Characterisation and mapping of the Booroola (FecB) gene using regression analysis in sheep

Abstract

The Booroola Merino strain of sheep carries a major autosomal mutation (FecB) which increases ovulation rate (Davis et al., 1982). To map the gene, heterozygous sires (B+) were mated to non-carrier ewes (++). The female progeny were then examined by laproscopy to determine ovulation rates and these phenotypes used to assign progeny genotypes (B+, ++ or undetermined). Linkage analysis between the assigned Booroola genotype and a set of marker genotypes was used to assign the Booroola gene to a region of sheep chromosome 6 (OOV6) (Montgomery et al., 1994). These studies relied on accurate genotype assignment and a constant gene effect across animals and breeding seasons. This study aims to use regression analysis to verify the validity of these assumptions.