Simultaneous genetic improvement towards Facial Eczema tolerance and maternal traits N.C. Amyes1, & P.L. Johnson2, M.C. Alexander3 1AgResearch Ruakura, 10 Bisley Road, Hamilton, New Zealand neville.amyes@agresearch.co.nz (Corresponding Author) 2AgResearch Invermay, Puddle Alley, Mosgiel, New Zealand, 3Chairman of Auckland Romney Development Group, RD2, Matamata, New Zealand Tolerance to the toxin sporidesmin, which causes Facial Eczema (FE) in grazing livestock, is known to be moderately to highly heritable. However, given reliable phenotyping of the trait requires use of a commercially offered testing service that is expensive, genetic selection for tolerance to FE is carried out through two-stage selection by the majority of breeders, using the estimated breeding values of retained sires to determine which should be phenotyped. A group of five Romney breeders in the north of the North Island of New Zealand, an area prone to high sporidesmin counts, have been using the commercial testing service since the early 1980’s. The rate of index gain they have achieved in the FE (DPX) and industry New Zealand Maternal Worth (NZMW) index are explored relative to known changes in their breeding programmes design. In their early period of FE testing, they predominately focused on the DPX index, however, from 2008 they expanded to include the NZMW index, which is reflected in increased genetic gain in the NZMW index being achieved, but with little loss in their rate of progress in the DPX index. From 2012, they have incorporated genomic testing into their breeding programme and use it as an additional tool in their two stage selection procedure. Whilst it is only early days for incorporation of genomics into their breeding programmes, since 2012 their rate of gain has almost doubled for both the NZMW and DPX indexes. The genetics trends of this group will continue to be monitored with additional years of data to determine the benefits of genomic selection on index gain.

Neville Amyes, Patricia Johnson

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Electronic Poster Session - Genetic Gain - Breeding Strategies 1, , 354, 2018
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