An evaluation of the effects of incisor dentition and of age on the performance of lactating ewes and their lambs

Abstract

AbstractNinety-six Border Leicester × Scottish Blackface ewes, aged 2 to 6 years, grazed perennial ryegrass pastures during lactation. The state of their incisor teeth was assessed at parturition on a scale from score 1 (sound teeth) to score 4 (poor teeth). Their live weights and condition scores during lactation were then related to incisor score and age by regression analysis. Lamb growth was similarly analysed. Herbage intakes and milk production were measured in a subset of 24 ewes.Ewe live weights were significantly lower, per unit incisor score, by 2·2, 2·5 and 2·1 kg at days 22, 50 and 96 of lactation respectively. In ewes with twin lambs, the equivalent reductions were 1·6, 2·8 and 2·1 kg respectively. Reductions in condition score, whilst still significant, were less marked. After adjusting for the effects of incisor dentition, there was no effect of age on ewe live weight or condition score.Incisor dentition did not markedly affect herbage intake or milk production, except in measurements at day 53 of lactation, where higher incisor scores resulted in significant reductions in the production of milk and its components. Effects on lamb performance were confined to twins, where live-weight gain to day 50 was reduced by 12·2 g/day, per unit increase in ewe incisor score. This resulted in reductions of 0·7 kg (day 50) and 0·9 kg (weaning) in the live weight of twin lambs.