Ewes that are homozygous carriers (FecXVFecX1) of the Inverdale prolificacy gene have small non-functional ‘streak ovaries’, and are infertile. This streak ovary condition can be utilised in a simplified progeny test enabling the Inverdale genotype of a ram to be established by the time it is 14 months of age. The presence or absence of streak ovaries is also a useful test where screening for new major genes is being undertaken. To avoid producing ewes with streak ovaries in a commercial breeding programme, breeders should not mate carrier rams (FecX1") with carrier ewes (FecX'/FecX*). The Inverdale gene has the potential to increase productivity in the sheep industry, although the identification of a reliable genetic marker is essential if matings producing ewes with streak ovaries are to be prevented. Because the streak ovary condition accurately differentiates FecXVFecX1 and FecXVFecX* genotypes, it should facilitate the early identification and validation of genetic markers for the Inverdale gene. If structures observed on some streak ovaries are confirmed to be ovarian tumours, flocks of FecX'/FecX1 ewes may be established specifically for medical research.

G. H Davis, G. D Bruce, P. J Reid

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 19. Selection and quantitative genetics; growth; reproduction; lactation; fish; fiber; meat., , 249–252, 1994
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