The performance and changes in body composition of steers offered cut grass or grazing following three patterns of nutrition in winter

Abstract

AbstractFriesian steer cahes were reared over winter on a silage (S) or on a silage plus concentrate (SC) diet to provide cattle of the same live weight, but of different ages for a comparison of grazing and feeding cut herbage indoors during the summer. A further group received fish meal (SF) as a supplement in an attempt to provide cattle of the same age as the S group, but of different body composition. Although supplementation improved the daily deposition of fat and protein, it did not lead to differences in body composition at the end of the winter period. The ratio of protein to fat deposition and the efficiencies of conversion were low for all groups, but they did improve as the level of supplementation increased.There was no carry-over effect of winter treatment on summer performance. However, housed cattle deposited significantly more fat.The trial demonstrated the inefficient use of nitrogen from silage with poor fermentation characteristics and the predisposition of cattle on such diets to low protein to energy retention. Whilst supplementation altered this balance, higher levels than given would be needed to have a marked effect. It was also concluded that the performance of housed cattle as an indicator of that of grazing cattle, is likely to be misleading because lower activity reduces maintenance requirement and leads to greater fat deposition.