A note on factors affecting lamb survival in Indian sheep

Abstract

SUMMARYRecords on lamb survival were available for 757 lambs, the progeny of 33 rams. Purebred lambs were of the Nali and Lohi breeds and crossbred lambs were produced by mating Nali ewes to Nellore or Mandya rams, and Lohi ewes to Nellore rams. For the flock as a whole 93% of those born survived to 14 days of age and 86% to weaning. A least-squares analysis of variance showed that among the factors investigated only lamb's weight at birth significantly affected survival to 14 days of age, and lamb's weight at birth, ewe's weight at lambing and the year of birth had significant effects on lamb survival from 15 days to weaning. Heritability estimates for lamb survival were based on half sib correlations. For the period from birth to 14 days of age the estimates were 0·08 for pure Nali lambs and 0·03 for the whole flock, and for the period from 15 days to weaning the estimates were 0·10 and 0·26 for the two groups respectively.