Effect of different energy supply on microbial protein synthesis and urea handling in Corriedale sheep consuming temperate fresh forages

摘要

The efficiency of microbial protein synthesis (g of microbial N/kg digestible organic matter apparently digested in the rumen) in Corriedale ewes is not modified when the animals are fed on a 57% reduced N diet, and this fact was accompanied by a reduction of the urinary elimination of urea (Tebot et al., 2002). However, the efficiency of N utilisation could be limited by a low ratio soluble carbohydrates/ N, frequently found in temperate fresh forages consumed by grazing ruminants (Garcia et al., 2000). For this reason energy supplementation is often practised in the winter time in order to improve the use of forage N for microbial protein synthesis.