Effects of the Pattern of Energy Supply on the Efficiency of Nitrogen Utilization for Microbial Protein Synthesis in the Non-Lactating Cows Consuming Grass Silage

Abstract

Effects of the pattern of energy supply on the efficiency of nitrogen utilization for microbial protein synthesis (MPS) were examined in cows consuming grass silage (7.1 kg DM/d) and supplement of 1 kg sucrose per day given as an intraruminal infusion. Three non-lactating cows received three experimental treatments in a 3 × 3 Latin square design with each period lasting 14 days. The treatments were (1) the basal diets of silage alone given in one meal each day at 09-30 h (BASAL), supplemented with (2) 1.0 kg sucrose given a 4-h infusion starting at 09:30 h (SYNC), (3) 1.0 kg sucrose given a continuous infusion for 24 h (CONT). Compared with BASAL, sucrose infusions altered (p<0.05) the pattern of variation in ruminai pH and the concentration of ammonia at 4 h after feeding but none of the sucrose treatments resulted in any changes in the ruminai concentration of VFA. All sucrose treatments increased (p<0.05) MPS relative to BASAL by 14% and 33% for SYNC and CONT, respectively, and that for CONT was greater (p<0.05) than for SYNC. It is concluded that synchronization of energy and nitrogen over the shorter term has no further advantage of the efficiency for MPS relative to CONT.