Meta-analysis to establish the response of having heavier mature ewes during gestation on the birthweight of the lamb and the weaning weight of the ewe and lamb.

摘要

There is much uncertainty about feeding ewes to maximise the performance of progeny and of the ewe itself to weaning. This includes questions about feeding the ewe to influence the lamb's birthweight for lamb survival, feeding to augment the ewe's lactation to maximise the lamb's growth potential before weaning and feeding the ewe to increase the probability of having multiple offspring. The objective of this study was to carry out a meta-analytic study to consider the response of having heavier mature ewes during gestation on lamb and ewe performance measured by birth and weaning weights. The birthweight of singleton lambs was the greatest, twins were intermediate and triplets the lowest (5.8, 4.8 and 4.1 kg, respectively; P<0.001). A similar trend (P<0.001) was observed for the weaning weight of the lamb (29.1, 25.2 and 23.7 kg for lambs weaned as a single, twin or triplet, respectively). The liveweight of ewe at weaning was greater (P<0.001) for those ewes that failed to wean a lamb (69.6 kg) or weaned a single lamb (67.8 kg) compared with ewes that weaned twin and triplet lambs (64.8 and 65.3 kg; respectively). A greater ewe liveweight during gestation gave different responses on the lamb birthweight, lamb weaning weight and the weaning weight of the ewe and this was dependent on birth and weaning rank category of the lamb (P<0.05). Overall, the response of heavier ewes on lamb birthweights and ewe and lamb weaning weights was small compared with the effect of birth and weaning rank of the lamb.