Abstract

The basic aim of selection in flocks in the 150 to 200% lamb drop range remains unchanged, namely to breed sheep of sound physical type and with the genetic potential to give maximum net profits per hectare from sales of meat and wool. However at these fertility levels the main thrust of selection moves off fertility due to the doubtful benefit of large numbers of triplets under commercial farm conditions. More emphasis can profitably be placed on milking ability as expressed by weaning weight. This has major implications in ensuring quick seasonal disposal of lambs to reduce the pressure on stocking rate brought about by high fertility. Also fleece weight gains in importance as increases in wool production do not involve increased stocking rate. In high fertility flocks health and behaviour traits such as free lambing, mothering ability and resistance to foot problems are of even greater importance. Overall, a very important factor to be considered in future selection in high fertility flocks is that per head gains in production be made while holding ewe body weights, i.e. an emphasis on efficiency for best per hectare results.

MT, Johnston, RW Kelly, and RR Webb

Proceedings of the New Zealand Society of Animal Production, Volume 42, , 47-50, 1982