Abstract

A major gene, affecting a quantitative trait in farmed livestock, is usually detected by observing segregation of the gene within families such as half-sib sire families. In the case of the Inverdale, a maternal family was observed to contain some highly prolific ewes. Progeny testing of four rams from this family revealed two rams with prolific progeny, but segregation amongst these progeny was not apparent. The data appeared to be consistent with the hypothesis of an X-linked major gene, but were not conclusive. A further progeny test involving six sons and five maternal grandsons of a putative Inverdale ram was undertaken. Three of the maternal grandsons but no sons had prolific daughters, confirming the X-linked hypothesis. Further major gene searches should consider X-linked as well as other modes of inheritance. The mode of inheritance, and effect of one and two copies of the Inverdale gene, have important consequences for its use in research and production.

KG, Dodds, GH Davis, JC McEwan, and PF Fennessy

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 291-293, 1995