Lamb survival, growth and fleece production in relation to birthcoat type among Welsh Mountain sheep

Abstract

Data on 2,055 Welsh Mountain lambs showing wide variation in birthcoat type were used to study the association of birthcoat type with lamb survival and subsequent performance. Each lamb was assigned to one of six grades on the basis of its distribution of halo hair.Lamb mortality up to weaning was associated with birthcoat type though the effect was significant only in the deaths of live-born lambs before 14 days of age. During this period fine birthcoated lambs showed the highest losses with a mortality rate of 13% compared with rates up to 5% for intermediate and hairy birthcoat lambs. The lowest overall mortality rates occurred among lambs with intermediate birthcoats.Growth of 669 surviving ewe lambs did not show any significant correlation with birthcoat grade at any stage up to 18 months of age. However, the carcass weights and dressing-out percentages of 570 wether lambs were significantly higher among fine birthcoat lambs.Fine birthcoats were also associated with better quality fleece grades, 86% giving rise to kemp-free fleeces with short fine fibres, while 92% of hairy birthcoats gave rise to kempy fleeces with coarser fibres.