Performance of purebred Welsh Mountain and crossbred ewes in a hill environment

The aim of this study was to compare the body weights, body condition scores, survival and litter weights of lamb produced by pure Welsh Mountain ewes with those of crossbred Cheviot, Lleyn, Poll Dorset and Texel ewes in a hill environment. Ewes were mated to Suffolk rams and recorded over the first 3 seasons of production. Between lambing and weaning, ewes rearing single lambs grazed semi-natural hill swards (1.5 ewes/ha) and those rearing twins grazed improved enclosures (10 ewes/ha). Crossbreeding significantly (P<0.001) increased body weights at all ages, with values for four-year old ewes of 45.9, 57.2, 51.6, 57.8 and 58.5 kg in purebred Welsh Mountain and Cheviot, Lleyn, Poll Dorset and Texel crossbred ewes respectively. Individual lamb growth rates from birth to 8 weeks and from 8 weeks to weaning were significantly higher in the progeny of crossbred ewes (P<0.001) with highest growth rates for lambs reared by Poll Dorset and Texel cross ewes. Individual lamb weaning weights were 27.0, 29.4, 29.2, 30.4 and 30.7 kg for lambs reared by purebred Welsh Mountain and Cheviot, Lleyn, Poll Dorset and Texel crossbred ewes respectively. Survival rates to third mating were 0.73, 0.77, 0.83, 0.72 and 0.75 (P<0.05), litter size reared was 1.22, 1.33, 1.49, 1.43 and 1.25 (P<0.001) and litter weights at weaning were 37.1, 43.5, 46.1, 46.5 and 44.2 (P<0.001) for purebred Welsh Mountain and Cheviot, Lleyn, Poll Dorset and Texel crossbred ewes respectively. Efficiency expressed as kg litter weight/kg ewe pre-tupping weight^0.75 was significantly improved (P<0.001) by crossbreeding. Total litter weight at weaning over three lamb crops per ewe entering the flock was increased from 78.4 kg in purebred Welsh Mountain ewes to between 97.1 kg in Cheviot and 109.7 kg in Lleyn crossbred ewes. It is concluded that where feed resources are adequate, the retention of crossbred ewes in the hill flock can give significant improvements in productivity.