Effect of twin-bearing ewe body condition score and late pregnancy nutrition on lamb performance

Abstract

This study aimed to investigate the effects of ewe body condition score and nutrition on twin-bearing ewes and their offspring. At maximum Day 112 of pregnancy (range 96–112 days), 185 twin-bearing ewes were allocated to either a ‘Medium’ or ‘ad libitum’ (Adlib) feeding treatment for the following 25 days (P112–P136). Each feeding treatment included ewes of body condition score: 2.0 (CS2.0, Medium n = 32, Adlib n = 28), CS2.5 (Medium n = 31, Adlib n = 33) or CS3.0 (Medium n = 30, Adlib n = 31). After P136 ewes were offered Adlib feeding conditions. Medium treatment ewes were lighter (P < 0.05) than Adlib ewes at P136 and P142 and displayed lower (P < 0.05) body condition score at P136 and back-fat depths at P142. CS2.0 ewes had lower (P < 0.05) liveweights and body condition score at P112, P136 and P142 than CS2.5 ewes, which in turn had lower (P < 0.05) liveweight and body condition scores than CS3.0 ewes. Ewe feeding treatment had no effect (P > 0.05) on lamb liveweight or apparent colostrum intake. Ewe body condition score had no effect (P > 0.05) on lamb birthweight or apparent colostrum intake. Lambs born to CS2.0 ewes had greater (P < 0.05) survival than lambs born to CS2.5 ewes. At the end of the study lambs born to CS2.0 ewes were lighter (P < 0.05) than those born to CS2.5 and CS3.0 ewes although, there was (P > 0.05) no effect of condition score on total litter liveweight. In conclusion, these results suggest twin-bearing ewes of body condition 2.0–3.0 can be offered restricted feeding levels to at least Day 136 of pregnancy with few implications for their lambs.