Effects of birth weight and energy gain preweaning on survival of lambs weaned at 21 days

Abstract

Lambs were fed on cows' milk from birth to 21 days and then weaned abruptly on to a pelleted food that had been available to them from 10 days of age. In experiment 1 six lambs were given only sufficient milk to maintain weight for 21 days (0.48 MJ gross energy/day per kg0 73). No lambs survived beyond a few days after weaning at 21 days. In experiment 2 20 lambs were offered milk to provide 1.44 MJ gross energy/day per kg0.73 for 21 days. After weaning, only five lambs survived for more than 4 weeks. Liveweight at weaning was the most important single factor determining the chances of survival after weaning. All lambs that weighed less than 5.2 kg at 21 days died. The energy gain between birth and 21 days was the main factor determining the length of time that lambs survived without food after weaning. It was estimated that all lambs which weighed more than 1.4 kg at birth and gained > 23 MJ in 21 days could survive for 15 days after weaning without eating.