Abstract

Glenbrae and Broomfield strains of Corriedale sheep were developed over a period of 19 years by selectively breeding from animals that remained free from clinical footrot when deliberately exposed to natural infection. Recent studies have demonstrated relative advantages in these bloodlines during footrot outbreaks in terms of significantly reduced incidence and severity of infection compared to unselected Corriedales. Similar benefits have also occurred in commercial flocks when first cross offspring of Glenbrae and Broomfield rams were compared to offspring of traditional rams. Introduction to the industry of these apparent genetic gains in footrot resistance has been through 2 approaches. Firstly the Broomfield Corriedale Group Breeding Scheme was established in 1982 with 1420 Sheeplan ewes recorded in 5 flocks screened from an estimated 28,000 ewes. The objective is to breed rams for commercial use utilizing performance records and a footrot challenge prior to selection as 2- tooths. Secondly the Corriedale Sheep Society initiated a top-crossing programme mating 3 Glenbrae footrot resistant rams to 81 registered Corriedale ewes in 1986. Details of these 2 approaches are given.

RW, Moore, CM Miller, BW Dow, and LD Staples

Proceedings of the New Zealand Society of Animal Production, Volume 48, , 109-112, 1988