EFFECTS OF METHOD OF HERBAGE CONSERVATION ON PERFORMANCE OF STORE LAMBS

The performance of Galway wether lambs, offered hay or silage made simultaneously from the same permanent pasture cut at two stages of growth, was examined over a 14-week feeding period. The performance of similar lambs offered these roughages but out-wintered on pasture (22.2 lambs/ha) was also examined. Lamb performance, in terms of both liveweight and carcass weight gain, was better (p < 0.001) on hay than on silage. Mean daily dry-matter intakes were 999 and 643 g/lamb/day for hay and silage respectively. Lamb performance on both silage and hay was better (p< 0.001) on the early- than on the late-cut herbages. The contribution of pasture did not improve the performance of the Iambs fed hay but it significantly improved the performance of those fed silage compared with the Iambs fed silage only. Despite large differences in carcass weight between the lambs fed hay and silage there was no difference in fat content of the best end joint. The significance of this together with the importance of gut-fill in any comparisons of animal performance on hay and silage are discussed. Although the range in digestibilities was narrow, the results showed that the intake of early-cut hay (60.7% DMD) was greater (p<0.001) than that of the late-cut material (57,2% DMD) while the intake of early-cut silage (62.2 % DMD) was less. (p < 0.001) than that of late-cut silage (59.7 % DMD). The apparent lack of appetite for silage by wether lambs observed in this and other experiments