The effects of postruminal supplements of casein and of soya-protein isolate with or without additional amino acids on silage intake and milk production in dairy cows

Abstract

When the proteins are given direct into the abomasum of dairy cows receiving diets based on grass silage, casein produces much greater responses of milk production than do equivalent amounts of soya-protein (Choung and Chamberlain 1991a, b). However, the cause of these differences of response is not known. In feeding trials, supplementation of silage diets containing soya bean meal with rumen-protected forms of the amino acids thought to be most limiting, methionine and lysine, has been without effect (Girdler et al 1988).