Activities of rumen micro-organisms in water buffalo (Bos bubalusL.) and in Zebu cattle

Abstract

SummaryTwo fistulated adult bulls of the Zebu breed and 2 fistulated adult buffalo steers were given a diet consisting of concentrate mixture (rice bran and cotton-seed cake in equal portions +2% calcium hydroxide + 1% common salt) and straw. This was later changed to an all-roughage diet of first cut berseem (Trifolium alexandrinum) Samples of the rumen contents were taken for determination of protozoal differential counts, concentration and relative proportions of volatile fatty acids (VFA), rate of cellulose digestion, fermentation rate, and net growth of rumen micro-organisms. Further data were obtained for the 2 buffalo steers fed sweet Sudan grass. When the feed consisted of concentrate and straw there were significant differences in the numbers of protozoa and in volatile fatty acid concentration in the 2 species of animals. Higher protozoal counts were observed in the rumen of bulls (7·2−8·1 × 105organisms/ml) than in the rumen of buffaloes (2·6−3·6 × 105organisms/ml). Greater concentration of VFA was found in the rumen of buffaloes (5·3−11·2 mequiv/100 ml rumen liquor) than in bulls (4·8−10·4 m-equiv/100 ml rumen liquor). With berseem, the concentration of VFA in the rumen was generally higher (6·73−11·0 m-equiv/100 ml rumen liquor) and the protozoal counts were lower (2·8−5·2 × 105organisms/ml) but there were no significant differences between bulls and buffaloes.The rates of cellulose digestion and the maximum fermentation rates were similar in the 2 species indicating a microbial population of the same order. Higher rates of cellulose digestion and of maximum fermentation when the ration consisted of berseem than when it consisted of concentrate + straw indicated a higher concentration of micro-organisms, mostly bacteria.