EFFECTS OF FAT LEVELS IN MILK REPLACERS AND PROTEIN LEVELS IN CREEP FEED ON THE PERFORMANCE OF ARTIFICIALLY REARED LAMBS

Abstract

Two growth trials were conducted to determine an optimum level of fat in milk replacer and an optimum level of protein in creep feed for artificially reared lambs. In experiment 1, milk replacers containing 31 or 36% fat (dry matter, DM, basis) were fed ad libitum to 58 lambs at 1 day of age. The protein was supplied by low-heat spray-dried skim milk powder and Na caseinate and the fat from a mixture of 10% coconut oil and 90% tallow. A finely ground unpelleted creep feed with 20% protein, on a DM basis, was fed ad libitum. The lambs consumed more of the 31% fat milk replacer and gained more live weight (288 vs. 254 g/day; P < 0.025) to weaning at 25–30 days of age than did lambs fed the 36% fat formula. Weight gains to 10 wk of age were 190 and 170 g/day, respectively (P < 0.10). In experiment 2, 84 lambs were fed a 26% fat milk replacer ad libitum, and creep feeds with 15, 20 or 25% protein (DM basis). The supplementary protein was supplied by herring meal and soybean meal. Weight gains of lambs to weaning at 24 days of age were similar on the three creep feeds. However, gains to 10 wk of age averaged 218, 235 and 244 g/day (P < 0.05) on the 15, 20 and 25% protein diets, respectively. One and 2 kg of DM were consumed/kg lamb body weight gain to weaning and to 10 wk of age, respectively. It was concluded that the milk replacer should contain 26–31% fat, and the creep feed 20% protein or more for maximal performance of artificially reared lambs.