Mothering ability was investigated in two breeds of sheep with twin and triplet litters in 2000. The study was carried out on a commercial sheep farm with high reproductive rates gained through intensive selection in its Coopworth flock and the introduction of East Friesian genes by crossbreeding. East Friesian Coopworth (EFCoop) ewes maintained body condition between pregnancy scanning and lambing whereas Coopworth ewes lost body condition (-0.35 CS). Plasma β-hydroxybutyrate (β -OHB) was significantly higher in Coopworth ewes prior to lambing. Coopworth and EFCoop ewes with triplet litters had elevated levels of plasma â- hydroxybutyrate concentration compared to ewes with twins (0.70 ± 0.03 vs 0.49 ± 002, P<0.0001). Coopworth ewes had higher triplet litter survival rates to tagging (0.86 ± 0.03) compared with EFCoop ewes (0.68 ± 0.05) (P<0.001). The maternal behaviour score (MBS) of ewes was determined within 24 hours of birth on the basis of their response to the shepherd tagging their lambs on a 5-point scale from 1 (ewe leaves litter and does not return) to 5 (ewe remains within 1m of her litter). The maternal behaviour score (MBS) was higher in Coopworth ewes (3.6 ± 0.04) than the EFCoop ewes (3.4 ± 0.07) and increased with litter size but remained constant for EFCoop ewes regardless of litter size. The results of this study suggest that ewes that maintain condition in late pregnancy provide a more suitable maternal environment to support their litters. This is increasingly important for triplet litters. This study shows that a ewe that has slightly higher plasma β-hydroxybutyrate levels, is not as receptive to the demands of her litter and is sensitive to human interference as indicated by lower MBS.
Proceedings of the New Zealand Society of Animal Production, Volume 64, Hamilton, 188-191, 2004
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