Effect of liveweight at the start of the breeding period and liveweight gain during the breeding period and pregnancy on reproductive performance of hoggets and the liveweight of their lambs

The effect of liveweight at the start of the breeding period and liveweight gain of hoggets during the breeding period and in pregnancy on breeding performance, pregnancy loss and liveweight and the performance of their progeny were examined. Two groups of hoggets with an average liveweight of 36 kg (denoted L) and 42 kg (denoted H) at the start of the breeding period were allocated to either medium or ad lib levels of herbage during pregnancy, resulting in four treatment groups (L-med, L-ad lib, H-med and H-ad lib). Liveweight changes of the medium and ad lib treatment hoggets were 153 and 208 g/day, respectively. Starting liveweight had no effect (P0.05) on the overall breeding performance, pregnancy rate, foetuses per hogget joined, number of hoggets lambing or pregnancy loss. Lambs born to the H treatment hoggets were heavier (P0.05) at weaning than those born to L hoggets (21.69 and 20.11 kg, respectively). More (P0.05) medium treatment hoggets were not bred during the 22 day breeding period than ad lib treatment hoggets (14 and 4%, respectively). The results indicate that heavy hoggets at the commencement of the breeding period increase the progeny liveweight at the time of weaning and increase hogget weaning weight, but with no effect on reproductive performance. On the other hand, ensuring hoggets are increasing in weight by more than 200 g/day during breeding and pregnancy results in fewer hoggets not bred and hoggets heavier at the time of weaning. Farmers should therefore ensure that adequate herbage is available so that hoggets can achieve these targets.