INDUÇÃO DA ACIDOSE RUMINAL COM AÇUCAR

Prévia do material em texto

W. W. Kezar and D. C. Church 
Lactic Acidosis in Sheep
Ruminal Changes during the Onset and Recovery of Induced
 1979. 49:1161-1167. J Anim Sci
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R U M I N A L C H A N G E S D U R I N G THE ONSET A N D 
RECOVERY OF INDUCED LACTIC ACIDOSIS IN SHEEP 1 
W. W. Kezar 2 and D. C. Church 
Oregon State University a, Corvallis 97331 
Summary 
Four crossbred wethers equipped with 
runten fistulas were used to study changes in 
rumen pH, motility and the synthesis of volatile 
fatty acids and lactic acid during the onset and 
recovery of induced lactic acidosis. Acidosis 
was induced by the addition of sucrose (15 g/kg 
BW) in 700 ml of water through the fistula. 
Mean maximum lactic acid concentration was 
near or in excess of 100 mM of rumen fluid 
during the first 48 hr postinducement. The 
minimum pH values observed for each sheep 
were 4.53, 4.13, 4.29 and 4.48. Propionic and 
butyric acids were absent from rumen samples 
by 14 hr postinducement. Acetic acid concen- 
trations decreased to < 5 mM during the first 24 
hr following the addition of the sugar. Rumen 
motility decreased in frequency and amplitude 
during the first 4 hours. Normal rumen motility 
was observed in one sheep by 52 hr but not in 
another, until 84 hr postinducement. Two of 
the four sheep were "off feed" by 4 postin- 
ducement, while the remaining two did not 
become anorexic until 7 hours. Animals began 
to consume small amounts of alfalfa when 
rumen pH values increased to >5.0 but con- 
sumption similar to preinducement intake was 
not observed until the rumen pl! was > 6.0 and 
lactic acid could no longer be detected in the 
ru~nen fluid. 
(Key Words: Acidosis, Lactic Acid, pll Motility, 
Anorexia, Volatile Fatty Acids.) 
Introduction 
Over a period of years numerous research 
reports have been published on lactic acidosis 
Technical paper No. 5037, Oregon Agr. Exp. Sta. 
2 Present address: Agricultural Industries and Ser- 
vices Division, Univ. of Minnesota Technical College, 
Waseca 56093. 
and the effects the disorder has on the reticulo- 
rumen (Hungate et al., 1952; Dunlop and 
Hammond, 1965; Allison et al., 1964; Huber, 
1971; Ryan, 1964; Uhart and Carroll, 1967). 
Changes that occur in rumen pH, volatile fatty 
acids, formation of lactic acid and rumen 
motility as well as many others have been 
documented and reviewed (Elam, 1976; Huber, 
1976; Slyter, 1976; Brent, 1976). 
The purpose of the present research was to 
induce lactic acidosis in sheep equipped with 
rumen fistulas and monitor rumen changes such 
as motility, pH, volatile fatty acids and lactic 
acid, not only in the developmental stages of 
the disorder but also during the recovery 
period. Many of the studies involving the 
inducement of acidosis have resulted in death 
of the animals and, as a result, data on recovery 
periods are lacking. The objectives were to 
observe the conditions existing at the time the 
sheep went "off feed" as well as when they 
began to consume feed again in order to gain a 
better understanding of the conditions existing 
when rumen stasis occurs and when rumen 
motility resumes. 
Materials and Methods 
Animals. Four crossbred wethers (A, B, C, 
D) weighing 48 to 55 kg were prepared with 
rumen fistulas following procedures outlined by 
McCann et al. (1973). Animals were given a 
minimum of 60 clays recovery time before 
rumen motility studies were conducted. The 
sheep were maintained on grass-alfalfa hay prior 
to the studies. Water and trace mineralized salt 
were available ad libitum at all times. 
Inducement o f Acidosis. The sheep were 
given sucrose at the level of 15 g/kg BW in a 
700 ml solution of water warmed to 39 C. The 
sucrose solution was placed in the rumen 
through the fistula at 0800 immediately follow- 
ing rumen motility tracings and rumen pH 
determination. 
3 Dept. of Animal Science. Rumen Motility Recordings. The sheep were 
1161 
JOURNAL OF ANIMAL SCIENCE, Vol. 49, No. 5, 1979 
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1162 KEZAR AND CHURCH 
TRANSDUCER 
TO 
RECORDER ' ~ ' - 
V A L V E " 
SYRI NG 
CATHETERS 
M TUBING 
Figure 1. Cross section through body cavity showing placement of balloon apparatus in the ventral sac of the 
rumen. 
placed in separate metabolism crates 3 days 
prior to any recordings. Rumen motility was 
recorded prior to the morning feedings and at 
4, 8 and 12 hr postfeeding on 2 consecutive 
days before inducing acidosis. Diets consisted 
of chopped alfalfa offered once daily, and the 
animals were allowed to eat ad libitum for a 
4-hr period. Rumen motility was recorded prior 
to the addition of sucrose and 2, 4, 7, 10, 14, 
24, 28, 32, 36, 48, 52, 60, 72, 76, 84, 96 and 
108 hr postinducement. 
The recording apparatus consisted of a thick 
wall balloon (finger cot) mounted over a one 
hole No. 2 rubber stopper which was connected 
to a 61 cm section of semi-rigid .64 cm O.D. 
aluminum tubing. A small plastic catheter was 
run down through the tubing, flared and sealed 
with wax to prevent any air leakage from the 
balloon once it was inflated. The balloon was 
securely fastened to the stopper by wrapping 
with suture material and covering with water- 
4Statham P 23 transducer, Statham Industries, 
Inc., Oxnard, CA 93030. 
SGilson polygraph, model MSP, Gilson Medical 
Electronics, Inc., Middletown, WI. 
proof tape. The catheter from the balloon was 
connected to a pressure transducer 4 with the 
aid of Leur-lock fittings. A second catheter 
tube led from the dome of the pressure trans- 
ducer to a 50-ml syringe with a Leur-Lock 
holder. The balloon was inflated with 30 ml of 
air. Back pressure on the syringe was eliminated 
with the aid of a three-way stopcock. A poly- 
graph s connected to the electrical transducer 
was used to record the movements of the 
reticulo-rumen. 
In preparation for recording the ballobn 
apparatus was inserted through the cannula and 
inflated with the aid of the syringe. A one-hole 
No. 5 rubber stopper that had been moved 
down over the aluminum tubing acted to hold 
the device in place by fitting tightly into the 
barrel of the rumen cannula (figure 1). Motility 
in different sections of the reticulo-rumen were 
recorded by bending the aluminum tubing 
towards the desired area. Further adjustment 
was possible by sliding the aluminum tubing in 
or out through the rubber stopper held in the 
barrel of the cannula. 
Rumen Samples. A sample of rumen con- 
tents from the ventral sac was removed through 
the fistula with the aid of a vacuum pump prior 
to every recording. The pH of the sample was 
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RUMINAL CHANGES DURING LACTIC ACIDOSIS 1163 
measured wi thin 1 min o f removal using a 
digital pH meter . 
A n a l y s i s . Lactic and volatile fa t ty acid 
(VFA) analyses on r u m e n samples were done 
by gas ch rom a tog raphy using a mod i f i ed 
p rocedure out l ined by Carlsson (1973). Prepar- 
a t ion of samples for gas ch roma tog raphy 
involved obta in ing a 5-ml sample o f rumen fluid 
and placing it in a centr i fuge tube conta in ing 1 
ml o f 25% me taphospho r i c acid. These tubes 
were al lowed to s tand unde r refr igerat ion for a 
m i n i m u m of 4 hr before being cent r i fuged at 
12,500 rpm for 20 minutes�9 Superna tan t s were 
removed and used for lactic and V F A analysis. 
This p rocedure does no t d i f fe ren t ia te b e t w e e n 
D and L fo rms of lactic acid. 
Results 
Acute acidosis developed in each of the four 
sheep (table 1) with typical s y m p t o m s being 
observed. All animals wen t o f f feed, became le- 
thargic, had increasedrespirat ion rates and 
developed m o d e r a t e diarrhea. Rumen fluid 
became very fluid in cons i s tency when the pH 
d r o p p e d be low 5.0. 
Animals A and B were anorexic by 4 hr 
p o s t i n d u cemen t , while animals C and D did no t 
refuse feed unti l 7 hr af ter the addi t ion o f the 
sucrose. Lactic acid was de t ec t ed in the rumen 
o f each animal at t he t ime the animals refused 
feed, wi th concen t r a t ions ranging b e t w een 20.3 
and 54.1 mM and cor responding pH values o f 
5.50 and 4.57, respectively�9 Max imum rumen 
concen t ra t ions o f lactic acid were near or in 
excess of 100 mM in each of the four sheep, 
b u t considerable variat ion was no ted in the 
t ime when the m a x i m u m concen t r a t i on oc- 
curred. Sheep B had its m a x i m u m concent ra- 
t ion 10 hr p o s t i n d u c e m e n t , while sheep C did 
no t reach the m a x i m u m unti l 48 hr pos t in- 
ducemen t . Sheep C appeared to be recoverying 
by 32 hr and began to eat alfalfa hay. The feed 
co n s u med seemed to re induce acidosis; t he 
animal became anorexic , lethargic and by 48 hr 
had a rumen lactic acid concen t r a t i on o f nearly 
twice tha t de t ec t ed in the 32-hr sample. Of the 
four animals, sheep C required the longest 
per iod to recover and consume p r e i n d u c e m e n t 
quant i t ies o f feed. Comple te anorexia cont in- 
ued in all animals unti l the rumen pH rose 
TABLE 1. EFFECT OF ADDED SUCROSE ON RUMEN pH AND LACTIC ACID CONCENTRATION (raM) 
Animal 
Sheep A Sheep B Sheep C Sheep D 
Time (hr) pH Lactic pH Lactic pH Lactic pH Lactic 
12 hr 
pre-sucrose 6.48 . . . 6.79 . . . 6.52 . . . 6.40 
0 (sucrose) 7.14 . . . 7 . 2 0 . . . 6.77 . �9 . 6.70 
2 5.71 11.49 6.04 - - . 5.31 5.43 
4 5.50 a 20.26 5.17 a 21.17 5.14 46126 5.28 
7 4.64 40.93 4.49 52.39 4.57 a 54.07 4.73 a 
10 4.56 68.95 4.44 99.23 4.40 88.42 4.53 
14 4.56 6 4 . 6 5 4.42 75.36 4.29 104.92 4.48 
24 4.53 85.62 4.30 71.38 4.32 78.93 4.61 
28 4.54 84.90 4.41 54.19 4.55 81.81 4.67 
32 4 . 6 6 109.54 4.13 58.47 5.07 b 68.77 4�9 
36 4.83 76.39 4.48 69.83 4.78 71.26 5.43 
48 5.34 b 64.91 5.56 b 54.50 4 . 6 6 a 126.79 6.10 c 
52 5.52 68.28 5.05 69.11 4.71 103.08 6.29 
60 6.50 1.83 6.37 28.39 4.68 106.29 6 . 0 9 
72 7.03 c . . . 7.26 c �9 . . 4.90 113.90 6.39 
76 6.95 . . . 7.16 . . . 5.17 b 58.64 6.42 
84 6.49 . . . 6.78 . . . 5.88 . . . 6.56 
96 6.72 . . . 6.79 . . . 6.07 c . . . 6�9 
108 6.28 . . . 6.18 . . . 6.58 . . . 6.37 
32116 
34.21 
54.54 
86.44 
91.57 
115.63 
96.56 
69.70 
aAnimal would no longer respond to feed. 
bAnimal began eating small amounts of feed. 
CAnimal consuming full feed. 
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1164 KEZAR AND CHURCH 
2O 
E 
E 20 E 
0 
MC 6 minu tes )I 
Pre-inducement pH 6.77 
2 hr post-inducement pH 5.31 
I0 hr post-inducement pH 4.40 
52 hr post-inducement pH 4,71 
2:E 
K 6 m i n u t e s -~ 
Pre-inducement pH 6.77 
2 hr post-inducement pH 5.3 I 
I0 hr post-inducement pH 4.40 
52 hr post-inducement pH 4.7 I 
Figure 2a. Ventral sac motility in Sheep C prior to 
and following inducement of acidosis. 2b. Reticulum 
motility recordings in Sheep C prior to and following 
the inducement of acidosis. 
above five. Lactic acid concentrations in rumen 
samples at the time first feed was consumed 
were between 55 and 70 mM. Intake at this 
point was minimal and animals would not stand 
and eat for more than 15 rain at any one time. 
Feed intake did not approach preinducement 
levels until rumen pH values were >6 and lactic 
acid could no longer be detected in the rumen. 
For sheep D, these conditions were present by 
48 hr, while for sheep C, normal feed intake did 
not occur until 96 hr postinducement. 
Motil i ty in the reticulo-rumen was greatly 
reduced 4 to 10 hr following the addit ion of 
sucrose to the rumen, indicating individual 
variation between sheep (figure 2 and 3). 
Considerable variation in moti l i ty was noted on 
the second and third days post inducement 
among the four sheep. Recordings indicated 
sheep D was the only animal exhibiting rumen 
contractions at 28 hr postinducement, although 
the contractions were below preinducement 
values in both frequency and amplitude. 
Rumen moti l i ty was evident in recordings from 
sheep C by 52 hr postinducement, but contrac- 
tions were reduced in amplitude and frequency 
compared to preinducement recordings (figure 
2a and 2b). 
The relationship of individual volatile fa t ty 
acid (VFA) to the inducement of acidosis is 
shown in figure 4. Both C3 and C4 acids were 
reduced to concentrations of <2 mM by 10 hr 
following the addit ion of sucrose to the rumen. 
By 14 hr neither acid was detected in the 
rumen fluid of any of the four sheep. With the 
exception of sheep D, the C3 and C4 acids were 
not detected again until 48 hr or later postin- 
ducement. Sheep C, which was off feed the 
longest, did not have C3 acid present in the 
rumen for a period of nearly 48 hours. Butyric 
acid in sheep C was absent for a period of 58 
hours. Sheep D, which was off feed the shortest 
period of time, did not have detectable levels of 
C3 and C4 acids for 12 and 20 hr postinduce- 
ment, respectively. Acetic acid concentrations 
in the acidotic sheep followed similar patterns 
to other VFA. Concentrations fell to 10 mM or 
less by 14 hr postinducement. While C2 con- 
centrations never reached zero, all four sheep 
did reach concentrations of <5 mM during 
the first 24 hr after inducement. 
Sheep D, the first to recover, had C2 con- 
centrations of >20 mM by 36 hr while sheep C 
did not reach this level until 84 hr postinduce- 
ment. At the time each animal had returned to 
near preinducement feed in take levels, C2, Ca 
and C4 acid concentrations were > 30, > 11 and 
> 5 mM/l i ter , respectively. 
Discussion 
The affect of added sucrose on the changes 
occurring in the reticulo-rumen of the experi- 
mental sheep was as expected. Previous experi- 
ments with graded levels of sucrose led us to 
the 15 g/kg BW level used. We wished to obtain 
pH values between 4 and 4.5 and lactic acid 
concentrations near 100 mM in the rumen 
fluid. Other work at our station as well as that 
of other researchers made us well aware of the 
high risk of death in the animal if the rumen pH 
fell below 4.0. 
Our lactic acid concentrations and pH values 
(mean values, hours 1 to 4) during the first 4-hr 
post inducement (20.26, 5.50; 21.17, 5.17; 
46.26, 5.14 and 32.16, 5.28) disagree with 
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RUMINAL CHANGES DURING LACTIC ACIDOSIS 1165 
2~ 
E 
E 20 f 
0 
~- 6 m inu tes )~ 
Pre-inducement pH 6.22 
4hr post-inducement pH 5.17 
24 hr post-inducement pH 4.30 
84 hr post-inducement pH 6.78 
21E 
3 
E 
E 20 E 
0 
K 6 m i n u t e s )1 
Pre-inducement pH 6.22 
4 hr post-inducement pH 5.17 
24 hr post-inducement pH 4.30 
84 hr post inducement pH 6.78 
Figure 3a. Caudal ventral blind sac motility in 
Sheep B prior to and following the inducement of 
acidosis. 3b. Reticulum motility recordings in Sheep 
B prior to and following the inducement of acidosis. 
those of Briggs e t al, (1957) who reported that 
lactic acid levels of >20 mM were always 
associated with a rumen pH below 5.0. We 
believe that the method of analysis used in this 
s tudy is possibly more sensitive, resulting in 
earlier detect ion of high levels of lactic acid 
earlier following inducement of acidosis. 
The effect of lactic acid concentrations on 
the animal going off feed is unclear based upon 
the results of this study. Sheep A, C and D were 
eating when rumen lactic acid concentrations 
were 11.49, 48.3 and 32.2 mM, respectively. 
All three animals were anorexic 3 hr later 
although the lactic acid concentrations were < 5 
mM greater for two of theanimals than when 
they were eating 3 hr earlier. Length of t ime 
following the appearance of lactic acid may be 
a factor but samples were not taken frequently 
enough during the first 8 hr to test this. Bueno 
(1975) infused DL-lactic acid into the duoden- 
um of sheep and reduce dry matter intake by 
50%. This would imply that rumen lactic acid 
concentration may not be the only factor 
affecting feed intake. 
The role of lactic acid on rumen moti l i ty 
remains unanswered. Juh~sz and Szegedi (1968) 
lowered the pH of the rumen below 5.0 with 
lactic acid but noted stasis of the rumen did not 
occur for 2 to 4 hburs. Our work showed there 
was a decrease in the frequency and amplitude 
of contractions at 2 hr postinducement, prior 
to the formation of detectable levels of lactic 
acid in the rumen fluid (figure 2). Although 
sheep C had a concentration of rumen lactic 
acid > 100 mM (52 hr), contractions were very 
evident (figure 2). These strong contractions, 
despite the high concentrations of lactic acid, 
cause one to further question the role of lactic 
acid as the major factor in inhibiting rumen 
motil i ty. Dougherty e t al. (1975) showed 
strong rumen contractions in two of four sheep 
with pH values of 4.4 and 4.5, 72 hr after 
inducing acidosis in sheep using corn and oats. 
Corresponding lactic acid concentrations were 
not given for the study. 
The near total absence of volatile fa t ty acids 
in the rumen fluid following the inducement of 
acidosis agrees with the work of Ryan (1965) 
for similar pH values and lactic acid concentra- 
tions. The amounts and percentages of VFA's 
present when preinducement feed intake levels 
were reached are in agreement with values 
reported by Uhart and Carroll (1967) for 
VFA's present at the time steers resumed eating 
after being off feed when suddenly switched to 
a high grain diet. 
Initial loss of rumen moti l i ty and anorexia 
seem to be closely related, at least with respect 
to time. Similar results were reported by Lane 
(1968). The sheep in the present experiment 
developed moti l i ty with reduced frequency and 
ampli tude while the animals were anorexic, but 
preinducement feed intake levels and prein- 
ducement mot i l i ty tended to occur at about the 
same time for individual animals. It remains to 
be answered whether the strong contractions of 
the reticulo-rumen induced normal appetite, or 
if increased feed intake induced contractions 
similar to those occurring before acidosis. 
One should consider other factors which 
occurred at the time normal levels of feed were 
being consumed following acidosis. Lactic acid 
in the rumen had declined to undetectable 
levels. The volatile fa t ty acid concentrations 
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1166 KEZAR AND CHURCH 
70 
60 
50 
g 
I 0 
0 
Sheep 
I 2 3 4 5 6 
Days 
20 <~ �9 B 
OoL ; , ; 
Days 
15 
f 
I 0 ' 
Sheep 
II 
2 3 4 5 6 
Days 
Figure 4. Volatile fatty acid concentrations in the 
rumen fluid of sheep prior to and following the in- 
ducement of acidosis. 
had risen to > 5 0 mM and the rumen pH was 
>6 . All o f these factors appear to be interrelat- 
ed in the recovery process that occurs in 
animals which have developed acidosis. Addi- 
t ional factors such as his tamine (Dougher ty , 
1942), endotoxins f rom bacteria (Mullinax et 
al., 1966) and secretin (Bruce and Huber, 1973) 
may very well be involved bu t were no t s tudied 
in these exper iments . 
The procedures for obtaining rumen mot i l i ty 
data used in this s tudy could lend themselves 
for use with any rumen fistulated animals wi th 
minor modif icat ions. The use o f a bal loon 
apparatus for measuring rumen mot i l i ty does 
no t give rise to as cont inuous or as high qual i ty 
recording as those using radio te lemet ic methods . 
It does have the advantage o f requiring much 
less t ime and expense in preparat ion. The most 
diff icult problem in the procedure was the 
p lacement o f the bal loon into the rumen for 
each reading since exact posi t ioning in the same 
locat ion required some adjustments for proper 
recording. This became easier as the opera tor 
became more familiar with the animals and 
apparatus. Differences in activities (eating, 
resting or ruminating) can account for some of 
the differences observed in recordings in the 
same locat ion at d i f ferent t imes (Church, 
1975). While we assembled more than one 
bal loon apparatus, we noted some variation 
be tween recordings when di f ferent units were 
used. We were for tuna te in that the device 
proved to be very durable, al lowing the same 
apparatus to col lect recordings on all four 
sheep. 
Literature Cited 
Allison, M. J., J. A. Bucklin and R. W. Dougherty. 
1964. Ruminal changes after overfeeding with 
wheat and the effect of intraruminal inoculation 
on adaptation to a ration containing wheat. J. 
Anita. Sci. 23:1164. 
Brent, B. E. 1976. Relationship of acidosis to other 
feedlot ailments. J. Anim. Sci. 43:930. 
Briggs, P. K., J. P. flogan and R. L. Reid. 1957. The 
effect of volatile fatty acids, lactic acid, and 
ammonia on tureen pH in sheep. Australian J. 
Agr. Res. 8:674. 
Bruce, L. A. and T. L. Huber. 1973. Inhibitory effect 
of acid in the intestine on rumen motility in 
sheep. J. Anim. Sci. 37:164. 
Bueno, L. 1975. Effect of l)L-lactic acid on voluntary 
food intake in sheep. Ann. Rech. Veter. 6:325. 
Carlsson, J. 1973. Simplified gas chromatrograph~c 
procedure for identification of bacterial meta- 
bolic products. Appl. Microbial. 25:287. 
Church, D. C. 1975. Digestive Physiology and Nutri- 
tion of Ruminants. Vol. l-Digestive Physiology. 
2nd Ed. O & B Books, Inc. Corvallis, OR. 
Dougherty, R. W. 1942. Studies of the effects of 
various drugs on rumen motility. CorneU Vet. 
32:269. 
Dougherty, R. W., J. L. Riley and H. M. Cook. 1975. 
Changes in motility and pH in the digestive tract 
of experimentally overfed sheep. Amer. J. 
Vet. Rcs. 36:827. 
Dunlop, R. H. and P. B. Hammond. 1965. D-lactic 
acidosis of ruminants. Ann. NY Acad. Sci. 
119:1109. 
Eiam, C. J. 1976. Aciodis in feedlot cattle: Practical 
observations. J. Anim. SO. 43:898. 
Huber, T. L. 1971. Effect of indigestion on compart- 
mental water volumes and osmolality in sheep. 
Amer. J. Vet. Res. 32:887. 
Huber, T. L. 1976. Physiological effects of acidosis on 
 by on April 20, 2009. jas.fass.orgDownloaded from 
http://jas.fass.org
RUMINAL CHANGES DURING LACTIC ACIDOSIS 1 167 
feedlot cattle. J. Anim. Sci. 43:902. 
Hungate, R. W., R. W. Dougherty, M. P. Bryant and R. 
M. Cello. 1952. Microbial and physiological 
changes associated with acute indigestion in 
sheep. Cornell Vet. 42:423. 
Juhasz, B. and B. Szegedi. 1968. Pathogenesis o f 
rumen overload in sheep. Acta Veterinaria 18:63. 
Lane, G. T. 1968. In vivo and in vitro studies of 
inappetence in ruminants . Nutr. Abstr. Rev. 
39:1016. 
McCann, C. P., R. J. McLaren, R. L. DeLay and J. K. 
Matsushima. 1973. Digestive tract cannulas for 
ruminants . Proc. West. Sec. ASAS. 24:377. 
Mullinax, C. H., R. F. Keeler and M. J. Allison. 1966. 
Physiologic responses of ruminants to toxic 
factors extracted from tureen bacteria and 
tureen fluid. Amer. J. Vet. Res. 27:857. 
Ryan, R. K. 1964. Concentrat ions of glucose and 
low-molecular-weight acids in the rumen of sheep 
following the addition of large amounts 
of wheat to the rumen. Amer. J. Vet. Res. 
25:646. 
Slyter, L. L. 1976. Influence of acidosis on rumen 
function. J. Anim. Sci. 43:910. 
Uhart, B. A. and F. D. Carroll. 1967. Acidosis in beef 
steers. J. Anim. Sci. 29:1195. 
 by on April 20, 2009. jas.fass.orgDownloaded from 
http://jas.fass.org