non-silage ration. However,

the hay and grain ration contained more digestible protein than the
silage ration.

While corn silage has been shown to have considerable nutritional

value for lactating cows, the belief that an unidentified grain factor
or factors was present in the silage has been reported from the
Michigan Experiment Station. Huffman and Duncan (1954a) studied milk
production when a portion of the total digestible nutrients in an all-
hay ration was replaced with corn silage. Nine trials using eight
Holstein cows were conducted in which the cows were fed an all-hay
ration until a plateau resulted in milk production. At this point,
corn silage replaced part of the hay, on an equal total digestible
nutrient basis, so that approximately 36 pounds of hay were consumed
per day in the depletion period, and 15 pounds in the experimental
period. Silage was consumed at a rate of approximately 55 pounds per
day. Within the first 15 days of the experimental period, milk pro-
duction was increased from 18 to 23 pounds, however, total digestible
nutrient consumption was slightly less in the experimental period as
compared to the depletion period as well as a decline in body weight.
The authors concluded that a pound of total digestible nutrients in a
corn silage-hay ration was of more value than an equal amount of

total digestible nutrients from an all-hay ration. These authors
postulated that the grain of the silage contributed an unidentified
grain factor or factors necessary to balance the all roughage diet.
Similar evidence for the unidentified grain factors has also been re-
ported by Huffman and Duncan (1954b), and Dunn e£_§l, (1954). Huffman
and Duncan (1954b) also suggested that previous efforts failed to show
an increase in milk production from the grain in corn silage because
of the large amounts of grain included in the rations. Dunn et_§1,

(1955) compared corn silage and recombined corn silage (grainless corn

silage plus dried ground ear corn recombined with the grainless corn
silage at the approximate levels of regular corn silage) for milk pro-
duction. The fat-corrected milk CF.C.M;) produced, body weight gains
and amount of digestible protein ingested were similar for both silage
feeding periods which indicated that the grain in corn silage was of
the same nutritive value as corn and cob meal.

Other factors which may effect the value of corn silage in
dairy cattle rations are the stage of maturity of the corn plant at
ensiling time and the optimum level of corn silage feeding. Bryant
g£_gl, (1965) compared milk and medium hard dough corn silages supple-
mented with either cottonseed meal or alfalfa-orchardgrass hay plus
grain. iMilk production, persistency of production and silage con-
sumption were higher for the more mature silage. Similar results have
been reported by Huber 95 21, (1963) and Huber 25 $1. (1965).

The optimum level of silage feeding has been studied by Pratt
and White (1930). Timothy hay (ad libitum) and grain (1:3 grain-milk
ratio) were included in a ration with corn silage fed at a daily rate
of 36 and 18 pounds. Four percent F.C.M. for the high and low silage
groups was 22.08 and 21.84 pounds per day, respectively, while total
group dry matter consumption was 9,370 and 8,901 pounds, respectively.
The low silage group lost more weight but produced more milk per unit
of dry matter than the high silage group. However, Brown 22 21. (1965)
reported that cows fed corn silage as the only roughage for a complete
lactation produced as much milk and milk fat as similar cows fed
alfalfa hay or a combination of silage and hay. Roughage dry matter

consumption increased as the level of hay in the ration increased

10

from 0 to 100 percent.

Converse and Wiseman (1952) reported an increase in milk pro-
duction for cows fed a grain mixture (grain to 4 percent F.C.M. ratio
of 1:1.2 to 1:2.1) and corn silage (17.2 to 36.5 pounds of silage per
day) compared with cows fed a grain, hay, pasture ration. Some of the
cows receiving corn silage had been raised from early life on a grain-
silage ration.

While corn silage has gained considerable merit as a roughage
for cattle rations, most of the research in the past fifty years per-
tains to its animal productivity value when compared with other grass
or legume silage crops or dry roughages. Reed and Fitch (1913) com-
pared corn silage and two sorghum silages (kafir and cane sorghum)
for milk production when fed with grain (according to production) and
hay. In a reversal type design, cows fed corn silage produced more
milk but gained less weight than when fed either of the two sorghum
silages. In a similar report, Cunningham and Kanney (1917) observed
that kafir silage was about equal to corn silage but corn silage was
superior to sweet sorghum silage. In another experiment, these three
silages proved about equal for maintenance of beef calves. Cunningham
and Reed (1927) using honeydrip sorghum silage and La Master and Marrow
(1929) using sweet sorghum silage reported similar results. Cunningham
and Reed (1927) reported little difference in the weight gain of cows
when fed the two silages. In all of these studies, the silages were
fed with either hay and a grain mixture or a simple grain mixture.

Owen et a1, (1957), Owen e£_§1, (1959), Haenlein and Richards

(1961), Lance 95 a1, (1964), and Rahman and Leighton (1965) reported

11

increased milk production for cows fed corn silage as compared to some
specie or type of sorghum silage. Owen e£_gl. (1957) and Lance e£_§l.
(1964) observed that cows fed corn silage consumed significantly more
silage or silage dry matter than those fed sorghum silage, whereas

Owen g£_al. (1959), Haenlein and Richards (1961) and Rahman and
Leighton (1965) found almost no differences in dry matter consumption
between the two silages. Body weight changes were also variable.

Owen e£.§1, (1957) reported highly significant body weight changes in
favor of the cows receiving corn silage, whereas Haenlein and

Richards (1961) and Rahman and Leighton (1965) reported greater weight
gains with sorghum silage. Lance EE.§13 (1964) found that cows fed
sorghum silage gained significantly more body weight than those fed
corn silage in one experiment, but the differences were not statis-
tically significant in a second experiment. Owen et a1. (1959) reported
that corn silage produced 0.7 pound body weight gain per day, Axtell
sorghum silage, 0.7 pound per day, and a forage sorghum hybrid (RS 303F)
0.6 pound per day, respectively. Browning g£_§l. (1961) used a switch-
back design with 18 lactating cows and 28 day periods to compare corn,
an intermediate forage type grain sorghum and a combined grain sorghum
silages. Silage was fed ad 1ibitum.along with 0.5 pound of alfalfa

hay per 100 pounds of body weight and a grain mixture. The dry matter
consumption per 100 pounds of body weight was highest for the sorghum
silages. The average persistency values for cows fed corn silage,
intermediate and combined grain sorghum silages were 80.5, 78.0 and
117.5 percent, respectively. Brannon g£_§l, (1965) compared Tracy

and Sart Sorghum silage harvested in the soft dough stage with corn

12

silage harvested in the soft dough stage. Cows fed the Sart and Tracy
sorghum silages produced 97 and 98 percent as much milk as the corn
silage groups with a lower average silage dry matter consumption. How-
ever, when cows were fed corn silage and Tracy sorghum silage ensiled
in the milk or hard dough stage, both sorghum silage groups produced
slightly more milk and consumed more silage than the corn silage group.

Corn silage has also been compared with clover hays and silages.
Clark (1913) compared two rations in which grain, clover and alfalfa
hay were compared with grain, clover and alfalfa hay and corn silage
harvested in the milk stage. Little difference was noted between the
clover hay or corn silage in cost of production, and production of
milk or fat. Greater live-weight gains were made on the corn silage
ration. Atheson and Anderson (1935) compared sweet clover silage and
corn silage in rations for milk produCtion and found that the two
silages were comparable in productive value even though less total
digestible nutrients and digestible crude protein were consumed per
100 pounds of 4.0 percent milk on the clover silage. In an Arizona
study (1917), no difference was observed in milk and fat production of
cows fed either 20 pounds of alfalfa hay plus 35 pounds of corn silage
or 30 pounds of alfalfa hay. Foster and Meeks (1920) in a similar
study found that milk production.was 4.0 percent greater on an alfalfa
ration than on an alfalfa hay-corn silage ration.

Hinton and wylie (1940) treated first cut alfalfa silage and
first cut Lespedeza sericea silage with a molasses-phosphoric acid
mixture and compared these silages with corn silage. The moisture

content in both legume silages was adjusted to 70 percent, and both

13

silages were fed with ad libitum ground alfalfa hay and 10 pounds of
a grain mixture. The milk and fat yields for the corn silage, lespedeza
silage, and alfalfa silage were 12,599, 555.5; 11,740, 506.5; and
13,277, 566.8 pounds, respectively, over a period of 120 days. However,
Hegsted e£.§l. (1939) comparing A.I.v. alfalfa silage, molasses alfalfa
silage and corn silage found that milk production was equally satis-
factory for rations containing these silages. waugh gt a}, (1943)
also observed little difference between a molasses treated alfalfa-
bromegrass silage and corn silage in F.C.M; and fat production per day
(27.9, 1.13 and 27.3, 1.12 pounds, respectively). However, cows fed
the corn silage gained slightly more weight than those fed the alfalfa-
bromegrass silage. Camburn et_al, (1942) in comparing rations con-
taining corn silage or grass silage reported that more 4.0 percent
milk equivalent was produced on the corn silage than on grass silage,
but in all cases cows receiving corn silage consumed more digestible
nutrients. Pounds of milk produced per pound of total digestible
nutrients on the corn and grass silage were 1.87 and 1.81, respectively.
Corn silage has also been compared with other crops such as oats,
vetch, sunflowers, ryegrass, and Bermuda-grass. King (1944) compared
corn silage, molasses oat-silage, and phosphoric acid-oat silage when
fed to milking cows. The average 4.0 percent F.C.M. production per
day and the average decline in production during the 18 week experiment
for these groups were 37.6, 5.0; 36.6, 7.7; and 33.5, 8.7 pounds and
percent, respectively. The intake of total digestible nutrients and
live weight gains were also highest for the corn silage group; however,

4.0 percent F.C.M; produced per pound of TDN was highest for the

W‘I

l4

molasses oat silage group. Lassiter e£_al. (1958) compared corn silage
and oat silage for milk production and found that oat silage was
superior to corn silage when 63 percent of the total roughage was
supplied as oat silage. However, when the proportion of the total
roughage intake supplied by silage was increased to 77 percent, corn
silage was superior. Jones (1922) reported that cows fed oat and vetch
silage produced more milk and fat than cows fed corn silage but that
sunflower silage was inferior to corn silage when fed with a hay and
grain ration. In a report from the California Experiment Station
(1922) undesirable silage from the standpoint of consumption was pro-
duced when sunflowers were cut at an early stage of growth and compared
with corn silage. However, Atkeson (1935) found that sunflower silage
was about equal to corn silage for milk production when fed with alfalfa
hay and a grain mixture at a 1:2.5 or 1:3.0 ratio. Sunflower silage
was more efficiently used for milk production, but corn silage was more
palatable and the cows showed a preference for the corn silage.

Arnold and Crockett (1964) compared boot stage ryegrass silage
and early dent stage corn silage in milking trials in which the silages
were fed with alfalfa hay at a rate of 0.5 pound per 100 pounds body
weight and concentrates at a ratio of 1:3. The average daily pounds
of 4.0 percent milk per cow fed corn silage or ryegrass silage for two
different years were 26.8, and 28.2 pounds for 1962, 25.3, and 26.3
pounds for 1963, respectively, while the silage dry matter intake per
100 pounds of body weight for these silages was 1.23, 1.40, and 1.57,
and 1.51 pounds, respectively.

In other experiments in which corn silage was compared with other

15

forages, Bender e£_§l, (1937) found that grass silage would replace hay
or corn silage without altering the production level, whereas W011 and
voorhies (1917) reported that similar amounts of milk were produced
when Indian corn silage, Sudan grass silage, or sweet sorghum silage
were used as supplements in a ration of alfalfa hay, with or without
grain. However, the sorghum silage was more efficiently utilized
(returns per 100 pounds dry matter) than the corn silage, while the
corn silage was better in this respect than Sudan grass silage. Zogg
e£_al. (1961) fed 27 lactating cows either corn silage and hay, oat
silage and hay, or sorghum silage and hay with high moisture corn at
three levels of moisture (22, 26, and 32 percent). When these were fed
with a soybean oil meal-mineral mixture, significantly less dry matter
was consumed by cows receiving oat silage as compared with those fed
the corn or sorghum silages. The oat silage was higher in moisture
content than the other silages which may have accounted for the dif-
ferences in intake. Cows fed the sorghum or oat silage were not as
persistent in milk production as the cows fed corn silage. Signifi-
cantly less milk was produced by the oat silage group as compared to
the other two groups.

Miller e£_al. (1965) fed Coastal Bermudagrass pellets, corn
silage, or a 50:50 Bermudagrass-corn silage mixture ad libitum to
groups of six cows in an eight week experiment. These rations were
fed with long Coastal Bermudagrass hay at three pounds per day and
concentrates at a 1:3 ratio of F.C.M. established from the standardiza-
tion period. The adjusted milk production averages for the last week

of the experiment for cows fed pellets, silage or the 50:50 combination

16

were 27.5, 29.3, and 34.3 pounds per cow per day, respectively. In
the same order the forage dry matter intakes were 29.0, 23.7 and 31.5
pounds per day. The increased dry matter consumption of the 50:50

combination was statistically significant.

Digestibility of Corn Silage

 

Schneider (1947) in comparing the composition and digestibilities
of many feeds found throughout the world reported the average digesti-
bility coefficients of regular corn silage for organic matter, crude
protein, crude fiber, nitrogen-free extract, and ether extract as 72,
49, 72, 74 and 79 percent for cattle, while for sheep these values
were 70, 53, 65, 76 and 82 percent, respectively. Huffman and Duncan
(1960) studied corn silages over a 17 year period. Digestibility co-
efficients were determined on eight of these silages, in which the
silage intakes when fed to cattle ranged from 31 to 49 pounds per day.
The digestibility coefficients for dry matter, organic matter, protein,
ether extract, crude fiber and nitrogen-free extract were 66.8, 67.8,
52.8, 73.7, 60.8 and 73.4 percent, respectively. Bryant e£_§l, (1965)
in comparing corn silages harvested at different stages of maturity
reported dry matter digestibility coefficients of 66.7 and 68.6 percent
for immature Cmilk) and mature (medimm hard dough) silages, respectively.
Huber gt_§l, (1965) reported the coefficients of apparent digestibility
of a hard dough silage for crude protein, fiber, nitrogen-free extract
and ether extract to be 54.8, 63.7, 70.4, and 79.5 percent, respec-
tively. Cattle, fed ad libitum silage and supplemental soybean meal,

were used as experimental subjects. Hammes e£_al, (1964) studied high

17

silage rations for beef steers when full fed and found that the apparent
digestion coefficients for dry matter, crude protein, ether extract,
crude fiber and nitrogen-free extract were 68.1, 55.6, 77.9, 57.0 and
75.4 percent, respectively, with a total digestible nutrient content

of 70.6 percent. Data for the digestion of stover silage, normal corn
silage and ear silage have been reported by Livesay E£.§l: (1940)

using steers, while Dunn eE_al, (1955) have presented data for both
regular corn silage and recombined corn silage using dairy cows.

The Use of Chemical Compounds to Improve
the Nutritive value of Corn Silage

 

 

Urea and Other Non-Protein-
Nitrogen Compounds

 

 

The corn plant is comparatively low in crude pretein content.
Morrison (1957) stated that the analysis of 237 samples of well-eared,
well-matured corn silages gave an average crude protein value of 2.3
percent of the fresh material. The same value was quoted by the
National Research Council (1958). Thus the low protein content of the
corn plant might be altered by crop fertilization or by feeding a
protein supplement. Bender and Prince (1934) could not improve the
protein percentage of the corn plant with nitrogen fertilization up
to 450 pounds per acre. Generally, the yield was increased which re-
sulted in an increased yield of total protein. Harshbarger e£_al.
(1954) increased the protein content of the leaf-stalk fraction of
corn silages with fertilizer, but the crops were grown on soils which

were low in plant food.

18

Since fertilization has not produced consistent and dependable
increases in the nitrogen content of the corn plant or silage made
therefrom, the addition of protein supplements has been necessary for
this purpose. The addition of protein supplements is expensive when
considered on the basis of the price per pound of protein. Since
ruminants have the ability to utilize the nitrogen from non-protein-
nitrogen compounds, these supplements which are more economical, must
be considered. Palatability problems may result when non-protein-
nitrogen compounds are incorporated into the feed at the time of
feeding, so that the use of these compounds at the time of ensiling
warrants further study. Urea is probably the most commonly used com-
pound for this purpose. Bentley e£_§l. (1955) ensiled corn silage with
17, 20 and 25 pounds of urea per ton. In addition, 20 pounds of urea
and 2.0 pounds of dicalcium phosphate were added to one silage. The
crude protein (dry basis) for a control, control plus 17 pounds of urea
per ton; control, control plus 25 pounds of urea per ton; control,
control plus 20 pounds of urea per ton; and control plus 20 pounds of
urea and 2.0 pounds of dicalcium phosphate per ton was 9.3, 15.1; 8.9,
19.9; 8.2, 14.6; and 13.4 percent, respectively. Brooks 23 a1, (1965)
added supplements to fresh corn fodder or corn silage. Those with
supplements containing limestone and urea ensiled with these forages
had higher crude protein values. Wise 35.21, (1944) ensiled corn silage
with the addition of 5.0 gallon of a urea solution (2.0 pounds of
crystals per gallon, 46 percent nitrogen) per ton of silage and found
that crude protein of the treated and untreated silages was 10.79 and

7.48 percent, respectively. Increases in crude protein content have

19

also been reported by Gorb and Lebedinskij (1961) using 0.65 percent
urea; by Goode (1955) using 0.5 percent urea per ton, by Palamaru e£_§l.
(1961) using 0.5 percent urea, and by Klosterman gt 31. (1961).
Klosterman e£_§l, (1962) and Klosterman st 21. (1963) suggested that
urea added to corn silage could replace a portion of the protein
supplement when fed to cattle. Hoffman and Fix (1965) reported that in
a series of 70 maize silage samples, in which approximately 4.0 kilo-
grams of urea per ton were added, the crude protein content averaged
1.99 percent with a range of 0.84 to 3.26 percent on a fresh basis.

Urea has also been added to sorghum silage to increase crude
protein content. Means (1945) compared an untreated sorghum silage with
sorghum silage treated with 10 pounds of urea per ton and found that
the urea silage contained approximately 41 percent more crude protein
and 10 percent less moisture than the non-treated silage. Davis e£_gl,
(1944) treated sweet sorghum with urea in a water solution at a rate
of 0, 10, 30 and 50 pounds of urea per ton. Crude protein determina-
tions revealed migration of nitrogen within the silos, but very little
of the urea was changed from its original form from the time of
ensiling until after the silage was removed from the silo.

Hydrogen Ion Concentration and Acid
Production in Urea Treated Silages

In further attempts to improve the nutritive value of corn
silages, chemical compounds, such as calcium carbonate, high calcium
and dolomitic limestone, and urea, have been ensiled with forage to
prolong fermentation. These compounds, because of their chemical action,

stimulate the total acid production within the silage and specifically

20

lactic and acetic acids. Barnett (1954) emphasized the fact that the
aim in silage production was to stimulate lactic acid production to
such a point as to inhibit other bacterial activity and preserve the
crop. watson and Nash (1960) stated that "The percentage of lactic acid
in silage varies somewhat but in good silage samples will range between
1 and 2 percent of the weight of the fresh silage. If conservation is
to be efficient the lactic acid should reach the neighborhood of 1
percent and should always exceed in amount the volatile acids." It

was also noted that acetic acid should generally range from 0.5 to

0.9 percent of the fresh material. Barnett (1954) also stated that
lactic acid should be at a concentration of 1 to 1.5 percent of the
fresh material in normal silage.

While limestone and calcium carbonate have been shown to stimu-
late acid production, non-protein-nitrogen compounds, which are gener-
ally added to improve the nitrogen content of corn silage, also acts
to prolong acid production. Klosterman gt a1, (1963) reported that urea
was not as strong an adjunct as either limestone or calcium carbonate;
however, Karr e£_al, (1964) indicated that this compound altered the
fermentation to some extent. Cullison (1944) added urea to sweet
sorghum as it entered the silo at an approximate rate of 10 pounds per
ton. An untreated silage was also prepared. The results indicated
that the treated silage had more total titratable acids, but the un-
treated silage a lower pH. Bentley e£_gl, (1955) ensiled corn silage
with various levels of urea. The pH values for a control corn silage,
control plus 25 pounds of urea, control corn silage, control plus 20

pounds of urea, and a control plus 20 pounds of urea and 2.0 pounds

21

of dicalcium phosphate were 4.70, 7.60, 3.70, 4.05 and 3.95, respec-
tively.

Klosterman g£_§l, (1963) reported that the pH for a control,
0.5 percent urea, and 1.0 percent urea whole plant corn silage was 3.8,
4.1 and 4.4, respectively. The percent acetic and lactic acid on a
dry matter basis for these same silages were 1.51, 8.33; 1.90, 8.71;

and 1.71, 12.00, respectively.

Relative Feeding value

Urea has probably been used more extensively than any other
non-protein-nitrogen compound as a nitrogen extender in sheep, beef,
and dairy cattle rations. Reid (1953) reviewed the research which
has been conducted on the utilization of urea when included in ruminant
rations as well as the many factors influencing the utilization of
this compound. Owen (1941) has also partially reviewed some of the
research up to the period of 1941. More recently McLaren (1964) re-
viewed the metabolism of nitrogenous and non-protein-nitrogen compounds
in ruminants. While an extensive amount of research has been done on
the nutritive value of urea when added in its original form to a ration,
the addition of urea to low protein silages has been extensively
studied in recent years. WOOdward and Shepherd (1944) ensiled corn
silage with 10 pounds of urea per ton of fresh forages. This was
fed to a group of cows along with low protein concentrates and hay
in a 100 day single reversal experiment. A second group of cows was
fed similarly, but in this case urea was mixed into the concentrates
instead of including it in the ensilage. Palatability was slightly

impaired with moderate additions of urea and became a greater problem

22

with heavier additions to either silage or grain. Wise e£_al. (1944)
observed lower intake when corn silage containing 5.0 gallons of a
urea solution per ton of silage (2.0 pounds of crystals per gallon,
46 percent nitrogen) was fed to two groups of 11 cows in a double re-
versal experiment. Silage served as the sole source of roughage and
grain was adjusted to the production of all cows. The daily silage
consumption for cows fed the treated and untreated silage was 52.5
pounds (15.5 pounds dry matter) and 60.0 pounds (16.9 pounds dry
‘matter) per cow, respectively. However, other reports indicated only
slight intake problems from adding urea to corn silage at the rate of
10 pounds per ton (Hillman, 1964 and Wbodward and Shepherd, 1944).
Milk production from cows fed urea treated silages has also
been reported by Wise e£_al. (1944) and Wbodward and Shepherd (1944).
Wise 95.21. (1944) reported the average pounds of 4.0 percent F.C.M.
for cows receiving the treated and untreated silages were 24.7 and 24.5
while the average total weight gains per cow were 43 and 56 pounds,
respectively. Milk production was similar even though cows fed the
treated silage consumed less silage dry matter than those fed the un-
treated silage (15.5 vs. 16.9 pounds per day). Wbodward and Shepherd
(1944) reported that production was maintained regardless of whether
the urea was incorporated into the silage or into the concentrates.
However, Sobczak (1961) found that milk production was 3.06 and 8.44
percent less when cows were fed rye and maize silages with urea than
when fed a control maize silage in a Latin-square designed experiment.
Opletalova and Lizal (1963) reported similar decreases in milk pro-

duction with maize silage containing either 0.5 or 1.0 percent urea.

23

Hoffman and Fix (1965) reported on a series of silages in which approxi-
mately 4.0 kilograms of urea were added per ton of silage. When a con-
trol ration with a protein to starch equivalent ratio wider than 1:7.6
was fed, the urea improved both daily milk yield by 1.4 kilograms and
fat by 47 grams. With a narrower ratio this effect was not apparent.

Huber e£_§l. (1965a) conducted two twelve week trials with 40
lactating cows in which ad libitum corn silage was supplemented on an
equal nitrogen basis with one of the following rations: (1) 15 percent
crude protein concentrate mixture (1 pound per 3.5 pounds of milk),

(2) soybean oil meal or cottonseed oil meal (fed at different experiment
stations, Blacksburg or Middlebury), (3) soybean oil meal plus urea

and cottonseed meal plus urea, and (4) urea. In the first trial at the
Blacksburg station, the silage dry matter intakes for these four supple-
ments were 1.78, 2.31, 2.30, and 2.30 pound per 100 pound of body weight
per day, respectively, while the milk yields were 51.3, 48.7, 43.6,

and 36.0 pounds, respectively. The persistency of production expressed
as a percent of the standardization period followed similar trends.

iMilk yields and silage consumption were highest for the third group at
the Middlebury station.

Urea has also been added to other high energy silages such as
sorghum. Davis e£_§l, (1944) ensiled sweet sorghum in four pilot silos
each containing about one ton of silage. urea, in a water solution,
was mixed at a rate of 0, 10, 30, and 50 pounds of urea per ton of
sorghum silage. Palatability observations revealed that the cows ate
the 0 and 10 pounds of urea per ton silage equally well followed by

the 30 pounds per ton silage. Complete refusal of the 50 pounds per

24

ton silage was observed until free ammonia had disappeared. Hastings
(1944a) and Hastings (1944b) noted that ammonia was released from soy-
bean silage after two days when urea was mixed with this silage.

urease activity was found in silage samples after seven days under
ordinary temperatures. There was no case of feed refusals, "off feed,"
or digestive disorders from ingredients containing 50 to 60 pounds of
urea per ton. A feeding trial was conducted in a herd of Holsteins
with one group (7 cows) of the herd serving as a test group and another
group (15 cows) as controls. urea was added to the concentrate mixture
to supply 17, 21 and 25 percent of the total ration nitrogen for three
successive months of the trial. During the remainder of the trial urea
supplied 29 percent of the total nitrogen. During the experiment no
significant differences were observed between groups in milk production,
‘milk composition or body weight gains. Reid (1953) in his review of the
research in which urea had been utilized in ruminant rations stated

the following: "The results of long-time experiments with appreciable
numbers of cows demonstrate that from the standpoint of milk yield and
maintenance of body weight there is no significant difference between
the value of urea nitrogen (fed at levels up to 27% of the required
nitrogen) and the nitrogen of high-protein supplements."

Besides being fed to lactating animals, urea silage has also
been utilized in wintering, growing and fattening rations for cattle
and sheep. Cullison (1944) added urea to sweet sorghum at an approxi-
mate rate of 10 pounds per ton. This was compared with an untreated
silage as a feed for wintering two groups of 15 Hereford and Angus

cows for a 78 day period. The rations fed were 5 pounds of

25

Johnsongrass hay plus 35 pounds of either treated or untreated silage.
The average loss in weight per head for the treated and untreated
silage rations during the feeding period was 0 and 47 pounds, respec-
tively. The treated silage was reported to be more palatable than the
untreated silage. Goode (1955) performed a similar experiment with
corn silage treated with 10 pounds of commercial urea. Mature cows
were fed urea treated and untreated silages as a wintering ration with
and without soybean oil meal. No significant differences in the gains
of these cows were observed and all gains were negative. In another
experiment four lots of steers and heifers were fed the following
wintering rations: (1) corn silage plus 0.5 pound soybean oil meal,
(2) urea-corn silage plus 0.5 pound soybean oil meal, (3) corn silage,
(4) urea treated corn silage. The silages were fed to appetite and
after 81 days the average daily gains were 1.12, 0.91, 0.76, and 0.65
pounds, respectively. From.these results the suggestion was made that
corn silage with 10 pounds of urea per ton lowered the feeding value.
Bentley eg 21. (1955) ensiled corn silage with 17 and 25 pounds of urea
per ton. These silages were used in growth studies with a limited
number of animals. While gains were slightly lower for animals fed
the treated silages, more of the treated silages was eaten per day
than the untreated silages. Grain rations with and without urea were
also fed to these steers. In a third feeding trial, larger numbers of
steers were used with five rations consisting of corn silage plus

(1) ground ear corn, (2) ear corn plus urea, (3) ear corn plus soybean
oil meal, (4) urea treated silage (20 pounds of urea per ton) plus

ground ear corn, and (5) urea-phosphate silage (20 pounds urea plus

26

2.0 pounds dicalcium phosphate per ton) plus ground ear corn. The
average daily gains of animals fed these silages were 1.62, 1.73,
1.87, 1.82, and 1.83 pounds, respectively, in a 112 day trial. From
these data the authors suggested that 20 pounds of urea per ton of
corn silage could be ensiled for fattening cattle. Similar recommen-
dations were reported by Bentley 25 al. (1956a). Gorb and Lebedinskij
(1961) using young bulls reported that maize silage with 0.65 percent
urea was superior to a control maize silage, but inferior to a silage
of equal parts maize and soybean. Lebedinskij (1960) also using bull
calves in a 90 day trial fed the following rations: (1) basal:
cereal meal, hay, sugar beets, and 16.06 kilograms of maize silage,
(2) basal ration with 15.22 kilograms maize silage and 0.65 percent
urea, (3) basal ration with 15.50 kilgrams of maize silage and soya
mixture in equal parts. These three rations supplied 533, 710, and
667 grams of digestible protein and produced average daily gains of
755, 833, and 890 grams, respectively. The feed units and kilograms
of digestible protein per kilogram of gain were 8.90 (0.73); 7.53
(0.90); and 7.19 (0.81).

Harvey §£_§l, (1962) compared the value of urea (10 pounds per
ton), limestone (10 pounds per ton) and sodium metabisulfite (8 pounds
per ton) when added to corn silage and fed to 57 Angus and Hereford
beef calves in a 104 day experiment. The silages were fed at a rate
of 14.4 pounds in a ration of rolled shelled corn, linseed oil meal,
alfalfa-brome hay, and free choice minerals. The average daily gains
for the control, sodium metabisulfite, limestone and urea silages were

1.76, 1.72, 1.71, and 1.59 pounds, respectively. The pounds of feed

27

per 100 pounds of gain were 1274, 1298, 1305 and 1400 pounds, respec-
tively. In a similar report (Harvey 35 $1., 1963), the average daily
gains for groups fed the control, limestone (10 pounds per ton), urea
(10 pounds per ton) and sodium metabisulfite (8 pounds per ton) silages
were 1.48, 1.48, 1.45, and 1.42 pounds, respectively. In the same
order the pounds of feed per 100 pounds gain were 1462, 1469, 1518,

and 1550 pounds, respectively.

Klosterman e£_al, (1964) prepared a complete corn silage com-
posed of the entire plant from one area and added ears from an equal
area. Urea at 20 pounds, pulverized limestone at 10 pounds and
dicalcium phosphate at 2.0 pounds per ton were added to the complete
silage. This silage was fed to two lots of seven steers with four other
lots receiving control corn silage plus ear corn at levels to equal the
energy content of the complete corn silage. Soybean.mea1 or a urea-
grain mixture were also fed to duplicate lots to approximate the crude
protein found in the complete silage. The average daily gains for the
groups fed the complete silage, regular silage plus corn and soybean
meal and regular silage plus corn and urea for the 126 day trial were
2.32, 2.44 and 1.98 pounds, respectively. Significantly less dry
matter per unit of gain was required by those steers consuming the
complete silage. In a similar experiment, Harvey e£.§l, (1964) com-
pared corn silages prepared in the following manner: (1) regular corn
silage; (2) corn silage plus 1.0 percent urea; (3) corn silage plus
24.4 percent shelled corn and 4.7 percent soybean meal; and (4) corn
silage plus 29.0 percent ground shelled corn and 0.7 percent urea.

These were all added at ensiling time in addition to 8 pounds of

28

sodium metabisulfite. The average daily gains for treatments one
through four were 1.61, 1.59, 1.63, and 1.55 pounds, respectively.

Means (1945) treated sorghum silage with 10 pounds of urea per
ton at the time of ensiling. This was compared with an untreated
silage for wintering mature beef cows and in rations for long yearling
heifers. Using three lots of ten cows each and three lots of ten
heifers each, a 77 day experiment was conducted. In the experiment
with mature cows, the following rations were used: (1) 30 pounds
untreated silage, 1.0 pound cottonseed meal, 5.0 pounds Johnsongrass
hay; (2) 35 pounds untreated silage and 5.0 pounds Johnsongrass hay
(3) 35 pounds urea treated silage and 5.0 pounds Johnsongrass hay.
The average weight change for cows in each group was 9, -99, and 13
pounds, respectively. In the heifer experiment less silage was fed,
but similar results were obtained. The standard ration of 25 pounds
of untreated silage, cottonseed meal, and JOhnsongrass hay produced
better gains than the treated silage, but the treated silage was
superior to the untreated silage-hay ration.

In rations for fattening cattle, van Arsdell e£_al, (1953a) and
Van Arsdell e£.§l, (1953b) fed four lots of eight steers each corn
silage and one of four supplements mixed with the silage. The four
supplements were: (1) similar to Purdue Supplement A.(soybean oil
meal, molasses, minerals, and vitamins); (2) a soybean supplement
containing minerals; (3) a corn-soybean supplement with molasses and
minerals; 04) a corn-urea-soybean supplement with minerals (urea
forming 8.4 percent of the supplement). Over a 146 day period, the

average daily gains for the four supplements were 2.33, 2.18, 2.07

29

and 2.37 pounds, respectively. Those fed the urea supplement ate less
silage per 100 pounds of gain and had the lowest cost per unit of gain.
The amount of supplement fed per animal per day for lots 1 through 3,
and lot 4 was 3.5 and 3.82 pounds, respectively.

In an extensive study on the evaluation of biuret and urea,
Karr e£_§l, (1965a) ensiled the following mixtures for metabolism and
feeding experiments with lambs: (l) basal (chopped corn plant, ground
yellow corn, calcium carbonate, and trace mineralized salt), (2) basal
plus 20 pounds of urea, (3) basal plus 23.5 pounds of pure biuret.
Calcium carbonate was added at a level of 10 pounds per ton to all
silages. Besides these ensiled mixtures, other groups of lambs were
fed a regular silage plus similar concentrate mixtures added at
feeding time. In this experiment the basal concentrate added at
feeding time was adjusted with soybean meal substituting for part of
the corn to equalize the nitrogen content of all diets. Both the non-
protein-nitrogen compounds (urea and biuret values combined) increased
gains by 26 percent and reduced the amount of feed required per pound
of gain by 1.35 pounds when added to the basal diet. Significant
increases in gains were not found when concentrate mixtures containing
the non-protein-nitrogen compounds were added at ensiling time compared

to feeding time, but feed requirements were reduced.

Digestibility and Balance Studies
McLaren (1964) reported that nitrogen utilization from non-

protein nitrogen (urea) compounds increased with time on that diet up

30

to 50 days. Karr e£_§l, (1965b) and Campbell e£_§l, (1963) also found
a better utilization of non-protein-nitrogen compounds with longer
adaptation periods. In both reports a longer adaptation period was
necessary for biuret than for urea. Johnson and McClure (1964) re-
ported that an adaptation for biuret occurred only when apparent
digestibilities were considered. This was not the case when either
nitrogen retention or biological value were taken into account. This
phenomenon was not observed in the case of urea.

Digestibility of urea-corn silages.--Bentley eg_gl. (1955)
performed digestibility studies using wether lambs in which the
following feed mixtures were studied: (A) corn silage, (B) corn-urea
silage, (C) corn silage plus soybean oil meal, (D) corn silage plus
ground corn-urea, (E) corn silage plus corn urea silage, (F) corn
silage plus ground corn-urea, (G) corn silage plus yellow corn plus
soybean oil meal. The treated corn silages contained 25 pounds of
urea per ton. The coefficients of apparent digestibility of dry matter
and crude protein for these silages were 74.4, 60.5; 73.4, 77.7; 75.0,
80.3; 74.8, 79.9; 75.3, 67.4; 75.1, 71.2; 77.7, and 72.9 percent,
respectively. Karr 95.31, (1965a) conducted three metabolism trials
with lambs and reported increased dry matter digestibility from adding
urea and biuret to a basal silage. However, this increase was signif-
icant in only one of three trials. No real improvement in urea
utilization.was noted with time on diet, but with added urea, dry
matter digestibility increased with time. There was an indication
that the utilization of biuret improved with time. When the concen-

trate mixtures were added at ensiling time rather than feeding time,

31

there was a highly significant increase in dry matter digestibility,
nitrogen digestibility, and daily nitrogen retention. Gorb and
Lebedinskij (1961) reported that urea (0.65 percent) added to maize
silage improved both protein and crude fiber digestibility. Likewise,
Lebedinskij (1960) reported that when either maize silage and 0.65
percent urea or a soya mixture were added to a basal ration, the
digestibility coefficients were higher for those calves getting urea

or the soya mixture for dry matter, organic matter, protein and fiber.

Nitrogen balance and biological value.--The major criteria

 

for nutritive value of a protein or nitrogen source is the nitrogen
retained in the body from this source. Urea has been evaluated

alone and in combination with true protein sources in its ability

to promote nitrogen retention. From the measurement of nitrogen
retention has come the expression of the nutritive value of a pro-
tein or nitrogen source called the "Biological Value." However,

this expression may be misleading as far as ruminant nutrition

is concerned. Annison and Lewis (1959) in their Methuen Series
Monograph, "Metabolism.in the Rumen," make the following statement as
to the contribution of a protein to the nutrition of a ruminant. "A
proportion of the dietary protein reaches the duodenum unchanged and
its nutritive value is the same as in monogastric animals; the portion
that is converted to microbial protein in the rumen.must be assessed
in terms of the value of that protein; and the nitrogen of the nucleic
acid fraction of the bacteria is probably not available to the host

animal. With good quality ingested proteins, the degree of protein

32

synthesis in the rumen may only slightly modify the nutritive value.
On the other hand, a protein that is deficient in certain amino acids
may be more effectively utilized because of synthesis of microbial
protein." Reid (1953) indicated many of the factors involved in
efficient non-protein nitrogen utilization.

The value of urea and other non-protein-nitrogen sources has
been assessed in this respect both when incorporated into silages
or used in protein supplements added to the ration at feeding time.

Nehring (1937) conducted metabolism trials with wethers in
which a simple nitrogen-bearing compound and potato flakes replaced
one-third of a basal hay ration. Equivalent total nitrogen contents
were attained. Data from nitrogen balance experiments indicated
positive results from the presence of the amides in the diet. A
transition from negative to positive balances occurred with ammonium
acetate producing the best results and urea somewhat less favorable
results. Nehring and Schramm (1937), added 15 pounds of urea to
'mixtures of either dried beet slices or wheat bran and molasses. When
these were used as supplements to a basal hay ration, wethers fed 150
grams of supplement and 600 grams of hay daily increased in nitrogen
retention 2.0 to 3.0 grams and 1.0 gram, respectively, over that of an
800 gram hay ration. Harris and Mitchell (1941a) and Harris and
Mitchell (1941b) performed several experiments in evaluating urea as
a source of nitrogen for maintenance and growth in ruminants. In
their first experiment these authors observed that fecal nitrogen
increased when lambs were switched from a low nitrogen ration to

either casein or urea supplemented rations. Nitrogen equilibrium was

33

maintained in the sheep on 202 milligrams of urea nitrogen and 161
‘milligrams of casein nitrogen per day per kilogram of body weight.

The biological value of urea nitrogen was 62 and casein nitrogen 79

at the point of nitrogen equilibrimm. In evaluating urea for growth,
Harris and Mitchell (1941b) used 23 wether lambs which received a

basal ration of corn silage, limestone, salt, and fortified cod liver
oil during a preliminary period. This ration would not support growth
or nitrogen equilibrium. Urea was added to bring the protein equivalent
from an average of 5.35 percent to 8, 11 or 15 percent on a dry basis.
The percent nitrogen in the form of urea was 34, 50, and 62 percent,
respectively. A carbohydrate supplement was also added to the urea
rations during the growth period. The 11 percent ration was superior to
the 8 percent ration in promoting growth and nitrogen balance, however,
the 11 and 15 percent rations were not significantly different in
growth promoting abilities. The biological value of the basal (5.35
percent crude protein), 8, 11, and 15 percent protein equivalent

rations was 82, 74, 60, and 44, respectively.

Chalupa e£_§1, (1964) fed a low nitrogen (0.23 percent nitrogen
on a dry matter basis) semipurified diet to steers (267 kilogram) in
which urea was used to supply 0, 46 or 92 percent of the nitrogen
requirement and corn gluten meal the remaining percentage. The
calorie to nitrogen ratios were similar for all diets. Fecal nitrogen
values were significantly increased and urinary nitrogen excretion
increased by urea. The nitrogen retained in grams per day, percent
biological value, and net protein utilization for the rations con-

taining 0 percent urea plus 92 percent corn gluten meal, 46 percent

34

urea plus 46 percent corn gluten meal, and 92 percent urea plus 0
percent corn gluten meal were 19.6 i- 1.96, 56.5 i 3.69, 51.2 i 2.66;
13.6 _-I_-_ 4.57, 50.6 _-|_- 5.28, 44.44 i 5.16; and 1.2 _-l_- 1.37, 36.8 i 3.79,
30.7 i;2.67, respectively. These differences were significant. The
percent of urinary nitrogen in the form of urea, ammonia and creatine
significantly increased with increasing amounts of urea in the ration.
Lassiter e£_§l, (1958a) also reported lower nitrogen balance for
animals receiving rations in which urea supplied 30, 50 and 70 percent
of the total nitrogen when compared to a ration containing no added
urea. When fed to Holstein cows the balance in grams per cow per day
was 47.1, 55.2, 52.5 and 60.2 grams, respectively. Similar balance
values were observed when rations supplying 30, 50, and 70 percent of
the total nitrogen as urea were fed to dairy heifers (Lassiter g£_§l.,
1958b). This was difficult to explain since rate of gain and feed
efficiency decreased significantly as level of urea increased. How-
ever, the sulfur content of the rations was not equalized. In a
third study, Lassiter g£.al, (1958c) gains were improved with equalized
sulfur in the rations.

Dinning et_§l, (1949) used two pelleted protein supplements
(urea supplying O, 25 and 50 percent of the total nitrogen) for main-
tenance, wintering and fattening rations for steers and lambs. In
only a few cases did the percent crude protein exceed 12 percent for
the rations of prairie hay and the pellet supplements of varying
amounts of hominy feed, blackstrap molasses, urea and cottonseed
meal. Nitrogen retention in both steers and lambs increased with

increasing additional nitrogen supplied by urea. The supplement

35

containing 50 percent urea nitrogen was as efficient in promoting
nitrogen retention as the supplement with 25 percent urea nitrogen.
lambs appeared to be more efficient in utilizing urea nitrogen and
appeared to tolerate higher percentages of urea in the rations than
steers. Urea increased the total-nitrogen in the urine, but did not
significantly change fecal nitrogen excretion. Hamilton e£_§l, (1948)
used nitrogen balance as the criterion to measure the utilization of
nitrogen from urea and feed proteins. Using growing lambs and a
paired-feeding procedure with a single reversal of rations, the nitrogen
from a ration with a 16.2 percent protein equivalent (63 percent from
urea) was less efficiently utilized than that of a ration with 11.4
percent protein equivalent (46 percent from urea). The nitrogen
balance was lower and the biological value significantly reduced in

the 63 percent urea ration. It was also shown that urea nitrogen is

as well utilized as the same amount of nitrogen from dried skimmilk,
dried skimmilk plus cystine, gluten feed, casein or cystine plus casein.
However the nitrogen from linseed oil meal was more efficiently
utilized. The conclusion was made that urea is a satisfactory nitrogen
source for lambs provided that at least 25 percent of the food nitrogen
is in the form of preformed protein and that the total protein equiv-
alent of the ration is not greater than about 12 percent. JOhnson
g£_§l, (1942) also found that urea additions to a low protein basal
ration to give a crude protein equivalent of 12 percent induced a
retention of nitrogen in lambs which was not increased by further
additions of urea. It was concluded from.their data that urea added

to a low protein basal ration could not promote protein synthesis at

36

a rapid enough rate for the nitrogen requirements of the lamb under
the conditions of this experiment. However, the utilization of urea
for metabolism was slightly higher than that of casein nitrogen, and
compared favorably with that of soybean oil meaanitrogen.

The effect of kind of carbohydrate on urea utilization versus
plant proteins was studied by Drori and Loosli (1961). Diets of poor
quality timothy hay plus molasses were supplemented with either glucose,
sodium sulfate and urea, or corn starch, sodium sulfate and urea, or
soybean oil meal and corn with urea supplying 69 percent of the dietary
nitrogen. The nitrogen retention for the glucose-urea, corn starch-
urea, and soybean oil meal-corn diets was 2.3, 2.6, and 4.1 gram per
day, respectively, while the biological value for these same diets was
42.9, 45.1 and 52.8 percent, respectively, with intakes being approxi-
mately 700 grams per day.

qworking with young dairy calves, both Loosli and McCay (1943)
and Brown e£.§l, (1956) reported that calves fed urea supplemented
rations made better gains than calves fed low protein basal rations.
However, Loosli and MbCay (1943) found that the urea fed calves were
75 to 90 percent of normal in weight and 95 percent of normal in
height of withers and heart girth at four months of age. Both reports
indicate that the urea fed calves were in positive nitrogen balance.

Johnson and McCIure (1964) compared the utilization of urea,
biuret and diammonium phosphate by four wether lambs fed rations con-
sisting of 50:50 roughage-concentrate mixtures in a 4 x 4 Latin square
designed experiment. The basal roughage--concentrate mixture (corn

cobs, soybean flakes, shelled corn, and starch) was 6.8 percent crude

37

protein and the nitrogen supplemented rations 12.0 to 12.6 percent
crude protein on a dry matter basis. Neither diammonium phosphate

nor biuret appeared to be utilized as well as urea from the standpoint
of digestibility or nitrogen retention.

Karr e£_§l, (1965a) reported increased nitrogen retention in
two experiments with biuret added to a basal silage mixture (chopped
corn plant, ground yellow corn, calcium carbonate and trace mineralized
salt), while urea additions produced lower retentions. Concentrate
mixtures added at ensiling time versus feeding time, resulted in a
highly significant improvement in daily nitrogen retention (urea and

biuret values combined).

Diammonium Phosphate

 

Diammonium phosphate has been investigated from the stand-
point of a nitrogen and phosphorus source in ruminant rations. There
are no reports in the literature, as far as this writer knows, where
diammonium.phosphate has been added to an ensiled mass. Mainly urea
and diammonium phosphate have been compared, physiologically and nutri-
tionally, as supplements added to sheep and cattle rations.

Shaw 25.31, (1946) reported the following about diammonium
phosphate: "At a level of 1% in the ration, it furnishes the equiva-
lent of 1.31% protein and 0.23% phosphorus or approximately 30%
more phosphorus than is supplied by an equal amount of bone meal."

In their study 1.0 percent diammonium phosphate or 1.0 percent of a
mixture of mono- and di-ammonium phosphate was added to grain mixtures

for milking animals receiving mixed hay and grain. These additions did

38

not effect the palatability of the rations in a 21 day test. "Fitting
rations" containing 3.0 percent diammonium phosphate or 3.0 percent of
a mixture of mono- and di-ammonium phosphate were fed to dry cows with
the result that diammonium phosphate was more palatable than the mixture
of the two phosphates. These authors recommended that diammonium
phosphate could be fed in amounts not to exceed 1.0 percent of the
concentrates. Cowman and Thomas (1962) also observed favorable results
with these ammoniated phosphates for gains during a wintering period

of 112 days and a fattening period of 168 days. However, in the
fattening period a comparable lot of cattle fed soybean oil meal gained
at a faster rate and more efficiently than the lot fed the ammoniated
phosphates. Diammonium phosphate also proved to be an adequate phos-
phorus source. Lassiter 25.31, (1962) conducted palatability trials
with nine Holstein cows in which alfalfa hay and a basal grain ration
containing 1.0, 2.0 and 4.0 percent diammonium phosphate were fed.
Incomplete eating or a slowness in grain consumption was noted for

some cows when the grain ration contained diammonium phosphate at 2.0
percent or higher. In digestibility and nitrogen retention trials, the
nitrogen digestibility of rations containing urea and soybean oil meal
was similar, and in both cases higher than the diammonium phosphate
rations. Similar trends were noted for nitrogen balance data. Oltjen
25.31, (1963) reported similar results as those of Lassiter 25.31,
(1962) for nitrogen balance and palatability when fed to sheep, but
diammonium phosphate did serve as a satisfactory source of phosphorus.
However, Russell g£_§l, (1961) observed no significant differences in

nitrogen retention in lambs when urea or diammonium phosphate supplied

39
30 percent of the nitrogen. In contrast, Johnson and McClure (1964)
observed that neither diammonium phosphate or biuret appeared to be
utilized as well as urea from the standpoint of digestibility or
nitrogen retention when these compounds were added to a 50:50 roughage-
concentrate mixture and fed to lambs. Lassiter 95 31, (1962) concluded
that diammonium phosphate nitrogen appeared to be utilized as well as
soybean meal or urea nitrogen. In a growth study with heifers com-
parable growth rates were observed when either diammonium phosphate or
urea supplied 35 percent of the nitrogen in the ration.

Diammonium phosphate has also been investigated frmm the stand-
point of its effect upon rumen pH, blood ammonia-nitrogen (NH3-N), and
toxicity. Russell e£_al, (1961) and Russell e£_al, (1962) reported
that larger amounts of diammonium phosphate were required to produce
adverse effects or toxicity in lambs than urea. When urea and
diammonium phosphate were infused into the lambs by a stomach tube on
an equivalent nitrogen basis, urea caused a greater increase in rumen
pH, and a highly significant increase in blood NHB-N.

An interesting observation has been reported by Oltjen e£_§l,
(1963) concerning the reaction of diammonium phosphate when placed in
either saliva or distilled water. They reported a release of ammonia
when diammonium phosphate comes into contact with these liquids and
as much as 30 and 10 percent of the nitrogen was lost in this form when
diammonium phosphate reacted with either saliva or distilled water,
respectively. Pelleting rations containing diammonium phosphate also
resulted in large losses. In more recent research dealing with this

observation, Reaves e£_al, (1965) determined the ammonia release from

40

reagent diammonium phosphate, regular diammonium phosphate and

stabilized diammonium phosphate in the presence of saliva. Stabilized
diammonium phosphate produced less ammonia in two different incubations

of different time lengths. When 1.5 and 3.0 percent stabilized diammonium
phosphate and 3.0 percent regular diammonium phosphate were incorporated
into a grain ration and fed with alfalfa hay against a control ration,

the mean consumption was 8.89, 7.86, 8.26 and 9.23 pounds per day,

respectively, for these rations.

Mineral Additives

 

The incorporation of limestone, calcium carbonate or dicalcium
phosphate into corn silage has been the subject of several research
reports as an attempt to prolong fermentation of the ensiled mass.

These compounds also supply additional calcium to the calcium deficient
corn silage. However, the major emphasis has been placed upon the
chemical action of these compounds which, as an end result, will
increase volatile and non-volatile fatty acid content of the silage
which serve as potential energy sources for ruminant animals.

Hydrogen Ion Concentration and

Acid Production in Corn Silage

Treated with Mineral Additives

Calcium carbonate and limestone.--Ca1cium.carbonate and different
grades of limestone have been added to silages, since the calcium ion will
form the salt of the organic acids. Simkins e£_al. (1964) added 13.6 pounds

of calcium carbonate per ton of corn silage and compared the fermentation

41

products with a control silage. The pH and total organic acid content
for the control and treated silages were 3.73, 6.52 percent, and 3.92,
11.24 percent of the dry matter, respectively. These differences were
statistically significant. Nicholson and Cunningham (1964) ensiled
several grasses and legumes at varying dry matter percentages in

glass jar silos with additions of 1.0 or 2.0 percent ground, high-
calcium feed grade limestone. These additions resulted in higher organic
acid content and pH with generally lower proportions of lactic acid

and higher proportions of butyric and acetic acids. Immature corn
silage was also ensiled with limestone additions which resulted in
higher proportions of lactic acid, organic acid content, and pH.

Byers e£_al, (1963) and Byers e£_§l, (1964) ensiled corn silage treated
with either 0 or 1.0 percent limestone. The pH of the control silage
was 3.85 as compared to 4.20 for the limestone treated silage. The
addition of limestone to the fresh crop at the time of ensiling pro-
duced a significant increase in acetic and lactic acids in the silage.
The acetic and lactic acid content of the control and treated silages
on a dry matter basis was 1.55, 3.16 and 5.36, 9.66 percent, respec-
tively. Succinic acid was also increased by 18 percent in the treated
silage.

Klosterman 95.51, (1962) ensiled ground ear corn and whole
plant corn silages with and without 0.5 percent high calcium limestone
and 0.5 percent urea. In another experiment whole plant and ground
ear corn silage with 1.0 percent high calcium limestone were ensiled.
These additions resulted in an increase in the organic acids. In an

earlier report Klosterman.e£.al, (1960a) revealed that in whole plant

42

corn silage ensiled with 0.5 percent urea the lactic acid was increased
78 percent. In an ear corn silage with 1.0 percent high calcium.lime-
stone and 6.0 percent added water the lactic acid was 125 percent
greater than a control silage. In a more extensive report, Klosterman
g£_§l. (1963) included research in which limestone and urea were used
singly and in combination with whole plant and ear corn silages. Using
glass jar silos, the pH for a control, 0.5 percent limestone, 1.0
percent limestone, and 1.0 percent dolomitic limestone whole plant

corn silages was 3.8, 4.0, 4.2, 4.3, respectively. The percentages

of acetic and lactic acid on a dry matter basis for these same

silages were 1.51, 8.33; 1.59, 9.72; 1.99, 11.05 and 2.63, 11.90 per-
cent, respectively. It was also noted that dolomitic limestone produced
variable results as far as increasing the acid production, when com-
pared to high calcium limestone.

However, urea did not increase the acid content as much as
calcium carbonate or high calcium limestone. Karr e£_§l, (1964) re-
ported that whole plant silage plus ground corn, calcium carbonate and
salt lowered the acetic acid, increased the lactic acid and increased
the total organic acid production in glass jar silos. Karr g£_§1,
(1965a) reported similar results.

Feeding Trials with Silages Treated
with Mineral Additives

The effects of adding these compounds to corn silage as a feed
for dairy cattle has been the subject of study at several institutions.
Byers e£_al, (1963) and Byers e£_§l, (1964) reported on work in which

24 Holstein, Brown Swiss and Jersey cows were fed ad libitum corn

43

silage treated with 0 and 1.0 percent limestone at the time of en-
siling or added to the silage at feeding time in an attempt to eval-
uate these silages for milk production, milk fat percent and rumen
volatile fatty acids. Alfalfa hay and a grain mixture were also fed
at specific rates. There were no significant differences among
groups in average daily F.C.M;, milk fat percentage or dry matter
intake corrected for body weight. There was a tendency for higher
rumen propionic acid levels when the cows were fed the treated silage.
Similar results were reported by Byers (1965). Simkins e£_§1, (1964)
and Simkins SE 31. (1965) reported little or no change in milk pro-
duction from adding 13.6 pounds of calcium carbonate per ton of corn
silage. However, the silage dry matter intake per 100 pounds of body
weight was significantly higher for the control cows (1.91 lb.) than
for the treated silage group (1.64 1b.). Similarly the greatest body
weight gains were made by the control animals. There was also a
significantly greater rumen concentration of total volatile fatty
acids in cows receiving the treated silage, but the percent acetic,
propionic and butyric acid were not different. Kesler §£_§1, (1964)
also reported a higher consumption of a control corn silage than a
limestone treated silage (1.0% limestone). McCullough e£_al, (1964)
reported decreased dry matter intake and milk production by cows fed
silage treated with 1.0 percent calcium carbonate as compared With
similar cows fed an untreated silage.

Limestone and calcium carbonate have also been used in rations
for heifer growth. McCullough (1964) prepared NK300 sorghum silage

with and without additions of 1.0 percent calcium carbonate and the

44

enzyme cellulase. When these silages were fed to heifers, the silage
dry matter intakes for the control, control plus 1.0 percent calcium
carbonate and control plus 1.0 percent calcium carbonate and 2.0 per-
cent enzyme were 11.06, 9.14 and 10.37 pounds, respectively. Nicholson
and Cunningham (1964) and Megli et a1, (1965) also reported reduced
feed intake and gain with limestone additions to corn silage. Mohler
g£_§l, (1962) compared regular corn silage and corn silage treated
with 0.5 percent limestone when fed to 72 beef calves with additional
protein. The average daily gains for the regular corn silage and
treated corn silage calves were 1.83 and 1.97 pounds, while the silage
required per 100 pounds of gain was 1705 and 1794 pounds, respectively.

A considerable amount of our present information concerning
the addition of adjuncts to silage has been performed at the Ohio
Experiment Station. Klosterman g£_al. (1960) studied the additions of
1.0 percent dolomitic limestone to whole plant corn silage. Results
of growth experiments indicated that steers fed the treated silages
made gains about the same or slightly higher than those fed untreated
silages. However, less silage dry matter was required per unit of
gain with the treated silages.

Similar results have also been reported for limestone or lime-
stone plus urea additions by Klosterman et_al, (1961), Klosterman
g£_gl. (1962) and Klosterman g£_§l. (1963).

Digestibility Studies with
Mineral Additive Silages

The digestibility of silages which contained limestone or

45

calcium carbonate was reported by McCullough (1964) and Klosterman
e£_§l, (1960). McCullough (1964) used NR 300 sorghum silage to study
the effects of calcium carbonate and cellulase additions. The addition
of calcium carbonate alone reduced dry matter digestibility as can be
seen from the following silage treatments and their digestibility
coefficients: control, 50.3 percent; control plus 1.0 percent calcium
carbonate; 42.6 percent; and control plus 1.0 percent calcium carbonate
plus 2.0 percent enzyme, 54.5 percent. Klosterman e£_§l, (1960) used
lambs to determine the digestibility of organic matter, cellulose,
crude fiber, protein and ether extract of an untreated and treated

(1.0 percent dolomitic limestone) whole corn silage. values of 67.1,
67.4; 40.5, 42.6; 37.9, 41.0; 59.8, 60.0; 64.9, 67.5 percent, were
found for the above constituents, respectively. In another experiment
with ear corn silage and dry ear corn with and without dolomitic
limestone, there was a significant depression in digestibility of

ether extract in the ration containing dry ear corn plus added lime-
stone. No depression was observed for the other constituents.

Colovos e£_§l, (1958) fed 12 dairy heifers either on an all roughage

or a mixed ration with added pulverized limestone or dicalcium phos-
phate to determine the effects of the added calcium on the utilization
of protein and energy. The roughages used were mixed grass hay or
grass to grass-legume silages. In the first experiment 100 grams of
limestone were fed per animal per day along with a grass-legume silage
with a second group receiving no supplemental calcium. In a second
experiment 0, 50 and 100 grams of limestone were fed with silage and

in the third experiment hay and a concentrate mixture (16 percent crude

protein) were fed plus either 2.0 percent limestone, 2.0 percent

46

limestone plus 2.0 percent dicalcium phosphate, 2.0 percent dicalcium
phosphate, or 0 level minerals. Limestone depressed the digestibility
of protein and energy, while dicalcium phosphate had no effect. When
the two supplements were fed in combination there was a decrease in
the depressing effects of limestone. It appeared that the added
calcium depressed protein and energy digestibility while phosphorus

additions increased protein digestibility.

Limestone Urea Combinations

 

Hydrogen Ion Concentration, Acid
Production and Crude Protein Changes

Limestone-urea combinations have been evaluated as silage
additives at several institutions within the past few years. In
chemical studies Newland and Henderson (1965) reported increases in
crude protein content when corn silage was ensiled with 10 pounds of
limestone and 10 pounds of urea per ton as compared to untreated corn
silage (3.19 vs. 2.48 percent). Klosterman e£_al, (1962) with similar
treatments also indicated that urea could replace a portion of the
supplemental proteins in the treated silages. These additions re-
sulted in increased organic acids. In an earlier report, Klosterman
g£_§l, (1960a) reported a 78 percent increase in lactic acid in a whole
plant corn silage ensiled with 0.5 percent high calcium ground lime-
stone and 0.5 percent urea. Klosterman e£_al, (1963) reported that
pH for a control and a 0.5 percent limestone plus 0.5 percent urea,
whole plant corn silage was 3.8 and 4.3, respectively. The acetic
and lactic acids on a dry matter basis for these same silages were

1.51, 8.33; and 2.13, 12.05 percent, respectively. In this same

47

report, chemical data on silages containing 1.0 percent dicalcium
phosphate, 1.0 percent limestone plus 0.5 percent urea and 0.5 percent
limestone plus 1.0 percent urea were reported. The pH, acetic and lactic
acids (percent on dry matter basis) for these silages were 3.8, 1.68,
8.51; 4.5, 3.22, 12.99; and 4.2, 2.33 and 11.06, respectively.
Feeding Studies with
Limestone-Urea Combinations

Newland and Henderson (1965) ensiled regular corn silage with
additions of limestone and urea (10 pounds each per ton). These were
fed to four lots of eight Hereford heifers comparing protein supple-
ments with and without urea, mineral sources and vitamin supplementa-
tion. Heifers gained 8 percent faster, were more efficient and made
cheaper gains when fed the limestone-urea corn silage. The urea
containing protein supplement did not significantly depress animal
performance when fed with the treated silage and overall the gains were
more economical for the groups receiving urea. Klosterman.e£_gl.
(1960a) reported similar results when whole plant silage was treated
with 0.5 percent limestone and 0.5 percent urea and incorporated into
a ration of alfalfa hay, soybean oil meal, minerals and a half feed
of dry, ground ear corn. In another experiment, steers fed a treated
silage gained somewhat less than another lot fed untreated silage.
The reverse was true when 8 pounds of corn was fed. Increased feeding
value was also reported by Klosterman e£_§l, (1962) with addition of
0.5 percent urea and 0.5 percent high calcium limestone in both whole

plant and ground ear corn silages.

48

Resume

Corn silage, when properly supplemented, is obviously one of the
better roughage sources for cattle from a production standpoint. Im-
provement in milk production or a good replacement value has been
reported by Carroll (1924), Fairchild and Wilbur (1925), and Converse
and Wiseman (1952). Corn silage may contain unidentified factors
necessary to balance other roughages (Huffman and Duncan 1954a,
Huffman and Duncan 1954b, and Dunn e£_§l, 1954). While the subject
of the optimum level of silage feeding is still under investigation,
this level may range from light silage feeding, (Pratt and White, 1930),
to the point where it serves as the sole roughage source (Brown e£_§l,,
1965), depending upon how it is supplemented. In growth experiments,
corn silage when fed alone has not produced good results unless sup-
plemented with grain or other roughages (Eckles, 1918); and Converse
and Wiseman, (1952). When corn silage was compared with other roughage
sources for milk production or growth, improvement in milk production
in favor of corn silage as compared with sorghum silage was reported
by Reed and Fitch (1913), Owen e£_al, (1957), Owen et_§l, (1961),
and Rahmon and Leighton (1965). However, comparisons with other
roughages are variable depending upon the experiment and roughage
comparisons.

The additions of various chemical compounds to whole plant corn
silage must be evaluated from the standpoint of the changes in the
chemical fermentation and the result of this change on the feeding

value and animal performance. Additions of urea to corn silage

49

resulted in increased crude protein equivalent, (Bentley e£_§l.,

1955), (Wise e£_al,, 1944), Gorb and Lebedinskij, 1961), (Goode, 1955),
(Palamaru gt_§l,, 1961), (Klosterman e£_al,, 1961, 1962, 1963),
(Hoffman and Fix, 1965), and (Davis, 1944). Bentley e£_§l,, (1955),
Cullison (1944) and Klosterman 25.31, (1963) also reported that urea
prolonged volatile and non-volatile fatty acid production, but the pH
of the treated silages has remained elevated when compared to control
silages. In general, urea additions resulted in comparable to slightly
less gains or milk production when fed to cattle and its value appears
to be in its economy as a protein source.

While there are no reports in the literature concerning the
addition of diammonium phosphate to corn silage, results when it was
supplemented into the ration are again variable ranging from equal to
poorer utilization than other non-protein-nitrogen sources.

Additions of either calcium carbonate or ground high calcium
limestone stimulated total acid production in treated silages and
elevated the pH, (Byers e£_al,, 1963), (Byers 35.31,, 1964), (Klosterman
§£_§l,, 1960, 1962, 1963), and (Karr e£_§l,, 1964). For milk pro-
duction, the addition of limestone or calcium carbonate does not
appear to improve the silage performance, (Byers gt 21. 1963), (Byers
§£_gl. 1964), (Byers §£_§l, 1965) and in some cases resulted in a
depression of feed intake (Simkins e£_§l, 1964), (Simkins e£_§l, 1965).
Improvements in animal gains have also been noted with additions of
limestone or calcium carbonate, but results are still variable.

Limestone and urea combinations resulted in increased crude

protein equivalent, CNewland and Henderson, 1965) acid production,

 

50

and pH values, (Klosterman e£_al,, 1960, 1962, 1963). Increased
feeding value with this combination has been reported by Klosterman
e£_al, (1960), Klosterman e£_gl, (1962), and Newland and Henderson

(1965).

EXPERIMENTAL PROCEDURE

The experimental data reported in this thesis covers a period

of two years' work with whole plant corn silage (excluding roots).

Experiment I

 

During the period of September 6 to September 10, 1963, whole
plant corn silage was harvested at approximately 27 percent dry matter
with a two row corn chopper. The fresh material was transported to
the Michigan State University dairy farm in self-unloading wagons where
each load was weighed prior to ensiling. Two silos were filled at the
same time by adding alternate loads to each silo. Approximately 35
tons of the fresh material were placed in each of four 10 x 40 foot
silos, while approximately 63 tons were placed in each of two 10 x 40
foot silos. The chemical compounds studied were distributed on top
of each load of fresh material on a fresh weight basis before it was
blown into the silo. Mixing occurred as the materials passed from the
wagons through the blower and into the silo. In the first experiment,
urea ("cyrea," minimum nitrogen 42.0 percent), diammonium phosphate
(21.21 percent nitrogen), calcium carbonate (38 percent calcium),
and dicalcium phosphate (average percent calcium, 25.5 and minimum
phosphorus, 21 percent) were added to the silage either singly or in

combinations.

51

52

The following design was used:

Silo 3: Control corn silage.

Silo 4: Corn silage plus 0.5 percent urea per ton.

Silo 5: Corn silage plus 1.0 percent diammonium phosphate per ton.

Silo 6: Corn silage plus 0.5 percent calcium carbonate per ton.

Silo 7: Corn silage plus 0.5 percent calcium carbonate plus 0.5

percent urea per ton.

Silo 8 Bottom: Corn silage plus 0.5 percent calcium carbonate plus
1.0 percent diammonium phosphate per ton.

Silo 8 Top: Corn silage plus 0.75 percent dicalcium phosphate plus
0.5 percent urea per ton.

When two different silage mixtures were ensiled within the same
silo, a sheet of black plastic separated the two silages. After a
silo was filled, the ensiled material was leveled, packed, and covered
with another sheet of black plastic.

Samples were removed for chemical analyses on the 0, 5, 10, and
20th day following ensiling which represents most of the fermentation
period. Two inch holes were drilled into the silo doors to provide
an entrance into the silage, and samples were removed with an auger.
The samples were placed in polyethylene bags, tagged and stored at
-2 to 3 degrees F. for future chemical analysis. The hydrogen ion
concentration, moisture, total nitrogen, volatile and non-volatile, were
determined on each of these samples. During the feeding experiments,
samples were taken from the top one-half foot of the silage surface.
These samples were preserved and analyzed in a similar manner as the

fermentation samples. With the exception of the first heifer growth

53

experiment, (1963-64 silages), these samples from each silo were
composited for the determination of volatile and non-volatile fatty
acids and proximate analysis. Supplementary feeds were also sampled

and composited for proximate analysis.

Heifer Growth Trial

 

The silages were evaluated on the basis of animal performance
in a heifer growth or a lactation study. In the heifer growth trial,
two silages were fed; corn silage treated with 0.5 percent calcium
carbonate plus 0.5 percent urea per ton (Silo 7) and corn silage
treated with 0.75 percent dicalcium.phosphate plus 0.5 percent urea
per ton (Silo 8-T). Sixteen Jersey heifers weighing 500 to 770 pounds
were allotted into two equal weight groups of eight animals each. One
animal was injured during the experiment and was removed so that only
fifteen animals completed the experiment. A.mixture of the corn
silages from the top of both silos 7 and 8 was fed for approximately
one week immediately preceding the 87-day experimental period. A
mixture of dicalcium phosphate and trace mineralized salt was fed at
the daily rate of approximately 55 grams. All animals were weighed
for three consecutive days and allotted into groups on the basis of
average body weights. subsequent weights were recorded at 30 day
intervals and three day weights at the end of the trial. During the
experimental period, each group was fed ad libitum silage from either
silo 7 or 8 top plus approximately 55 grams of a 50-50 mixture of
dicalcium phosphate and trace mineralized salt. The silage fed as

well as orts were weighed and recorded daily for each heifer.

54

Samples of silage and orts were taken on Monday, wednesday, and Friday

of each week for dry matter determinations.

Lactation Study

In the lactation study, six silages from silos 3 to 8-B, page 52
were fed.

Thirty-six Holstein cows were divided into six outcome groups
on the basis of milk production. Each cow within an outcome group was
randomly allotted to one of the six treatment groups in a randomized
block design. Ad libitum corn silage and grain at a grain to milk
ratio of 1:3.5 were fed during an 18 day preliminary period. During
the 90 day experimental period, the six silages were fed ad libitum.
Based on the assumption that cows would consume approximately 80
pounds of silage, the rations were equalized in T.D.N. and crude pro-
tein by supplementing the 80 pounds of silage with either 2.0 pounds
of soybean oil meal for the non-urea silages or 2.0 pounds of ground
shelled corn for the urea silages. This level of silage intake and
concentrate supplementation would theoretically supply enough T.D.N.
and crude protein to support maintenance plus 30 pounds of milk
testing 3.5 percent fat. The difference in production between this
30 pounds of milk and the average actual milk production within each
outcome group was supported by feeding various levels of a 16.1 per-
cent crude protein grain mixture consisting of 1470 pounds of ground
shelled corn, 390 pounds of soybean oil meal, 100 pounds of molasses,
20 pounds of dicalcium phosphate, and 20 pounds of trace mineralized

salt. Approximately one month after the beginning of the experiment

55

the cows were not consuming 80 pounds of silage. The grain supplemen-
tation level was recalculated on the basis of 70 pounds of silage and
all rations adjusted accordingly. Grain changes were made at approxi-
mately 28-31 day intervals throughout the experiment according to the
average milk production within an outcome group. Approximately 55
grams of a 50-50 mixture of dicalcium phosphate trace mineralized salt
were also fed. A11 cows were weighed for three consecutive days
immediately preceding and at 30-day intervals throughout the 90 day
experimental period. Daily feed consumption was recorded for each
cow and samples of silages and orts were taken three days each week
for dry matter determinations. Samples of the different concentrates
were also taken at various times throughout the experiment for dry
matter determinations.

Daily milk weights were recorded for each cow and a composited
sample taken twice weekly for both butterfat and solids-not-fat
(SNF) analysis. During the first month of this experiment, the
butterfat and SNF determinations were not made. The values for
butterfat were taken from the monthly Dairy Herd Improvement Associa-
tion testing sheet and averaged with the first butterfat test made
during the experiment to obtain a value to use for the missing period.
For the missing SNF value, the average of the second month's SNF
values were used to replace this value for the first month of the

experiment.

56

Experiment II

 

In a second experiment, calcium carbonate and optimum levels of
urea additions to corn silage were studied. Whole plant corn silage
(excluding roots) at approximately 29 percent dry matter was harvested
and ensiled from September 1 to September 5, 1964 in a similar manner
as that of Experiment I. Approximately 62.5 tons of the fresh material
was ensiled in each of six 10 by 40 foot silos with calcium carbonate
(ground high calcium limestone, minimum calcium 38 percent), or urea
(minimum nitrogen 42 percent), added either singly or in combination
as silage treatments.

The following treatment design was used:

Silo 3: Control corn silage.

Silo 4: Corn silage plus 0.5 percent urea per ton.

Silo 5: Corn silage plus 0.75 percent urea per ton.

Silo 6: Corn silage plus 0.5 percent calcium.carbonate per ton.

Silo 7: Corn silage plus 0.5 percent urea plus 0.5 percent calcium
carbonate.

Silo 8: Corn silage plus 0.75 percent urea plus 0.5 percent calcium

carbonate per ton.

After each silo was filled, the ensiled material was leveled,
packed, and covered with a sheet of black plastic plus additional
fresh chopped corn. All sampling and chemical analysis for silage
samples were the same as outlined in Experiment I.

The silages were evaluated in three animal performance experi-

ments consisting of a heifer growth trial, a lactation study, and a

57

digestion and nitrogen balance study.

Heifer Growth Trial

In the heifer growth trial, 42 Holstein and six Jersey heifers
were brought into the barns from.summer pasture on October 20, 1964.
From October 21 to October 30, the heifers received hay and corn
silage. From October 31 to November 11 a mixture of the experimental
silages were fed ad libitum plus 55 grams of a 50-50 dicalcium phosphate-
trace mineralized salt mixture. All heifers were weighed for three
consecutive days at the beginning of the trial, twice weekly during
the trial, and for two consecutive days at the end of the trial. The
42 Holstein heifers were divided into seven outcome groups of six
heifers each on a weight basis. Each heifer in an outcome group was
randomly assigned to a treatment group in a randomized block design.
The remaining six Jersey heifers, regardless of weight, were randomly
assigned to treatments. During the 70 day experimental period, each
treatment group was fed one of the silages ad libitum, plus 55 grams
of a 50-50 dicalcium phosphate trace mineralized salt mixture. The
sampling of the silages for both dry matter determinations and

chemical analyses was the same as in Experiment I.

Lactation Study

Thirty Holstein cows were used in a 90 day lactation trial to
evaluate these silages as the sole roughage source for lactating dairy
cows. The first group of 18 cows was allowed a 16 day preliminary
period in which herd silage and later a mixture of the treated silages

was fed ad libitum. Grain intakes were decreased during the preliminary

58

period to increase silage consumption and to approximate grain levels
to be fed during the experimental period. The cows were placed into
outcome groups according to their expected production for a 120 day
feeding trial, and randomly allotted to treatment groups. The fol-

lowing equation was used to predict the expected production:

f
= __2___ ..
P120 Pp (£1) + 120 1)

where P120 is the expected cumulative milk production for the 120 day
experimental period, Pp is the cumulative milk production from parturi-
tion to the time of the experiment, fp is a ratio factor (chosen for
appropriate age, number of days in the preliminary period, and season
of calving) for estimating 305 day production from the preliminary
production and fp + 120 is the ratio factor (chosen for appropriate
age, season of calving, and number of days to the end of the 120

day experimental period) for estimating 305 day production from pre-
liminary and 120 day experimental production.

A second group of 12 Holstein cows was placed on experiment
approximately two months after the first group. These animals received
similar treatment during a 14 day preliminary period as the first
group of cows with the exception that two cows, 281 and 755, were on
the preliminary regime for only three days. Two of the original 12
cows were not compatible with the remaining animals with respect to
‘milk production and were replaced by these two animals.

During the experimental period, the cows were fed the various
silages ad libitum according to treatment groups. In this experiment,

it was assumed that each cow would consume 70 pounds of corn silage.

59

The T.D.N. and crude protein content of all silages was equalized by
supplementing with 3.0 pounds of soybean oil meal (50% C.P.) and 5.0
pounds of shelled corn for the 0 percent urea silages, 2.0 pounds of
soybean oil meal and 6.0 pounds of shelled corn for the 0.5 percent
urea silages, and 8.0 pounds of shelled corn for the 0.75 percent urea
silage. The above amounts of feed would theoretically support main-
tenance plus 39.0 pounds of milk testing 3.5 percent fat. Cows pro-
ducing more than 39 pounds of milk were fed additional ground shelled
corn and soybean oil meal according to calculated requirements (N.R.C.,
1958). Grain changes were made at 30-day intervals during the experiment
according to the mean persistency of each outcome group. However, the
grain intake for any cow was never reduced below the point at which
the silages were equalized for T.D.N. and crude protein. Approximately
55 grams of a dicalcium.phosphate-trace mineralized salt mixture was
fed daily. During the experiment the daily recording of feed con-
sumption and milk production was the same as in the first experiment.
weekly analysis for butterfat and S.N.F. were conducted throughout the
experimental period. Likewise, all feed sampling techniques and sample
analysis were the same as in the first experiment.
Digestibility and Nitrogen
Balance Study

Near the end of the lactation study, April 10, 1965, sixteen
wether lambs weighing approximately 70-95 pounds were fed a regular
herd corn silage ration plus additional ground shelled corn and a
50-50 dicalcium phosphate-trace mineralized salt mixture. On April 14,

twelve of the original sixteen lambs were randomly assigned to the

60

silage mixtures from silos 3, 4, 5, and 7. These silages were chopped
in a hay chopper and stored in a walk-in refrigerator in order to improve
the intake and prevent selection of silage particles by the lambs.
During the 19 day preliminary period, the lambs were given 8.0 pounds
of silage per day. The various silage treatments were equalized for
T.D.N. and crude protein by supplementing the silages with 0.524 pound
of cornstarch and 0.276 pound of soybean meal (50 percent C.P.) for
the lambs receiving the 0 percent urea silage, 0.718 pound of corn-
starch, and 0.082 pound of soybean meal for the lambs receiving the
0.5 percent urea silages, and 0.800 pound of cornstarch for the lambs
receiving the 0.75 percent urea silage. The total feed offered to
each lamb was equalized at 8.8 pounds per day.

Following a seven day change over period, eight of the twelve
lambs from the first study were used in a second digestion trial and
fed the remaining two silages from.silos 6 and 8. The silages were
fed at a rate of 8.0 pounds per day and were supplemented the same as
the 0 and 0.5 percent urea silages fed in the first study equalizing
the total feed offered, T.D.N. and crude protein.

In both studies, the lambs were placed in digestion crates one
day prior to the seven day total collection period. During the col-
lection period, the supplemented silages plus a 50-50 dicalcium
phosphatedmineralized salt mixture were fed daily with free access
to water. Feed, orts and feces were weighed and recorded daily. The
fecal material was collected in polyethylene bags cemented to the
lambs with branding cement. The bags were emptied twice daily and the

feces stored in a walk-in refrigerator with thymol as a preservative.

61

At the completion of the collection period, the amount of fecal
material was weighed, mixed, sampled, and dried at approximately 80° C.
for 72 hours. The dried samples were ground in a Wiley mill and
stored until chemical analysis could be completed. Urine was col-
lected under toluene with sulfuric acid as a preservative. Urine
volume was determined once per day and approximately 5 to 10 percent
by volume composited and frozen for nitrogen analysis. Complete
proximate analysis was performed on feed, orts, and fecal samples.

The weight of each lamb was determined before and after the collection

period.
Computation of Data--Production Trials

All feed consumption data were computated on a dry matter basis.
In the milk production trials, T.D.N. intake was calculated and feed
utilization was expressed on a T.D.N. per pound of 4.0 percent milk
basis. Net utilization was calculated as T.D.N. per pound of milk
after correcting for body weight change (using the factor of 2.1
pounds of T.D.N. per pound of body weight change, Brody, 1945).

Mfllk production was expressed on a 4.0 percent fat-corrected
basis (Gaines, 1928) using the following equation:

4% F.C.M. = .4 (pounds of milk production) + 15 (pounds of fat)

Milk and S.N.F. were computed on a 30-day basis and summed for
the complete experimental period. Regression equations of Erb §£_gl.
(1960) and Erb (1963) were used in computing the S.N.F. datafiom the
Golding Bead test.

The nitrogen balance data were computed using the method of

62

Mitchell (1924) and the factors of Harris and Mitchell (1941) for

endogenous urinary nitrogen and metabolic fecal nitrogen.

Chemical Analysis

 

Moisture, pH, Total Nitrogen

 

Moisture was determined on silage samples with a hot air oven
at 100-1050 C. for 24 hours. Dry matter determinations for feed and
orts samples were performed by drying in a hot air oven at approxi-
mately 800 C. for 72 hours. The hydrogen ion concentration was deter-
mined with a Beckman pH meter equipped with an external glass electrode.
Nitrogen was determined by procedures outlined by the Association of
Official Agricultural Chemists and adapted for corn silage. The total
nitrogen values from each silage sample were multiplied by 6.25 to

obtain the crude protein equivalent values.

Volatile Fatty Acids

Samples for both volatile and non-volatile fatty acids were
prepared by mixing 100 grams of silage with 100 to 150 m1. of 0.4N
sulfuric acid and stored at 38 to 39° F. for at least 72 hours. The
liquid portion was extracted and centrifuged at 2000 R.P.M; The
supernatants were removed, strained through two layers of cheese
cloth and stored under refrigeration with Thymol as a preservative.
The volatile fatty acids (acetic, propionic, and butyric) were deter-
mined with a Wilkens Hi-Fi Aerograph, Model 550 or 600, equipped with
hydrogen flame detectors. The column materials were either 20 percent

carbowax on chromosorb "W" or 10 percent FFAP on chromosorb "W" DMCS

 

63

acid washed. The column temperature was approximately 135° C. The
nondvolatile fatty acid, lactic, was determined by the Barker and

SUmmerson (1941) method.

Analysis of Data
The data were analyzed according to the methods for com-

pletely randomized and randomized block designed experiments, (Li,

1964).

RESULTS

Chemical Data

 

2g

In Experiment I two silage treatments were fed to heifers:
corn silage plus 0.5 percent calcium carbonate and 0.5 percent urea
(silo 7), and corn silage plus 0.75 percent dicalcium phosphate and
0.5 percent urea (silo 8-T) (Table 1). Both treated silages were
higher in pH than the control silage (silo 3). In the remaining silages
of Experiment I, the single additive treated silages (silos 4, 5, and
6) showed similar trends to those of silos 7 and 8 when compared to
the control silage (silo 3). Silo seven contained 0.5 percent calcium
carbonate plus 0.5 percent urea. The final pH of this silage treatment
was higher than the remaining silage treatments (P < 0.01). Diammonium
phosphate (1.0 percent) and calcium carbonate (0.5 percent), when used
as single additives to corn silage (silos 5 and 6), produced slight
increases in pH as compared to the control silage. The ions of
diammonium phosphate (NH4+ and H PO4-, HPO4=, etc.) ammonium and
phosphate may have opposite effects upon pH of the silage. Calcium
carbonate (0.5 percent) and diammonium phosphate (1.0 percent) were
used in combination as a silage treatment (silo 8-B). The pH of the
as fed samples of this silage was higher (P < 0.01) than all other
silages fed during the lactation trial except the silage containing

0.5 percent calcium carbonate and 0.5 percent urea (silo 7). The

64

65

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66

standard error of the mean of the silage pH values for the first
lactation trial was 10.042.

The silages studied in the second experiment were treated with
different levels of urea with and without a second adjunct, calcium
carbonate. The single additive treatments of 0.5 percent urea, 0.75
percent urea, and 0.5 percent calcium carbonate (silos 4, 5, and 6)
influenced the silage pH values similarly to the single additive treat-
ments of the first experiment. In silo 7, calcium carbonate and urea
were both added at 0.5 percent per ton, while in silo 8 these two come
pounds were included in the silage at 0.5 percent and 0.75 percent,
respectively. The pH of the 0.5 percent calcium carbonate plus 0.75
percent urea silage was higher than all other silage pH values
(P < 0.01), while the 0.5 percent calcium carbonate plus 0.5 percent
urea treated silage was significantly higher than only the control
silage (silo 3). In this trial, the standard error of the treatment
means was 19.029.

The pH values of similarly treated silages from Experiments I
and II were combined to give weighted means and standard error of the
means for each treatment. These values for the control, 0.5 percent
urea, 0.5 percent calcium carbonate, and 0.5 percent calcium carbonate
plus 0.5 percent urea silages were 3.64 i .024, 3.71 _-I_-_ .024, 3.72 _-i_-
.024, and 3.90 ;_I-_ .024.

The greatest rate of decrease in pH occurred within the first
five days indicating active microbial and chemical changes. While
single additive treatments resulted in increased silage pH values,

combination chemical treatments produced even greater increases in

67

pH irrespective of sampling time (silos 7 and 8). Similar trends were
noted for samples composited during the feeding trials. No significant
differences were observed in pH of silages treated with calcium car-
bonate or urea in either Experiment I or II. When both of these com-
pounds were added to the same silage, the urea-calcium carbonate

combinations significantly increased pH in both experiments (P-< 0.05).

Crude Protein Equivalent

 

The addition of either 0.5 percent urea, 0.75 percent urea, or
1.0 percent diammonium phosphate per ton increased the crude protein
equivalent of the resulting silages (Table 2). In Experiment I, the
only variable in the chemical treatments was the calcium.source
(calcium carbonate, silo 7, and dicalcium phosphate, silo 8-T). Each
silage contained 0.5 percent urea so that the mean crude protein values
for these silages were 11.89 and 11.83 percent, respectively. The
remaining silages contained two different nitrogen sources, diammonium
phosphate and urea, both added on an approximately equal nitrogen
basis. The two silages containing no added nitrogen, control (silo 3)
and 0.5 percent calcium carbonate (silo 6), had mean crude protein
equivalent values of 9.34 and 8.88 percent, respectively. Silages
containing 0.5 percent urea, (silos 4 and 7) had mean crude protein
values of 13.81 and 12.12 percent, respectively, while similar values
for the diammonium phosphate treated silages (silo 5 and 8) were 12.07
and 13.87 percent, respectively. Crude protein equivalent values for
all nitrogen treated silages were higher (P‘< 0.01 or P‘< 0.05) than
the untreated silages with a standard error of treatment means of

10.82.

 

1"

 

68

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69

In the second experiment, a definite relationship was observed
between the percent added urea and crude protein equivalent content
of the silages. The average crude protein equivalent values for
silages containing 0, 0.5, and 0.75 percent urea were 9.5, 13.1, and
15.4 percent, respectively. As in the first experiment, these dif-
ferences between the treated and untreated silages were significant
with a standard error for the treatment means of i0.97. When the
values for similarly treated silages were combined for both years, the
mean and standard error for the control, 0.5 percent urea, 0.5 percent
calcium carbonate and 0.5 percent calcium carbonate plus 0.5 percent
urea silages were 9.72 i 0.64, 13.57 i 0.64, 9.35 i 0.64, and 13.49 i
0.64 percent, respectively.

The average crude protein equivalent value (one composited
sample per silo) for all silages treated with similar levels of urea
and diammonium phosphate are presented in Table 3. Increases in the
added nitrogen increased the corresponding crude protein equivalent
values for these silages.

The percent loss of urea crude protein equivalent added as well
as the percent of theoretical crude protein equivalent in each silage
are also presented in Table 3. The average crude protein equivalent ex-
pressed as a percent of the theoretical crude protein equivalent for the
0.5 percent urea, 0.75 percent urea, and 1.0 percent diammonium phosphate
silages were 86.7, 87.2 and 87.4 percent, respectively. The greatest
loss in added urea crude protein equivalent occurred in the 0.5 percent
urea and 1.0 percent diammonium phosphate silages, while the lowest

occurred in the 0.75 percent urea silage. One-half percent urea and

70

1.0 percent diammonium phosphate represent equal amounts of added
nitrogen. The average urea crude protein equivalent loss for all non-
protein nitrogen treated silages was 37.9 percent.

TABLE 3.--Effect of urea and diammonium phosphate additions on silage
crude protein equivalent content (dry matter basis)

 

r
—

 

0% 0.5% 0.75% 1.0% a
Treatment Urea Urea Urea D.A.P.
Percent
Crude Protein
equivalentb 9.64 12.37 14.85 12.26
% of Theoretical
C.P.E.c
1963-64 100 85.2 -- 87.4
1964-65 100 88.9 87.2 --
% Urea C.P.E. lossd
1963-64 0 44.5 -- 36.7
1964-65 0 35.5 31.6 --

 

aD.A.P.--diammonium phosphate.
bValues are from samples taken during feeding trials.

cTheoretical value of treated silage divided into actual or
analyzed value = % of Theoretical.

dTheoretical value--analyzed value divided by urea crude protein
equivalent = % of urea crude protein equivalent lost.
Organic Acid Production

The effect of treatment on acetic and lactic acid production is
illustrated in Table 4. Silages containing 0.5 percent calcium car-
bonate and 0.5 percent urea (silo 7) or 0.75 percent dicalcium phosphate
and 0.5 percent urea (silo 8-T) contained more acetic and slightly

less lactic acid than other combination additive silages during the same

71

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72

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.mumammoam Guacamoannuamofinn
.mumnmmonm Edwaoaamwnuum<nm

 

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mcnqoma

73

year (1963-64). The silage from silo 7 produced higher (P < 0.05)
amounts of lactic acid than the silage from silo 8-T. There was no
statistical difference in lactic acid production among the silages from
silos 3, 4, 5, 6, 7, and 8-B even though the combination additive silages
produced larger amounts than the single additive silages. The silage
containing 0.5 percent calcium carbonate and 0.5 percent urea produced
greater (P < 0.05) amounts of acetic acid than the remaining silages
(silos 3, 4, 5, 6, 7, and 8-B). The silage containing 0.5 percent
calcium carbonate had larger, but not significant, amounts of acetic
acid than the remaining single additive and control silages (silos 3,
4, 5). A similar trend was also true for the 1964-65 silages. When
compared to these same silages, the 0.5 percent calcium carbonate
silage contained the greatest amount of lactic acid (1964-65 silages).
Multiple treatment comparisons are also presented in Table 4.
When compared to the control silage the use of chemical additives
(silo 3 vs. 4 - 8-B or 4 - 8) increased the lactate production (P 2
0.07) 1963-64 silages and (P 2 0.10) 1964-65 silages. Similar trends
were noted for the acetate production, but this was significant
(P < 0.05) only in the 1964-65 silages. Combination additive silages
(silo 7 - 8) increased (P < 0.05, 1963-64 silages), (P 2 0.10,
1964-65 silages) lactic acid production when compared to the control
silage. The 0.5 percent calcium carbonate silage (silo 6, 1964-65)
produced similar results (P 2 0.10). Significant increases in acetate
production were noted for the combination additive silages (silo 7 - 8)
in 1964-65 (P < 0.05). In the 1964-65 silages, the 0.5 percent calcium

carbonate silage (silo 6) contained greater amounts (P < 0.05) of

74

acetate than the control silage (silo 3). This same trend was noted
in all calcium carbonate silages (silos 6, 7, 8) and was significant
for lactate (1963-64 silages, P Z 0.10) and both acetate and lactate

in the 1964-65 silages (P‘< 0.05 and P 2 0.10).

Chemical Composition of Silages

 

The proximate analyses of the experimental silages are presented
in Table 5. The addition of either calcium carbonate or diammonium
phosphate increased the ash content of the silages. In general, the
greatest increase in ash was in the combination additive silages.

Crude protein content was increased but only in silages containing

added nitrogen.

Animal Performance

 

Heifer Growth Trials

 

Silages from both experiments were offered to growing dairy
heifers to measure relative feeding value of the various treated
silages. Data from the first experiment are given in Table 6.

Heifers fed calcium carbonate plus urea silage had an average
live body weight gain of 1.22 pounds per day while those receiving the
dicalcium phosphate plus urea silage gained 1.31 pounds per day. One
heifer in the first group (CaCO3-urea silage) was off feed for a short
time during the experiment which may have effected the group average
since she completed the experiment with only a 0.91 pound per day

gain. Differences between groups in dry matter consumption and feed

utilization were small.

75

 

 

 

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+ moose em.o

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momeHm Hmucoefiummxo mo aoHufimomaoo Hmoaeasouu.m mum<H

 

76

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m «.mw Hmoa ammnhom

dotmomfi

 

mQUQHUfiQOfiOU

77

TABLE 6.--Growth of dairy heifers fed treated corn silages
(1963-64 silages)

 

 

0.75% Dicalcium

 

0.5% CaCO3 Phosphate
Treatment 0.5% Urea 0.5% Urea
Number 7 8
Feed intake (lb. DM/day) 13.65 14.04
Average daily gain (87 days) 1.22 1.31
Feed utilization (lb. DM/lb. gain) 11.38 10.98

 

All silage treatments in the second experiment were utilized
in a 70-day heifer growth trial. The daily live body weight gains,
feed intake, and feed utilization data are given in Table 7.

There was an increase in the silage dry matter consumed per day
as the urea level in the single additive treated silage was increased.
The dry matter intake was depressed (P < 0.05 and P < 0.01) in the
groups receiving the silages containing 0.5 percent calcium carbonate.
When urea and calcium carbonate were added in combination, the depressing
effect of the calcium carbonate was decreased. Similar trends were
noted in the average daily live body weight gains with the 0.75 percent
urea group gaining 2.11 pounds per day followed by the 0.5 percent
urea group and the control group gaining 2.00 and 1.91 pounds per
day respectively. The group receiving silage containing 0.5 percent
calcium carbonate gained the least of any group with slightly greater
gains being made by the groups receiving the combination additive
silages. The two groups gaining 1.49 and 1.55 pounds per day (0.5
percent calcium carbonate and 0.75 percent urea and 0.5 percent

calcium carbonate) were lower (P < 0.05 and P < 0.01) than

78

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HmmmeHm mo-¢omHv

79

the remaining groups. The feed utilization (pound of dry matter per
pound of gain) of the different silage groups showed similar trends.
The group receiving the 0.5 percent calcium carbonate plus 0.75 percent
urea silage required more silage dry matter per pound of gain than any
other group (P < 0.05). Similarly, the group receiving 0.5 percent
calcium carbonate silage required more dry matter per pound of gain
than the remaining four groups, but this difference was not signifi-

cant (P < 0.05).

Lactation Studies

 

The remaining silages in Experiment I, which were not utilized
in the heifer growth trial, were fed to 36 lactating Holsteins in a
90 day trial. Feed consumption and production response data are
presented in Table 8.

The silages in this experiment were equally acceptable to the
cows as indicated by the silage dry matter intake per day, or per 100
pounds of body weight with the exception of the silage containing
1.0 percent diammonium phosphate which was significantly lower (P <
0.05) than all other groups in silage dry matter intake per day and
silage dry matter per 100 pounds of body weight (P < 0.05 and P <
0.01). Because of lower nutrient consumption, this group produced
less 4.0 percent fat-corrected milk, solids-not-fat, and milk fat per
day than the remaining treatment groups. NOne of these differences
were significant, except for the pounds of solids-not-fat produced per
day (P < 0.05). In the latter measurement, comparisons of all pos-

sible pairs by Duncan's Multiple Range test failed to reveal any

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80

 

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m-w a o m a m ”oHHm

 

 

HmommHHm 40-noaHv HmHuu aoHumuomH--.m mqm<a

81

significant differences at the 0.05 probability level, except that the
difference between silos 5 and 6 approached this level. It was also
noted that cows receiving either 0.5 percent calcium carbonate plus

0.5 percent urea or 0.5 percent calcium carbonate plus 1.0 percent
diammonium phosphate required more (P.< 0.05 and P < 0.01) total digest-
ible nutrients per pound of 4.0 percent fat-corrected milk than cows
receiving either the control or 0.5 percent calcium carbonate silages.
No other differences were observed among treatment groups.

Results of the lactation study using silages from the second
experiment are presented in Table 9. Cows fed either the 0.75 percent
urea silage or the 0.5 percent calcium carbonate plus 0.75 percent
urea silage consumed less (P‘< 0.05, Pv< 0.01) silage dry matter per
day than the remaining treatment groups with the exception of the group
receiving the 0.5 percent calcium carbonate plus 0.5 percent urea
silage. The latter group consumed less (P < 0.05) than the 0.5 percent
calcium carbonate group. Similar trends were noted in silage dry
matter per hundred pounds of body weight, total dry matter intake per
day and total digestible nutrient intake per day. In all values, the
two 0.75 percent urea silages were inferior to the other silages.

The production response indicated that the groups receiving
either of the two silages containing 0.5 percent urea produced the
most 4.0 percent fat-corrected milk per day (44.3 and 42.7 pounds),
while the group receiving the 0.5 percent calcium carbonate silage
produced the least amount (35.7 pounds) of 4.0 percent fat-corrected
‘milk. All remaining groups were intermediate to these levels and

differences were not statistically significant. Differences among

82

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QQHD N05 o O MGM: Nm. o 0 moqu mm“: .meD wfioz UCGEUNQHH.

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Amowmawm moneomav Hmauu coaumuomquu.m mqm¢a

83

treatment groups in percent SNF, pounds of SNF per day, percent milk
fat, and pounds of milk fat per day were not statistically significant.
While little difference was observed in efficiency values (pound TDN
per pound gain), the group receiving 0.5 percent calcium carbonate
silage produced less milk and therefore was less efficient than all
other groups.

Digestibility and Nitrogen
Balance Studies

 

 

Wether lambs were used in digestibility and nitrogen balance
studies to further evaluate silages fed in the second experiment
(1964-65). The results of this study are presented in Table 10.

The total feed (silage plus grain) intake per day was as follows:
Control, 7.267 pounds; 0.5 percent urea, 7.250 pounds; 0.75 percent
urea, 7.210 pounds; 0.5 percent calcium carbonate plus 0.5 percent
urea, 7.629 pounds; 0.5 percent calcium carbonate, 8.452 pounds and
0.5 percent calcium carbonate plus 0.75 percent urea, 8.248 pounds,
respectively. When analyzed across trials, differences in feed intake
among groups were not statistically significant. Within trials the
range between the low and high feed intake was 0.419 pounds in Trial

I and 0.204 pounds in Trial II. In Trial I, there was a definite
depression in digestibility of dry matter, ash, and protein in the
treated corn silages with a significant (P < 0.05, P < 0.01) depres-
sion of crude fiber digestibility in the 0.5 percent urea silage. In
Trial II, similar trends were noted in ash, ether extract, and protein
digestibility when urea was present. In this trial, ash digestibility

was depressed (P < 0.05) when urea was added in combination with

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mHH HmHue

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+ moomo N... .o
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m.m+ q.Hm a.mo ~.Hm man.mm ~.- m.~a mmmHHm «my: am.o
a.o+ «.mm s.mo m.mm maa.om m.mm «.ma mmmHHm Houuaoo
mH HmHua

mucoaummua
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moamamm ommz samuoum uomuuxm umnam sm< Houumz unaduwumaou
cowouuaz Hogan owauo mun

 

 

Emma:m mouqoaHv anamH ou emu

mommHHm auoo HmuaoeHuodxo mo cosmHmn sowouuws was muaaanwumowww mo musowowmmooonu.oH mnm<a

85

calcium carbonate. The effect of urea level on apparent digestibility

is presented in Table 11.

TABLE ll.--Effect of urea on apparent digestibility of treated corn
silages '

 

 

Chemical Dry Crude Ether Nitrogen-
Constituent Matter Ash Fiber Extract Protein Free Extract

 

Urea level

 

0% urea 72.5 34.5 51.0 82.9 66.6 80.4
0.5% urea 73.0 22.8 45.4 82.4 64.9 81.7
0.75% urea 72.2 27.0 51.8 81.5 64.0 80.0

 

When urea was used as an additive in silage, there was a slight
depression in the digestibility of ash and protein. The depression
in ash digestibility was highly significant but confounded with time
and thus difficult to evaluate. When these data were analyzed across
trials, ash digestibility was significantly lower in the 0.5 percent
urea, 0.75 percent urea and 0.5 percent urea plus 0.5 percent calcium
carbonate silages than in the control silage. The crude fiber digest-
ibility of the 0.5 percent urea silage was also lower (P < 0.01) than
the control, 0.75 percent urea, and 0.5 percent calcium carbonate plus
0.5 percent urea silages. The differences in dry matter digestibility
approached significance (P < 0.05). There were no significant dif-
ferences in nitrogen balance within or across trials by levels of urea.
The nitrogen balance for the 0, 0.5, and 0.75 percent urea silages
was +5.12, +5.05, and +3.46 gm. per day, respectively. Likewise, there

was no difference in the urinary or fecal nitrogen excretion per day

86
as the level of urea increased. These values for the 0, 0.5 and 0.75
percent urea silages were 10.34, 7.80; 8.78, 7.49; and 9.44, 7.26 gm.
per day, respectively.

The urea containing silages appeared to have a diuretic effect
upon the lambs as there was a slight increase in total urine volume
as the level of urea increased. The total urine volume for the lambs
fed the 0, 0.5 and 0.75 percent urea silages was 4,170, 5,140, and
4,739 ml., respectively. These differences were not significant.

The biological values of the silage proteins were determined
with the data presented in Table 12. Only two lambs are represented
for the value of the 0.5 percent urea silage. The third lamb had a
higher calculated metabolic fecal nitrogen excretion than the total
fecal nitrogen excretion and could not be used. The value for the
0.5 percent calcium carbonate silage was higher, 68, but a low
biological value, 16.19, from one lamb reduced the group value. How-
ever, no real trends could be concluded from the data because of wide

variation within treatment groups.

TABLE 12.--Biologica1 values of experimental corn silage proteina

 

W L
_—____—

0.5% 0.75% 0.5% 0.5% CaC03 0.5% CaCO3

 

Treatment None Urea Urea CaCO3 0.5% Urea 0.75% Urea
Percent
Biological value 67 70 54 55 60 62

 

aSilages supplemented with cornstarch and soybean oil meal.

87

Silage Input-Output Data

 

The loss in dry matter from the silages is presented in Table
13. Less silage was put into silos 3 - 6 (1963-64) than in silos
7 and 8. The remainder of the silos were filled with high moisture
corn silage, used in another experiment, and was separated from the
whole plant corn silage by a sheet of black plastic. The average
percent loss of dry matter for the 1963-64 and 1964-65 silages was

8.6 and 11.0 percent, respectively.

 

88

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DISCUSSION

During the past two decades, many chemical adjuncts have been
added to corn silage in an attempt (1) to improve nutritional qualities
or (2) to alter fermentation processes.

In some cases, such chemicals exert buffering actions in the
silage mass. Because of the complexity of the system, the exact
manner by which they do so is not as yet clearly understood. Chemical
additives probably combine with silage organic acids to form the cor-
responding salts and water which is a weakly ionized compound. This
reaction neutralizes the acid and thus prevents the rapid decrease in
pH normally associated with silage fermentation. Thus, organic acid
production continues until all buffering components are saturated and
pH decreases to the point of inhibiting fermentation processes. In a
biological system, such as a silage fermentation, other reactions pro-
ducing the same end result (stimulation of organic acids) are con-
ceivable. The organic acids, depending upon their equilibrium constant
(pka), probably exist in a state of equilibrium between the acid salt
and the free acid form. Upon ionization, an increase in hydrogen ions
would be expected. In a silage containing no added buffers, but con-
taining the necessary media for an active bacterial fermentation, the
only resistance to a rapid decline in pH occurs from naturally occurring
buffer compounds. This process would occur until the hydrogen ion

89

90

concentration is great enough to inhibit further fermentation processes.
If compounds are added to the silage containing buffering components,
such as NH4+, Ca++, or C03-” ions, an increase in the buffering action
would occur. Calcium carbonate in solution may be hydrolyzed to form
calcium hydroxide and carbonic acid. The calcium hydroxide, which is
strongly ionized, would form Ca++ and OH- ions with the result that the
OH- ions could remove free hydrogen ions from solution. Urea, under
the action of bacterial or plant enzymes, would be broken down to
ammonia and carbon dioxide. The carbon dioxide could react with water
to form carbonic acid, a weak acid, and ammonia with water to form
ammonium hydroxide or hydrogen to form NH4+. In all cases, free
hydrogen ions would be removed from the media and, until the different
buffer components become saturated, the hydrogen ion concentration
would not increase at as rapid a rate as in untreated silage. All
these reactions and undoubtedly many others occur in a buffered silage.
However, which reactions actually occur and which function as the pre-
dominant buffering reactions is still a matter of theoretical con-
jecture.

In the present study, there was a slight increase in pH when
either urea, diammonium phosphate, calcium carbonate, or dicalcium
phosphate was included in the silage. While urea produced only slight
increases in pH in this study during the fermentation period, the
values for those samples taken during the feeding experiments were
comparable to the untreated silages. Bentley g£_al, (1955) and

Klosterman g£_§1, (1963) reported pH values ranging from 4.1 to 7.6.

However, most of their silage mixtures contained 10 to 25 pounds of

91

urea. Bentley g£_§1, (1955) also ensiled corn silage with 20 pounds
of urea and 2.0 pounds of dicalcium phosphate per ton. The resulting
pH of the silage was 3.95, while in the present study with 15 pounds
of dicalcium phosphate and 10 pounds of urea, the pH was 4.4. The
difference in level of chemical additives may account for the dif-
ference in pH observed in the two studies.

Limestone or calcium carbonate produced similar trends in pH.
The mean pH values of these as fed samples for the two calcium carbonate
treated silages in the present study were 3.7 and 3.7, respectively.
Simkins £5 31, (1964), Byers g£_§l, (1964) and Klosterman g£_§1, (1963)
reported pH values of 3.9 to 4.2 for silages treated with 10 to 20
pounds of limestone.

As mentioned previously, no reports were available on the
effect of adding diammonium phosphate to silage. From the data of
this study, diammonium phosphate may react similar to urea in its
chemical action by the formation of acid salts. The phosphate portion
of this compound could conceivably react with available hydrogen ions,
forming a phosphoric acid radical, thereby creating an opposing force
to the elevation of pH. However, since this would occur only at a
neutral or basic pH, the quantitative effect of this reaction is
questionable.

Additive combinations increased the silage pH.more than a
single additive (P‘< 0.01). This was true for all additive combina-
tions, and especially at their higher concentrations (0.5 percent
calcium carbonate plus 0.75 percent urea). All chemical additions

resulted in increased organic acid production compared to the control

92

silage. When used as the only additive, calcium carbonate stimulated
greater amounts of organic acids than urea or diammonium phosphate in
the 1964-65 silages, but this did not occur in the 1963-64 silages.
A slight difference in acid production due to either the height in the
silo at which the silage was taken or the time of year at which it
was fed was noted in the 1963-64 silage containing 0.5 percent calcium
carbonate plus 0.5 percent urea. The samples taken for the growth
trial were from the top of the silo during the time of the year be-
tween January and April. The lactation study was performed during
early summer with silage from the bottom one-half of the silo. The
acetate was higher and lactate lower in the top half of the silo
whereas the reverse occurred in the bottom half of the silo. Whether
this was due to a difference in fermentation at varying levels in
the silo, to elevated environmental temperatures or elevated silage
temperatures from surface fermentation, or sampling error is not
known.

The range for all silages of acetate and lactate expressed on
a dry matter basis was 1.08 to 2.28 and 8.42 to 13.06 percent, respec-
tively. These values are in close agreement with those reported by
Klosterman §£_§1, (1963) for chemically treated corn silages. The
use of adjuncts increased the lactate production over that found in
the control silage (P 2 0.07, 1963-64 silages and P 2 0.10, 1964-65
silages). Chemical additives also increased acetate production, but
differences among treatment means were significant only in the 1964-65
silages (P < 0.05). When additives were combined, lactic acid was

increased over that found in the control silage (P < 0.05, 1963-64

93

silages and P 2 0.10, 1964-65 silages). The same trend was also true
for acetate production (P < 0.05, 1964-65 silages). This would indi-
cate an even greater chemical action allowing greater acid production
when the concentration of chemical components increased. In 1964-65,
the silages containing 0.5 percent calcium carbonate contained greater
amounts of lactic and acetic acids than the control silage (P 2 0.10
for lactate) and (Pv< 0.05 for acetate). Silages with added calcium
(silos 6, 7, 8) contained greater amounts of both acetic and lactic
acid (P 2 0.10 for lactate, 1963-64 and P < 0.05 and P 2 0.10 for
acetate and lactate, 1964-65). These acid data in the present study
indicate that calcium carbonate is a stronger chemical adjunct than
urea and are in agreement with the results of Klosterman g£_§l, (1963).
Urea and diammonium phosphate additions increased the crude
protein equivalent of the treated silages (P‘< 0.01 and P < 0.05 for
both additives). In general, the crude protein equivalent of the
silages increased in proportion to the level of urea added to the
silage. These data are in agreement with reports by Bentley §£_§l,
(1955), Wise gt_§l, (1944), Gorb and Lebedinskij (1961), Goode (1955),
Palamaru et a1. (1961) and Klosterman g£_gl, (1961). Whether this
increase in crude protein is in the form of bacterial protein or
other nitrogenous compounds is not known and deserves further study.
The percent of theoretical crude protein equivalent of the
treated silage and the percent loss of protein equivalent from added
non-protein nitrogen (NPN) were computed with the following considera-
tions. The crude protein of the control dry matter times the dry

matter of the treated silage would give the crude protein of the

IN

94

treated silage before NPN was added. The pounds of added NPN times

the percent crude protein equivalent of the NPN (262 percent for urea
and 132 percent for diammonium phosphate) would give the pounds of
crude protein equivalent added to the treated silage. The sum of both
crude protein equivalent values (natural plus added NPN) would give the
theoretical crude protein in treated silages. When the theoretical
values of the treated silage were divided into the actual or analyzed
crude protein equivalent value, the percent of theoretical was obtained.
The theoretical value minus the analyzed value divided by the NPN
crude protein equivalent which was added to the silage would give the
percent of NPN crude protein equivalent lost. The percent of the
theoretical crude protein ranged from 85 to 89 percent, while the per-
cent NPN crude protein equivalent lost ranged from 32 to 45 percent.
Bentley g£_§1, (1955) reported apparent urea recovery values ranging
from 94 to 112 percent, respectively, over a three year period for
silages containing 17 to 25 pounds of urea. In the present study, the
lowest loss (31.6) occurred in the silages containing 15 pounds of
urea. These values are subject to error in sampling accuracy, loss

of NPN at the time of ensiling or any factors which would prevent the
attainment of the theoretical crude protein equivalent.

Further evaluation of the data indicated that within the first
twenty days after ensiling, 25 to 30 percent of the NPN crude protein
equivalent was lost. This loss may occur due to fermentation pro-
cesses. However, the possibility still exists that all of the cal-
culated amount of NPN did not become ensiled which would enter a

larger error into any loss calculations. This loss was computed in

95

the same manner as the total NPN crude protein equivalent loss using
the 0 to 20 day samples. Approximately 86 percent of the NPN crude
protein equivalent present after 20 days fermentation was recovered
in the samples fed during the feeding trials.’

The addition of compounds containing either calcium or phosphorus
increased the ash content of the silages. The greatest increase in ash
content appeared in the combination additive silages. Whether the
increase in ash content could be attributed directly to a rise in
either calcium or phosphorus is not known. The crude protein content
of the silages was increased, but as noted previously, this was true
only in those silages with added non-protein nitrogen compounds. No
other changes in composition were noted, except for the 1964-65 con-
trol silage which contained a higher percentage of ether extract than
the remaining silages. The reason for this is not known.

In growth trials, heifers made adequate live body weight gains
when fed the treated silages. These gains were not different statis-
tically for the two silages compared the first year (1963-64). In the
second year (1964-65), the individual silages were fed without equal-
izing protein intake to compare the silage mixtures as the sole feed
for growing heifers. The heifers receiving the silages containing 0.5
percent calcium carbonate either alone or in combination with 0.5 or
0.75 percent urea gained less than similar heifers fed the control or
urea treated silages (probability range of 0.01 to 0.05). Cattle fed
the 0.5 percent calcium carbonate silage consumed less silage dry matter
per day (probability range of 0.01 to 0.05). The group receiving the

0.5 percent calcium carbonate plus 0.75 percent urea silage required

96

more dry matter to produce a pound of gain (P < 0.05). These results
are in agreement with McCullough (1964), Nicholson and Cunningham
(1964) and Megli g£_§1, (1965) who have reported reduced gains or in-
take with limestone treated silages. However, Mohler gt 31, (1962)
and Klosterman §£_§l, have not reported these adverse effects.

The heifers receiving silages with urea serving as the only
chemical additive made slightly better gains as the level of urea in-
creased. These gains were significantly better than the gains made by
heifers receiving 0.5 percent calcium carbonate or 0.5 percent calcium
carbonate plus 0.75 percent urea silages (probability range of 0.01 to
0.05). This improvement in gains was probably due to increased crude
protein equivalent in the silages. When combined with 0.5 percent
calcium carbonate, increased gains were not associated with increasing
levels of urea. Bentley g£_§1, (1955), Bentley §£_g1, (1956a), Harvey
§£_§l, (1962), Harvey g£.§1, (1963), Klosterman 35 21, (1964), and Karr
g£_§l, (1965a) have reported good live body weight gains with urea
silages and in addition Newland and Henderson (1965), Klosterman gtwgl.
(1960) and Klosterman g£_§1, (1962) reported good results with
limestone-urea silages. In most of these studies, additional energy
and protein were fed while in the present study corn silage was the
sole source of energy and protein. Even under this regime, the group
receiving untreated control silage gained an average of 1.91 pounds
per day. The control silage provided approximately 10 percent crude
protein (D.M; basis) and raises the question concerning additional
protein supplementation from concentrate feeds for raising heifers

in this weight range (380-900 pounds) on a corn silage diet. In the

97

present study ad libitum silage feeding was followed. If controlled
fed, protein intake would probably have limited growth of heifers fed
control silage but not those fed the urea supplemented silages.
Heifers fed ad libitum corn silage for long periods may become exces-
sively fat. However, if the silage contains 0.5 percent urea, con-
trolled feeding practices may be employed and still meet both energy
and protein requirements for normal growth.

In the lactation studies, corn silage was the major source of
nutrients for all cows on experiment. In the first year's work (1963-
64), the animals receiving the 1.0 percent diammonium phosphate silage
consumed less silage dry matter per day, dry matter per hundred pounds
of body weight, total dry matter and T.D.N. per day (probability
range of 0.01 and P < 0.05). As a consequence, less 4.0 percent FCM
was produced by the animals of this group. Oltjen g£_§l, (1963) re-
ported that ammonia was released when diammonium phosphate was added
to saliva or distilled water. The amount of this compound remaining
in the silage after fermentation is not known. If this compound is
broken down in a similar manner as urea, (Schmutz g£_§l, 1964) a
small amount of diammonium phosphate may be present in the silage after
cessation of active fermentation processes. A small amount in the
presence of saliva may release sufficient amounts of ammonia to reduce
silage consumption. When 0.5 percent calcium carbonate was added in
combination with diammonium phosphate, the depression in intake was
not observed. Similarly, in contrast to observations in the heifer
trial (1964-65), no depression in silage intake by milking cows was

observed when 0.5 percent calcium carbonate was used as the sole

98

chemical additive as reported by Simkins gE_§1, (1964), Simkins §5_§1,
(1965) and Kesler g£_§1, (1964). Byers gt a1, (1963) and Byers g£_§l,
(1964) also reported no difference in production or dry matter intake
when silage preserved with limestone was fed.-

In the second lactation study (1964-65), the animals receiving
the 0.75 percent urea silages consumed less silage dry matter per day,
silage dry matter per hundred pounds of body weight and total dry matter
per day (probability range of 0.01 to 0.05). Total digestible nutrient
intake was also lower for these two groups (P < 0.05). In this study,
0.5 percent calcium carbonate did not improve performance when included
with 0.75 percent urea. Because of this depressed intake, milk pro-
duction was lower (38.6 vs. 42.1 pound/day) for these two groups than
the remaining groups with the exception of the group fed silage con-
taining 0.5 percent calcium carbonate. The highest yield was from
the 0.5 percent urea groups (44.3 and 42.7 pounds/daY). In the 1964-
65 lactation study, the intake of grain was not equalized for each of
the silage groups. When the cows were randomly assigned to the silage
treatments, by chance, several of the lower producing cows within each
outcome group were assigned to the 0.5 percent calcium carbonate
silage. Since at the start of this experiment each cow was fed to
meet her requirements for maintenance and milk production, these cows
were fed lower amounts of grain. This was continued throughout the
experiment since each outcome group was fed according to the mean per-
sistency decrease in milk production for that group. Because of lower
grain feeding, this group (0.5 percent calcium carbonate) consumed more

silage dry matter per day than most of the remaining groups (probability

99

range of 0.01 to 0.05). This group also consumed as much or more total
dry matter per day and T.D.N. per day as the remaining groups. However,
this group produced less 4.0 percent F.C(M. than the remaining groups.
Whether this difference in production is due to a lower feed utilization
(pounds T.D.N./pound 4% F.C.M.) or to a slight difference in energy con-
centration in the total ration is not known. In this trial the animals
were randomly placed into outcome groups according to their expected
milk production during the experimental period. The average actual
milk production expressed as a percentage of the expected production
for the control, 0.5 percent urea, 0.75 percent urea, 0.5 percent calcium
carbonate, 0.5 percent urea, plus 0.5 percent calcium carbonate, and
0.75 percent urea, plus 0.5 percent calcium carbonate silages was 93.4,
91.4, 89.4, 86.2, 92.4, and 92.6 percent respectively. With the ex-
ception of the control and the 0.75 percent urea plus 0.5 percent calcium
carbonate silages, similar trends were noted as that found with daily
F.C.M. production.

The question may be raised whether stimulation of organic acid
production in silage is warranted when the silage is fed to animals
for different production purposes. Lactic acid appears to increase
more than any of the other organic acids in treated silages. In
many cases, treated silages have not significantly affected weight
gains or milk production. When organic acids are included in ruminant
rations, the rumen fermentation plays a predominant role in assessing
the nutritional value of these acids. In this media, one of the
recognized breakdown products of lactic acid is propionic acid. When
these acids (acetate, propionate or lactate) were fed to lambs or

steers, slight to no differences in gains were noted (Bentley g£_§l,

100

1956b; Klosterman g£_§1, 1960). A depression in intake in proportion
to the lactic acid concentration as well as a depression in gains was
reported by Emery g£_§l, (1961). However, there was an increased feed
efficiency in proportion to the intake of lactic acid and with lactate
salts the depression in appetite was not as great as with the free
acid. In a second report (Emery g£_§l, in press), lactic acid feeding
did not significantly increase gains or milk production whencompared
to an equal amount of corn. Similar results for milk production have
been reported by Radloff and Schultz (1963). Rook and Balch (1961)
infused acetic, propionic and butyric acids intraruminally to study
their effect upon lactation. While acetate increased the yield of
milk, fat percentage and daily fat yield, propionate and butyrate
infusions resulted in a change in milk composition but not in milk
yield. Other research by Armstrong and Blaxter (1957) and Armstrong
g£_al, (1958) in which acetic, propionic and n-butyric acids were
infused either singly or in combination indicated that there was an
increased nitrogen retention and the major portion of energy retained
in the body was in the form of fat. Ekern and Reid (1963) indicated
that diets creating a higher proportion of propionic and butyric acids
relative to acetic acid in the rumen favored the energetic efficiency
of body gains.

In reports where limestone treated corn silage has been fed to
lactating animals, there have been tendencies toward higher rumen
propionic acid levels (Byers g£_§1, 1964 and Simkins £5 31, 1965).

In both reports, milk yield was not significantly affected by the

feeding of treated silages. However, milk fat percentage was lower

101

(P1< .10) in the treated silage group (Simkins gg_al, 1965), while
Byers §£_§l, (1964) reported no difference in milk fat percentage.
However, Byers g£_§l, (1964) included hay in the total ration (approx-
imately 8.2 to 9.0 pounds per day) which maintained rumen acetate
levels at 63.6 molar percent. When normal rumen acetate levels are
maintained no depression in milk fat percentage would be expected.
In the study by Simkins g£_§l, (1965) corn silage was the only roughage
source. The rumen acetic acid concentration for both control and
treated silage groups (approximately 56.0 on a weight percent basis)
was lower than the corresponding levels reported by Byers §£_a1, (1964).
Infusion or feeding either lactate or propionate did not appear to
stimulate milk production. This would be expected since propionate
represents one of the major end-products of rumen fermentation of
lactic acid. However, since lactic acid has produced variable results
for growth or fattening, end-products of lactic acid degradation in
the rumen may be beneficial for animal gains. Because of the apparent
difference in intermediary metabolism of these compounds, the addition
of chemical compounds, other than to improve protein content appears
to be a questionable practice for lactating dairy cows. While the
infusion or feeding of organic acids has presented the basis for this
discussion, the metabolism of these acids naturally occurring in feed
or derived from feed via ruminal fermentation may be somewhat different
from the results of infusion or feeding experiments.

In digestibility studies, there was a slight, but not signifi-
cant, depression in apparent digestibility of dry matter, ash and

protein in the treated corn silages of the first trial. There was a

102

significant depression in crude fiber digestibility in the 0.5 percent
urea silage (probability range of .01 to .05). In the second trial,
comparing silages containing 0.5 percent calcium carbonate and 0.5
percent calcium carbonate plus 0.75 percent urea, a depression in
apparent digestibility of ash, ether extract and protein was found in
the silage containing urea. The difference in ash digestibility was
significant (P<< 0.05). As the level of urea increased, there was a
slight but non significant depression in digestibility of protein.
These data are in contrast to Karr §£.§1, (1965a) who reported an
improvement in dry matter digestibility with added urea, and Gorb and
lebedinskij (1960) who found that urea added to maize silage improved
both the protein and crude fiber digestibility. In the present study,
the rations offered to each lamb were equalized in TDN, and protein.
In the study of Karr 25.3l: (1965a) a low protein basal ration was
compared with non-protein nitrogen supplemented rations. The ration
variable may explain the differences in digestibility observed in the
two studies.

Urine excretion level increased as the amount of urea in the
silage increased. Hart §£_§l, (1939) and Drill (1954) both state urea
can be diuretic. Krug and McGuigan (1955) in discussing the pharma-
cological effects of urea stated that, "It inhibits water absorption
in the tubule of the kidney and thus produces diuresis."

Since total collections of urine and feces were made for all
lambs, biological values were computed using a value of 0.0333 gm.
endogenous nitrogen excretion/kilogram body weight and 0.55 gm.

metabolic fecal nitrogen/100 gm. of dry matter consumed as stated

103

by Harris and Mitchell (19413). These values were used because of the
similarity of the lamb body weights in the two studies. In a second
study (Harris and Mitchell, 1941b), similar values were reported when
corn silage and urea were fed to lambs in a growth experiment. The
biological value of protein in the control corn silage was 67 percent.
Biological values for the treated silages were lower (ranging from
54-62) with the exception of the 0.5 percent urea silage which had a
value of 70 percent. This value represented the average of only two
lambs since the third lamb had a higher calculated metabolic fecal
nitrogen excretion than the total observed fecal nitrogen excreted and
could not be used. Because of wide variation among animals treated
alike, definite conclusions could not be made. The assumed metabolic
fecal and endogenous urinary nitrogen excretion values may have
contributed to the observed animal variance.

The loss of silage dry matter from the silo ranged from 8.6 to
11.0 percent. These losses resulted from spoilage, silage juice
runoff, fermentation losses, and waste upon removal of the material
from.the silo. In the 1964-65 silages, three silos (3, 5, and 7)
were equipped with automatic silo unloaders. In the remaining silos
(4, 6, and 8), the silage was removed by hand. These data indicate
less spoilage throughout the silage mass when automatic unloaders
were employed than when the silage was removed manually. However, the
automatic unloaders would mix spoiled silage with good silage and
thus minimize detection of spoiled silage unless present in large

quantities.

SUMMARY AND CONCLUSIONS

The value of treated whole plant corn silage was studied over
a two year period with urea, diammonium.phosphate, calcium carbonate
and dicalcium phosphate serving as chemical additives. The fermenta-
tion pattern was followed with measurements of pH, crude protein
equivalent, and organic acid production. The nutritive value of the
individual silages was evaluated by conducting two growth, two lacta-
tion, and two digestibility trials.

The initial and final pH values for two untreated control
silages were 5.1, 3.6; and 5.4, 3.7, respectively. There was a slight
increase in pH when either urea, diammonium.phosphate, calcium carbonate,
or dicalcium phosphate were included in the silage. While urea pro-
duced only slight increases in pH in this study during the fermentation
period, the values for those samples taken during the feeding experi-
‘ment were comparable to the untreated silages. Limestone or calcium
carbonate produced similar trends in pH.

Chemical combinations increased the pH more than single chemical
additions (P‘< 0.01). This was true for all chemical combinations, and
especially at their higher concentrations. No significant differences
in pH were observed among silages containing either urea or calcium
carbonate. However, the interaction between these two compounds
significantly increased the pH values (P‘< 0.05).

Urea and diammonium phosphate additions increased the crude

104

105

protein equivalent of the treated silages (P‘< 0.01 and P < 0.05 for
both additives). In general, the crude protein equivalent of the
treated silages increased in proportion to the level of urea added

to the silage. The percent of the theoretical crude protein recovered
ranged from 85 to 89 percent, while the percent N.P.N. crude protein
equivalent lost ranged from 32 to 45 percent. However, 25 to 30
percent of the N.P.N. crude protein equivalent loss occurred between
the zero and twentieth day of fermentation.

All chemical additions resulted in increased organic acid
production compared to the control silage. Calcium carbonate stimulated
greater amounts of organic acids than urea or diammonium.phosphate
in the 1964-65 silages, but this did not occur in the 1963-64 silages.
The range of acetate and lactate production expressed on a dry matter
basis was 1.08 to 2.28 and 8.42 to 13.06 percent, respectively.
Chemical combinations increased lactate production in both years
(probability range of 0.05 or 0.10) and acetate production in the
1964-65 silages (P < 0.05). Silages with added calcium contained
greater amounts of acetate and lactate in the 1964-65 silages (prob-
ability range of 0.05 and 0.10) and lactate in the 1963-64 silages
(P 2 0.10).

The ash content of the treated silages was increased by addi-
tions of either calcium carbonate or diammonium.phosphate. Silages
with added N.P.N. compounds also contained increased crude protein
equivalent values.

In growth trials, heifers made adequate gains when fed treated

corn silages. In the first trial, differences between two 0.5 percent

106

urea silages with different calcium sources were not significant. In
a second trial, heifers receiving the silages containing 0.5 percent
calcium carbonate either alone or in combination with 0.5 or 0.75 per-
cent urea made lower gains per day than either the untreated control
silage or the 0.5 or 0.75 percent urea silages. This difference was
significant (probability range of 0.05 to 0.01) for the 0.5 percent
calcium carbonate and the 0.5 percent calcium carbonate plus 0.75
percent urea silages and could be explained by either a significant
depression in intake or feed utilization. Those heifers receiving the
silages with urea serving as the only added chemical made slightly
better gains (probability range of 0.05 to 0.01) as the level of urea
increased.

In lactation studies, animals receiving the silage containing
1.0 percent diammonium.phosphate consumed less (probability range of
0.01 to 0.05) silage dry matter per day, dry matter per hundred pounds
of body weight, total dry matter and T.D.N. per day and produced
less 4.0 percent F.C.M; per day. When 0.5 percent calcium carbonate
was added in combination with diammonium phosphate, or when 0.5 percent
calcium carbonate was added as the only additive, this depression in
intake did not occur. In a second lactation study, silages containing
0.75 percent urea followed a similar pattern as the 1.0 percent
diammonium phosphate silage in the previous study. One-half percent
calcium carbonate did not improve the performance when included with
0.75 percent urea. Because of this depressed intake (probability
range of 0.01 to 0.05), milk production was lower for these two groups

than the remaining groups with the exception of the 0.5 percent

107

calcium carbonate silage which was lower. The highest yields were
from the two 0.5 percent urea groups.

In digestibility studies, there was a slight but non-significant
depression in apparent digestibility of dry matter, ash, and protein
in the treated corn silages of the first trial. Crude fiber digest-
ibility was significantly depressed (probability range of 0.01 to
0.05). In a second trial, in which silages with and without 0.75 per-
cent urea were compared, a slight depression in apparent digestibility
of ash, ether extract, and protein was found in the silage containing
urea. The difference for ash digestibility was significant (P'< 0.05).
As the level of urea increased, there was a slight depression in
digestibility of protein.

The biological values of the silage proteins were variable and
definite conclusions could not be made. This may have resulted from
assumed endogenous urinary and metabolic fecal nitrogen values.

The losses of silage dry matter averaged from 8.6 to 11.0

percent for both years of the experiment.

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