Differences in meat quality traits between ‘‘white’’ and ‘‘red’’ muscles, and between certain breeds are generally well acknowledged. However, it is not clear to what extent MyHC fibre type
composition accounts for such quality differences. Are certain MyHC fibre types more likely to confer better meat quality traits? A molecular understanding of MyHC fibre type characteristics on meat traits could facilitate breeding schemes for improving meat quality. In this study, we examined, for the first time, the relationship between MyHC fibre types and meat quality traits between muscles within breeds, and between the same muscles of different breeds (traditional Berkshire and Tamworth, and modern Duroc-based and Large White-based breeds). We found clear differences in the relative abundance of MyHC 2a, 2x and 2b fibres between fast longissimus dorsi (LD) and slow psoas muscles within breeds, which could account for the differences observed in a number of meat quality traits. However, there was no clear-cut relationship between the relative abundance of a particular fibre type and a specific meat quality trait, consistent across both muscles and all breeds, but within individual breeds, there were significant correlations between the abundance of certain fibre types and meat quality traits. This finding
was in line with the view that a given fibre type could have considerable variations in phenotype between
breeds, and even, between muscles, which in turn could result in contrasting correlations with meat quality
traits.