PRODUCTION RESPONSES OF HIGH PRODUCING COWS FED RUMEN BYPASS DL-2-HYDROXY-4-(METHYLTHIO)BUTANOIC ACID COATED WITH CALCIUM SOAPS OF FATTY-ACIDS

DL-2-Hydroxy-4-(methylthio)butanoic acid coated with Ca-soaps of palm fatty acids (BHMB) was found to be inert in the rumen and was used as a source of methionine in a ration for high producing cows where methi onine was the first limiting amino acid as determined using the Cornel l net carbohydrate and protein system for evaluating cattle diets. Cow s fed BHMB for 120 DIM consumed on average 0.4 kg/d less DM and yielde d 1.3 kg/d more milk; no change occurred in milk fat or protein percen tages. Milk protein yields increased by 40 g/d. Plasma concentration o f urea and non-esterified fatty acids was higher in cows fed; BHMB, gl ucose, triglycerides and protein were unchanged. It is concluded that BHMB can enhance production in dairy cows when methionine is the first limiting amino acid.