Department of Animal Science i j 970 Florida Agricultural
Mimeograph Series No. AN70-8 Experiment Station
April, 1970 Gainesville, Florida
F.A.S. Univ. of Florida
PROBLEMS IN FORMULATING RATIONS TO AVOID DIGESTIVE DISORDERS
IN FULL-FED BRAHMANS AS COMPAREDTO CATTLE
OF BRITISH BREED ORIGIN!
J. F, Hentges, Jr.
"Inherited characteristics which enable an individual to quickly adapt to
one environment may prove to be a hindrance to adaptation in a different envi-
ronment." This quotation may explain why some Brahman cattle adapt easily to
low-protein tropical forage diets but become susceptible to digestive disorders
on high-concentrate diets in feedlots.
The scientific literature contains many reports of research to confirm the
fact that the American Brahman breed is well equipped to withstand the stress of
hot, humid and seasonally dry tropical environments. They have a faster rate of
passage of food through the forestomach (Philips et al., 1960) and a faster rate
of r'.iaen fermentation (microbial digestion of-f6bdo than the cattle breeds of
European origin (Heingate et al., 1960). Also, they drink less water per unit
of feed dry matter consumed (Philips, 1960). They are reported to have a lower
mair;.:enan.-e requirement for protein and a higher efficiency of nitrogen utilization
when low protein diets are fed (Marshall et al., 1961; Elliott and Topps, 1963).
A timely question is, "How do Brahmans and European breeds compare when nutri-
tionally adequate diets are fed in temperate climates?" In 18 Florida digestion
trials with Brahmans and Herefords (Howes, Hentges and Davis, 1963), Brahmans
consumed more feed dry matter per day and digested it more efficiently when the
diet was low in protein and energy, but when the diets were nutritionally adequate
there were no apparent digestibility differences between breeds.
The problems facing most cattle feedlot operators are quite different from
those facing cattle ranchers in Gulf Coast and tropical regions. Instead of low-
protein, fibrous forage diets they have been forced by economic pressures to use
high-concentrate diets which are more efficiently converted to -weight gains.
These high-efficiency diets present a continual threat of digestive disorders
(Crane, 1969; Elam, 1969; Jensen and Mackey, 1965; Maclean, 1966). Their content
of soluble and rapidly fermentable carbohydrates frequently results in the accu-
mulation of excessive quantities of lactic acid in the rumen and a condition termed
"bovine lactic acidosis." The syndrome is commonly called "founder" or "feedlot
founder." In scientific publications, it has.been variously termed acute indiges-
tion, "off-feed," engcrgement toxemia, lactacidemia, acute impaction, overeating
disease and d-lactic acidosis (Brawner, 1969). Closely related to bovine lactic
acidosis is a group of diseases, namely enterotoxemia (Griesemer, 1962), listeriosis,
1/ Text of talk presented by Dr. James F. Hentges, Jr., Professor and Animal Nutri-
tionist, at the University of Florida Beef Cattle Short Course, Gainesville,
Florida, on 7 May 1970.
IBR (infectious bovine rhinotracheitis) and others caused by various clostridial
organisms. The clostridial diseases seem to occur in direct proportion to stress,
especially those stresses arising from modern feedlot practices (Crane and Poulous,
While all breeds of feedlot cattle are susceptible to digestive disorders
when high-concentrate diets are fed, purebred Brahmans are claimed (unpublished
reports) to be most affected. Founder has been reported among Brahmans in show
herds, postweaning bull performance tests and feedlots. Various methods of pre-
vention have been practiced. One cattleman mixes 3% salt in the diet to induce
more water consumption and more frequent eating. Another puts a minimum-of 20%
coarse roughage (hay, hulls, etc.) in the diet. Another starts his cattle on
diets containing only 1% of bodyweight as concentrates and takes three weeks to get
up to a maximum content of 85% concentrates. Another replaces some of the pro-
cessed grains (source of rapidly fermented carbohydrates) in his fattening diets
with bulkier industrial by-products of rice, citrus, wheat and corn. All of these
practices slow down the rate of passage of food through the forestomach and also
avoid a rapid microbial fermentation or conversion of feed carbohydrates to organic
acids. Some feeders dislike these feeding practices which may reduce efficiency
of feed conversion. Also reported is the necessity of separating the predominate-
ly Brahman cattle into pens where they can be offered special diets.
In 1968 and 1969, a team of University of Florida animal nutritionists and
veterinarians worked with others in the Medical Center to study digestive disorders
in purebred Brahmans, Angus and Herefords. In one study (Brawner, 1968), they
simulated the stresses encountered in feeder cattle by taking Brahman, Hereford
and Angus yearlings directly from a pasture forage diet, fasting them for 24 hours,
hauling them on a truck for 4 hours, fasting them for another 24 hours and then
offering them free choice (ad libitum) access to a high concentrate diet. The
diet was composed of 60% steamed rolled corn, 24% steamed rolled barley, 8% expel-
ler soybean meal and 8% standard cane molasses. The response of all cattle was
similar in that all consumed large quantities (8 to 18 pounds) of feed within a
few hours, all were "off feed" within 12 hours and only one resumed eating within
60 hours. Their forestomach contents before they ate the feed were about neutral
(rumen fluid pH of 7.6) but after eating, the pH dropped to 5.24 at 6 hours and
to 4.56 at 32 hours. Concurrent with this increase in rumen acidity, there was
an increase in rumen lactic acid content. Some of the lactic acid was absorbed
from the rumen into the bloodstream as evidenced by a drop in blood pH. Unlike
the finding of Ahrens (1967) the concentration of histamine in the blood did not
increase but varied from 0.10 to 0.12 micrograms per milliliter which is apparently
a normal level. See table 1 for a summary of the average biochemical changes in
all of the experimental cattle.
Table 1. Summary of Biochemical Changes
Rumen pH 7.61 to '4.56 <.01
Rumen lactate 0.33 to 99.41a <.01
Blood pH 7.40 to 7.28 <.01
Blood lactate 4.84 to 6.38a <.01
Blood histamine variable N.S.
aMillimoles per milliliter
Variable between .100 and .120 mg/ml
- 3 -
Other symptoms observed were severe diarrhea, lethargy (sluggishness), craving
for roughage and ulceration of the true stomach abomasumm).
In every trial, Brahmans experienced a faster build-up of blood lactite
(17.25 vs. 23.25 hours to peak acidity), apparently indicating a more rapid ad-
sorption of lactate. and a lower tolerance to.change.-in the biochemical balance
than the Herefords and .Angus. The most severely affected animal in the experiment,
Brahman 915, not only had the largest accumulation of rumen lactic acid but also
had the most 'sustained peak concentration, maintaining a level of 135 millimoles
per liter or higher from 12 to 31.5 hours after feed was offered. For 72 hours
after the animal went "off feed," it would.not stand on its front feet, or if
provoked to do so, it extended its front feet to stand on its heels. It declined
to walk or'to put pressure on the toes of its front feet. When lying down, it
extended its front feet. A postmortem examination revealed findings typical of
those described in the 'literature for cattle engorged with grain and with highly
acid gastrointestinal contents... If one considers lactic acid to be the toxic
factor in "feedlot cattle founder," these observations may explain the reason for
Brahmans to exhibit founder more easily ihan breeds of Bos taurus species when
offered high-concentrate diets.
It has been reported (Uhart'and Carroll, 1967; Tremere et al., 1968) that the
time an engorged animal is "off feed" is actually'the time required for adjustment
of the microbial population in the rumen to a high concentrate diet. This theory
was supported by the findings of thesis research at the University of Florida, by
Brawner (1968) and Taylor (1968). Their work illustrates the importance of for-
mulating rations for new feedlot cattle in such a manner that their rumen micro-
bial population will have sufficient time to adjust to a high-concentrate diet.
Individual variation within breed.s was evident throughoJut ctir research results,
indicating that the tendency to develop digestive disorders*T 'ght be heritable to
some degree and thereby controlled to some degree by selection methods.
To further test the theory that feedlot cattle digestive disorders were cor-
related with increased rumen and blood concentrations of lactic acid, Taylor (1968)
infused the rumens of fistulated Brab:.tan and Hereford males with lactic acid,
histamine and lactic acid plu-. h:isb;.vne. All cattle previously had been re- .
stricted to a forage diet. T!-.e quantity of lactic acid added t.hrou.h the fistula
to the rumens increased the rumen acidity to a pH Of 3.9. This resulted in signifi-
cant differences between breeds with the Brahmans reacting much more quickly with
much higher concentrations of whole blood lactic acid. The highest concentrations
of blood lactic acid were correlated with the lowest blood pH values. These data
are complementary with those reported. for stressed cattle by Erawner (1968). They
are illustrated by the response of Brahman 275 to lactic acid infusion as shown in
table 2 (see page 4).
Histological studies of the forestomach epithelium revealed marked changes
(lesions) after infusion of the lactic acid. This finding raises a question about
the degree of gastrointestinal damage which occurs every time the forestomach
contents become excessively acid causing an "off feed" or "founder" condition.
To summarize, numerous research reports have explained fundamental causes
for the digestive disorder termed "bovine lactic acidosis" and have reported dif-
ferences in response of cattle of Brahman and European breed origin to diets
which are high in concentrates. These findings can be used by nutritionists to
formulate diets for both groups of cattle during changes from roughage to concen-
trate diets without subjecting them to digestive disorders.
Table 2. Relation of Clinical Signs to Physiological Criteria,
.Clinical Hr. after Blood lactic Blood
signs infusion pH acida histamineb
Appearance normal 0 7.405 1.33 0.066
i 7.384 2.23
1 7.350 3.97 0.062
3 7.355 4.56 0.062
Signs of distress
at 5 hr. 4 7.354 5.26 0.053
Apparent tenderness in 8 7.38? 4.80 0.053
feet at 9 hr.
12 7.415 4.53 0.043
Condition improving at
14 hr. 18 7.425 3.57 0.056
Appearance normal 22 7.458 2.11 0.075
SMillimoles per liter
Micrograms per milliliter
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