Maternal behaviour and the survival of lambs in superfine wool sheep

Superfine merino lambs from superfine and medium-wool ewes were compared to test the hypothesis that superfine ewes have poorer maternal capacity than broader wool ewes. All lambs were sired by one ram using artificial insemination in the superfine ewes and embryo transfer in the medium-wool ewes. This ensured a similar genetic background in all lambs. Single born lambs from the superfine ewes were 1.5 kg lighter than those from medium-wool ewes (3.3 v. 4.8 kg, P<0.05). Compared with the medium-wool ewes, in the first hour after birth the superfine ewes spent less time grooming their lambs (8.7 v. 25.2 min, P<0.05) and more time separated from them (21.3 v. 0.0 min, P<0.05). The lambs of superfine ewes also stood and attempted to suck for less time (17.7 and 2.4 min v. 32.4 and 10.5 min, P<0.05) than those of medium-wool ewes. Twenty-nine per cent of lambs from superfine ewes died in the first 4 weeks after birth compared with only 4% of lambs from medium-wool ewes. It was concluded that superfine ewes lost more lambs than medium-wool ewes and that this was associated with their lambs being smaller at birth and with the ewes being poorer mothers.