The effect of nutrition during pregnancy on the behaviour of adolescent ewes and their lamb(s) within 12 hrs of birth

摘要

Hogget mating has become more common in recent times as a management strategy to produce additional lambs. The productivity of hogget mating is limited by low lamb birth weights and poor lamb survival. A study has shown that maternal nutrition duringpregnancy in hoggets had no effect on the birth weight or survival of lambs. This study investigated the effect of nutrition during pregnancy on the post-parturient behaviour of hogget ewes and their lambs. On day 13 after the mid-point of breeding hogget ewes were stratified by breed and live weight and randomly allocated to one of three feeding regimes: Low (gained 10kg of live weight by parturition), Medium (20kg) and High (30kg). Within 12 hours of birth lambs were ear tagged and the maternal behaviour of hogget ewes was recorded using a maternal behaviour score (MBS) a five point measure of a ewe's response to the handling of her lambs. Behavioural observations of the hogget and her lamb(s) were made for 5 minutes after the completion of tagging the lamb. Singleton-bearing hogget ewes fed on the high plane of nutrition had significantly (P<0.05) greater maternal behaviour scores than singleton-bearing hoggets fed on low or medium planes. In the low fed group, significantly (P<0.05) fewer hoggetsbleated in response to their lamb (60%) compared with medium (73%) and high (85%) fed hoggets. Of the lambs that bleated, those born to hoggets in the medium fed group bleated significantly (P<0.05) more than lambs born to hoggets in the low or high fedgroups. Feeding hogget ewes on a high level of nutrition had a positive impact on hogget and lamb behaviour within 12 hours of birth. A high level of nutrition during pregnancy may result in behaviours that increase survival of lambs born to hogget ewes.