Variability in the rate of decline in birth weight as litter size increases in sheep

Abstract

AbstractCarrying multiple foetuses leads to a decline in lamb birth weight. The rate of litter size-dependent birth weight decline (LSDBD) in a population can be obtained by calculating the linear relationship between the reciprocal of lamb's birth weight and the respective litter size. Based on published data on lamb birth weight and by using the reciprocal approach, LSDBD rate was calculated for 70 purebred and crossbred sheep populations in which birth weight of lambs born as singles ranged from 1·3 to 6·3 kg. High variability in LSDBD was found. Both genetic and environmental factors may contribute to the variability of this trait.