Myostatin (MSTN) gene haplotypes and their association with growth and carcass traits in New Zealand Romney lambs

Myostatin, which is also known as growth and differentiation factor 8 (GDF8), acts as a negative regulator of skeletal muscle growth. Genetic variation in the myostatin gene (MSTN) has been associated with variation in muscularity in many animals including sheep. Polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) analysis was used to investigate the haplotypic diversity of MSTN and the association between the MSTN haplotype and variation in lamb growth and carcass traits. A total of 1379 Romney male lambs from 19 sire-lines were tested in this study. Five MSTN haplotypes including H1, H2, H3, H5 and H7 were identified. Using a restricted maximum likelihood (REML) mixed-model approach in both half-sib and pooled-data analyses, H1 was associated with an increase in birth weight, tailing weight and draft weight in lambs and had a significant effect on loin yield, leg yield, total yield and proportion loin yield from lamb carcasses. Haplotype H2 in lambs was associated with an increase in draft weight and an earlier drafting age, together with an increase in loin, shoulder and total yield of lean meat. H3 was associated with an increase in growth rate to weaning, leg yield and total yield of lean meat. The presence of haplotype H5 in lambs was associated with a decrease in loin yield, shoulder yield and total yield of lean meat yield. The association of haplotype H7 with a decrease in leg yield was identified for the first time in this study. These results suggest that the variation in ovine MSTN in NZ Romney is associated with differences in lamb growth and carcass traits and thus meat production. It also suggests that using MSTN as a marker-assisted selection tool for improved carcass traits in NZ Romney is a future possibility