Selection for resistance to parasites in sheep

A.G.H. Parker

Wairunga, R.D. 12, Havelock North, New Zealand

The Wairunga flock was established in 1956. It has since been selected for production traits and, recently, also for 'disease' traits (resistance to footrot, dags and internal parasites). Records of weaning weight, autumn weight, winter weight, faecal egg count (FEC) and fleece weight have been collected on ewe and ram lambs from the 1987- born crop onwards, in a management programme which involved withholding anthelmintic drench for a monitored period in autumn. Dag scores have also been taken at the time of faecal sampling from the 1988-born crop onwards. Experiences already show that there is keen interest from ram buyer clients in 2-tooth rams that have grown without a drench. Results show significant potential savings in numbers of drenches on weaned lambs, and large differences among sire groups in the parasite susceptibility of progeny groups. Because of the need to withhold drenches, a major change in the whole concept of ram breeding and performance testing will be required by ram breeders and their clients before much progress can be made in breeding for resistance to internal parasites.

Keywords: NZSAPAB; Sheep; internal parasites; resistance; breeding; dags

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Last Updated 25-01-1997