EFFECT OF SACCHAROMYCES-CEREVISIAE YEAST CULTURE SUPPLEMENT ON RUMINAL METABOLISM IN BUFFALO CALVES GIVEN A HIGH CONCENTRATE DIET

The effect of inclusion of live yeast culture (YC, Saccharomyces cerevisiae plus growth medium) in a high concentrate diet given to buffalo (Bubalus bubalis) calves on the rumen microbial population and fermentation pattern and in sacco dry matter disappearance of dietary constituents was examined. Six rumen-fistulated buffalo calves of about 120 kg live weight were divided into two equal groups. The control group was given a diet consisting of, on a dry-matter basis, 0.90 kg wheat straw, 1 kg berseem (Trifolium alexandrinum) and 1.80 kg concentrate per day per calf and the yeast group the above diet plus 5 g YC which was put directly into the rumen via the fistula. After feeding this diet for 6 weeks (supplementation period), inclusion of YC was stopped and both groups were given the control diet for a period of 3 weeks to examine the performance of the YC group after withdrawal of YC. At week 4 of YC supplementation the pH was significantly increased (P < 0.01) and lactate concentration was decreased (P < 0.01) in the rumen fluid for up to 6 h post feeding. The number of total bacteria, total viable bacteria, cellulolytic bacteria, amylolytic bacteria and protozoa were increased proportionately by 0.554 (P < 0.01), 0.482 (P < 0.01), 0.670 (P < 0.01), 0.077 (P < 0.05) and 0.079 (P > 0.05), respectively. The concentrations of total volatile fatty acids, particularly at 4 h post feeding (P < 0.01), acetate (P < 0.01) and propionate and the acetate to propionate ratio were higher in the YC compared with the control group. On YC inclusion, the concentration of ammonia-nitrogen was decreased while that of trichloracetic acid insoluble protein was marginally increased. All these differences in rumen variables started to disappear on YC withdrawal and values returned to control levels by the 3rd week after YC withdrawal. YC supplementation increased the in sacco dry-matter disappearance of various dietary components particularly after 3, 6 and 12 h incubation.