Effect of hogget nutrition in pregnancy on lamb birthweight and survival to weaning

Abstract The effect of hogget nutrition during pregnancy on birthweight and survival of lambs has not been thoroughly examined under pastoral conditions in New Zealand. The aims of the present study were to examine the effect of three hogget nutrition levels during pregnancy on both lamb birthweight and lamb survival, and hogget performance. Hoggets were offered either a “low”, “medium” or “high” level of nutrition of herbage during pregnancy, which resulted in total liveweight increases of 12, 21, and 30 kg, respectively over the period from 13 days after the average day of mating to average day 130 of pregnancy. Hogget nutritional treatment failed to affect either lamb birthweight or lamb survival. Nutritional treatment also failed to consistently affect ewe metabolic status. However, “low” group hoggets weaned significantly ( P < 0.05) lighter lambs and were themselves significantly ( P < 0.05) lighter at weaning and produced significantly ( P < 0.05) less wool. The results of this study indicate that offering pregnant hoggets a level of nutrition that increases their liveweight gain above that of the expected conceptus growth will not benefit lamb birthweight or survival rate to weaning, but will increase hogget fleece weight and lamb weight at weaning. On the other hand, and in contrast to some earlier research, an even higher level of nutrition in pregnancy did not reduce birthweight or survival rate to weaning. This suggests that when farmers are aiming to achieve heavy lamb weaning weights and two‐tooth mating weights, they need not avoid offering hoggets a high level of nutrition in pregnancy.