Effect of Plants Containing Secondary Metabolites as Feed Additives on Rumen Fermentation and Rumen Microbial Profile of Buffaloes

Four fistulated adult Murrah buffaloes were fed on a basal diet consisting of wheat straw and concentrate mixture in a 4x4 Latin square design to study the effect of feeding plant secondary metabolites on rumen function and microbial ecology. The four groups were, no additive (Control), essential oil mixture (Mix 1), mixture of seeds rich in saponin and essential oil (Mix 2) and mixture of seeds rich in saponin and fruit pulp rich in tannin, saponin and essential oil (Mix 3). Daily intakes of feed was similar (P>0.05) in all the four groups. Feeding of any of the additives have not affected (P>0.05) rumen pH. The concentration of ammonia N was reduced (P<0.001) in the treatment groups supplemented with additives. The ruminal enzymes viz. carboxymethyl-cellulase, avicelase, xylanase, protease and acetyl esterase activities and concentration of lactic acid were not affected (P>0.05) by supplementation of any additives. The additives have not affected the population of Ruminococcus flavefaciences, fungi and methanogens, whereas, Fibrobacter succinogenes population increased and protozoa decreased in the entire additive fed groups. To study the rumen methanogen diversity, mcrA (methyl coenzyme M reductase) gene was amplified. The number of clones analysed were 44 from control animals and 89 were from Mix 1 fed animals. The bootstrap analysis showed that in control group, 60% of the clones were uncultured microbes whereas it was 25% in Mix 1 group. In Mix 1 group, 26% of the clones were related to that of Methanobrevibacter millerae strain ZA10 in comparison to only 3.39% in control group. It is concluded that feeding of additives containing PSM have not exerted any adverse effect on rumen fermentation of buffaloes. However there was change in different microbial groups with additives supplementation. The additives containing essential oils (Mix I) resulted in shifts within the methanogen population in comparison to control animal.