Genetic variation in the bovine myostatin gene in UK beef cattle: Allele frequencies and haplotype analysis in the South Devon

Work on Belgian Blue cattle revealed that an 11 base pair (bp) deletion wit hin the bovine myostatin gene (GDF8) is associated with the double-muscled phenotype seen in this breed. Investigations focusing on other European bre eds known to show double-muscling identified several mutations within the c oding region of the gene associated with the double-muscled phenotype in di fferent breeds. The number of mutations found suggest that myostatin is hig hly variable within beef cattle. Variations that alter the structure of the gene product such that the protein is inactivated are associated with the most pronounced form of double-muscling as seen in the Belgian Blue. Howeve r, other mutations may have a less extreme affect on muscle development. Wh ile overt double-muscling gives rise to a high incidence of dystocia (calvi ng difficulty), it is possible that some variants may give enhanced musclin g, but with limited calving problems. We describe sequence analysis of the myostatin gene in ten beef breeds commonly used in the UK and show that the Il-bp deletion responsible for double-muscling in the Belgian Blue is also present in the South Devon cattle population. Allele frequencies and haplo types in the South Devon and a polymerase chain reaction (PCR) based test f or the deletion are described. PCR amplification across the deleted region provides a quick and effective test with clear identification of heterozygo us individuals. We discuss our results with regard to the effect of genotyp e on phenotype and differences observed between the Belgian Blue and the So uth Devon.