Effects of induced cryptorchidism on lamb weaning and carcase weights

Abstract

In three flocks at two sites, male lambs, sired by Dorset Horn rams from Border Leicester X Merino ewes, had their testes forced into the abdominal cavity at ages of up to three weeks. The growth rates, weaning weights, carcase weights, and carcase values of these lambs were compared with those of lambs castrated at the same age and of lambs left entire. In one flock with a growth rate of approximately 0.3 kg day-1 cryptorchids and rams each had significantly higher weaning weights than did wethers. In the other two flocks the same trend was present at growth rates of 0.23-0.26 kg day-1 but differences were not significant. Carcase weights did not differ significantly between treatments, but in the flock with the highest growth rate, the weights of cryptorchids and rams were higher than those of wethers. In view of the diverging growth rates between wethers and the other groups at the time of slaughter (to produce carcases averaging 17 to 20 kg), it would be profitable to test the effects of these treatments at higher carcase weights.