Abstract

New Zealand's national lamb weaning percentage has hovered around 100% since 1960. This is a disappointing figure considering the number of sheep recording and performance analysis packages that are available to ram breeders. The present "average" NZ ewe probably drops about 1.20 lambs. Assuming 14% lamb losses from birth to weaning, and 6% ewes that die or are dry, each ewe mated weans about one lamb that grows at about 200g per day. One obvious way of improving these figures is to increase lambing percentage. For example, introducing 1/4 Finnish Landrace genes into the base flock has the potential to increase lamb drop by 20%. However, lamb growth rates must also be improved. Incorporating genetically superior milk producing breeds into the dam side as well will also increase lamb growth rates, resulting in lambs with the ability to grow at 250g per day or better. Ewes that produce 30% less wool than their contemporaries, but at the same time wean an extra 0.2 lambs that are 20% heavier than the flock average, can increase nett sheep-derived income by around 20%. The advantages are not just an immediate improvements in gross margins. Additional to this is the increased flexibility in management policies that result from having faster growing lambs that can be weaned earlier to provide better carcass weights or bigger replacements. This flexibility can be enhanced by introducing breeding programmes that utilise terminal sire breeds to further improve profitability. The major advantage of this more productive ewe is that it breaks the 100% lambing "poverty trap".

D, Walpole

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 326-327, 1995