Impact of Mutations in the NCAPG and MSTN Genes on Body Composition, Structural Properties of Skeletal Muscle, Its Fatty Acid Composition, and Meat Quality of Bulls from a Charolais × Holstein F2 Cross

Cattle breeds are optimized either for milk or meat production and secrete consumed nutrients in the form of milk or accrete nutrients as skeletal muscle tissue, respectively. Surplus energy is usually stored in the form of fat in adipose tissues. To gain more insight into the physiological and genetic background of nutrient accretion as either protein or fat, an experimental F2 population was generated crossing Charolais (CH) bulls and German Holstein (GH) cows. Mutations in two genes with known, profound effects on growth were segregating in this population: the I442M mutation in the non-SMC condensin I complex, subunit G (NCAPG) gene, and the Q204X mutation in the myostatin (MSTN) gene. The major aim of this study was to close the gap between the described effects of the NCAPG/LCORL region and MSTN SNPs on carcass and meat quality traits, as well as on the structure and composition of the underlying tissues. Whole carcass data, meat quality traits, composition of major cuts and their dominating muscles, including muscle and fat cell structure, were analyzed as well as chemical and fatty acid composition. Mutant alleles of both loci were associated with higher weights, increased muscularity, and reduced fatness, e.g., each explaining about 15% of the observed variance. However, both loci apparently affect traits in a specific manner, influencing either dimensional traits or mass accretion.