Abstract

Data were analysed to investigate the association between ewe body condition score (BCS) and lamb growth rate (LGR). Ewe BCS was assessed on a scale of 1 to 5 pre-lambing (BCSL) and at weaning (BCSW). Change in BCS throughout lamb rearing (BCSChange) was calculated as the difference between BCS at weaning and pre-lamb. The three way interaction between birth rank, BCSL and BCSChange was significant (P <0.05). When the interaction was examined for birth rank, it was significant between BCSL and BCSChange in singles (P <0.05) and twins (P <0.01), but not in triplets. In singles and twins, lambs with the highest LGR were from dams that had high BSCL and negative BCSChange or those with low BCSL and positive BCSChange. Triplets had a similar trend whereby lambs with the highest LGR were from dams with a high BCSL and a negative BCSChange. This study suggests that if farmers manage their ewes to achieve a high BCS at lambing time this is likely to improve lamb growth to weaning. In addition, identifying ewes with a low BCS at lambing and preferentially feeding them to increase BCS during rearing may increase single and twinlamb growth rates.

HC, Mathias-Davis, GH Shackell, GJ Greer, AL Bryant, and JM Everett-Hincks

Proceedings of the New Zealand Society of Animal Production, Volume 73, Hamilton, 131-135, 2013