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SOME FACTORS AFFECTING INTAKE OF
ROUGHAGES BY DAIRY CATTLE

By

Bruce I. Veltman

AN ABSTRACT OF A THESIS

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

MASTER OF SCIENCE

Department of Dairy

1962

ABSTRACT

SOME FACTORS AFFECTING INTAKE OF
ROUGHAGES BY DAIRY CATTLE

by Bruce I. Veltman

The study herein was conducted to obtain informa-
tion on the various factors which affect the intake of
roughage feeds by dairy cattle.

Intraruminal administration of hay, beet pulp,
direct-cut alfalfa silage, and two silage fractions in-
creased total dry matter intake of rumen fistulated cows
in every case. Voluntary intake was reduced except when
the silage extract fluid was added.

Dried beet pulp administered intraruminally to cows
fed grain and hay appeared to be digested rapidly and re-
sulted in no change in rumen pH, whereas, cows fed only
hay did not appear to digest beet pulp as rapidly. This
resulted in an accumulation of beet pulp in the rumen and
a greatly reduced rumen pH. NaHCO3 added into the rumen
of one cow restored pH to normal and resulted in a rapid
reduction of beet pulp accumulation and increased numbers
of rumen microflora.

Rumen ammonia concentrations were higher when cows
were fed direct-cut alfalfa silage than when fed alfalfa'
hay. There was little difference in rumen pH. Higher

Bruce I. Veltman

concentrations of acetate and a higher acetate-to-
prOpionate ratio was observed in rumen fluid when hay was
fed, but butyrate concentrations were higher when silage
was fed.

Rumen retention time of dry matter and fiber was
reduced as roughage dry matter intake increased. Percent
dry matter as well as total dry matter in the rumen in-
creased as roughage dry matter intake increased while

total weight of rumen contents remained nearly constant.

SOME FACTORS AFFECTING INTAKE OF
ROUGHAGES BY DAIRY CATTLE

By
[1"
I . (I

Bruce ItVeltman

A THESIS

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

MASTER OF SCIENCE

Department of Dairy

1962

ACKNOWLEDGEMENTS

The author wishes to express his sincere appreci-
ation for the assistance, advice, and detailed criticism
given by Dr. J. W. Thomas in the preparation of this
thesis. The author is also grateful for the critical
reading and helpful suggestions of Dr. R. S. Emery, Dr.
H. Haffs, Dr. W. D. Collings, and numerous other pe0ple in
the dairy department.

The author is indebted to Dr. C. A. Lassiter for
the appointment of research assistant thereby making this
project possible.

The author wishes to thank his wife, Mary, for her
unselfish help, encouragement, and patience during the

preparation of this thesis.

TABLE OF CONTENTS

Page

INTRODUCTION . . . . . . . . . . . . . . . . . . . . 1

REVIEW OF LITERATURE . . . . . . . . . . . . . . . . 2
Factors Affecting Intake of Roughages by Ru-

minants. . . . . . . . . . . . . . . . . . . 19

Factors Affecting Intake of Legume Silage . . . 51
PROCEDURES 0 O O O O O O O 0 O O O O O O O O O O O O 54

Procedures for Intraruminal Treatments. . . . . 54
Procedures for Preparation of the Two Silage

Portions O O O O O 0 O O O O O O O O O O 0 O 36
Procedures for Rabbit Trial . . . . . . . . . . 38

Procedures in the Beet Pulp Study . . . . . . . 39

Procedures for Studying Rumen Characteristics
When Cows Were Fed Silage Versus Hay . . . . 42

Procedures for Laboratory Analysis. . . . . . . 43

Dry matter determination . . . . . . . . . 43
Collection and preparation of rumen fl id

samples . . . . . . . . . . . . . . . . 45
In vitro fermentation. . . . . . . . . . . 44
Determination of pH. . . . . . . . . . . . 46
Carbohydrate determination . . . . . . . . 46
Uronic acid determination. . . . . . . . . 46
Rumen ammonia determination. . . . . . . . 47
Rumen volatile fatty acid analysis . . . . 48
Measurement of rumen contents. . . . . . . 50
Fiber analysis . . . . . . . . . . . . . . 50
Carbohydrate analysis. . . . . . . . . . . 51

RESULTS. . . . . . . . . . . . . . . . . . . . . . . 55

Effects of Intraruminal Administration of Feed
Materials on Dry Matter Intake of Fistulated
cows 0 O O O O 0 O O O O O O O O ' O O O O O O 55

TABLE OF CONTENTS (Continued)
Page

Intake by Rabbits Fed Silage-Juice Treated
Pellets. O O O O I O O O O O O O O O O O O O 59

Factors Affecting Rate of Beet Pulp Digestion
and Effects of Beet Phlp on Rumen Character-
iStics O O O O O O O O O O O O O O O O O O O 62

Rumen Characteristics of Cows Fed Bay or Direct-
cut Alfalfa Silage . . . . . . . . . . . . . 76

Retention Time and Other Relationships in the
Rumen Affected by Rates of Intake of Rough-
ages . . . . . . . . . . . . . . . . . . . . 85
DISCUSSION 0 O O 0 O O O O O O O O O O O O O O O O O 96
WY. 0 O O O O O O O O O O O O O O O O O O O O 0 118
LITERATURE CITED 0 O O 0 O O O O 0 O O O O O O O O O 122

APPMDIX O O O O O O O O O O O 0 O O O O O O O O O 0 1-52

TABLE

10

LIST OF TABLES

Average Voluntary and Total Intake of Cows
When Six Feed Materials Were Placed in the
men. 0 O O O O O O O O O O O O O O O O O 0

Effect on Intake When Two Cows Were Admin-
istered- Silage Juice 0 O C O O O O O O O O 0

Dry Matter Intake and Weight Gains by Rab-
bits Fed Pellets Treated with Silage Juice
Vs. Control Pellets. . . . . . . . . . . . .

Rumen Uronic Acid Concentrations for the

Three Days and Sample Times Indicated in Re-
lation to Intraruminal Beet Pulp Administra-
tion to Each of Three Cows . . . . . . . . .

Rumen Total Soluble Carbohydrates Concentra-
tions for the Three Days and Sample Times
Indicated in Relation to Intraruminal Beet
Pulp Administration to Each of three Cows. .

Rumen Volatile Fatty Acid Concentrations
Before Feeding and Average Concentrations
After Feeding for the Three Days in Relation
to Intraruminal Beet Pulp Administration to
Each of Three Cows . . . . . . . . . . . . .

General Microscopic Observations of Rumen
Microflora of Two Cows While Receiving Large
Amounts of Beet Pulp for Eleven Days . . . .

Summary of Results of Beet Pulp in Vitro
Fermentation Trial Using Rumen Fluid from
Cows Fed Hay, With and Without Beet Pulp and
Cows Fed Grain + Hay, With or Without Beet
Pulp O O O O O O O O O O O O O O O O 0 O O 0

Analyses of Variance of Results of the Beet
Pulp in Vitro Fermentation Trial . . . . . .

Rumen pH in Cows Fed Silage Vs. Hay at Three
Levels and Six Times During the Day. . . . .

Page

57

6O

65

68

7O

73

74

77

TABLE
11

12

15

LIST OF TABLES (Continued)
Page

Rumen NH in Cows Fed Silage Vs. Hay at
Three Leéels Six Times During the Day. . . . 78

Average Rumen Volatile Fatty Acid Concen-
trations for Cows Fed Hay Vs. Silage . . . . 79

Average Acetate-to-Propionate and 2-to-5
Carbon VFA Ratios for Cows Fed Hay Vs. Si-
lage O O O O O O O O O O O O O O O O O O 0 0 8O

FIGURE

LIST OF FIGURES

The effects of intraruminal administration
of beet pulp on percent beet pulp in rumen,
rumen pH, and voluntary dry matter intake

of three cows, A103 fed grain and hay, Al92
and T20 fed hay . . . . . . . . . . . . . .

Average postprandial rumen pH of two cows
fed alfalfa hay or direct-cut alfalfa si-
lage at three levels, 5 lb. D.M./day, 12
lb. D.M./day, and ad libitum. . . . . . . .

Average postprandial rumen ammonia concen-
trations of two cows fed alfalfa hay or
direct-cut alfalfa silage at three levels,
5 lb. D.M./day, 12 lb. D.M./day, and ad
libitum O O O O O O O O O O O O 0 0 O O O 0

Relation between rate of dry matter intake
and rumen retention time calculated as lb.
D.M. in the rumen divided by daily dry mat-
ter intake. . . . . . . . . . . . . . . . .

Relationship between rate of fiber intake
and rumen retention time calculated as lb.
fiber in the rumen divided by daily fiber
intake. . . . . . . . . . . . . . . . . . .

Relationship between rate of dry matter
intake and percent dry matter in the rumen.
The solid line represents all feeds. The
long-dashed line represents S cows fed hay
paired by rate of intake with S cows fed
silage given the short-dashed line. . . . .

Relationship between rate of intake and dry
matter in rumen contents as percent of body
weight 0 O O O O O O O O O O O O O O O O O 0

Relationship between rate of intake and
total weight of rumen contents as percent
Of bOdy weight. 0 O O O O O O O O O O O O 0

Page

65

81

82

86

87

91

92

95

LIST OF APPENDIX TABLES

APPENDIX
TABLE Page

I Analysis of Variance Tables of Results
When Rabbits Were Fed Silage Juice Treated
Pellets Vs. Control Pellets . . . . . . . . 155

II Rumen Uronic Acid and Total Soluble Carbo-
hydrate Concentration During Intraruminal
Beet Pulp Administration. . . . . . . . . . 154

III Rumen Volatile Fatty Acid Concentrations in
Cows Fed Hay and Silage . . . . . . . . . . 155

IV Analysis of Variance of Rumen Volatile
Fatty Acid Concentrations for Cows Fed Hay
vs. Silage at Three Levels and Six Times
During the Day. . . . . . . . . . . . . . . 156

V Analysis of Variance of Acetate-to-PrOpion-
ate and 2-to-5 Carbon VFA Ratios for Cows
Fed Hay vs. Silage at Three Levels and Six
Times During the Day. . . . . . . . . . . . 158

VI Data of Rumen Emptyings . . . . . . . . . . 159

VII Relationships between Dry Matter and Fiber
in the Rumen, Retention Time and Intake . . 140

VIII Relationships between Dry Matter Intake
and Rumen Contents. . . . . . . . . . . . . l4O

IX Comparing Rumen Retention Time of Five Cows
Fed Hay vs. Five Cows Fed Silage at Similar
Levels of Dry Matter Intake . . . . . . . . 141

X Intake and Rumen Retention Time Comparing
Five Cows Fed Hay with Five Cows Fed Hay
Plus Silage Juice 0 O O 0 O O O O O O O O O 142

XI Intake and Rumen Retention Time Comparing
Four Cows Fed Hay Administered Washed
Pressed Silage vs. Four Cows Fed Hay Ad-
ministered Silage Juice . . . . . . . . . . 142

INTRODUCTION

Dairy cattle feeding during recent years has under-
gone many changes. DeveloPment of forage harvesting
equipment especially that for making silage has enabled
dairymen to completely mechanize harvesting and feeding
Operations. This has permitted the harvesting of large
amounts of forage crops during the relatively short period
of Optimum quality and yield while at the same time reduc-
ing field losses and weather damage. These advances have
permitted more efficient feed production and handling,
but meanwhile have created other problems.

Observations over a period of years have shown that
cows consume larger quantities of hay in terms of dry mat-
ter than of silage produced from forage of comparable
quality. Because of the economic advantages in harvesting
hay crOps as silage, a study to investigate factors re-
sponsible for the limited consumption of silage may even-
tually lead to a solution of this problem.

The object of the studies in this report is an at-
tempt to learn more about factors affecting intake of
roughages by dairy cattle. Through a better understanding
of these factors, investigators will be able to plan a
more systematic approach to the problem of limited intake

of silage by dairy cattle.

REVIEW OF LITERATURE

Undoubtedly one of the first learning processes of
an infant is that the pain of hunger is relieved by the
intake of food. Only in relatively recent times have ef—
forts been made to understand the basis and mechanisms
responsible for the feeling of hunger and subsequent in-
take of food. Early theories explaining the sensation of
hunger were approached largely through speculation. One
early theory considered the stomach to be the exclusive
seat of hunger feelings. Gastric contractions were be-
lieved to result from the empty stomach and these contrac-
tions were said to be responsible for hunger feelings (48).
The validity of this theory was seriously doubted by inves-
tigators who observed that an animal's intake of food was
unaffected when the stomach was removed or denervated mak-
ing gastric contractions impossible (96, 100). Others ac-
cording to Anand's review (1) postulated that the sensation
of hunger resulted from.depletion of body energy reserves.
They speculated that within the brain some center sensitive
to depletion of these reserves initiated the feeling of
hunger causing the animal to search for food.

Roux (96) and others late in the 19th century sug-
gested the idea that hunger was a sensation of general

origin involving all or many organs of the body including

2

the circulating blood and brain centers. More recent and
comprehensive investigations with the benefit Of modern
technology tend tO support the theory that regulation Of
food intake is a central nervous phenomena influenced by
various organs Of the body (1).

During the 19th century clinicians described cases
where obesity in humans has apparently resulted from brain
tumors and lesions in the base of the brain (1). Later
Keller and his group (62, 65, 64) experimentally produced
lesions in the hypOphysiOhypothalamic region in dogs and
cats which resulted in obesity in animals surviving the
Operation. They established that this Obesity was asso-
ciated with an increased food intake. Hetherington (51),
in 1940 with the aid of improved surgical techniques, was
able to selectively produce lesions in the hypothalamus
without involving the hypOphysis. He was able to relate
the resulting Obesity in rats exclusively to damage Of
the hypothalamus.

The fact that damage to the hypothalamus was re-
sponsible for increased food intake and resulting Obesity
has prompted intensive investigations to elucidate the
role Of the hypothalamus in regulation of food intake.

Hetherington (51, 55) Observed that bilateral le-
sions produced in the ventromedial nuclei or immediately

lateral to this nucleus were most effective in producing

Obesity in rats. Anand and Brobeck (2, 5) Observed bi-
lateral lesions restricted tO the region lateral to the
ventromedial nuclei and sparing the lateral nuclei also
produced hyperphagia and Obesity. They produced lesions
in the extreme lateral portion of the lateral hypothala-
mus producing complete aphagia and death Of the animal
by starvation. This effect of lateral lesions occurs
whether the ventromedial region is intact or has been pre-
viously destroyed. They suggested that axons from the
ventromedial region project laterally to produce inhibi-
tion in the lateral area.

The Observations of these investigators (2, 5) and
others not listed lead to the suggestion that the lateral
hypothalamic area be designated a "feeding center" and
the medial area a ”satiety center.”

WOrk has been done with other species indicating
-that the hypothalamic centers are similarly located and
that they have much the same action regardless of species.
Anand et al. (5, 54) observed that electrical stimulation
in the lateral hypothalamic area in cats produced a marked
increase in daily food intake. Larsson (69) produced simi-
lar effects in goats by electrically stimulating the la-
teral hypothalamic area. Hypertonic salt solutions locally
injected in the lateral area also produced increased food

intake. Local injections Of an anesthetic into these

lateral areas caused temporary aphagia in starved goats.
Larrson (69) also occasionally produced hyperphagia in
goats by electrical stimulation in regions caudolateral
to the mammillary body. Stimulation Of the lateral
hypothalamus produced such effects as licking, swallowing,
and chewing. These Observations suggest that facilita-
tory influences from the lateral hypothalamus project
caudally into the brain stem and thus bring about augmen-
tation Of the feeding reflexes (l).

Feeding reflexes in experimental animals have been
shown capable Of being carried on independently of higher
brain centers. Miller and Sherrington (84) showed decere-
brate cats capable Of swallowing and even to rejection of
certain material placed on the tongue. Dell (55) de-
scribed the rOle of the reticular formation in exploration
and feeding behavior. The reticular formation, except for
the special sensory and motor nuclei, makes up much Of the
gray matter portion Of the brain stem. He stated that
blood sugar begins to drOp some time after a meal, at which
time the circulating adrenaline level rises to augment
liberation Of glucose from liver glycogen stores at a
faster rate. The reserves Of glycogen rapidly decline,
causing a greater reduction in blood glucose accompanied
by a continuing rise in adrenaline levels. Adrenaline is

a powerful stimulant to the reticular formation. This

6

excitation initiates a random locomotor activity while at
the same time lowering the threshold to stimulation
throughout the reticular formation. At this point, nerv-
ous stimulation from higher brain centers (e.g., cerebral)
can easily influence the action of the lower reflex cen-
ters in the reticulum and give some purposeful action in
food seeking behavior tO this random activity. It does
not seem unreasonable tO suggest that the hypothalamus
sends inhibitory or excitatory impulses integrating the
activity of the feeding mechanisms and perhaps in this
way regulates the quantity Of food intake.

Though the hypothalamus has been the Object Of in-
tensive investigation, there is much more to be learned
about its functions. Experimental Observations to date
are very sketchy and incomplete regarding the interwork-
ings between the hypothalamus and higher brain centers.

Evidence suggests that cerebral structures Of the
frontal and temporal lobes included in the "limbic system”
may influence food intake. The limbic system, not well
defined, lies superior to the thalamus and hypothalamus
and is believed to be connected both directly and indirectly
with these bodies. It is believed the limbic system has
some integrating control on the functions Of the hypo-
thalamus as well as the autonomic system. The studies
imply the possibility Of both facilitation and inhibition

7

of feeding behavior from the limbic level. Anand (6) has
noted that changes in food intake after limbic lesions
were more marked in monkeys than in cats while Anand and
Brobeck (4) did not find any change in food intake in
rats with similar lesions. This species difference sug-
gests a process Of "encephalization" in higher animals at
the limbic levels. Other Observations suggest the limbic
region in higher animals may have more to do with choice
or discrimination between different foods than with quan-
tity Of food intake. Anand (6) noted monkeys, especially
after temporal lobe lesions, lost their discriminatory
power between edible and nonedible Objects.

The hypothalamus is generally recognized as the
center responsible for maintenance Of the balance between
energy input and expenditure within the animal body (21,
65, 80). This regulatory influence Of energy intake is
accomplished by inhibitory or excitatory impulses on re-
flex feeding centers lower in the brain stem and possibly
directly to organs involved. Information from several
sources throughout the body is continually acting on the
hypothalamus which ultimately integrates it into action.

Circulating metabolites Of the blood have received
considerable attention regarding their influence on the
hypothalamus. Blood glucose was the first metabolite to

receive attention. Early Observers (65, 50) noted blood

8

glucose levels were high soon after a meal and gradually
declined until hunger was evident. Carlson in 1916 (50)
advanced the idea that control of food intake was based
on the concept that lowering Of blood sugar occurring be-
tween meals stimulated stomach contractions producing
hunger pains which in turn motivated the animal to eat.
This theory found wide acceptance for many years among
investigators and was used as a basis in designing experi-
ments.

Later, Mayer and colleagues (79, 80, 81) postulated
glucoreceptors sensitive to blood glucose levels exerted
influence on the "satiety centers” in the hypothalamus and
thus regulating the body energy balance through appetite
regulation. Mayer and associates conducted several experi-
ments attempting to locate glucoreceptor mechanisms in an
effort to establish their theory. Mayer and Marshall (77,
78, 82) demonstrated a rapid uptake of glucose in the
hypothalamus as indicated by the accumulation of gold fol-
lowing injections Of goldthioglucose. Later studies using
goldthioglucose showed the hypothalamus was not exclusive
in its high utilization Of glucose. After intravenous in-
jections Of radio active glucose phosphate, Forssberg and
Larsson (41) noted a greater uptake Of P32 in the hypo-
thalamic feeding center than in other hypothalamic areas

Of hungry rats. They emphasized such results indicated

9

only an over-all increased activity in this region and not
direct evidence to indicate the hypothalamus being a pri-
mary glucoreceptor mechanism center.

Anand (8) implanted electrodes in areas throughout
the hypothalamic region Of monkeys and cats for recording
the electrical activity produced. Blood glucose levels
were changed by intravenous infusion Of glucose or intra-
venous injection Of insulin. He Observed increased elec-
trical activity,in the "satiety centers” with the produc-
tion Of hyperglycemia, while electrical activity was re-
duced in the feeding center. Conversely, hypoglycemia
decreased activity in the "satiety centers" with a slight
increase noted in the "feeding centers." He did not
interpret these findings as convincing evidence of gluco-
receptors in the hypothalamus. 'This evidence does estab-
lish, however, a relationship between glucose utilization
and activity within hypothalamic areas.

Grossman (47) and Janowitz (60) Observed that blood
sugar levels per so were not a good indicator in deter-
mining appetite. They found hunger did not occur simul-
taneously with the lowest level Of blood sugar, but later
when it had started to rise. These same investigators
(57, 59) Observed in rats and dogs that production Of
hyperglycemia did not decrease food intake. Grossman (45),

experimenting with normal human subjects, Observed that

10

production of hyperglycemia did not suppress food consump-
tion. Mayer (80) suggests, that for studying the influ-
ence Of blood glucose on appetite, absolute blood glucose
levels by themselves do not give a measure of glucose
availability. Van Itallie (108) was able to demonstrate

a generally reliable representation of glucose utiliza-
tion by measuring ateriovenous glucose differences. His
experiments showed these A-V glucose differences were high
in normal humans after a meal and that hunger was always
Observed as these values approached zero.

The mechanism by which the hypothalamus regulates
body energy balance is not clear when one considers blood
glucose the only metabolite concerned in this balance.
Evidence presented to date does not appear to be in mutual
agreement.

Changes in concentrations Of other metabolites have
been implicated as having a relationship with intake and
possibly with energy expenditure. Study of the nonesteri-
fied fatty acid (NEFA) fraction of blood plasma has re-
vealed a close inverse correlation between ateriovenous
blood glucose differences and (NEFA) levels. These also
correlated well with satiety and hunger feelings. The
(NEFA) fraction in the blood appears to originate pri-
marily from adipose tissue with the amount in the blood

regulated by some lipolytic factor presumably in the

11

circulation (87). Evidence suggests that a fat mobilizing
hormone exists which is believed to be associated with
long term food intake regulation and also short term
energy mobilization (26). The experiments of Bates (11)
showed that the amount Of fat mobilized daily was prOpor-
tional to the size Of fat deposits. These more recent
findings tend to support the early ideas Of Kennedy (66)
who postulated that the long range control of food intake
was regulated by some element sensitive to varying con-
centrations Of circulating metabolites. He suggested that
the hypothalamus might be the receptive sight which in
turn exerts its control on appetite.

Mellinkoff (85) correlated appetite with serum
amino acids and blood sugar concentrations in normal human
subjects given hydrolyzed protein and glucose. Evidence
suggested an inverse relationship between serum amino acid
concentration and appetite. Little experimental work has
been reported in support of this postulated control mechan-
ism exoept to confirm that such a relationship does exist.

Brobeck in 1948 proposed the hypothesis Of thermo-
static regulation Of feed intake (20). He wrote, "Animals
eat to keep warm, and stop eating to prevent hyperthermia.”
He stated that specific dynamic action Of a ration deter-
mines the amount Of food eaten. The effective regulator

was not the energy value Of the food but rather the amount

12

Of extra heat released in its assimilation. This signals
the hypothalamic mechanisms to adjust the total quantity
of food eaten.

Since Brobeck stated his hypothesis much experi-
mental evidence has been accumulating substantiating this
principle as being a function in regulation of body energy
balance.

Kibler and Brody (25, 67) Observed feed intake Of
cattle was drastically reduced when exposed to high en-
vironmental temperatures in which they were unable to
adequately dissipate body heat to maintain normal body
temperatures. Brobeck (20), studying effects Of tempera-
ture on rats, found food intake falls with temperature
rise to a point where they will not eat due to hyperthermia.
Appleman and Delouche (10) observed the feed intake of
goats declined slowly as temperatures advanced to 90° F.
and then dropped Off more abruptly as temperature increased.
Feeding stopped when body temperatures rose to 104° F.
From these results there appears to be two possible rela-
tionships between temperature and feeding: (l) a gradual
fall in intake as temperature rises may be a response to
stimulation Of peripheral thermal receptors without change
in central body temperature, and (2) the more abrupt
drop in intake may result from central hyperthermia (22).

Assimilation Of food consumed produces a heat rise in the

13

body above the postabsorptive level. This has been
termed specific dynamic action. Passmore and Ritchie (89)
demonstrated the promptness Of specific dynamic action in
experiments measuring skin temperature of human subjects
after a meal. Within one hour there was a detectable
rise in temperature. Booth and Strang (18) recorded the
elevation Of skin temperature which follows a meal on nor-
mal and Obese human subjects. They attempted a correla-
tion between this heat rise with onset Of satiety and sug-
gested the possibility that heat itself produces satiety.
The effect Of specific dynamic action appears to partici-
pate more prominantly in satiety when environmental tem-
peratures are high. This additional heat is much more
likely to act upon the central receptor mechanism to bring
about more heat elimination and inhibition Of food intake.
Conversely in a cold environment the animal produces extra
heat to maintain body temperature. The specific dynamic
action, under these conditions, is then a small portion Of
the total heat produced and is insufficient to produce a
thermal effect (22). MacDonald and Bell (72) Observed
that intake Of milking cows increased 6 to 9 percent when
average daily temperatures drOpped from 40° F. tO 0° F.
Several experiments have been conducted in an ef-
fort tO understand the mechanism by which temperature af-
fects the central nervous system and ultimately body

energy balance.

14

Magoun et a1. (75) showed that local warming of
the preOptic area caused mobilization Of various heat
loss mechanisms. This has been considered the site of a
”heat loss center.” More recently, Kundt et a1. (68)
have shown that local cooling of the area induced periph-
eral vasoconstriction. This evidence indicates the pre-
Optic and rostral hypothalamus area is a "temperature
control center." Anderson (9) Observed an interesting re-
lationship between heat and cold applied locally in this
area and appetite Of goats. Eating was initiated by cool-
ing this area in a feed satiated animal, but ceased when
temperatures returned to normal. When cooling was con-
tinued intermittently for an hour, eating occurred during
periods Of cooling. Meanwhile, the thermal regulating
mechanism Of the animal was actuated, resulting in general
peripheral vasoconstriction. This allowed body tempera-
ture to rise above the temperature at which a goat nor-
mally stops eating. In this case the goat kept on eating
normally. Warming this area soon after beginning the
regular meal caused the animal to stOp eating and begin
drinking large volumes Of water. Peripheral vasodilata-
tion and gradual lowering of body temperature followed.
These Observations indicate a close relationship between
thermo sensitive elements in the preOptic area and ros-

tral hypothalamus and the hypothalamic "feeding center."

15

It now appears that Specific dynamic action acts
directly upon cells in or just ahead Of the hypothalamus
to evoke cutaneous vasodilatation, and this is accompanied
by central inhibition Of appetite and induction Of sati-
ety. This would tend to indicate that under normal con-
ditions the thermostatic regulation is Of minor influence,
but under heat stress conditions this mechanism exerts a
powerful influence on feed intake.

Gastric hunger contractions have been considered
to be one Of the primary hunger sensations from early
times. A consideration Of how the gastrO-intestinal area
fits into present day concepts Of the regulation Of food
intake is Of interest.

Early investigators attempted to specifically lo-
cate these contractions and determine where they origi-
nated. Carlson (50) noted the sensation Of hunger pangs
was chiefly related tO activity in the fundic portion of
the stomach and that motility in the pyloric antrum dur-
ing digestion caused nO sensation Of hunger. Such con-
tractions may be as great as those occurring in the empty
stomach during a hunger period. Action in the fundic
portion Of the stomach, associated with hunger, may
greatly exceed that Observed during digestion. Quigley
et al. (95) employed the triple balloon technique for a

detailed study Of hunger sensations. The subject

16

indicated the feeling Of hunger sensations during these
tests. Pangs were Observed most commonly in the distal
region Of the stomach; though, at times, when the distress
Of hunger pangs was greatest, several contractions over
the stomach were observed simultaneously. Employing a
double balloon in the duodenum along with the stomach
balloons, Quigley Observed that mild hunger pangs initialky
originated in the duodenum. As the hunger became more
intense, stomach pains predominated.

Following these early investigations, attempts have
been made to ascertain the basic factors which regulate
hunger contractions and the associated hunger sensations.
Carlson (50) stated that the gastric hunger mechanism is
primarily automatic or independent of blood changes and
central nervous influences. More recently Stunkard et al.
(104) and Quigley (94) have demonstrated in human subjects
that small ateriovenous glucose differences coincide gen-
erally with gastric hunger contractions and hunger sensa-
tions. When A-V glucose differences were large along with
higher levels Of blood sugar, stomach contractions were
inhibited as well as hunger sensations. Several investi-
gators (25, 60, 94) found no correlation between absolute
levels Of blOOd sugar and spontaneous gastric hunger con-

tractions.

1?

Grossman and Janowitz and associates (58, 59, 98)
produced evidence that gastric distension is important in
bringing about satiety. Inert bulk placed into the stom-
ach Of a dog which had undergone esOphagostomy was as ef-
fective as food in producing inhibition of eating. On
the other hand, Quigley (94) reported food substances,
confined to the stomach, did not inhibit hunger contrac-
tions; in fact the substances might stretch the stomach
and augment hunger contractions. Stomach contractions
were inhibited soon after food entered the upper intes-
tine. He also reported evidence that a gastric inhibit-
ing substance released from the intestine was enterogas-
trone. Janowitz (59) noted that enterogastrone inhibited
gastric contractions when given experimentally but did
not alter the amount Of food eaten. Grossman (46) and
Quigley (94) agree it is not essential that animals or
humans experience gastric hunger sensations for normal
regulation of food intake.

Sharma et a1. (99) have recently studied relation-
ships between the hypothalamus and gastric contractions
in various experiments by recording electrical activity
in the hypothalamus. Inflation Of an intragastric bal-
loon increased electrical activity Of the "satiety cen-
ter." They believe this emphasizes the role played by
gastric distension in bringing about satiety through

18

activation Of "satiety centers." Glucagon injections,
followed by a subsequent rise in blood sugar and A-V
differences, resulted in increased activity in the
satiety center and simultaneous inhibition of gastric
hunger contractions. Glucagon administered after destruc-
tion Of satiety centers produced a rise in blood glucose
but no inhibition Of gastric hunger contractions nor any
change in electrical activity Of the hypothalamic region.
This evidence supports the idea that increased activity
of satiety regions is the factor which inhibits gastric
hunger contractions.

Gastric hunger sensation is but one factor in-
volved in motivation Of food intake in the maintenance Of
life. The exact role Of gastric contractions in the
hunger state is not clear, although it seems certain that
they can be inhibited by the satiety mechanism.

In contrast to the extensive work on feed intake
regulation in small animals, there is very little experi-
mental work on factors that influence the intake of farm
animals. The mechanisms by which ruminant animals regu-
late feed intake may be quite different from those in
small animals. Ruminants consume bulky feeds which are
low in energy, while the simple stomached animals con-
sume feeds high in energy having a minimum of bulk. Food

eaten by small animals is broken down in the stomach and

19

small intestine and assimilated. In ruminants, on the
other hand, a large portion Of food eaten is broken down
by the fermentative action Of rumen microflora and absorbed
from the rumen before reaching the lower digestive tract.
Ruminants, used primarily for meat and milk production,
have been bred to consume large quantities Of feed. More
rapid weight gains in fattening beef cattle and greater
milk production in dairy cows has been shown to be re-
lated to larger feed intake. Greater feed intake by cat-
tle is Of major economic importance to cattlemen as well
as the consumer. Little is known, however, about the

factors involved in regulating feed intake by ruminants.

Factors Affecting Intake of
Roughages by Ruminants

Information on feed intake of dairy cattle up to
1950 was summarized by Blaxter (l4) and indicated that the
amount Of feed intake, measured in terms of dry matter,
increased as energy concentration Of the ration increased.
This was based on feeding grain mixtures in addition to
a diet primarily composed Of roughages. Experiments con-
ducted by Blaxter and associates (15, l6, 17) since that
time have led them to suggest that purely physical factors
dominate the regulation Of intake Of roughages by sheep.
Reports by Campling and Balch et a1. (27, 28) and Makela

2O

(74) regarding roughage intake by dairy cattle are in
agreement with this idea. This appears to be the reverse
of the situation Of intake regulation in simple stomached
species. Data of Mayer (80) showed that rats increase
food intake as energy concentration Of the ration is re-
duced in order to maintain a constant caloric intake.
Persson and Svensson (90) Observed intake of chickens fol-
lowed the same trend, concluding that this species eats
tO maintain a constant energy intake. Experiments Of
Peterson et al. (91) in which they used wood cellulose to
increase the bulk in the ration fed to chicks stated:
”The primary factor in the voluntary food intake Of young
chicks appears to be the need for energy.” Kennedy (66)
suggests that a regulation Of food intake Of the same
general type must occur in humans, based on the very constanqy
of an adult body weight in man, consuming a wide variety Of
diets and expending variable amounts Of energy.
Illustrating the principle that ruminants consume
more high than low quality roughages, Blaxter (1?) fed
sheep low, medium, and high quality long hay. Quality
was determined in digestibility trials and expressed as
apparent digestibility. Intake and rate Of passage in-
creased with improvement in apparent digestibility.
Campling, Freer, and Balch conducted a series of

investigations to study physical factors in the rumen

21

affecting voluntary intake Of hay by cows. In their first
report (27) they determined the importance Of the amount
Of digesta in the rumen at different times relative to
the time of feeding. Fistulated cows were used and con-
tents were removed at defined times after eating. The
cows had been trained to consume the entire daily ration
during a relatively short time after feeding, usually
three to four hours. In the first experiment, food boluses
were removed from the rumen as the hay was eaten during
a normal feeding period Of three hours. The food removed
amounted to 76 to 96% Of the normal daily intake. After
this time the cows were allowed to eat normally. Eating
was prolonged for another three or four hours resulting
in an increased total intake, 70 tO 85% over the normal
daily intake. These results suggested that the accumula-
tion Of swallowed food in the rumen exerts a direct and
immediate effect on the time the cow ceased to eat hay
and on the amount consumed.

In the second experiment, 50 pounds Of digesta
(rumen contents) containing 7.1 pounds Of dry matter or
equal to 8.4 pounds of hay were removed from the rumen.
The digesta were removed at three different times which
were: 1) during the meal, 2) just after the meal, and 5)

mid-way between meals. The cows increased their hay

22

intake 2.4, 6.2, and 0.4 pounds for the three treatments,
respectively. The cows never completely compensated for
the food removed. The nearest compensation occurred when
50 pounds of rumen contents were removed just after the
meal when only 2.2 pounds less hay than normal were con-
sumed. When 50 pounds of digesta, with an estimated dry
matter content of 10% (a low estimate), were added to the
rumen before a meal the cows decreased their hay intake
by 4 to 5.8 pounds. These results indicate that a cow
eats to a nearly uniform distension Of the rumen or other
non-defined conditions therein.

In a third experiment water filled bladders con-
taining up to 100 pounds were placed in the rumen. In-
take decreased 0.54 pounds Of hay for each 10 pounds Of
water added. While this was a small decrease, calcula-
tions showed that 0.6 pounds of dry matter in digesta,
which contain about 10% dry matter, occupy about the same
space as 10 pounds of water. When 100 pounds Of water were
poured directly into the rumen daily, voluntary intake Of
hay was not changed significantly. Campling et a1. con-
cluded from the results Of their experiments that changes
in intake, due to the transfer Of digesta, were due tO
the dry matter or volume associated with the dry matter
in the rumen rather than the water alone. Thomas (106)

dripped water into the rumen Of heifers with no effect on

23

intake. Hillman (54) and Thomas et al. (106) found that
the addition Of water to hay or silage, which was fed to
heifers and cows, did not cause an appreciable change in
dry matter intake.

All this evidence indicated that a cow eats until
the rumen becomes distended to some critical pressure
giving rise to a feeling Of satiety, and she then stOps
eating. A reasonable extension Of this assumption could
be that the amount of food eaten during the following meal
may depend upon the rate of breakdown Of food in the rumen
and its subsequent disappearance from the rumen.

Ingalls (56) Observed that sheep fed alfalfa and
trefoil hay ate more frequently and consumed more Of this
forage than when fed brome and reed canary grass. These
Observations suggest the possibility that the legumes
may have been broken down in the rumen more rapidly than
‘the grasses. It also could be that the sheep preferred
the taste Of the legumes or found them physically easier
to handle while eating than the grasses.

Campling et a1. (28) determined the amounts of di-
gesta in the rumen at given intervals after a meal. They
then attempted to relate the amount of reduction Of in-
gested feed in the rumen after a meal and the quantity
of a roughage consumed during the following meal. Rumen

fistulated cows were fed hay or straw ad libitum once

24

daily in part Of this experiment. Rate of breakdown of
ingested feed in the rumen was estimated from rate Of dis-
appearance Of cotton thread placed in the rumen. Mean re-
tention time Of undigested food residues in the alimentary
tract was measured by placing a small amount of stained
food particles in the rumen and counting the number of
stained particles in subsequent samples of feces. Reten-
tion time Of the lower digestive tract was determined by
introducing milled stained food particles into the aboma—
sum at feeding time. The time required for these parti-
cles to appear in the feces was termed lower tract reten-
tion time. The amount Of digesta in the rumen was meas-
ured directly by manually emptying the rumen. Mean volun-
tary intake was 22 pounds of hay and 10 pounds of straw.
The mean digestibility Of dry matter was 65% for hay and
45% for straw. Estimated rate Of digestion as measured
by 25% loss Of weight Of cotton threads in the rumen was
26 hours for the hay compared to 166 hours for the straw,
or six times faster in the hay fed cows. Retention time
Of undigested residues varied greatly between cows. how-
ever, retention time was less in cows with greater feed
intake than in those at lower levels of intake. This was
true for both hay and straw. These Observations led to
the suggestion that some cows have characteristically long

retention time Of undigested residues, and that this

25

factor may account for individual variations in voluntary
intake. The mean amounts Of ingesta in the rumen Of cows
fed hay before feeding was 165 pounds (14.4 lb. D. M.) and
128 pounds (15.6 lb. D. M.) for straw fed cows. This dif-
ference in dry matter amounted to only 6%. After eating
to the limit Of appetite rumen contents Of the hay fed
cows averaged 250 pounds (27.2 lb. D. M.) and for the
straw fed cows 184 pounds (20.2 lb. D. M.). These results
indicate that a cow does not eat to a critical distension
Of the rumen unless this point is different for each
roughage. The rate Of disappearance of feed from the
rumen to some low critical level for a particular feed
proceeding the next meal appeared to determine the amount
Of feed consumed.

Earlier experiments by Campling et al., described
above, indicated that a cow ceased to eat when the rumen
became distended to some critical point. Under the cOn—
ditions Of this experiment, however, the authors have
interpreted the results to indicate that intake was regu-
lated by the amount of ”ingesta” in the rumen some time
before feeding. Whether intake was regulated by rumen
distension or some low critical level Of "some factor"
in the rumen, the amount Of a roughage consumed was
directly related to the rate of disappearance Of ingested

feed in the rumen.

26

Campling et al. (29) recently reported another ex-
periment in which dry matter intake by cows fed straw
alone ad libitum with the addition Of urea into the ru-
men was 40% greater than when no urea was added. These
cows were allowed to eat only Once daily during a short
period as in the experiment described above. Retention
time of dry matter in the rumen was reduced during the
period Of urea administration. The before feeding weight
Of rumen contents was only 7% greater during urea treat-
ment while dry matter in the rumen was the same for both.
After feeding, cows receiving urea had 11%:more dry mat-
ter in the rumen than those fed straw alone. This was
submitted as additional evidence supporting Campling's
et a1. more recent conclusions.

Makela (75) Observed that total weight Of rumen
contents did not vary extensively between cows fed high
and low levels of feed intake. In contrast, dry matter
in the rumen tended to increase as intake Of dry matter
increased. He develOped a method Of expressing rumen re-
tention time of feed components in the rumen and found
with increased feed dry matter intake the retention time
of dry matter in the rumen was reduced. Thomas et al.
(105) Observed little change in the weight of total rumen
contents of cows 4 tO 5 hours after feeding hay or silage

ad libitum or at submaintenance levels. There was,

27

however, considerably more dry matter in the rumens Of
cows fed at the higher level Of intake. Calculations Of
dry matter retention time indicated an inverse relation-
ship between dry matter intake and dry matter retention
time in the rumen. Evidence from the literature

strongly indicates that intake Of feed is directly re-
lated to the rate Of disappearance Of feed primarily from
the rumen.

At this point a review of some of the factors re-
sponsible for differences in rates of time for ingested
food tO disappear from the rumen may be Of interest.

Blaxter (1?) fed sheep long hay, medium ground
cubed, and finely ground cubed hay from the same source.
The before feeding rumen fill was greater in sheep fed
long hay than when they were fed medium and fine ground
grass cubes. Ad libitum intake of long hay was 1800
grams per day compared with 2400 grams per day for the
ground cubed hay. He concluded that changes in physical
form Of a roughage can modify its passage through the
digestive tract. Another explanation could be that the
grinding Of the hay greatly increased the exposed sur-
face area for more rapid attack by rumen microflora re-
sulting in faster digestion. Makela (88) noted the con-
centrate portion Of a ration consisting of ground grains

disappeared much more rapidly from the rumen than hay

28

fed at the same time. He attributed much Of this faster
rate to the small particle size Of this feed. Another
possibility could be that rumen bacteria break down con-
centrate in preference to hay. Difference in particle
size could not explain the more rapid disappearance from
the rumen Of one hay than another when sheep were fed
long hay from two sources. The possibility that one for-
age was broken down more rapidly by rumen microflora than
the other was suggested (16).

Crampton (52) postulated that the simple matter Of
bulk could not be the cause for differences in voluntary
intake Of forages as there is little difference in bulk
between forages that are eaten in widely different
amounts. He suggested that the rate of digestion of the
forage or, more specifically, the rate Of reduction of
rumen load is involved. Therefore the frequency Of eating
ultimately depends upon the ease and vigor of the attack
by microflora on the cellulose and hemicellulose Of the
ingested forage. He also stated that the rate Of diges-
tion may be retarded by circumstances which interfere
with the numbers or activity Of microflora including ex-
cessive lignification (51).

Dehority et a1. (55) studied the rate and extent
of hemicellulose fermentation by rumen bacteria on for-

ages with respect tO stage Of maturity by in vitro

29

technique. It was noted that the extent of hemicellulose
fermentation was reduced with advancing maturity. When
mature forage was removed from the fermentation, however,
and exposed to a ball milling process in which particle
size was greatly reduced, and re-exposed to fermentation
the extent of hemicellulose fermentation increased. This
experiment provides evidence that hemicellulose digestion
is influenced by the maturity Of the forage and suggests
'that this effect is the result of lignin forming a physical
barrier between the plant hemicellulose and rumen bacteria.
Crampton (52) also noted that one species Of forage may
naturally contain a higher percentage of lignin than an-
other. This may explain why one forage is broken down
more rapidly than another and consequently eaten in greater
amounts.

Low nitrogen content in forages can be another fac-
tor responsible for reduced numbers or activity Of rumen
microflora and the resultant retarded breakdown of the
cellulose portion Of forages (51).

A good illustration for this point was brought out
in the experiment by Campling et a1. (29) when straw
alone was fed to fistula cows. Voluntary intake Of straw
was increased by 40%»when 75 grams of urea was placed into
the rumen. Mean retention time of food residues was re-

duced 20%»even when intake was restricted to a pretreatment

50

level. €It was also interesting to note that retention
time through the remainder Of the digestive tract was not
changed by this treatment, thereby, emphasizing the role
Of the rumen in influencing feed consumption. Another
experiment, where urea was fed or directly infused into
the rumen Of sheep and steers fed straw, did not increase
the digestibility Of the straw, and the addition Of urea
reduced voluntary consumption Of straw 12 to 15% (85).

In his review on urea supplementation, Reid pointed out
that urea may not increase microbial activity or percent
digestion Of a feed low in readily available carbohydrates
(95).

Crampton suggests that specific mineral deficien-
cies besides nitrogen or excess bacteriostatic agents in
feed may reduce the rate Of digestion affecting voluntary
intake Of roughages (51).

Smart et al. (101) have demonstrated a factor in
sericea forage that is inhibitory to rumen cellulolytic
activity.

The appetite depressing effects caused by defi-
ciencies Of several inorganic elements has been reviewed
by Lepkovsky (70). Most of the work in this field has
been done with non-ruminant animals and may not apply to

ruminants.

31

Research regarding intermediate products Of rumen
fermentation and deficiencies Of specific metabolites in
the rumen fermentation process has not progressed far
enough at this time for a comprehensive review to be
written regarding relationships between products Of rumen

fermentation and feed intake Of cattle.
Factors Affecting Intake Of Legume Silage

Research regarding intake Of hay-crop silage com-
pared with hay has been extensively reviewed in the thesis
by Hillman in 1959 (54). More recent reports on consump-
tion of silage stored with varying amounts Of dry matter
have been published (45, 86, 107). Research indicates
with few exceptions that cattle consume more pounds Of
dry matter in the form Of hay than silage. There is a
tendency for greater consumption Of silage as the dry mat-
ter percent increases when starting with high quality
early cut forages.

Some work has been reported in the literature show-
ing attempts to isolate various factors responsible for
the decreased intake Of silage. Intravenous infusions Of
glucose and various volatile fatty acids were performed
by Dowden and Jacobson (57) on dairy heifers to study the
effects Of these metabolites on feed intake. They found

infusions Of acetic acid and propionic acid, providing

32

12.5% of daily maintenance requirements for energy, sig-
nificantly depressed intake. Infusions Of glucose, bu-
tyric, valeric, hexonic and lactic acids each providing
6.5% of daily requirements had no significant affect on
appetite. They suggested the possibility Of chemoreceptor
response to changes in blood constituents being a mechanism
regulating intake Of metabolites including these acids.
Silage contains significant amounts Of these acids and
these authors suggested the possibility that these acids
may be a factor responsible for reduced intake Of silage.
Emery et al. (40) fed corn silage soaked with varyb
ing amounts Of lactic acid tO dairy heifers. They Observed
a reduced dry matter intake with increasing amounts Of
U.S.P. lactic acid on the silage. Intake was only slightly
depressed, however, when lactic acid salts were fed in One
instance. The U.S.P. lactic acid may have contained more
impurities and polymers than the lactate salt mixture.
This may explain why intake was depressed more when the
U.S.P. lactic acid was fed. Rusoff and Randel (97) fed
hay soaked with mixtures Of major organic acids repre-
sentative Of those found in good and poor silage. They
Observed heifers consumed significantly more hay soaked
with acid mixtures representative of poor silage than Of
the gOOd silage. They concluded that any decrease in
palatability Of poor quality silage does not appear to be

33

due to its characteristic volatile fatty acid content and
suggested that some other constituents of silage must be
responsible for this decrease.

Thomas et al. (106) conducted a series Of trials
using dairy heifers to study factors that influence the
rate Of consumption of alfalfa silage. In one trial of a
preliminary nature a wide variety Of materials was added
tO silage fed to heifers. In another trial these materi-
als were placed directly into the rumens of heifers. Sev-
eral materials fed or administered had no significant ef-
fect on total dry matter consumption. However, intake was
depressed by addition Of such materials as glucosamine,
large amounts Of lactic acid alone or with other volatile
fatty acids, effluent liquid from a silo, various extracts
and residues from silage, and ammonium salts. These
trials were Of an exploratory nature attempting to sepa-
rate factors responsible for the low intake Of silage.

Investigations should be continued exploring frac-
tions of silage to identify the constituents which limit
voluntary intake. This limiting effect on intake is
probably a metabolic effect rather than a result of
palatability. The relationship Of metabolic products
from silage and/or the rumen with body intake regulation
centers should be studied exhaustively to gain a better
insight regarding the factors which limit consumption Of
silage by cattle.

PROCEDURES
Procedure for Intraruminal Treatments

All animals, except cows A103 and 660, used during
this experiment were non-lactating non-pregnant mature
cows fitted with plastic rumen fistula plugs. The cows
were retained in stanchions with individual mangers con-
structed to minimize feed loss and make possible the
measurement of daily feed intake and refusal. Water was
available at all times. Most cows were fed hay only two
times daily, at 7:50 A. M. and 1:50 P. M. The two lac-
tating cows were fed alfalfa hay plus a grain mixture,
and in the other trials one dry cow was fed fresh-cut
alfalfa forage. The amount of forage fed was at least
10%Iin excess of voluntary consumption. The hay fed as
well as that refused was weighed, and moisture content
was determined for all materials fed or administered.
This allowed calculation of dry matter intake. Alfalfa
hay Of medium quality from the same source was fed
throughout these trials.

The experimental feedstuffs were placed in the
rumen at twelve hour intervals beginning at morning feed-
ing time. Intraruminal infusions of experimental fluids
were made three times daily: during the morning feeding,

six, and twelve hours later. The portion for each infusion

54

35

was stored in glass jugs suspended above the cow and
transferred through rubber tubing into the rumen by way of
the fistula. Administration of dry material required 15
minutes each time and liquids required approximately 20
minutes for each infusion. The amount of dry material
placed in the rumen was administered to the full capacity
Of the rumen.without causing Obvious discomfort to the
cow. However, for any one material, a standard amount was
usually established so that suitable comparisons could be
made between cows. I

The daily amounts and materials placed in the rumen
ranged from 20 to 50 pounds of fresh-cut high quality
mixed alfalfa-grass forage, 10 to 12 pounds of chOpped
hey (the same material as that fed), and 12 to 15 pounds
Of beet pulp, 50 to 52 pounds of grass silage, 50 pounds
of washed pressed silage, and 55 to 56 pounds of the
fluid portion Of alfalfa silage. In two special trials
larger amounts of this fluid were administered. The ef-
fect that each of these materials exerted on voluntary
intake was calculated.

Average daily intake 6 days before and after treat-
ment was compared with consumption during the experimental
period of 8 days. It was reasoned that elimination of
intake on days immediately following a change would give

a more true expression Of the effect Of that treatment on

36

voluntary intake. Consequently, intake on the first day
Of treatment, two days for silage fluid and washed pressed
silage treatment, and two days following treatment were

eliminated from the average.

Procedure for Preparation of

the Two Silage Portions

A hand powered hydraulic lard press was employed
to express the liquid portion from the solid portion of
the direct—cut alfalfa silage used in these experiments.
The capacity of the press was 2.65 cu. ft. which held ap-
proximately 100 pounds of silage as removed from upright
concrete stave silos. A force, up to 160 lbs./sq. inch,
was sustained on the material in the press for a period
Of 45 minutes.

The original silage contained 26.1% dry matter. On
the first pressing, called lst extract, 56 pounds Of juice
were removed from 100 pounds of silage. Approximately
the same amount of water as was in the juice was added to
the remaining silage and allowed to stand 6 to 12 hours.
This permitted the silage to soak up the water and equili-
brate with the soluble portion. The silage was pressed
again and this juice was saved separately. This was called
2nd extract. The juice was stored in ten gallon milk cans

at a temperature of 40° F. for periods up to seven days.

37

The dry matter of the silage juice, carbohydrate, and
volatile fatty acid contents appear below.

1st extract 2nd extract

Dry matter é%) ' 8.42 4.54
carbohydrate " 0.554 0.14

Volatile fatty acids (uM/ml.) 440.00 170.21
formic acid " 8.78 7.52
acetic acid " 178.15 74.25
propionic & butyric " 5.14 0.0
lactic & succinic " 250.50 88.66

pH 4.40 4.45

After the second pressing, the solid material was
removed from the press and placed into a garbage can with
a perforated bottom. The silage was then flushed with
cold water for an hour to remove as much Of the remaining
soluble material as possible.

After the third pressing, the remaining product
averaged 54% dry matter. This was believed virtually ex-
hausted Of the normal silage juice constituents as the pH
of this expelled fluid on pressing was 5.9 compared to 4.4
and 4.45 for the two previous fluid portions. This pro-
duct was called washed pressed silage and was stored in a
cool place, 40 to 50° F., until used in the trial. Dry
matter, fiber, and soluble carbohydrates for the original
silage, the washed pressed silage, and hay fed are pre-

sented below.

38

Silage Washed pressed Hay

 

‘____§ilage
Dry matter (%) 26.1 54.14 86.92
Fiber (% of D.M.) 40.47 53.70 39.75
Soluble
carbohydrate " 18.40 21.70 20.20

Procedures for Rabbit Trial

Since the infusion of silage juice into the rumen
had caused a change in feed intake by cattle, a feeding
trial using rabbits was performed to Observe the effects
this fraction might have on the intake of this species.

The silage juice (first extract) was incorporated
into regular rabbit pellets. This was accomplished by
sprinkling the juice over trays of pellets 2 or 5 times
daily allowing them to air dry between applications.
Caution was taken to prevent the pellets from disinte-
grating and molding. Sufficient juice was added over a
period Of a week to make the juice dry matter amount to
‘5% Of the total dry matter of the pellets. The control
pellets were sprinkled with water in a similar manner to
give them the same physical appearance as the silage
sprinkled pellets.

Six half grown male rabbits kept in individual pens
in a controlled environment were used in this trial. A

preliminary 8 day period was used to establish rate of

39

intake and body weight gain. The rabbits were assigned

to two balanced groups based on intake and body weight.

During the next 8 days one group was fed control pellets
while the other group was fed pellets soaked with silage
juice. The treatments were reversed and the trial con-

tinued for 8 more days. Intake and weight gains were

measured by four day intervals.
Procedures in the Beet Pulp Study

An exploratory investigation was conducted to study
some Of the possible causes for results Observed in the
previous trial when beet pulp had been placed into the
rumens of fistulated cows.

In the first period Of this experiment, a study was
set up to determine whether "cows" adapt to more rapid
digestion of beet pulp after it is fed for a period of
time, and to determine if the ration affects rate of beet
pulp digestion. During the second period a study was
conducted to determine the effect of rumen pH on the di-
gestibility or disappearance of beet pulp from the rumen.

In the first part of the adaptation experiment,
three fistulated cows previously fed hay ad libitum were
used, one Of which was also fed 10 pounds of a dairy cOn~
centrate mixture daily. During the experiment the cows
were continued on ad libitum hay feeding along with beet

4O

pulp placed into the rumen. Voluntary consumption Of hay
was measured as previously described. An attempt to de-
termine if any adaptation occurred was made by determin-
ing the concentration of total soluble carbohydrate and
uronic acids on the day before intraruminal beet pulp ad-
ministration (control day), the lst day, and the 7th day
of treatment. Lower concentrations of carbohydrate and
uronides on the seventh day than on the first day would
be taken as an indication of adaptation. Rumen volatile
fatty acid concentrations were also determined on these
days. This was done to Observe any changes in volatile
fatty acid concentrations associated with adaptation.
Samples of rumen fluid were collected immediately
before feeding, 1.5, 2.5, 5.5, and 4.5 hours after morning
feeding and intraruminal placement of beet pulp. The pro-
cedure for collection and preparation Of rumen fluid is
explained later in the section on laboratory procedures.
The second part of the first period Of this experi-
ment involved an in vitro fermentation using rumen fluid
collected from eight cows to determine if beet pulp, used
as a substrate, was digested more rapidly by cows receiv-
ing beet pulp in their rations than those not receiving
beet pulp. This group was again divided into those cows
fed hay plus grain and those fed hay only. The cows re-

ceiving beet pulp in their ration or intraruminally had

41

been on this diet for at least two weeks, while those cows
not receiving beet pulp had not been fed beet pulp for at
least a month prior to this trial.

Initial and post incubation samples were taken from
the in vitro fermentation apparatus for measurement Of
disappearance of total uronides, total carbohydrates, and
soluble uronides. Gas production was also measured to in-
dicate relative activity among the samples. Total solids
of each fermentation flask were determined for an approxi-
mation of substrate digestion during fermentation.

The second period of this exploratory investigation
involving intraruminal administration Of beet pulp was a
continuation Of the first phase using the two hay fed
cows.

Beet pulp was placed in the rumen for a further
period of 11 days. After the third day of the second
period, NaHCOB was placed in the rumen of one cow in addi-
tion to best pulp. Sufficient NaHCO5 was used to return
rumen pH to the pretreatment level for that cow. The
other cow served as control.

Observations were made on rumen pH, gross visual
approximation Of the percent beet pulp in the rumen in-
gesta, and microscOpic Observations of rumen contents.
Microscopic Observations were made to obtain a rough ap-

proximation Of rumen microbial populations.

42

Procedures for Studying Rumen Characteristics

When Cows Were Fed Silage Versus Hay

Several experiments (44, 55, 71, 107) have shown
that cows consume somewhat larger amounts of dry matter
as hay than as silage when both were made from forage of
comparable quality. The possibility that there may be a
difference in the way these feeds are broken down in the
rumen or that the rate Of breakdown may influence the dif-
ference in intake of these feeds was considered. This ex-
periment was set up to Observe rumen pH, NH} concentra-
tions and volatile fatty acid concentrations when cows
were fed both hay or silage. This was done in an effort
to determine if feeding silage would result in different
values Of these measurements than when cows were fed hay.

Two rumen fistulated cows, T25 and T19 were fed
once daily at three levels of intake beginning with a sub-
maintenance level Of approximately 5 pounds of dry matter
per day, then 10 pounds per day, and finally ad libitum.
These levels will be referred to hereafter as low, medium,
and high, respectively. Hay was fed to one animal while
silage was fed to the other for a period of two weeks at
each level Of feeding beginning at the low level. Rumen
fluid samples were taken on one day toward the end of

each period. The feed to each animal was then reversed

43

and the trial continued beginning on the low level with
another ten days allowed for adjustment at this level.
Jmeen samples were taken on one day of each period: at
1.5, 2.5, 5.5, 4.5, 6.5, and 12 hours after feeding. The
rumen fluid samples were collected and preserved by the
method described in the laboratory procedures. T19 went
"Off feed” when silage was fed at the high level making it

necessary to use a substitute animal, Arthur.
Procedures for Laboratory Analysis

Dry matter determination. All samples Of feed,
materials added into the rumen, and rumen contents for
dry matter determination were handled in the following
way. Individual samples were weighed out into tared pans
and placed in a forced air oven at 80° C. for 48 hours.
The samples were then removed and reweighed. The weight
difference divided by the original net weight times 100
was expressed as the percent dry matter.

Collection and preparation of rumen fluid samples.

The rumen contents were mixed by hand to ensure repre-

 

sentative sampling of the entire rumen. If the contents
could not be mixed adequately, handfuls of contents were
taken from several locations inside the rumen in order to
Obtain reasonably representative sampling. Handfuls Of

rumen contents from the various locations in the rumen

44

were squeezed and the fluid collected in glass jars. These
samples were then immediately taken to the barn laboratory
where pH was determined within five minutes after removal
from the rumen. The samples were then centrifuged at
52,000 times gravity for five minutes to remove solid
particles in the fluid. Fifty ml. (milliliters) of this
sample were measured into a bottle to which 1 m1. Of 50%
H2S04 was added. This was stored in a refrigerator for
carbohydrate, uronic acid, and volatile fatty acid analy-
ses. Another 10 ml. portion of the sample, for the carbo-
hydrate and uronic acid determinations only, was preserved
in 50 ml. of absolute ethyl alcohol and refrigerated until
analyzed.

In vitro fermentation. Samples of rumen fluid
(500 ml.) strained through a double layer of cheese cloth
were Obtained from eight cows about three hours after the
morning feeding. One hundred fifty m1. Of this rumen
fluid and 50 ml. of buffer solution were added to the 250
ml. erlenmyer fermentation flask to which 1 gm. (gram) of
finely ground beet pulp had been previously added. The
buffer solution of anhydrous salts, containing 2.04 gm.
KH2P04 plus 4.56 gm. NazHP04, was made up to 500 ml. with
H20. This resulted in a V10 molar buffer solution with
a pH of 7.0. Each flask was then attached to a gas bur-

ette and placed in a 59° C. water bath. pH Of the rumen

45

fluid mixture was taken at the beginning of the fermenta-
tion. Fifty ml. of each rumen fluid sample were preserved
with 1 m1. of 50% H2S04 (v/v) and stored in a refrigerator
for glucuronic acid and soluble carbohydrate analysis at

a later date. Ten m1. of each rumen fluid sample were
preserved with 2 ml. of 6N H01 for total uronic acid and
total carbohydrate determination. A blank flask contain-
ing 150 ml. of water and 50 ml. of buffer plus 1 gm. of
beet pulp was also included in this fermentation_trial.
Gas production was measured at 0.5, 1, 1.5, 2, and 5

hours after discarding an initial adjustment period of

15 minutes. The flasks were mixed before each reading.
After 5 hours Of fermentation a 50 ml. aliquot Of the fer-
ment was removed and preserved with 10 ml. 6N H01 for
final total uronic acid and carbohydrate determination.
Another portion was removed and centrifuged for 5 minutes
at 1400 times gravity. Fifty ml. Of the supernatant were
preserved with 1 ml. H2804 for determination Of final
soluble uronides and carbohydrates. Another 50 ml. ali—
quot was placed in a sediment tube and centrifuged at

1400 times gravity for 10 minutes and the volume of the
sediment and liquid was immediately read. This volume

was used as an estimate of total solids remaining in the
fermentation flask. Final pH was also determined after

the fermentation in each flask.

46

Determination of pH. The pH of feed and rumen
contents was determined on the Beckman pH meter and
glass electrode using standard procedures recommended by
the manufacturer.

Carbohydrate determination. A method for hydroly—
sis Of beet pulp was developed prior to the fermentation
trial so that samples could be completely solubilized and
hydrolyzed to Obtain representative amounts of substrate
present in the fermentation flasks. In the preliminary

experiments 10 ml. portions of 1/10 N, 1 N, and 6 N H SO

2 4

and 1/10 N and l N HCl were heated with 0.5 gm. samples
Of finely ground beet pulp for 50 minutes on a hot water
bath. Results of the phenol-sulfuric acid carbohydrate
determination (58) indicated a much higher carbohydrate
value for the sample hydrolyzed in l N HCl. An Optimum
hydrolysis time Of 50 minutes on the hot water bath was
established after trying hydrolysis times ranging from
10 to 60 minutes.

Upgpic acid determination. The modified carbazole
reaction of Bitter (15) was used for determination of
uronic acids which result from hydrolysis Of the pectin
in beet pulp. The procedure that was used follows. Six
ml. of the sulfuric reagent (195 ml. H2504 and 5 ml.

M Na2B407) were placed in glass-stOppered test tubes and
cooled to approximately 0° C. One ml. Of the test sample

47

containing between 4 and 60 gm. Of uronic acid/m1. was
added and mixed thoroughly. A set of tubes containing 1
m1. of known concentrations of uronic acid within this
range were run with each analysis. The tubes were then
heated on a boiling water bath for 15 to 20 minutes and
cooled in water to room temperature. Two tenths m1. Of
the carbazole reagent (0.1% carbazole in ethanol) was
added to the tubes, the tubes shaken, heated at 100° C.
for a further 10 minutes and kept in the dark for 5 hours.
The pink color appeared after the second mixing and de-
velOped during the 5 hour period. Optical density was
read at 550 mu.

Rumen ammoniapdetermination. The following pro-
cedure used for determining rumen ammonia was a modifica-
tion Of the Permutit method (50). Two ml. of rumen fluid
sample were measured into a 100 m1. volumetric flask to
which 2 gm. Of Amberlite IR-120H were added and allowed
to stand. A period Of at least 10 minutes was allowed so
the ammonia in the sample would be absorbed onto the
resin. The resin was then washed free of all sample and
2 ml. of 10% NaOH were added to free the ammonia from the
resin. Ten minutes were allowed for this reaction. Seventy
ml. of water and 2 drops of Gum Ghatti solution were added
to the flask followed by the addition of 10 m1. Nessler's

Reagent. After mixing the flask was filled to volume.

48

The Optical density of the resulting colored solution was
read on a Beckman model B Spectrophotometer at wave
lengths ranging from 480 to 520 mu. The frequency that
gave an adequate range on the photometer scale on that
particular day was used. The Optical density reading of
the sample was compared to readings Obtained from a ser-
ies of known concentrations containing a range from 0.2
to 2 mg. N/ml. from a standard ammonia solution that had
been nesslerized in the same way.

Rumen volatile fatty acid analysig. Volatile fatty
acid concentrations in the beet pulp study were determined
by the modified method Of Wiseman and Irvin (111). This
method employed column.partition chromatography using
Celite columns with alphamine red-R as the internal indi-
cator and acetone-petroleum ether solutions as eluents.
Two ml. samples of rumen fluid were mixed with Celite and
placed on the prepared column. Various percentages of
acetone in.petroleum ether (1, 5, 10, 15, 20, 50, and 40%)
were used to elute the various organic acids. The acids
separated into colored bands as they descended the column
and were collected in separate receiving flasks as each
band was flushed from the column. The organic acids usu-
ally collected from rumen fluid were eluted in the follow-
ing order: butyric, propionic, acetic, formic, lactic,

succinic acid. Columns containing a mixture of known

49

concentrations of these acids were run at the same time
along with a blank column as a check for accuracy. The
receiving flasks containing an indicator were titrated
for acidity using 0.1 N KOH. The acidity from the blank
flask for each acid was subtracted from that of each
sample flask to determine the acid equivalents Of each
acid in the sample.

Rumen volatile fatty acids during the experiment
when hay versus silage was fed were determined by gas
chromatography. A model SRL Sargent Recorder coupled to
an Aerograph model A-600-D ”Hy-F1” gas chromatOgraph with
hydrogen flame ionization detector was employed. The ab-
sorbing column was 8 ft., V8 inch CD, of stainless steel
packed with 20% Carbowax 20M on Chromabsorb W. The cham-
ber was maintained at a temperature Of 118° C. and the
injection part at 200° C. The nitrOgen carrier gas flow
rate was 50 m1./min., and the hydrogen gas flow was
25 m1./min. Two to 4 ul. portions of preserved rumen
fluid samples (in H2804) diluted 1:1 with distilled water
were injected into the apparatus. Acetic, prOpionic,
and butyric acids were the only acids which gave a suffi-
cient response so that they could be measured. Calcula-
tion of the amounts of acids in the samples was done by
measuring the area under the curve on the recording chart

compared to areas Of known amounts when standard acid

50

solutions were used. Area, expressed in square centi-
meters, was determined by measuring peak height times
peak width at one half peak height. This gave a more
accurate measurement than measuring peak height alone.

Measurement of rumep contents. All rumen emptyings
were made 4.5 to 5 hours after feeding. Cows were weighed
and returned to their stalls. The entire contents of the
rumen and reticulum were removed and placed into tared
quart jars. The contents were then returned to the rumen.
The closed sample jars were washed of extraneous material
and weighed to determine net contents. The entire con-
tents Of the jars were quantitatively transferred to tared
aluminum drying pans using 150 to 200 m1. ethanol. Dry
matter determinations were made as previously described.

Fiber analysis. Fiber analysis was done by the
acid detergent method described by Van Soest (109).

.Two grams Of air dry material were weighed into a
glass beaker for refluxing. A conventional crude fiber
apparatus was used. One hundred ml. of 2% hexadecyltri-
methylammonium bromide dissolved in l N H2804 were added
in the beaker. Two m1. of decahydronapthalene wenaadded
as an antifoamant and to facilitate removal of pigments.
The mixture was heated to boiling and refluxed on the
fiber apparatus for 60 minutes. The acid-detergent fiber

was filtered on a previously weighed sintered glass

51

crucible, using light suction. The filter mat was lightly
stirred while washed with a stream of hot water (90 to 100°
C.) until filtrate became free from color and foam. The
contents were then washed repeatedly with cold acetone un-
til washings became clear. The crucible was sucked free of
acetone and dried in a forced draft oven at 100° C. for 2
hours, cooled in a dessicator and weighed.

Carbohydrate analysis. The phenol-sulfuric acid
carbohydrate procedure by Dubois et a1. (58) was used for
determining carbohydrate in feed analysis, rumen carbohy-
drate, and carbohydrate in the in vitro fermentation
trial. A brief description of this procedure follows.

The filtrate from the acid detergent fiber deter-
mination was made up to 2000 ml. with water. Five m1.

Of this dilution were then made up to 50 ml. by addition of
water and 2 ml. were placed in a testube. One ml. of a
standard 1% glucose solution in water was made up to 200

m1. Five tenths m1., 1.0, 1.5, and 2.0 m1. of this were
measured into testubes and brought up to 2 ml. volume

with H20. A blank containing 2 m1. H20 was also included.
Five hundredths ml. phenol reagent (80%Iphenol) was added
in each tube and mixed. Using a syringe pipette, 5 ml.
concentrated H2SO4 were rapidly added to each tube to insure
mixing and additionally mixed on a Vortex mixer. After the

tubes were cooled to room.temperature, Optical density

52

was read at 490 mu on the photometer. A plot was made of
the Optical density of the glucose standards against con-
centration and Optical density Of the sample was used to

determine the amount of carbohydrate in the sample.

RESULTS

Results of the various experiments performed dur-
ing these studies are divided into five sections and ap-
pear in the following order: (1) Effects Of intraruminal
administration of feed materials on.dry matter intake.
(2) Intake by rabbits fed silage juice treated pellets.
(5) Factors affecting rate of beet pulp digestion and ef-
fects of beet pulp on rumen characteristics. (4) Rumen
characteristics of cows fed hay or direct-cut alfalfa si-
lage. (5) Retention time and other relationships in the

rumen affected by rates of intake of roughages.

Effects of Intraruminal Administration Of
Feed Materials on Dry Matter Intake
of Fistulated Cows

Results listing the materials administered and

their effects on voluntary intake are given in Table 1.
Located in column one of the table is the number of cows
in each trial. The kind Of feed Offered is given in the
second column. The material placed in the rumen is given
in the third column. Average dry matter intake for six
days before, eight days during, and six days after treat-
ment are given in the next three columns. The seventh

column shows the change on voluntary intake during

53

TABLE I

AVERAGE VOLUNTARY AND TOTAL INTAKE OF CONS WHEN SIX
FEED MATERIALS WERE PLACED IN THE RUMEN

     
    
   

  
    
   

 
    
   
   

 

 

Material Dry Hitter Consumption Differ-
of placed 6 days 8 days 6 days placed ence
Cows in before during after
rumen _ _ f _ ,
lb/day lb/day lb/dey lblday lb/day lb/day
1 Fresh lresh 20.55 17.58 17.15 -1.70 7.0 5.3
alfalfa alfalfa
1 Hey Fresh 37.27 34.19 37.70 -3.29 4.75 1.46
alfalfa
2 Hey Hay 27.23 24.48 28.06 -3.17 10.30 7.13
3 Hey Hay 37.76 32.39 37.63 -5.31 10.44 5.13
grain
(milk production) 38.08 37.11 33.14 +1.50
4 Hey Beet 25.61 16.11 -9.50 11.37 1.87
pulp
2 Hey Beet 35.24 31.78 37.61 -4.65 12.70 8.05
grain pulp
(milk production) 32.02 27.99 27.65 -l.85
2 Hey Alfalfa 41.89 35.17 40.75 -6.15 8.26 2.11
grain silage
4 Hay Washed 25.27 19.56 24.90 -5.52 10.24 4.72
pressed
silage
4 Hey Silage 23.56 25.43 .25.05 +1.12 3.22 4.34
fluid '
6 Hey Silage 24.94 25.95 +1.01 3.42 4.43

fluid

55

administration when compared to the average of pretreat-
ment and post-treatment periods. The eighth column gives
the amount of material placed in the rumen, and the last
column shows the total increase in dry matter intake by
the intraruminal administration of feed materials.
Placing these materials in the rumen increased
total intake in all experiments as shown in Table 1, how-
ever, voluntary intake decreased in.most instances.
Voluntary intake was depressed about the same when
hay or fresh alfalfa was administered to cows fed hay,
yet, total intake increased more when hay was placed in
the rumen. More hay dry matter was placed in the rumen
than dry matter as fresh alfalfa. When hay was adminis-
tered to cows fed grain plus hay, their voluntary intake
of hay was depressed somewhat more than in cows fed only
has (5.51 vs. 5.17 lb., P . 0.05). When beet pulp was
administered to cows fed hay, voluntary intake of hay was
significantly reduced compared to the addition Of hay in
the rumen (9.50 vs. 5.17, P I 0.01). Three cows fed hay
plus grain decreased their voluntary intake 5.51 lb. when
10.44 lb. hay was given intraruminally compared to 4.65
lb. when 12.7 lb. beet pulp was given intraruminally.
When 8.5 lb. alfalfa silage dry matter was given intra-
ruminally, the voluntary intake decreased by 6.15 lb.
The differences in voluntary intake between these three

treatments was not statistically significant.

56

Two hay fed cows were used in a single reversal
trial comparing intraruminal administration Of two silage
fractions. Administration of washed pressed silage de-
pressed intake of hay more than the fluid portion (-5.52
vs. +1.12, P <'0.0l). The fluid portion appeared to have
a stimulating affect on intake in three out of the four
trials. The washed pressed silage depressed intake
slightly more than when hay was administered to these
cows in an earlier trial (-5.52 vs. -5.l7). A coeffi-
cient Of correlation between change in intake when all
materials in Table 1 were considered versus dry matter
placed in the rumen was r a 0.719, P < 0.05.

' Results of two single trials, when silage juice was
infused in increasing amounts, are shown in Table 2. The
intake figures are averages excluding the first day after
each increase in fluid infused since voluntary intake was
usually depressed on the first day of each change. Volun-
tary intake Of A192 was slightly decreased at all levels
of administration Of the silage fluid although total in-
take was increased slightly because Of the dry matter in
the silage fluid.

I Voluntary intake as well as total intake Of T26
was increased while given silage fluid infusions up to
28 liters per day, but at the level of 52 liters per day
this cow went ”Off feed." This indicated that the fluid

57

TABLE 2

EFFECT ON INTAKE WHEN TWO COWS WERE ADMINISTERED
SILAGE JUICE

 

 

 

Cow Days Voluntary Total
NO. Silage juice administered intake intake
liters7day lb/day 1b/day

A192 before 0 25.5 25.50

12 5 22.9 25.41

16 5 20.0 23.35

20 5 22.28 26.47

20 2 37.0 37.19

28 3 34.3 40.20

52 2 16.0 22.70

 

portion of silage had very little, if any, depressing ef-
fect on voluntary intake of hay, and not until large
amounts of this fluid were given was intake depressed.
This was a result of the cow going "Off feed."

Voluntary intake decreased by 9.5 lb. when four
cows fed hay were given beet pulp intraruminally (Table 1,
item 5). The decrease nearly equalled the beet pulp dry
matter added (11.57 1b.) into the rumen. Voluntary in-
take during the first few days Of treatment was not appre-
ciably affected, but became progressively depressed after
this initial period to the end of the experimental period.
In each case a build-up of best pulp was noted in the ru-

men. Gross visual Observations revealed an accumulation

58

of beet pulp in the rumens of these cows from 20 to
nearly 100%Iat the end of the trial. This was an indi-
cation that beet pulp placed in the rumen was apparently
not being digested as rapidly as the rate of input. Ob-
servations on rumen pH showed a definite decline through
the treatment period. pH of rumen contents of two cows
was 7.05 and 7.18 when Observed before feeding on the
first day. On the seventh day the pH had drOpped to 6.28-
and 6.50 before the time Of feeding and beet pulp admin-
istration. Three to 4 hours after feeding, the pH had
drOpped below 6.0. pH was depressed to 4.78 in one cow
with nearly 100% beet pulp in the rumen.

In the other trial when beet pulp was administered
to cows fed grain and hay, such adverse affects were not
Observed. The data in Table 1, item 6, indicate that
there was a small depression in voluntary intake which
was about the same as that observed when hay was admin-
istered. There was no Obvious build-up Of beet pulp in
the rumen of these cows, and voluntary hay intake was not
progressively depressed as in the hay fed cows. Rumen pH
did not show the pronounced drOp that appeared in the cows
fed hay alone. Before treatment rumen pH in one cow was
7.18 while on the 7th day before feeding and treatment
the pH was 6.56, also, the total dry matter intake Of the

cows fed grain plus hay was increased during treatment by

59

8.05 lb. compared to only 1.87 lb. for cows fed hay. The
cows fed hay appeared to decrease voluntary intake to com-
pensate for the additional dry matter administered intra-
ruminally, while the cows fed grain plus hay had no such
voluntary compensation.

Milk production decreased both times that the cows
fed hay plus grain were given beet pulp even though total
dry matter intake increased approximately 8 pounds; how-
ever, milk production increased slightly during adminis-
tration Of hay to three cows fed hay and grain.

Intake by Rabbits
Fed Silage-Juice Treated Pellets

Table 5 gives the data on intake and weight gain
of each rabbit when fed the treated and control pellets.
Analyses of variance of the data are shown in Appendix
Table I.

The analysis of feed intake indicates no signifi-
cant differences, however, there was slightly less con-
sumption Of the silage juice treated pellets than Of the
control pellets (440.4 gm./day vs. 467.6 gm./day). When
the rabbits were fed the silage juice soaked pellets,
their pellet intake during the first four days was less
than in the last four days. This could have been caused

by the rabbits not being accustomed to the taste of such

Table 3

DRY MATTER INTAKE AND WEIGHT GAINS BY RABBITS FED PELLETS
TREATED WITH SILAGE JUICE VS CONTROL PELLETS

 

m Matter Intake flay)
Rabbit No. Silage Juice Water Pellets

 

 

 

 

 

 

 

 

Pellets
275 297 396
let 4 days 271 394 543
2.7.3 5.4.3. an
Average 378 517
Group 1
275 434 391
2nd 4 days 271 503 541
21% .522 an
Average 5 l 488
258 292 286
let 4 days 268 504 419
.21.; its. an
Average 414 374
Group 2
258 292 350
2nd 4 days 268 527 558
2.7.2 25.7 291
Average 459 492
Average per treatment 440.4 467.6
Weight Gains (gm./treatmant)
Rabbit NO. Silage Juice Water Pellets
Pellets
Group 1 275 108.0 32.5
: 271 196.0 109.0
312 120.0 95.0
Average 141.3 78.8
Group 2 258 21.0 6.5
268 69.5 142.5
313 110.0 164.0
Average 66.8 104.3

 

Average per treatment 104.08 96.58

61

pellets, but after becoming accustomed to them the rabbits
ate as much of the silage juice pellets as of the control
pellets.

Rabbit 258 would not eat the silage juice treated
pellets during the first four day period, however, during
the second four days this rabbit ate them fairly well.
The intake of the second four days was substituted into
the first period of the analysis for this rabbit to avoid
unfair biasing of the analysis in favor of the water
soaked pellets.

Weight gains averaged slightly higher during the
period when silage juice treated pellets were fed than
when the control pellets were fed (104.08 gm. vs. 96.58
-gm.). This difference was not significant. Apparently
the variability in weight gains of rabbits on both ra-
tions was too great to show any real differences between
the treatments. Results from this trial indicated very
little difference in feed dry matter intake or weight
gains when rabbits were fed silage juice treated pellets

or the control pellets.

62

Factors Affecting Rate of Best Pulp Digestion and
Effects of Beet Pulp on Rumen Characteristics

A graphic presentation of the percent beet pulp in
the rumen, rumen pH, pounds of beet pulp placed in the
rumen, and voluntary intake of dry matter of cows used in
this investigation is shown in Fig. 1. Concentrations of
uronic acids and total soluble carbohydrates in rumen
fluid from three cows administered beet pulp intrarumin-
ally is shown in Appendix Table II. This includes data
from the day before treatment, the first day and the
seventh day of treatment. Samples preserved with H2804
and ethyl alcohol were averaged, since the two samples
were found to be closely correlated. Uronic acid con-
centrations between the two samples had a correlation
coefficient of 0.987. A comparison of the means by the
”t" test showed that they were not different (P ‘ 0.01).
The correlation coefficient for concentration of total
carbohydrate was 0.98 between samples preserved with
32804 and ethanol. The mean concentration for the ethanol
preserved samples was not significantly different than
that of the H2804 preserved samples (P < 0.01). With
this evidence that the samples preserved both ways were
not different, they were considered as duplicates and
averaged. This was considered desirable for greater ac-

curacy. Tables 4 and 5 give the average values of con~

A feeding

I Beet Pulp in Rumen

12 hrs.

Rumen pH
5-12 hrs. A

lb./day

Beet Pulp

Voluntary Intake
D.M. 1b./day

feeding

 

0‘

U!

NN
CU!

y—s
U'I

g—s
U10

LOU)
CU!

NM
0U!

p—s
U!

H
00

 

 

 

 

\¢P""""" Pic-’s ‘

X— ‘—‘-" \“\~ \-.—.—-—

 

 

 

 

 

 

 

"\ I

F x...
t»--- \,/"/| x\ /X\.l___‘___.x——l/ /'

 

 

i

‘------------ \
‘ X/ 0"
‘\ 0’ ‘§
\ "
"

 

I
\~‘~ I
O
' \‘go"

 

> 1 L I 1 s a
{J 2 4 6 8 10 12 14 16 18
‘ Days *

 

Figure l. The effects of intraruminal administration of
beet pulp on percent beet pulp in rumen, rumen pH, and
voluntary dry matter intake of three cows; A103 fed grain
and hay, A192 and IZD‘fed hay.

I

I

l

20

TABLE 4

RUMEN URONIC ACID CONCENTRATIONS FOR THE THREE DAYS
AND SAMPLE TIMES INDICATED IN RELATION TO INTRARUMINAL
BEET PULP ADMINISTRATION TO EACH OF THREE COWS

 

Hours Can No. Control Day I Day 7 Average
Day
mg.fm1. mg.7m1. mg./m1. mg./ml.

- .l . A103 .136 .120 .101 .119

A192 .122 .130 .116 .123

T20 .101 .127 .144 .372

.122

1.5 A103 .155 .632 .222 .336

A192 .164 .894 .136 .398

T20 .102 .507 .715 .441

.392

2.5 A103 .117 .200 .140 .152

A192 .168 .290 .157 .205

T20 .099 .156 .160 .138

.165

3.5 A103 .131 .154 .126 .137

A192 .128 .197 .174 .166

T20 .085 .163 .162 .137

O 147

4.5 A103 .120 .136 .119 .125.

A192 .127 .150 .154 .144

T20 .085 .152 .170 .135

.135
Average .613 1.336 .932
Average A103 .132 .248 .142
A192 .142 .332 .147
T20 -.094 .221 .270

Analysis 2; Variance Table

 

Source Sum of Squares DP Mean Square P Ratio Sig.
Day 0.1574 2 0.0787 4.575 0.05

Time 0.4582 4 0.1145 6.657 0.01

Cow 0.0085 2 0.0042 0.244 n.s.

D x T 0.3009 8 0.0376 '2.186 n.s.

D x C 0.084 4 0.0210 1.22 n.s.

T x C 0.018 8 0.0022 0.128 n.s.

Error 0.2767 16 0.0172

Total 1.2119 44

TABLE 5

RUMEN TOTAL SOLUBLE CARBOHYDRATES CONCENTRATIONS FOR
THE THREE DAYS AND SAMPLE TIMES INDICATED IN RELATION
TO INTIARUMINAL BRET PULP ADMINISTRATION TO EACH OF

 

 

 

THREE COWS
Hours Cow No. EontroI Day I Day 7 Average
Day
mg7m1. mg./ml. mglml. mgfml.
-0.1 A103 .661 .660 .757 .693
A192 .305 .274 .473 .351
T20 .242 .229 .876 .449
.497
1.5 A103 .837 6.416 1.920 2.480
A192 .341 2.080 .582 1.001
T20 .270 1.332 1.697 1.099
1.527
2.5 A103 .648 1.690 1.101 1.146
A192 .479 .783 .584 .615
T20 .234 .380 .585 .400
.720
3.5 A103 .720 .968 .807 .832
A192 .348 .511 .526 .462
T20 .199 .395 .406 .333
.542
4.5 A103 .690 1.139 1.031 .953
A192 .340 .362 .483 .395
T20 .234 .402 .520 .385
.578
Average .437 1.175 .708
Average A103 .711 2.175 1.778
A192 .362 .802 .530
T20 .236 .548 -.871
Analysisigg Variance Table
Source Sum of Squares D.F. Mean Square F Ratio Signif.
Day 4.1824 2 2.0912 3.7443 0.05
Time 6.7529 4 1.6882 3.0227 0.05
Cow 4.5241 2 2.2620 4.051 0.05
DIT 10.3969 8 1.2996 2.3269 ----
080 3.9843 4 .9960 1.7833 ----
Txc 1.5961 8 .1996 .3573 ----
Error 8.9373 16 .5585
Total 40.3740 44

66

centrations in the rumen samples preserved both ways.
These tables give average concentrations for each cow on
each day of sampling and for times during the day. Analy-
sis of variance is also shown in these tables.

Uronic acids in the rumen were higher (P"<0.05)
on day one of treatment than on control day for all cows
(1.356 vs. 0.615, Table 4). These averages include the
-.1 hour sample. At 1.5 hours after feeding, rumen
uronic acids were much higher on day one than on control
day for all cows. However,on day 7, these concentrations
were near control levels for A192 and A105, but had in-
creased in T20. Average rumen uronic acid concentrations
were lower for A105 and A192 on the seventh day post-
treatment than on the first day of treatment. These
values indicated that these 2 cows were breaking down the
pectins in beet pulp more rapidly on the seventh day than
on the first day.

A positive coefficient of correlation between
uronic acid and total carbohydrate values determined from
rumen fluid samples preserved in Hasq+was 0.6424 (P «:0.01).

Concentration of total soluble carbohydrate in
rumen fluid on day one of treatment was higher than on
the control day for all cows (1.175)» 0.457, P ‘0.05).

Total soluble carbohydrate values were also higher on day

67

one than on day seven for cows A105 and A192 (2.175 and
0.802 vs. 1.778 and 0.550). These comparisons indicated
that there was a more rapid disappearance of total carbo-
hydrates on the seventh day of treatment than on the

first day for these two cows. This could be interpreted
to indicate some type of adaptative process was taking
place in these two cows. Total soluble carbohydrate
values were higher on day seven for T20 than on day one
indicating that this "cow" did not adapt to more rapid di-
gestion of beet pulp (0.871 ’ 0.548).

Visual observation of beet pulp in the rumen con-
tents confirmed the above findings. The tOp graph of
Fig. 1 shows that best pulp appeared to be accumulating
in the rumen of T20 by the seventh day while the amounts
were declining for A105 and A192.

Rumen volatile fatty acid concentrations listed in
Table 6 show no particular trends associated with the
beet pulp treatment. The acetate-to-proPionate ratio
likewise shows no trend. The lactate concentration was
highest on day one for A105 while for A192 and T20 the
lactate concentration was highest on the seventh day.

The amount of best pulp administered to A105 was
increased to 16 pounds on the seventh day of treatment
and increased to 22 pounds per day on the thirteenth and
fourteenth days to observe the build-up of beet pulp in

68

TABLE 6

RUMEN VOLATILE FATTY ACID CONCENTRATIONS BEFORE FEEDING AND
AVERAGE COMENTRATIONS AFTER FEEDING FOR TE THREE DAYS IN RE?
LATION TO INTRARUMINAL BRET PULP ADMINISTRATION TO EACH
OF THREE COWS

—_—__—.—_.-..__'_. “Ma—~—

 

 

   

 

"n.§"” _ “'Acetate Propionate Lactate Ac. Prop.
. Acids
molar 1 molar 1 molar'! uM/ml.
A103 7 0 72 16 -- 4.50 107.8
0 1.5-3.5 71 16 .07 4.44 100.5
1 " " 71 17 .15 4.18 108.4
7 " " 68 22 .09 3.05 138.7
A192 0 0 69 19 .06 3.63 71.5
1 0 60 23 .06 2.61 60.1
7 0 67 19 .08 3.53 125.4
0 1.5-4.5 69 21 .08 3.29 136.5
1 "' " 73 15 .08 4.87 141.7
7 " " 72 18 .14 4.00 140.0
T20 0 0 68 21 .05 3.24 64.2
1 0 65 23 .05 2.83. 74.0
7 0 65 23 ~.05 2.83 133.5
0 1.5-4.5 58 33 .03 1.76 92.8
1 " " 68 24 .17 2.83 114.0
7 " " 70 18 .41 3.88 145.0

69

the rumen. The tap graph of Fig. 1 shows that on the
tenth day the rumens of both cows contained about 80%
best pulp. Rumen pH at this point was considerably de-
pressed. On the ninth day low pH readings of 5.0 and
5.45 were observed in A192 and T20, respectively.
Microsc0pic observation of rumen fluid samples
from these cows revealed that the protozoa population
seemed to be sensitive to low pH in the rumen. Table 7
shows the microflora changes in the rumens of A192 and
T20 on days that microscopic observations were made. By
the tenth day no protozoa were visible in the rumen sam-
ples from A192, while a greatly reduced number was visible
in samples from T20. 0n the 12th day protozoa numbers in
the rumen of T20 had returned to normal. A slight reduc—
tion in the percent of beet pulp in the rumen ingesta
and a rise in pH was also noted at this time. This trend
was only transient, however. On the thirteenth day total
microflora numbers had reduced considerably accompanied
by an increased accumulation of beet pulp in the rumen
and a decreased rumen pH. This condition continued to
progress for the next five days until the end of the ex-
periment.

0n the tenth day NaHCO was added in the rumen of

3
A192 to bring the pH up to 6.4 - 6.6. This was a normal

post feeding pH for this cow before initiation of the

70

TABLE 7

GENERAL‘MICROSCOPIC OBSERVATIONS OF RUMEN MICROFLORA
0! TWO CONS WHILE RECEIVING LARGE AMOUNTS OF BEET
PULP FOR ELEVEN DAYS

 

 

 

 

 

Mas mods gotal numberr—I-
treatment A192 T20 A192 T20 A192 T20

6 2* 3 3* 3 3* 3

9 0 1 2 2 2 3

11 0 1 2 2 2 2

12 1 3 2 3 2 3

l3 3 3 3 3‘ 3 2

16 3 2 3 2 3 1

* 3 normal numbers
2 reduced numbers
1 very few
0 none visible

a Large numbers of short rods were clumped around feed particles.

71

beet pulp treatment. Beet pulp accumulation in the rumen
of A192 was not reduced markedly until after the four-
teenth day. Rumen microflora numbers did not return to
normal until the thirteenth day and remained normal
through the remainder of the treatment period. After the
fourteenth day the percent of beet pulp in the rumen
rapidly decreased. This seemed to be associated with the
increased rumen pH and normal rumen microflora numbers.
The chart at the bottom of Fig. 1 shows that voluntary dry
matter intake returned to the pretreatment level in two
days for cows A105 and T20, while A192 had not yet reached
this level on the second day after the end of treatment.
The results of this trial suggest that rumen
microflora, especially protozoa, are sensitive to low
rumen pH. This is in agreement with published informa-
tion (92). It was observed that both numbers and activi-
ty of microflora were greatly reduced when the pH de-
creased to 5.5 or below for a portion of the day. Under
these conditions there was a visible increase in percent-
age of beet pulp in the rumen ingesta. This could be the
result of a decreased rate of breakdown of the best pulp.
More work is necessary in order to understand why addi-
tion of beet pulp depressed the pH in the rumen of cows
fed only hay while in that of cows fed grain and hay there

was very little change in rumen pH.

72

Data giving changes in pH, carbohydrates, and
uronides when rumen fluid from different cows was added
to a best pulp substrate and fermented in vitro are shown
in Table 8. Rumen fluid samples were obtained from cows
A192 and T20 on the 17th day of intraruminal administra-
tion of beet pulp; two cows, 174 and 188,fed hay, grain,
and beet pulp for a month; two cows, K159 and T26, fed
only hay; and two other cows, A105 and T5, fed hay and
grain. The last four cows had not received beet pulp for
at least a month prior to the trial.

Analyses of variance of the results of the in
vitro fermentation trial are given in Table 9. In the
analysis of variance table when samples from cows receiv-
ing beet pulp were compared to those not receiving beet
pulp, the groups were subdivided into cows fed hay and
cows fed grain. This was considered as four treatments.
In the other analyses samples from cows fed hay and grain
were compared to samples from cows fed hay and considered
as two treatments.

pH changes from the initial to the final pH were
not significantly different in fermentations from cows
receiving beet pulp and those not receiving beet pulp.

Total solids remaining were used as an indication
of best pulp substrate disappearance. These values did

not show any consistant difference between fermentations

'73

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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74-

TABLE 9
ANALYSES OF VARIANCE OF RESUBTS OF THE BRET PULP
IN VITRO FERHENTAIION TRIAL' ‘_

A192 120 [(139 1‘26 5103 T3 NWT—'-

 

 

 

Change in pH «.66 -.21 ~.51 —.61 -.66 -.51 -.71 -.71
Beet pulp vs no beet pulp
gouree DP 8. Squarea Hean Squarea F Ratlo Signif.
Treatment 3 0.0763 .0254 .8668 n.a.
Reaidual _3_ 0.1175 .0293
Total 7 0.1938
Total aolida 17.0 14.0 13.5 15.0 9.0 14.5 8.0 8.5
Remaining Grain + hay fed va hay fed alone
Treatment 1 47.53 47.53 8.22 0.05
Reaidual ‘_§_ 34.69 5.78
Total 7 82.22

Beet pulp va no heat pulp

 

 

 

 

Treatment 3 2.53 .843 .04 n.a.
Realdual 4 79.69 19.92
Total 7 82.22
Gaa produced 120 ml. 62 m1.86 ml. 86 ml.112 ml. 120 ml. 114 ml. 84 ml.
Grain + hay fed va hay fed alone
Treatment 1 722.0 722.0 1.748 n.a.
Reaidual 6 2478.0 413.0
Total 7 3200.0
Total 030
Z Diaappear 22.6 24.5 27.2 25.7 37.7 29.3 27.0 38.3
Grain + hay fed va hay fed alone
Treatment 1 129.09 129.09 6.88 .05
Residual ‘_§_ 112.51 18.75
Total 7 241.60
Beet pulp vs no beet pulp
Treatment 3 139.55 46.52 1.8235 n.a.
Realdual _4_ 102.05 25.51
Total 7 241.60
Total Uronidea 24.3 32.6 13.2 27.2 17.8 30.3 36.5 18.7
Beet pulp va no beet pulp
Treatment 3 85.17 28.39 . .3079 n.a.
Reaidual _§_ 368.99 92.20
Total 7 454.16

Soluble Uronldea 65.7 73.0 68.3 65.4 69.3 80.2 78.8 79.9

 

I Dlaappear Grain + hay fed va hay fed alone
Treatment 1 160.25 160.25 8.1345 0.05
38.14.51 _g_ 118. 25 ‘ 19. 7
Total 7 278.50

75

from cows receiving beet pulp and those not receiving
beet pulp (15.4% vs. 11.9%). There was, however, less
substrate remaining in the fermentations using rumen
fluid from cows fed grain than by using rumen fluid frOm
cows fed hay (10.0%r’ 14.9%, P < 0.05). .

Gas production, which was an indication of fermen-
tation activity, was too variable between samples to show
any trend, but gas production was much less inthe fermen-
tation flask representing cow T20 than from any other
flask.

Disappearance of total carbohydrates was greater
in fermentations using rumen fluid from cows fed grain
than in those using rumen fluid from cows fed hay
(53.1%»» 25.0%, P < 0.05). There was not a significantly
greater disappearance of total carbohydrates using rumen
fluid from cows fed beet pulp than by those not receiving
beet pulp (28.3% vs. 50.0%).

Disappearance of total uronides was too variable
to show any trend. In spite of a difference of 6% between
cows receiving beet pulp and those not receiving beet
pulp (28.2 vs. 22%) the variability was too great to be
statistically significant.

Disappearance of soluble uronides was greater in
fermentations using rumen fluid from cows fed grain than

in those using rumen fluid from cows fed hay (77.05%"68.1%,

76

P < 0.05). The differences between fermentation flasks
from cows receiving beet pulp and those not were not
significantly different (74.5% vs. 70.8%).

These results indicated that in general rumen
fluid from cows receiving beet pulp did not ferment beet
pulp more rapidly than rumen fluid from cows not receiv-
ing beet pulp. These results do show, however, that ru-
men fluid from cows fed grain digest beet pulp more
rapidly than rumen fluid from cows fed only hay. The
results of the in vitro fermentation failed to show a dif-
ference in the rate of fermentation of beet pulp between
cows A192 and T20. Visual observation indicated that
best pulp was disappearing more rapidly from the rumen
of A192 which had been receiving NaH005 for seven days

before this sample was obtained.

Rumen Characteristics of Cows Fed

Hay or Direct-cut Alfalfa Silage

Data on rumen characteristics of two cows fed hay
or direct-cut alfalfa silage each at three different
levels in a reversal experiment are shown in Tables 10,
11, 12, and 13; and in Appendix Tables III, IV, and V; and
in Figs. 2 and 5.

Rumen pH, NH}, and volatile fatty acid concentra-

tions were determined and analyzed statistically by

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pH

pH

pH

O‘O‘O‘O‘O‘
U'IO‘

O‘O‘O‘O‘VNV

O‘NCD‘O

81

 

th‘ON

N

N

CH

High Intake

 

 

I \/ “\‘\
‘s
I “\ \
\‘ \
_ 0-.-“: \ Silage
.9------.\
b Hay.‘-‘o
W
’vv Medium Intake
P 0“
b ‘\‘ ---’----o
---‘.~-‘--u ........ ’-‘.ilay

\‘\
P \\
L \ \ \ — — — — — — —
LA Silage
N
' a. Low Intake

I' \
A’ X ‘4
“
‘\----\

D ‘s‘ Silage

\

7

 

 

. H ! a 1 l I .J
' 0 . . 3J5 4.5 6.5 12

Hours after feeding

Figure 2. Average postprandial rumen pH of two cows fed
alfalfa hay or direct-cut alfalfa silage at three levels;
5 1b. D.M./day, 12 lb. D. M./day, and fig libitum.

82

0.5 ~ //“"‘\ High Intake

0.4 " ”’\\\
/’ \‘ \_ Si lage

0.3
mg./ml. ‘

O. 2 “‘~‘ Hay

.-----
..
---------‘--
------
-

0.1 *

0.5 ' Medium Intake

NH3 ‘\~“\ \ \ Silage
0.3 r ~.‘
mg./ml. ~ \

0.2 .\

0.1 '

 

 

Low Intake

‘ \ Silage

‘.
‘-
.....
Ԥ
Q.
~

 

 

o 135 2:5 315 4.5 6.5 12
Hours after feeding

Figure 3. Average postprandial rumen ammonia concentrations of
two cows fed alfalfa hay or direct-cut alfalfa silage at three
levels; 5 lb. D.M./day, 12 lb. D.M./day, and ad libitum.

85

analysis of variance and are given in Tables 10 and 11.
The usefulness of these analyses for interpreting the re-
sults of this experiment were somewhat limited. Rumen
fluid samples were taken only one day on each level of
feeding and the use of only two animals limited the num-
ber of observations for establishing average concentra-
tion values on any particular level of feeding of hay or
silage. The time element in carrying out the sequences of
feeds and feeding levels also may have confounded results
somewhat. Aside from this, another animal was substituted
for T19 on the high level of silage feeding and this may
have complicated results at the high level of feeding.

T19 at this time whould not consume silage in high amounts
because of some "off feed" condition.

Rumen pH values, shown in Table 10 and Fig. 2, de-
clined at much the same rate during the day when the cows
were fed hay or silage. The pH values at 1.5 and 2.5
hours after feeding were higher when the cows were fed
hay than when fed silage at all levels of intake. The
average pH of the rumen was higher for cows fed hay than
for cows fed silage. The analysis of variance given in
Table 10 showed that rumen pH was influenced significantly
(I’ ‘0.01) by several items.

Rumen ammonia concentrations shown in Table 11 and
Fig. 3 were consistantly higher throughout the day when

cows were fed silage than when fed hay. This occurred at

84

all levels of feeding. On the medium and high levels of
silage feeding the NH5 concentrations reached their peak
2 to 2.5 hours after feeding, and a smaller peak was
noted 5 to 6 hours after feeding. When hay was fed at
medium and high levels, NH3 concentrations were highest
1.5 hours after feeding and continued to decline grad-
ually throughout the day. The analysis of variance given
in Table 11 showed that rumen ammonia concentrations were
affected significantly (P < 0.01) by several items.

Rumen volatile fatty acid concentrations shown in
Appendix Table III had a rather large range of values
between cows on the different levels of feeding and
showed no consistant differences in amounts when cows
were fed hay or silage. Concentrations of acetate, pro-
pionate, and butyrate appeared to increase as the feed
intake increased. These average concentrations in rumen
fluid are shown in Table 12. Concentrations of these acids
were not significantly different since individual animals
reaponded differently at the three levels of intake. The
results of the analysis of variance of these volatile
acids are shown in Appendix Table IV. The concentration
of butyrate was consistently higher when silage was fed
at all levels than when hay was fed. The average acetate-
to-propionate ratio was consistently higher when cows were

fed silage at all levels and at all times of the day.

85

The 2-to-3 carbon ratio was calculated assuming
that a mole of butyrate is broken down into two moles of
acetate. The 2-to-5 carbon ratio averaged higher in
fluid from animals fed hay at the low and medium levels
of feeding, while at the high level there was no differ-
ence in this ratio when hay or silage was fed. Averages
of the acetate-to-prOpionate ratio and 2-to-3 carbon ratio
for the three levels of feeding and six times of the day
are given in Table 1}. Analyses of variance for these
ratios are shown in Appendix Table V. These ratios ap-
peared to be significantly affected by differences be-
tween animals as well as differences between the hay and

Silage.

Retention Time and Other Relationships in the Rumen

Affected by Rates of Intake of Roughages

The combined data representing 52 rumen emptyings
using eight rumen fistulated non-lactating cows and given
six different roughage rations are located in Appendix
Table VI. Rumen retention times of roughage dry matter
and fiber over a wide range of intake are shown in Figs.
4 and 5.

The ratio of dry matter in the rumen divided by
daily dry matter intake was used as a measure of rumen

retention time. The data indicate that retention time

Rumen Retention Time (Days)

865

 

 

L A L 4—0
9.5 1.0 1.5 2.0 2.5
(Consumption (lb. D.M./cwt.)
x Hay a Hay + washed pressed silage I Fresh alfalfa
. Silage D Hay + silage juice A Hay + beet pulp

Figure 4. Relation between rate of dry matter intake and rumen
retention time calculated as lb. D.M. in the rumen divided by
daily dry matter intake.

Rumen Retention Time
(Days)

87'

 

0.25 0.5 0.75 1.0
Consumption (lb. fiber/cwt.)
X Hay 0 Ray + washed pressed silage IAlfalfa (fresh)
0 Silage DHay + silage juice A Hay + beet pulp

Figure 5. Relationship between rate of fiber intake and rumen
retention time calculated as lb. fiber in the rumen divided by
daily fiber intake.

88

decreased as dry matter intake increased. For example,
when dry matter intake was limited to 0.5 lb./cwt. per
day, mean retention time was approximately two days.

When dry matter intake increased above 1.5 lb./cwt. per
day, mean rumen retention time was less than one day.

A line representing the relationship between retention
time and intake was drawn free-hand in Fig. 4. It is in-
teresting to note that all points regardless of type of
forage fed are reasonably close to the free-hand drawn
line; also, the relationship was not linear over the range
of intake.

Fiber retention time was calculated by dividing
fiber content of the rumen by daily fiber intake. The re-
tention time of fiber in the rumen decreased as fiber in-
take increased. This is shown in Fig. 5. Fiber retention
time was correlated with dry matter retention time
(r - 0.9755, I"<0.0l, Appendix Table VII). Rumen reten-
tion time for dry matter was 1.5 days when 1 lb. of dry
matter per cwt. was fed daily. This value was more than
the similar value of 0.75 days for retention time of fiber
when 1 lb. of fiber per cwt. was fed daily (P < 0.01). Dry
matter intake was greater than fiber intake for all feeds
(P < 0.01) and was significantly correlated (r a 0.9736,
Appendix Table VII).

89

Even though the cows were paired with themselves
their intakes while on low, medium, and high levels of hay
or silage were not as close together as desired. Conse-
quently, five arbitrary pairs having the same dry matter
intake per cwt. of hay and silage were selected. Intake
and rumen characteristics of five cows fed silage and five
cows fed hay are shown in Appendix Table IX. Rumen dry
matter retention time of the cows fed hay was highly cor-
related with retention time of the cows fed silage over
the wide range of feed dry matter intake (r a 0.997,

P c 0.01). A ”t" test of mean retention times of the hay
fed group compared with the silage fed group indicated
that the retention times were not different (P . 0.5).

The retention time of fiber in the rumen was com-
pared between cows fsd silage and cows fed hay, shown in
Appendix Table IX, and found to be correlated ( r - 0.994,
P < 0.01). The "t” test of mean retention times of these
groups showed no significant difference (P » 0.7).

Appendix Table X gives data on rumen retention
time of five cows fed hay compared to five cows fed hay
with silage juice infused intraruminally at comparable
levels of intake. Rumen retention time of dry matter in
the cows fed hay compared to the dry matter retention
time of the cows fed hay with silage juice added in the

90

rumen was correlated r a 0.816, approaching P = 0.05. A
comparison of mean retention times of these groups indi—
cated that they were not statistically different (P - 0.7).

Appendix Table XI shows a comparison between four
cows fed hay plus washed pressed silage (WPS) and four
cows fed hay plus silage juice. Retention time of dry
matter in cows fed hay and WPS was not significantly cor-
related with dry matter retention time of the cows fed
hay plus silage juice. Intakes of these cows were not
well matched over the range of dry matter intake. This
may have been the cause of a low coefficient of correla-
tion. A comparison between mean retention times of each
group indicated they were not different (P > 0.5).

In all comparisons the infusion of silage juice ap-
peared to reduce retention time, but the reduction lacked
statistical significance.

Relationships found between dry matter intake per
cwt. versus percent dry matter in the rumen, dry rumen
contents as percent of body weight, and rumen contents
(wet) as a percent of body weight from data in Appendix
Table VI are shown in Figs. 6, 7, and 8, respectively.

The percent dry matter in the rumen showed a posi-
tive relationship with dry matter intake. A fairly wide
range in.percent dry matter was observed between cows at

any given dry matter intake, however, the points shown in

Rumen Contents (1 Dry Matter)

15

14

12 P

11»

10 .

 

91

 

 

8 r
X
7 b
6 I
X’
5 1 4L J A L
0.5 1.0 1.5 . 2.0 2.5
Consumption (1b. D.M1cwt.)
X Hay OHay + washed pressed silage I Fresh alfalfa
O Silage D Hay + silage juice 4 Kay + beet pulp

Figure 6. Relationship between rate of dry matter intake and percent
dry matter in the rumen. The solid line represents all feeds. The
long-dashed line represents S cows fed hay paired by rate of intake
with S cows fed sih ge given the short-dashed line.

Dry Matter in Rumen Contents (as Z of body weight)

N
0

ya
u:
—F

'92

 

 

 

X'
1.0% X
X o
X
X
.5 L.
L f E I— J ‘ i—
0.5 1.0 1.5 2.0 2.5
Consumption (lb. D.M./cwt.)
x Hay O Hay + washed pressed silage I Fresh alfalfa
o Silage D Hay + silage juice A Ray + beet pulp

Figure 7. Relatinnship between rate of intake and dry matter in
rumen contents as percent of body weight.~

Rumen Contents
(as % body weight)

93

 

 

 

X
16 r U
Ah
X.
15 b .
0 o
X
14 r
13 I
12 p
11 r
x x o D x
10 r X
Q D
X E!
9
8
4—t A J;_ 1_, .
0.5 1.0 1.5 2.0 2.5
Consumption (lb. D.l./cwt.)
X Hay OHay + washed pressed silage I Fresh alfalfa
I Silage DHay + silage juice AHay 4» best pulp

Figure 8. Relationship between rate of intake and total
we ght of rumen contents as percent of body weight.

94

Fig. 6 show a definite tendency toward a higher percent
dry matter in the rumen with increasing dry matter intake.
The "b" term, which is an expression of the relationship
between the Y and the X axis, was 2.3. For example, for
one pound of dry matter increase there is an increase of
2.5 percentage units dry matter in the rumen.

Dry matter in rumen contents as a percent of body
weight showed a tendency to be related to dry matter in-
take in Fig. 7. The "b" term for the regression line in
Fig. 7 indicated that for an increase of one pound dry
matter intake the dry matter in rumen contents as a per-
cent of body weight increased 0.148%. There was some in-
dication that different forages have somewhat different
relationships of dry matter in the rumen to dry matter in-
take, but with so few points for any given forage it was
decided that such relationships may not be meaningful. A
correlation between dry matter in rumen contents as per-
cent of body weight and dry matter intake using all cows
fed the various forages indicated that a positive relation-
ship existed, however, this was not significant (Appendix
Table VIIIL

Fig. 8 shows the relationship between wet weight of
rumen contents as percent of body weight and dry matter
intake. The "b" term from the regression formula in Ap-

pendix Table VIUZindicates a negative relationship. Total

95

rumen contents as percent body weight decreased 0.41% for
each increase of one pound of dry matter intake. The co-

efficient of correlation was not statistically signifi-

cant.

DISCUSSION

The data presented in Table 1 show that total in-
take of the cows was increased in every instance by the
addition of various feed stuffs into the rumen. This is
confirmation of work reported by Campling and Balch (27)
who observed an increase in total intake when 50 pounds of
rumen ingesta were added into the rumens of cows. This
indicates that something has limited voluntary intake and
that by force feeding an animal the digestive tract must
handle more feed. It appears that the ability of the di-
gestive tract to digest the extra feed may not be the only
factor in limiting voluntary intake of roughage feeds.
Other factors must contribute to the regulation of feed
intake. Little work has been done to determine what other
factors may participate in the regulation of feed intake
of cattle. Possibly unidentified metabolites in the cir-
culating blood after feeding may have some effect on sati-
ety. Workers have shown that blood sugar levels are
rather constant and show no particular relationship to the
times when cows eat (54). The role of non-esterified fatty
acids in the blood of the bovine in relation to hunger has
not been reported. The possibility that the increased ac-
tivity of microflora in the rumen after feeding and the

subsequent slight temperature rise has been suggested as

96

97

another factor in producing satiety after eating. These
factors and others not yet considered may all have a role
in regulation of feed intake by cattle.

The results of this trial and those of Campling
and Balch do not appear to be entirely consistant with
the generally accepted idea stated by Blaxter (14) that
intake of ruminants is entirely based on the rate of dis—
appearance of ingested feed from the rumen. This may be
a major factor, but there is reason to believe from other
evidence presented here that other factors must be in-
volved in the regulation of feed intake by ruminants.

When Campling and Balch (27) removed 50 pounds of
rumen ingesta from the rumen, they observed that the cows
did not eat enough additional feed to compensate for the
dry matter in the ingesta removed. If rumen fill is the
only means by which intake of roughage is regulated, it
seems that the cows in this experiment would have com-
pletely compensated for the material removed.

In the trials reported in this paper, certain feeds
produced greater differences in total intake than others.
For example, the addition of washed pressed silage re-
sulted in less increase in total intake than hay when
comparable amounts of dry matter from these feeds were
placed in the rumens of cows fed hay. This could possi-
bly be explained on the basis that the washed pressed
silage, devoid of much of the readily digestible material,

98

was digested more slowly in the rumen than hay and thereby
the dry matter was retained in the rumen longer when
washed pressed silage was added than when hay was added
in the rumen. Fig. 4 shows that the retention time of
dry matter in washed pressed silage administered to four
cows was well within the range of the retention time ex-
pected when hay was fed at the same levels of dry matter
intake. These data are limited but from these observa-
tions it does not appear that washed pressed silage was
retained longer than the hay dry matter in the rumen.
Possibly factors in the washed pressed silage other than
slower breakdown were responsible for the small increase
in total intake. There is a possibility that products
of fermentation during the ensiling process may be re-
sponsible for the effect on total intake.

Total intake increased less for cows fed grain and
hay than with cows fed hay only when hay was given intra-
ruminally to both. This is shown by data given in Table l.
Kamstra and Miller (61) noted in vitro digestion of cellu-
lose was reduced in rumen fluid from sheep and steers
after changing the diet from hay to grain and hay. This
is taken as evidence that the cellulose in hay was broken
down more slowly in the rumen of cows fed grain and hay
than in cows fed hay only. This may not be the only rea-

son for the difference in total intake of these cows. It

99

is possible, too, that the addition of grain in the diet
may have produced some effect on the satiety mechanism
responsible for the somewhat less total intake increase
of the cows fed grain.

The administration of silage juice (Table 1) re-
sulted in a significantly greater increase in total in-
take per pound of dry matter added in the rumen than any
of the other materials added in cows fed hay. Thomas et
al. (106) reported decreased intake when silage juice was
infused into heifers. Their trials lasted only three days.
In the eight day trials reported in this paper, voluntary
intake of hay decreased only on the first day of infusions
and increased in most cases through the remainder of the
trials. There is a good possibility that this material
increased the rate of breakdown of feed in the rumen al-
lowing a greater total intake. The ash content of the
silage juice was rather high, 8.42% (page 37). There is
a possibility that the mineral content of this ash had
some stimulating effect on.microflora activity in the
rumen resulting in a more rapid breakdown of feed.
Borroughs et a1. (19) observed that a complex salt solu-
tion increased in vitro cellulose digestion in rumen fluid.
Fig. 4 shows that dry matter retention time was consis-
tantly less when silage juice was added than for dry matter

in most other feed materials administered. Appendix Tables

100

X and XI both show that dry matter retention time was less
when silage juice was administered than dry matter reten-
tion time for hay or washed pressed silage when fed at
comparable levels. This does not exclude the possibility
of other factors in silage juice affecting intake of the
cows.

When large amounts of silage juice were added in
the rumen of one cow and another not previously reported,
these cows went "off feed." It is possible that some
factor(s) in large amounts of silage juice disturb normal
rumen microflora activity or the ion balance in the rumen
which may be responsible for the observed anorexia.
Hillman (54) observed cows fed large amounts of silage
as the only feed occasionally went "off feed" during his
experiments. The cow T19 in one trial reported here al-
most completely ceased eating silage while receiving si-
lage ad libitum. No work has been reported in the litera-
ture attempting to explain the reasons why cows go "off
feed" occasionally when fed silage. The results from
intraruminal administration of both solid and liquid por-
tions of silage in these experiments indicate the factor(s)
may be located in the fluid portion of silage.

Data of preliminary trials in which rabbits were
fed regular rabbit pellets treated with silage juice

failed to show an increased intake of these pellets over

101

the control (Table 3). Perhaps subsequent trials using
larger numbers of rabbits fed for longer periods on pel-
lets containing a range of juice dry matter concentra-
tions may more accurately demonstrate whether or not the
silage juice portion influences feed intake in rabbits.

The study on beet pulp reported here was an at-
tempt to determine if “cows" adapt to more rapid diges-
tion of beet pulp, and what effect ration has on adapta-
tion. Adaptation, as it was used here, was indicated by
the faster rate of digestion and utilization of beet pulp
in the rumen after seven days of feeding beet pulp com-
pared with the rate on the first day of feeding.

Beet pulp contains a greater amount of pectic sub-
stances than other feeds commonly fed to cows. According
to two reports in the literature, beet pulp contains an
average of 11% pectic substances (24). Upon hydrolysis,
these pectic substances are primarily broken down to
uronides. Analysis of beet pulp used in the in vitro
fermentation trial in this report showed that it contained
10.4% uronides. The method used for laboratory analysis
of uronides in this report gave variable results. Re-
coveries of known amounts of uronides added to samples
ranged from 46 to 67%. With such low and variable re-
coveries, it was decided to perform analysis for soluble

carbohydrates in rumen fluid since carbohydrates are

102

primary products of beet hydrolysis. Analysis of total
carbohydrates in beet pulp was 85% (Table 8) which agreed
closely with values in other reports. Recoveries of
carbohydrates added to samples ranged from 95 to 105%.
This was believed to give a more reliable indicator of
concentrations of products of beet pulp hydrolysis than
the uronide analysis. A report found in the review by
Brown (24) after these analyses were made indicated that
dried beet pulp contained at least 24% galacturonic acid.
The investigators in this report used a pectic enzyme for
beet pulp hydrolysis. This may explain the variable re-
sults obtained in the uronide analysis in this report.
Uronic acid concentration in the rumen was used as
one measurement of best pulp disappearance. It was as-
sumed that hydrolysis of beet pulp in the rumen would
yield uronic acid and that this product would be utilized
by the micro-organisms in the rumen fluid more rapidly
with increased adaptation to utilization of beet pulp.
Total carbohydrate concentrations in the rumen
were used as another measurement of adaptation. It was
also assumed that hydrolysis of beet pulp in the rumen
would yield soluble carbohydrates which would be utilized
more rapidly with increased adaptation to digestion of

best pulp.

103

Gross visual observation of the amount of beet
pulp in the rumen was used as another estimate of adapta-
tion to the digestion of beet pulp in the rumen.

Cow A103, fed grain and hay, appeared to digest
beet pulp more rapidly at the end of seven days of beet
pulp administration than on the first day as indicated
by lower rumen concentrations of uronides and total solu-
ble carbohydrates on the seventh day than on the first
day of beet pulp administration (Tables 4 and 5). Visual
observation also indicated somewhat less beet pulp in the
rumen 12 hours after feeding on the seventh day than on
the first day of treatment (Fig. 1). It is questionable
if the total amount of volatile fatty acids or percent-
ages of individual volatile fatty acids (Table 6) indi-
cated any adaptation in the rumen of this cow except that
the lactate concentration on the seventh day had nearly
returned to the pretreatment level. Voluntary intake of
feed dry matter was nearly as high on the seventh day as
on the first day of treatment. Rumen pH remained at the
pretreatment level throughout the seven days of the trial.

The results of the in vitro fermentation trial
(Tables 8 and 9) show some indication that beet pulp was
digested somewhat more rapidly in rumen fluid from cows
fed grain and beet pulp than in rumen fluid from cows

fed grain but not receiving beet pulp. The solids

104

remaining at the end of the fermentation were less when
using rumen fluid from cows fed grain and beet pulp than
when using rumen fluid from cows fed grain without beet
pulp. There was also a slightly increased disappearance
of total uronides than with rumen fluid from cows fed
grain without beet pulp. This is additional evidence
that cows fed grain and beet pulp for a period of time
digest beet pulp more rapidly than cows which have not
been fed beet pulp.

In the trial when the two cows fed hay were given
beet pulp to determine if they could adapt to more rapid
digestion of best pulp, A192 digested beet pulp more
rapidly on the 7th day than on the lst day of administra-
tion.

Rumen concentrations of uronides and soluble car-
bohydrates were lower on the 7th day of beet pulp adminis-
tration than on the first day in A192 (Tables 4 and 5).
This was taken as an indication that beet pulp was being
metabolized more rapidly on the seventh than on the first
day. Visual observation of rumen contents 12 hours after
feeding (Fig. 1) showed very little change from the first
to the seventh day. Other indications showed that con-
ditions in the rumen were not returning to normal. Lactic
acid concentrations in rumen fluid on the seventh day in-

creased over the first day level (Table 6). Rumen pH,

105

which had drOpped on the first day of treatment was fur-
ther depressed on the 7th day. Vo1untary intake of hay
was diminished, although it showed some improvement on
the 7th day.

Evidence indicated cow A192 was adapting to a more
rapid beet pulp digestion by the seventh day. The amount
of beet pulp administered in this trial may have been
more than could be handled in the rumen without causing
marked changes in rumen pH and lactic acid concentrations
when hay was the only other feed given to this cow.

Cow T20 on the other hand showed no indication of
digesting beet pulp more rapidly on the 7th day of adminis-
tration. Rumen uronide and soluble carbohydrate concen-
trations (Tables 4 and 5) were higher on the seventh than
on the first day of treatment. Lactic acid concentra-
tions in the rumen were considerably higher on the seventh
than on the first day (Table 6). Percent beet pulp in
the rumen increased markedly by the seventh day. Rumen
pH, which had dropped on the first day of treatment,
showed no indication of returning to the pretreatment
level on the seventh day. Voluntary intake of hay de-
clined through the treatment period (Fig. 1). All of these
indications showed that this cow was not adapting to di-

gesting beet pulp while A192 demonstrated some adaptation.

106

It was noted in Fig. 1 that dry matter intake before the
trial was considerably less for T20 than for A192. Both
cows, however, received the same amount of beet pulp in
the treatments. The suggestion was made above that ru-
men conditions in A192 may have been changed by the large
amounts of beet pulp administered. In T20, beet pulp
made up a larger prOportion of intake, perhaps aggravat-
ing the changes in the rumen even more than in A192 and
thus causing a more unfavorable environment for rapid di-
gestion of beet pulp.

The in vitro fermentation of rumen fluid from both
of these cows showed that the fluid from T20 digested the
beet pulp substrate as rapidly, perhaps somewhat more 6
rapidly, than rumen fluid from A192. In vivo, however,
after receiving NaHCO5 in the rumen, A192 was apparently
digesting beet pulp much more rapidly than T20 (Fig. l).
A possible explanation for these results was that the
buffer solution in the in vitro fermentation mixture
raised the pH and thus enhanced conditions for microflora
activity in the rumen fluid from T20 to digest beet pulp
more rapidly than was occurring in vivo. MicroscOpic ob-
servations of rumen samples indicated greatly reduced
microflora numbers on days when rumen pH was low (Table 7).
Based on the results of these studies it is questionable

if cows fed hay can adapt to the digestion of beet pulp in

107

quantities as large as those used in these trials. In
contrast to the cows fed hay, cow A103, fed grain, demon-
strated ability to digest rather large amounts of beet
pulp (Fig. 1). Results of the in vitro fermentation
trials (Tables 8 and 9) showed further evidence that the
beet pulp was digested more rapidly in the rumen fluid

‘ from cows receiving grain than in rumen fluid from cows
fed hay. There was a significantly greater reduction in
solids and a greater percent disappearance of total car-
bohydrate as well as soluble uronides in rumen fluid fer-
mentations from cows fed grain plus hay than from those
fed only hay.

Makela fed beet pulp and hay to cows and also
swedes and hay. Swedes are a root crop similar to sugar
beets. He observed that when beet pulp and hay were fed
the carbohydrate portion of the rumen ingesta had a
longer retention time than when hay and swedes were fed.
He also cited earlier data comparing rumen retention time
of carbohydrates of cows fed grain, hay, and beet pulp to
cows fed hay and beet pulp and found that the former had
a shorter retention time of the carbohydrates than the
latter (76).

This information provides evidence that beet pulp
is not digested as rapidly in the rumen of cows fed hay

and best pulp as when cows are fed hay, grain, and beet

108

pulp. All this evidence indicates that "cows" fed grain
digest beet pulp more rapidly and also adapt to digesting
larger quantities than cows fed only hay. Perhaps the
rumen microflora in cows fed grain have to change less

to adapt to digesting beet pulp than rumen microflora in
cows fed hay.

When larger amounts of beet pulp were administered
to A192 and T20, the rumen pH was greatly reduced which
appeared to have a considerable influence on rumen micro-
flora activity (Fig. l). Microscopic observations (Table
7) indicated a reduction in total numbers when pH was
greatly reduced. It seems logical to conclude that re-
duced digestive activity would be associated with fewer
numbers. When NaH005 was added in the rumen of A192 to
reduce the acidity, total numbers of microflora increased.
Apparently digestive activity increased at the same time
and resulted in the increased rate of disappearance of
beet pulp in the rumen along with increased hay intake
by A192 (Fig. 1).

For some yet unexplained reason pH is considerably
reduced in cows fed hay and receiving beet pulp. This may
be one of the main reasons for the apparent slower digestion
of beet pulp in the rumens of the cows in these experiments.

Table 1 shows milk production declined when beet
pulp was added in the rumen in two cows while milk produc-

tion increased when hay was added in the rumen of cows fed

109

hay and grain in three cows. The difference in milk pro-
duction response to these treatments cannot be explained
on the basis of dry matter intake. The addition of beet
pulp increased dry matter intake more than the hay. The
possibility that addition of beet pulp changed rumen
microflora activity to the production of other less effi-
cient intermediate metabolites was considered. The vola-
tile fatty acid concentrations shown in Table 6 indicated
a higher proportion of propionate to acetate concentra-
tion in the rumen of A103 after seven days of beet pulp
treatment compared to concentrations found in the rumen
the day before treatment. The total volatile fatty acid
concentrations (Table 6) increased from 100 uM/ml. on the
let day to 139 uM/ml. of rumen fluid after seven days of
treatment. Such a change in total concentrations of acids
is often associated with increased milk production. The
possibility of a change in intake of protein from the feed
was considered. Calculations from estimates of protein
content of feed intake showed that before administration
of best pulp the ration contained 14.47% crude protein
while during administration of beet pulp the feed, includ-
ing the beet pulp, averaged 13.95% crude protein. Average
protein figures for beet pulp appearing in the literature
were 8.8% (24). This small change in protein seems un-

likely to have caused the drop in milk production. From

110

the information available, the drOp in milk production
resulting from administration of beet pulp cannot be
explained.

Throughout various parts of these studies attempts
have been made to find ways that silage may behave differ-
ently in the rumen of cows than when hay is fed. This has
been done in an effort to discover possible causes for
the somewhat reduced dry matter intake of silage than hay.

The single reversal trial reported here in which
hay and silage each were fed to cows revealed only a few
differences. Perhaps the most outstanding difference was
the consistantly higher rumen ammonia concentrations
found when silage was fed than when hay was fed (Fig. 3
and Table 11). El-Shazly (39) observed higher rumen am-
monia concentrations throughout the day in sheep when si-
lage was fed than when hay from the same source was fed.
Williams and Christian (110) fed sheep ten different
direct-cut grass silages. They observed that ruminal am-
monia levels in the sheep were higher just after feeding
when silage containing greater amounts of ammonia and
residual nitrogen was fed than when silages containing
less ammonia and residual nitrogen was fed. It is known
that during the silage fermentation process a portion of
the plant material is broken down by the action of micro-

organisms resulting in the production of varying amounts

111

of ammonia and non-protein nitrOgen. It appears logical
then that more ammonia would be found in the rumen of cows
after eating silage than hay since hay does not go through
a fermentation process in which protein nitrogen is broken
down to ammonia as in silage. The ammonia in the silage
apparently raised the ammonia concentration in the rumen
at feeding time and perhaps was not efficiently eliminated
from the rumen or utilized as well by rumen microflora as
the protein nitrogen thus resulting in the prolonged higher
concentrations than when hay was fed. This does not ex-
plain the higher concentrations found at the medium and
high levels of feeding 4 to 6 hours after feeding (Fig. 3).
The higher concentrations of rumen ammonia found in
this study when silage was fed than when hay was fed may
be associated with higher concentrations of other non-
protein nitrogen breakdown products such as those found
in the investigations of Williams and Christian (110). It
is possible that ammonia and/or other non-protein nitro-
gen compounds associated with higher amounts of ammonia
in silage may be responsible for limiting consumption of
this feed. Thomas et al. (106) observed intake of heifers
was depressed when ammonium salts, glucosamine, and urea
were placed in the rumen. The silage used in this trial
‘was not analyzed for ammonia content but appeared to be

of very good quality as judged by appearance and a

112

desirable odor with no indication of ammonia present and
by acceptance by heifers in another trial. Perhaps other
silage of lower quality and less acceptable may contain
greater amounts of ammonia and non-protein nitrogen com-
pounds which could be responsible for the limited in-
take. Ammonia and other non-protein nitrogen compounds
should be thoroughly investigated to determine if such
compounds are responsible for the limited intake of hay
crOp silage.

The rumen volatile fatty acid concentrations in
cows fed hay or silage were so variable in the experiments
reported here (Table 11) that even the averages are of
questionable significance. A given cow on different
levels of the same feed as well as the same feed fed to
both cows gave inconsistant concentrations, however, keep-
ing in mind the questionable reliability of these average
figures certain differences were seen when silage or hay
was fed (Table 12). When silage was fed, average buty-
rate concentrations were higher throughout the day on all
levels of feeding. Pr0pionate also averaged slightly
higher during the first 6.5 hours after feeding when si-
lage was fed, however, acetate concentrations averaged
higher when hay was fed. The acetate-to-prOpionate ratio
and the 2-to-3 carbon ratios were higher when hay was fed

(Table 13).

113

Rumen pH values (Fig. 2 and Table 10) showed
basically the same trends through the day on the three
levels of feeding when silage or hay was fed. This evi-
dence indicates that even though the silage was acidic
(pH, 4.4) it did not appear to cause a marked difference
in rumen pH 1.5 hours after feeding. In general there
was no appreciable difference in pH when either hay or
silage was fed throughout the day.

As mentioned earlier, comparative retention time
for silage and hay dry matter fed to the cows in this
trial was not measured in all cases; however, a comparison
of five pairs of cows fed hay and silage over a wide range
of closely matched dry matter intakes are shown in Ap-
pendix Table IX. Retention time of dry matter and fiber
was very similar.over the range of intake for cows fed
either hay or silage. A relationship of percent dry mat-
ter in rumen contents versus dry matter intake (Fig. 6)
showed that the dry matter percent in the rumen was
slightly higher when hay was fed than when silage was fed.
These findings are in agreement with those of Thomas et
al. (105) when they compared dry matter intake and percent
dry matter in the rumen when silage and hay wemafed to
cows. When silage or hay was placed in the rumens of

cows fed grain and hay, the effects on voluntary intake

114

as well as total intake were very similar (Table l).

Silage fed from the same silo as used in the hay
versus silage trial reported herein was well liked by the
heifers in another feeding trial. The average consump-
tion was very close to that of comparable hay fed during
the trial. The differences noted when comparing hay to
a silage of high quality might not be as large as differ-
ences when comparing this same hay to a silage of low
quality or acceptability. A trial using a less well ac-
cepted silage compared to hay may shew more significant
differences in rumen pH, volatile fatty acid concentra-
tions and ammonia in the rumen. From the results of ru-
men ammonia differences in this trial, it would be ad-
visable to run analyses on other non-protein nitrogen
compounds in the silage as well as in the rumen when ani~
mals were fed silage compared with animals fed hay. 'In
this way possibly factors reaponsible for limiting in-
take of silage can be isolated.

Makela (75, 76) measured the rate of disappearance
or retention time of ingested feed in the rumen by meas-
uring rumen contents four hours after feeding. He found
the retention time of dry matter in the rumen increased
was dry matter intake was decreased, and that this relation—
éship was curvilinear. Thomas et al. (105) found a similar

Irelationship between rumen retention time and dry matter

115

intake when cows were fed hay or silage. This group also
measured rumen contents approximately four hours after
feeding. They emptied the rumens of fistulated cows to
obtain their data as was the case in this report, while
Makela, above, slaughtered cows to measure rumen contents
in obtaining his data.

In the study reported here (Fig. 4) results very
similar to the above work were reported. It was inter-
esting to note that regardless of the roughage fed the
retention time for dry matter at any intake was reason-
ably close to the hand-drawn line, however, at lower dry
matter intakes there was a greater range in retention
time.

In this study rumen retention time of fiber was
also determined. Similarly as‘with dry matter, increased
fiber intake resulted in a reduced time for fiber to be
retained in the rumen (Fig. 5). It should be noted that
the fiber portion associated with the dry matter of any
forage fed had a somewhat longer retention time in the
rumen. For example, the retention time for intake of 1
lb. dry matter per cwt. was 1.4 days while the retention
time for the fiber associated with the dry matter of hay
and silage (approximately 40% or 0.4 lbs.) was 1.8 days.
This was probably due to the fact that the dry matter

portion was more readily digested than the fiber portion

116

of a feed. In the time between feed consumption and when
the rumen contents were measured 4.5 to 5 hours later, a
greater prOportion of the more readily digestible dry
matter was digested and had left the rumen than the fiber
which was digested more slowly. Relationships such as
those between retention time of dry matter and fiber for

a given roughage may become useful in evaluation of rough-
ages.

Thomas et al. (105) noted that the following rela-
tionships existed between dry matter intake and rumen con-
tents: as dry matter intake increased the percent dry
matter in the rumen increased, as dry matter intake in-
creased dry matter in the rumen as percent of body weight
increased somewhat, and as intake increased the weight of
total rumen contents (wet) as a percent of body weight
remained nearly constant, although, showing a slight
tendency to increase.

Using data from Makela (76) the same relationships
were seen to exist. The relationships reported here
(Figs. 6, 7, and 8) were very similar to the above cited
work with one possible exception. In this study a slight
negative, but non-significant correlation was seen be-
tween weight of rumen contents as percent of body weight

and dry matter intake.

117

Measurement of rumen retention time of feeds and
feed constituents such as carbohydrate, dry matter, fiber,
and lignin can be very useful in estimating the relative
digestion rates or the digestibility of different feeds.
Very likely a more thorough study of relationships as
- those given above can be useful "tools" in understanding
differences in feeds and aid in the effort to increase
efficiency of feed utilization for more efficient live-
stock production. This is, of course, the ultimate goal

in most nutrition work with livestock.

SUMMARY

Rumen fistulated cows fed hay and two lactating
cows receiving grain were administered hay, beet pulp,
direct-cut alfalfa silage, and two silage fractions,
silage juice, and washed pressed silage, through their
rumen fistulas. Total and voluntary dry matter intake
was measured six days before and after and eight days
during administration of these feedstuffs. Total dry
matter intake was increased in every case which ranged
from 1.43 to 8.05 lb./day. Voluntary intake decreased
1.70 to 9.50 lb./day except during administration of the
silage juice fraction when voluntary intake increased 1.01
to 1.12 lb./day.

Dry matter intake of rabbits was not significantly
changed when pellets impregnated with silage juice were
fed compared to control pellets.

Dried beet pulp was intraruminally administered to
two cows fed hay and one cow fed hay and grain to deter-
mine whether beet pulp introduced into the diet was di-
gested more rapidly on the seventh than on the first day.
Concentrations of uronic acids and total carbohydrates
in rumen fluid were determined before feeding and four
‘times of the day after feeding. Lower concentrations of

‘these constituents on the seventh day compared to the

118

119

first day were considered as an indication of adaptation.
The cow fed hay and grain appeared to have adapted to a
more rapid digestion of beet pulp on the seventh day.

One cow fed hay showed some adaptation while the other
cow did not appear to show any adaptation.

Another experiment was conducted to determine
whether cows fed hay and grain digest beet pulp more ra-
pidly than cows fed only hay. In an in vitro fermentation
trial with beet pulp as substrate using rumen fluid from
four cows fed hay and grain and four cows fed hay there
was greater disappearance of substrate, total carbohy-
drate, and soluble uronides (P < 0.05) using rumen fluid
from cows fed hay and grain than fluid from cows fed
only hay.

Intraruminal administration of beet pulp to a cow
fed hay and grain and cows fed hay resulted in an accu-
mulation of beet pulp in the rumens of cows fed hay and
also a reduction in rumen pH while the cow fed grain and
hay did not show an increased percent beet pulp in the
rumen and pH was not depressed. While beet pulp was ac-
cumulating in the rumens of the two cows receiving hay
and beet pulp, NaHCO5 was added into the rumen of one
cow to restore pH to normal and the other cow served as
control. Beet pulp continued to accumulate in the rumen

of the control cow while a marked reduction resulted in

120

the rumen of the NaHCO5 treated cow. General micro-
sc0pic observations of rumen fluid revealed that a reduc-
tion in total numbers of microflora, especially protozoa,
was associated with low rumen pH.

Rumen pH, NHB’ and volatile fatty acid concentra-
tions in two cows fed hay or direct-cut alfalfa silage at
three levels were determined six times during the day to
observe differences in the concentrations when animals
were fed these roughages. Rumen pH was slightly higher
1.5 hours after feeding when hay was fed but followed the
same trend through the remainder of the 12 hours as when
silage was fed. The greatest differences were higher con-
centrations of rumen NH3 when silage was fed at all levels
and times of the day. Volatile fatty acid concentrations
were variable although average acetate concentrations
and acetate-to-propionate ratios were higher when hay
was fed, and butyrate was higher when silage was fed.

Rumen emptyings were performed during the above
trials 4.5 to 5 hours after morning feeding. Rumen dry
matter, fiber, percent dry matter in the rumen, and total
weight of rumen contents were determined. Rumen retention
time of dry matter expressed in days was calculated by
dividing daily dry matter intake by dry matter in the
.rumen and similarly for daily fiber intake. Retention

time of dry matter was reduced as dry matter intake

121

increased. A similar relationship was noted between
fiber intake and fiber retention time. As dry matter
intake increased percent dry matter in the rumen and
rumen dry matter as percent of body weight increased,
while there was a tendency for total weight of rumen con-

tents as percent of body weight to decrease slightly.

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APPENDIX

132

ANALYSIS OF VARIANCE TABLES OF RESULTS WHEN RABBITS WERE FED
SILAGE JUICE TREATED PELLETS VS CONTROL PELLETS

APPENDIX TABLE I

 

Grams dry matter {Etake by four day intervals 6y raSSIts fed
silage juice treated pellets vs control pellets

Analysis 2; Variancg Table

.133

 

 

 

 

Source D.F. Sum of ngeres Mean Square F Signif.
Treatments 1 4428.166 4428.166 .41 n.s
Periods 1 26533.5 26533.5 2.49 "
Groups 1 9048.166 9048.166 .85 ”
T x P 1 2903.994 2903.994 .27 "
T x C 1 5765.998 5765.998 .54 "
T x G x P 1 20768.172 20768.172 1.95 ”
Error 18 170453.34 10653.3
Total 23 241192.0
Grams weight gains by eight day intervals of rabbits fed
silage juice treated pellets vs control pellets
Analysis 2; Variance Table
Source D.F. Sum of Squares Mean Square F Signif.
Treatments 1 468.78 468.78 .14 n.s
Groups 1 1800.78 1800.78 .54 ”
T x C 1 7500.00 7500.00 2.27 "
Error 8 26432.14 3304.0
Total 11 36201.7

APPENDIX TABLE II

RUMEN URONIC ACID AND‘TOTAL SOLUBLE CARBOHYDRATEeCONCEN-
TRATION DURING INTRARUMINAL BEST PULP ADMINISTRATION

 

 

 

134

 

Day Uronic Acid Total Carbohydrate
Hours after feeding Hours after feeding
-.l 1.5 2.5 3.5 4.5 -.l 1.5 2.5 3.5 4.5
(ugm./m1.) (ugm.7m1.)
A103 H2804 Preserved
O .152 .169 .128 .140 .125 .570 .810 .680 .764 .740
1 .130 .696 .222 .166 .146 .690 7.200 1.790 .600 1.110
7 .116 .241 .152 .142 .133 .800 1.920 1.130 .846 .920
Ethanol Preservld
0 .121 .142 .106 .122 .115 .752 .864 .616 .677 .650
l .110 .568 .178 .143 .126 .630 5.632 1.590 1.336 1.168
7 .087 .204 .129 .110 .105 .715 1.930 1.072 .768 .852
A192 H2804 Preserved .
0 .133 .185 .189 .139 .123 .396 .388 .530 .395 .378
1 .145 .965 .334 .214 .165 .265 2.081 .775 .510 .390
7 .135 .169 .188 .189 .180 .490 .560 .596 .497 .487
Ethanol Preserved
0 .112 .144 .147 .118 .131 .216 .294 .428 .301 .302
l .116 .824 .247 .180 .135 .284 2.080 .792 .512 .334
7 .098 .103 .126 .160 .128 .456 .604 .572 .556 .480
T20 H2804 Preserved
0 .108 .107 .113 .090 .085 .308 .340 .308 .242 .300
l .144 .575 .176 .183 .170 .237 1.252 .373 .380 .373
7 .155 .766 .180 .144 .135 1.180 1.610 .575 .408 .445
Ethanol Preserved
0 .095 .098 .085 .081 .085 .176 .200 .160 .156 .168
1 .110 .440 .136 .144 .134 .222 1.413 .388 .410 .432
7 .134 .664 .140 .180 .205 .572 1.784 .596 .404 .596

H280 Preserved
Ave. 0.2161 St. Dev. 1 0. 694 Ave. 1.0747 St. Dev. i 0.836

Ethanol Preserved
Ave. 0.1724 8t. Dev. 1 0.1414 Ave. 1.0089 St. Dev. 1 0.936

"t" P (.05 n.s. P‘<.05 n.s.
Correlation Coeff. H2804 vs. ethanol 0.9874 (P ‘0.06)
r - 0.980 (P < 0.01)

135

APPENDIX TABLE III

RIJMEN VOLATIIE FATTY ACID CONCENTRATIONS IN COWS
FED HAY AND SILAGE

_-
L

 

W

 

 

 

ineL Silage
Time Acet. Prop. Duty. Acet. 2:3 Acct. Prop. Duty. Acet. 2:3
after Prop. Carbon Prop. Carbon
feed ;
(”1111.) (I'M/ml.)

119 Low Level

1.5 .053 .012 .003 4.42 4.92 .045 .015 .002 2.00 3.27
2.5 .057 .012 .003 4.75 5.25 .048 .013 .003 3.69 4.15
3.5 .058 .011 .003 5.27 5.82 .045 .012 .002 3.75 4.08
4.5 .052 .012 .004 4.33 5.00 .047 .011 .003 4.27 4.82
6.5 .069 .016 .006 4.31 5.06 .053 .011 .063 4.80 5.36
12.0 .093 .018 .005 5.16 5.72 .045 .012 .002 3.75 4.08
'1'231mLeve1

1.5 .044 .009 .001 4.89 5.12 .673 .018 .004 4.05 4.50
2.5 .048 .010 .002 4.80 5.20 .060 .015 .003 4.00 4.40
3.5 .045 .009 .002 5.00 5.44 .068 016 .004 4.25 4.75
4.5 0039 .007 .001 5.57 5.86 .066 .016 .005 4.12 4.75
6.5 .048 .008 .002 6.00 6.50 .060 .014 .004 4.20 4.86
12.0 .037 .006 .001 6.17 6.50 .056 .010 .005 5.60 6.60
119 Medium Level

1.5 .055 .012 .003 4.58 5.08 .070 .020 .011 3.50 4.60
2.5 .049 .009 .002 5.44 5.89 .064 .017 .010 3.76 4.94
3.5 .046 .007 .001 6.57 6.86 .071 .019 .010 3.73 4.79
4.5 .046 .009 .001 5.11 5.33 .067 .019 .010 3.53 4.58
6.5 .051 .010 .003 5.10 5.70 .06! .019 .012 3.63 5.42
12.0 .058 .011 .004 5.27 6.00 .076 .022 .011 3.45 4.45
'1'23 Medium Level

1.5 .088 .018 .005 4.89 5.44 .061 .013 .004 4.69 5.41
2.5 .089 .019 .006 4.68 5.32 .063 .016 .005 3.94 4.56
:3.5 .089 .017 .006 5.20 6.00 .060 .013 .004 4.60 5.23
4.5 .089 .017 .005 5.20 5.82 .066 .015 .004 4.40 4.93
«5.5 .093 .019 .006 4.89 5.53 .073 .018 .005 4.05 4.66
1.2.0 .075 .014 .005 5.36 6.07 .059 .013 .005 4.54 5.31
'119 High Level (Arthur)

1.5 .073 .018 .007 4.05 4.83 .052 .015 .007 3.47 4.40
:2.5 .066 .015 .006 4.40 5.20 .067 .021 .010 3.59 3.67
3.5 .071 .017 .005 4.18 4.76 .064 .020 .010 3.20 3.70
4.5 0.80 0.16 .007 5.00 5.87 .059 .014 .008 4.20 5.36
6.5 .113 .025 .009 .4.52 4.84 0076 .025 .011 3.04 3.92
12.0 .101 .021 .009 4.80 5.66 .069 .019 .011 3.63 4.79
'1'23 High Level

1.5 .069 .017 .005 4.05 4.65 .072 .015 .008 4.80 5.97
:2.5 .083 .019 .007 4.37 5.10 .071 .013 .007 5.46 6.54
:3.5 .081 .015 .006 5.40 6.20 .059 .012 .006 4.92 5.91
4.5 .080 .017 .005 4.70 5.29 .064 .013 .007 4.92 6.00
6.5 .102 .023 .009 4.43 5.22 .072 .014 .008 5.14 6.43
12.0 .107 .024 .011 4.46 5.37 .074 .014 .007 5.29 6.29

136

APPENDIX TABLE IV

ANALYSIS OF VARIANCE OF RUHEN VOLATILE FATTY ACID
COMENTRATIONS FOR COWS FED HAY VS SILAGE AT THREE
LEVELS AND SIX TIMES DURING THE DAY

 

 

 

Acetate
Source M. Sum of §3uares gen Square’ F Signif.
Feed 1 .000755 .000755 27.2 0.01
Time 5 .00130 .00026 9.4 , 0.01
Animal 1 .000584 .00058 20.9 0.01
leavel 2 .00565 .002825 101.6 0501
F x T 5 .000499 .000099 3.6 0.05
P x A 1 .000008 .000008 ---- ----
Pa]. 2 .001445 .000722 25.9 0.01
T x A 5 .000575 .000115 4.1 0.05
'1' x L 10 .001085 .000108 3.9 0.05
A x L 2 .000903 .000451 16.2 0.01
I x T x A 5 .000297 .000059 2.12 ----
P a T x l. 10 .000693 .0000693 2.49 ----
F x A x l. 2 .00475 .00237 85.2 0.01
‘1' x A x I. 10 .000647 .000065 2.34 ----
Error 10 . 000278 . 00002 78
Total 7 1 . 019469
Prppionate
Source 0.3. Sum of Squares Mean Square 1' Signif.
reed 1 . 025 . 025 8. 3 0. 05
Time 5 .070 .014 4.7 0.05
Animal l .011 .011 3.6 ----
Level 2 .348 .174 58.0 0.01
I s T 5 .024 .0048 1.7 ----
1' x A 1 0056 .056 18.7 0.01
I x L 2 .137 .0685 22.8 0.01
T x A 5 .043 .0086 2.8 no-
'r x L 10 .085 .0085 2.8 --.-
A x L 2 .052 .026 8.7 0.01
F x T x A 5 .014 .0028 .9 ----
F x T x I. 16 .045 .0045 1.5 ----
F x A x I. 2 .318 .159 53.0 0.01
T x A a l. 10 .077 .0077 2.7 ----
Error 10 . 030 . 0030
Total 71 1.335

Appendix Table IV concluded

 

137

Butyrate

§ource D.F. Sum of Squares Mean Square F gignif.
Feed 1 58. 680 58. 680 43. 7 0. 01
Time 5 30.736 6.147 4.6 0.05
Animal 1 21.014 21.014 15.6 0.01
Level 2 268.028 134.014 99.7 0.01
1" x T 5 4.074 .814 .6 ----
P x A 1 26.125 26.125 19.4 0.01
F x L 2 32.195 16.09 12.0 0.01
T x A 5 .74 .148 ---- «~-
'1' x I. 10 13.476 1.35 1.0 ----
A x l. 2 1.698 .849 ---- «~-
1' x T x A 5 9.95 1.99 ---- "--
7 x T x L 10 6.30 .630 ---- ~---
I x A x L 2 ‘ 138.75 69.375 51.5 ----
T a: A x I. 10 6.798 .6798 ---- ----
Error 10 13 . 436 1 . 3436

Total 71 632.0

138

APPENDIX TABLE V
ANALYSIS OF VARIANCE OF ACETATE-TODPROFIONATE AND
ZeTO-3 CARBON VFA RATIOS FOR COWS FED HAY VS SILAGE
AT THREE LEVELS AND SIX TIMES DURING THE DAY

Acetate-to-Propionete

 

 

 

.ggurce 4_§.F. SggZQf Squares Mean Square F Signif.
Feed 1 11.97 11.97 53.4 0.01
Time 5 2.88 .576 2.6 ----
Animal 1 6.00 6.00 26.7 0.01
Level 2 .43 .21 .9 ----
F x T 5 .67 .13 .6 ----
F a A 1 2.71 2.71 7.6 0.05
F x L 2 2.54 1.27 5.7 0.05
T x A 5 .60 .12 .5 ----
T x L 10 2.44 .244 1.1 ----
A.x L 2 1.36 .68 3.0 ----
ETA 5 1.24 .25 1.1 ----
FTL 10 .62 .062 .3 ----
PAL 2 2.28 1.14 5.1 0.05
TAL 10 2.16 .216 .9 ----
Error 10 2.24 .224

Total 71 40.137

2~to-3 Carbon Ratio

'gqqrce 0:1. Sum of Squares Mean Square F Signif.
Feed 1 6.119 6.12 29.1 0.01
Time 5 3.81 .762 3.6 0.05
Animal 1 5.287 5.29 25.2 0.01
Level 2 .74 .37 1.7 ---~
F x T 5 1.21 .24 1.1 .--.
F x A 1 2.65 2.65 12.6 0.01
FxL 2 3.06 1.53 7.3 0.05
T x A 5 .78 .16 .7 ----
T x L 10 2.85 .285 1.3 ----
A.x L 2 2.71 1.35 6.4 0.05
F x T x A 5 1.61 .322 1.5 ----
F x T x L 10 .61 .061 .3 ----
F x A x L 2 2.27 1.13 5.4 0.05
T x A x L 10 4.30 .43 2 0 ----
Error 10 2.11 .211

Total 71 40.12

J

APPENDIX TABLE VI

DATA OF RUMEN EMPTYINGS

—_

Rumen

139

 

Cow No. D.M. Rumen % D.M. Fiber Rumen
Intake Contents D.M. in intake fiber
Wet D.M. Intake rumen inuae
D.M. fiber
(lb/bwt.) (%[body wtfj (%f (lb/cwt.)
Hay fed
T26 2.527 11.959 1.608 .656 15.45 1.080 .780
T26 2.757 10.270 1.512 .475 12.78 1.178 .569
K159 1.526 15.060 1.440 1.086 11.05 .482 1.428
T19 .425 10.460 .755 1.779 7.20 .154 2.555
T25 .446 12.910 .684 1.555 5.50 .162 1.650
T25 .484 14.593 1.194 2.467 8.50 .178 5.149
T19 .429 11.507 1.265 2.945 10.97 .158 4.556
A192 2.258 15.479 1.782 .789 15.22 .866 1.040
T20 1.551 10.526 1.029 .665 9.78 .588 .726
T26 2.229 9.427 1.427 .640 15.14 .845 .828
T19 .842 12.789 1.650 1.954 12.74 .519 2.495
T25 .501 9.902 .884 1.766 8.95 .186 2.085
T25 .952 16.666 2.082 2.186 12.49 .585 2.615
T25 2.535 15.506 2.185 .957 14.28 .940 1.248
Silage fed
T25 1.216 14.898 1.559 1.265 10.55 .405 1.674
T19 .557 9.812 .868 1.562 8.87 .184 2.176
Art 1.084 17.044 1.907 1.760 11.19 .595 2.487
T19 1.670 14.677 1.708 1.025 11.64 .609 1.552
Art 2.042 14.685 1.856 .971 12.64 .745 1.248
Hay + Silage juice
T26 2.591 10.560 1.254 .517 11.94 .891 .666
T20 1.791 11.200 1.190 .665 10.65 .550 .980
A192 1.585 15.757 1.510 .946 8.55 .292 1.799
T26 2.602 9.726 1.200 .460 12.54 .986 .624
T20 1.622 9.805 1.121 .691 11.45 ---- ----
Hay + Washed Pressed Silage
T20 1.790 15.140 1.654 .915 12.44 .815 .965
T26 2.421 11.270 1.611 .665 14.29 1.004 .784
T20 1.758 12.040 1.544 .764 11.16 .786 .904
T26 2.406 10.244 1.150 .470 11.05 -—-- ----
Fresh Cut Alfalfa
K159 2.117 11.417 1.474 .696 12.91 .767 .970
K159 1.455 12.560 1.665 1.158 15.49 .525 1.657
Hay + Beet Pulp
T20 1.584 12.442 1.554 .980 10.89 .464 1.215
A192(NaH005) 2 . 180 15. 560 Q105 . 964 15 . 69 . 765 1 . 296

 

 

 

140
APPENDIX TABLE VII
RELATIONSHIPS BETWEEN DRY MATTER AND FIBER IN THE EUT TEN,
RETENTION TIME AND INTAKE

Dry matter retention time vs fiber retention time

(N = 50)
I‘ = 00975, P ( 0001 t = 10847, P > 0095
Dry matter intake (lbs./cwt) vs fiber intake (1b./cwt.)
(N = 50)
I‘ = 009756, P ( 0001 t = 60658, P ’ 0099

APPENDIX TABLE VIII
RELATIONSHIPS BETWEEN DRY MATTER INTAKE AND RUMEN CONTENTS

Dry matter intake (1b.{cwt.) gs percent dry matter in rumen
N = 52

I' 8 0074’ P ‘ 0001 + Y 8 708 + 203x
std. error of est. - 1.497

Dry matter intake (1b./cwt.) vs dry matter in rumen as per-
cent of body weight

(N = 52)

r - 0.28, P <-0.05 + Y = 1.19 + 0.148X
std. error of est. - .5728

Dry matter intake (1b. /cwt. ) vs weight of rumen contents
(wet) as percent of body weight
(N a 52)

r a -0. 15, P < 0. 05 Y a 15.2 - 0.47X
std. error of est. - 2. 252

Dry matter intake (1b. /cwt. ) vs percent dry matter in rumen
(N = 5) cows fed silage

I‘ . 00944, P ‘ 0005+ Y 3 70827 + 20565X
std. error of est. - 0.559

Dry matter intake (1b. /cwt. ) vs percent dry matter in rumen
(N = 5) cows fed hay

r a 0.7545, P < 0.05 Y = 7.865 + 2.755X
std. error of est. - 1.95

141.

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amaze vow otou e> hon tom :50 we aim... ocuufluuou annual .03 gm

ad a m 22.6 n :H: .86 m .hmmd a u

amm~.~

 

 

 

 

 

 

 

 

 

 

 

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NH an. Mug

142

APPENDIX TABLE X

INTAKE AND RUMEN RETENTION TIME COMPARING FIVE COWS
FED HAY WITH FIVE CONS FED HAY PLUS SILAGE JUICE

 

 

 

 

etent on
(lb/cwt) time (lb/cwt) time
(daze) (dugL
T26 2.757 .476 T26 2.602 .460
A192 2.258 .789 T26 2.391 .517
T26 2.229 .640 T20 1.791 .666
T20 1.551 .665 T20 1.622 .691
K122 1.526 1.086 A1 2 l. 8 .946
mean .0 42* .7508 . .656

Rumen dry matter retention time of cows fed hay vs cows fed
hay plus silage Juice

1‘ - 0082 nos. "t" . 0056 P . 007

APPENDIX TABLE XI
INTAKE AND RUMEN RETENTION TIME COMPARING FOUR CONS

FED HAY ADMINISTERED WASHED PRESSED SILAGE VS FOUR
COWS FED HAY ADMINISTERED SILAGE JUICE

Fe: E + washed ressed sIIa e Fed hay pIus sIIage 32E
Cow DE Intake RetentIon ow M ntake etention

 

 

 

 

(lb/cwt) time (lb/cwt) time

(dazq) (days)

T20 1.758 .7644 T20 1.622 .6910

T20 1.790 .915 T20 1.791 .6659

2222 22°.g 2222 222;
mean 2:095’ : O 2II02 :

Rumen dry matter retention time of cows fed hay administered
washed pressed silage vs silage Juice

r 3 0046 11.8. "t" . 0078 P I 007

.*-‘"- ‘
1.. .
IF

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