Effects of varying the degree of synchrony of energy and nitrogen release in the rumen on the synthesis of microbial protein in lactating dairy cows consuming a diet of grass silage and a cereal-based concentrate

✍ Scribed by Kim, Kyoung H; Choung, Jai-Jun; Chamberlain, David G

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 138 KB
• Volume: 79
• Category: Article
• ISSN: 0022-5142
• DOI: 10.1002/(sici)1097-0010(199908)79:11<1441::aid-jsfa385>3.0.co;2-z

✦ Synopsis

The object of the experiment was to test the hypothesis that altering the degree of synchrony in the ruminal release of available energy and nitrogen would affect microbial protein synthesis (MPS) when the diet contained a high proportion of readily fermentable carbohydrate. Four lactating dairy cows were given a basal diet of (kg DM day À1 ) 8.0 grass silage, 4.2 barley and 1.8 groundnut meal containing 31.4 g N kg À1 DM. The experiment was designed as a 4 Â 4 Latin square with periods lasting 14 days. The treatments were (1) the basal diet given in two equal meals at 10:00 and 22:00 h (BASAL), supplemented with (2) 2.0 kg maltodextrin given as a continous intraruminal infusion (CONT), (3) 2.0 kg maltodextrin as two 6-h infusions starting at 10:00 and 22:00 h (SYNC) and ( 4) 2.0 kg maltodextrin given as two 6-h infusions starting at 16:00 and 04:00 h (ASYNC). All three infusion treatments reduced (P 0.05) the concentration of ruminal ammonia relative to BASAL but only the CONT and SYNC treatments increased (P 0.05) MPS over the level with BASAL; the value for ASYNC was the same as that for BASAL. Lactic acid was a minor product of the ruminal fermentation with all treatments. All three infusions reduced (P `0.05) the plasma concentration of urea and the urinary output of nitrogen but there were no differences among the infusion treatments. It is concluded that with this diet, containing about 30% of DM as fermentable carbohydrate, altering the degree of synchrony in the rates of ruminal release of energy and nitrogen had a marked effect on MPS.