An evaluation of the effect of the Booroola gene, Fec B, on productivity in a Border Leicester x Merino prime lamb production system

The direct effect of the Booroola gene, Fec B, on ewe reproduction rates and ewe productivity traits has been evaluated in a typical Border Leicester x Merino prime lamb production system. The ovulation rate and prolificacy of the Border Leicester x Booroola Fec B^b+ ewes were significantly higher than those of traditional Border Leicester x Merino ewes. This advantage was offset by significantly lower lamb rearing ability with the result that there was no advantage in terms of lambs weaned/ewe joined or in $ returned/ewe joined. Targeted supplementary management strategies (ultra-sound scanning, supplementary feeding) appear to show promise in realising the gains from the increased prolificacy.