Influence of dietary protein and energy sources on rumen environment of crossbred calves

Abstract

With an aim of'ascertaining the effects of dietary cereal source on the rumen environment of ruminants fed diets differing in ruminal protein degradability, a study was conducted on 4 rumen fistulated yearling crossbred cattle in a 4x4 switch over design. The dietary treatments included feeding of 4 concentrate mixtures varying in protein and cereal sources i.e. a combination of groundnut-meal and cottonseed-meal (low degradable) with barley (D1) and jowar (D2), or groundnut-meal alone (high degradable) with barley (D3) and jowar (D4). The ruminal pH was significantly reduced on diet D3, containing both cereal and protein of high degradability. The mean total volatile fatty acids (TVFA) concentration of the strained rumen liquor (SRL) was higher on the same D3 diet (16.31±0.82meq/dl) compared to other 3 diets. The ammonia nitrogen was lower in D1 and D4 groups compared to D3. Barley based diets induced lower ruminal pH compared to jowar based diets. Likewise, feeding of high degradable protein resulted in greater TVFA than their slow degradable counterparts. No effects of the dietary treatments were evident on the total- TCA perceptible, and non protein-nitrogen levels in the SRL. Feeding of high degradable protein diet induced greater (P&lt0.05) activities of a-amylase and carboxymethyl celulase, whereas the activity of aspartate transaminase was higher upon feeding ofjowar than barely based diets. The source of protein and degradation quality of protein did not have any influence on the activities of xylanase, protease and alanine transaminase. Overall, it is concluded that feeding of protein and cereal (carbohydrate) sources of matching (higher) degradability induced a better rumen fermentation as evidenced by higher concentration of metabolites as well as enzymatic activities.