Effects of birth weight on survival in twin born lambs

Morel PCH, Morris ST, Kenyon PR
Proceedings of the New Zealand Society of Animal Production, Volume 69, pp 75-79, Jun 2009
Proceedings of the New Zealand Society of Animal Production, Volume 69, pp 75-79, Jun 2009
Article class: Conference Presentation
Subject Terms: Animal production/wastage, Bodyweight/liveweight/condition score, Mortality/morbidity, Reproduction, Reproduction - female, Twinning/parity
Animal Type: Sheep
Publisher: New Zealand Society of Animal ProductionAbstract
Lamb survival to weaning decreases as litter size increases (single > twin > triplet > quads), with birth weight being a major factor affecting survival. The purpose of the present study was to investigate the effects of birth weight (BWT) and related traits on survival in twin born lambs. Data from a total of 3,834 twin lambs born to mixed aged ewes were analysed. For statistical analysis the lambs were allocated according to birth weight (BWT) within litter to three groups (Light = Lightest lambs within pairs, Equal = Lambs of similar weight within pairs and Heavy = Heaviest lambs within pairs). The survival rates differed (P <0.05) between Light, Equal and Heavy (80%, 89% and 83%, respectively). BWT was positively related (P <0.001) to survival in the Light group, but not in the other two groups. The smaller the difference in BWT between siblings, the higher the likelihood of the Light lambs surviving. Therefore, reducing the difference in BWT within a set of twins will have the potential to increase overall lamb survival.The whole of the literary matter of the Proceedings of the New Zealand Society of Animal Production is copyright New Zealand Society of Animal Production, Downloading this article signifies agreement with the terms and conditions of electronic access.
