Selection efficiency in ram breeding flocks

C.J. Dodd and J.R. Delahunty

Ministry of Agriculture and Fisheries, Hastings and Ministry of Agriculture and Fisheries, Wellington

Proceedings of the New Zealand Society of Animal Production. 1983, 43: 193-196

A sheep selection efficiency analysis developed to supplement recording on Sheeplan was applied to performance records in 8 groups- breeding scheme central flocks. Average flock size was 756 ewes, and 170 rams were selected from 4 birth-years for central flock use. Selection efficiencies for the Sheeplan two-tooth index were 64%, 74%, 70% and 68% for rams born in 1977/80 and the corresponding efficiencies for two-tooth ewes were 29%, 27%, 42% and 44% respectively.

The selection of two-tooth ram and ewe replacements is expected to result in annual rates of improvement of 0.67% in lambing rate, 0.16 kg in weaning weight, 0.34 kg in hogget live weight and 0.029 kg in hogget fleece weight. Other traits breeders emphasised included structural soundness, wool quality and hogget lambing performance. Opportunities for increasing rates of progress in sire breeding programmes are discussed.

Keywords: NZSAPAB; Sheep; selection efficiency; Sheeplan; selection index; breeding objectives; group breeding schemes

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Last Updated 03-05-1997