Effect of dietary methionine supplementation on hoof horn growth in primiparous cows

Abstract

Horn growth rate does not appear to be related to the amino acid profile of the major protein source for dairy cattle (Offer, Logue & Roberts, 1997), but it is possible that sulphur amino acids are limiting in early lactation, when the homeorhetic drive to milk production is most extreme. Supplementation of a high production ration for dairy cows with protected methionine should increase milk production, and allow any sulphur amino acid limitation on horn growth to be alleviated (Mengal, Galbraith, Souri & Scaife, 1997).A total of 60 in-calf Holstein heifers were divided into two groups in a randomised block design. The study commenced approximately three weeks pre-calving until 26 weeks post calving, and animals were housed in one of three systems for the duration. Two diets were formulated based on a grass silage:maize silage mixture (50:50 DM basis), with rolled wheat, soya bean meal, sugar beet feed and rapeseed meal and were offered from approximately five days post calving for the remainder of the 26 week period.