Effects of energy and nitrogen supplementation of silage diets on rumen fermentation in fistulated heifers

Abstract

SummaryExperiments were carried out to assess the effects of silage diets given with and without supplementary energy as barley and/or nitrogen as groundnut meal or urea on rumen fermentation in growing heifers.Silage based diets resulted in a stable pH and a high molar percentage of acetate in rumen liquor. Total V.F.A. concentrations were significantly increased by supplementary energy plus protein but were not consistently increased by energy only, and were linearly related to M.E. intake but not to D.M. digestibility. Effects of energy and nitrogen supplementation on the molar percentage of rumen V.F.A. were small and not always significant.Rumen NH3-N levels were normal on the basal silage diets and were linearly related to N intake. Levels were significantly reduced by energy supplementation but significantly increased by protein supplementation. Results are discussed in relation to energy and nitrogen utilization on silage based diets.