Rumen metabolites and enzymatic profiles in crossbred cattle bulls fed on high and low levels of tanniniferous oak (Quercus incana) leaves

Abstract

The rumen studies were conducted in two male fistulated crossbred cattle fed on three different feeding systems prevalent in high hill Himalayan regions of Uttarakhand involving control (OL0) animals (rumen fistulated crossbred cattle bull, 312 kg BW) fed on grass hay (GH), OL40 on GH + oak leaves (OL) at 60:40 artio and OL60 on GH + OL at 40:60 ratio in a complete switch over design each lasted for 6 weeks. Strained rumen liquor was assayed immediately for pH and then fractioned for ciliate protozoa count, rumen biochemical attributes and enzyme profile. Increasing the levels of OL enhanced (P10 times) in all the feeding systems. Rumen pH was comparable in the three dietary groups (6.92-7.06). The N fractions (total N, ammonia N, non-protein N) except trichloroacetic acid precipitable N increased linearly (P < 0.05) with the increased levels of OL feeding. The volatile fatty acid (VFA) profile showed decreased (P < 0.01) acetate and butyrate concentration with increased levels of OL feeding resulting in non-significantly narrower (P = 0.155) acetate: propionate ratio. There was a significant decline (P = 0.020) in total VFA concentration in OL60 (54.20 mM/L) compared to other dietary groups (OL0, 77.11 and OL40, 72.66 mM/L). Carboxymethyl cellulase and xylanase activities showed an increasing trend (P < 0.01) with increased in OL, but protease activity remained unaffected. The study revealed an increased feed and nutrient intake and positive shift in rumen fermentation pattern with increased level of OL, which needs to be validated based on production performance prior to recommending an optimized level in the feeding system at high hill Himalayan region