Factors affecting preweaning lamb survival in continuously housed sheep

Abstract

Summary. Preweaning lamb survival for intervals of up to 8 weeks was studied in the progeny of the local fat-tailed Naeemi and imported Border Leicester × Merino ewes mated to Naeemi rams. An intensive system of management with zero grazing was used to conform to the most probable type of production system to be used in Kuwait. The effects of year and season of lambing, litter size, sex, genetic group and birth weight were determined. Lamb survival rates from birth to 1 week, from 1 to 4 weeks and from 4 to 8 weeks were 96, 99 and 97% respectively. Overall survival from birth to weaning at 8 weeks was 91%. Genetic group, litter size, sex of lamb and year of lambing had no significant effects on survival. Season was significant from birth to 1 week, from 4 to 8 weeks and from birth to 8 weeks. Lamb birth weight was the most important factor affecting lamb survival, through a quadratic relationship between weight and survival.