Genetic variability of foetal bovine myoblasts in primary culture

Selected strains of adult bovines and those which either have high muscle g rowth capacity or are double-muscled present particular characteristics of muscle fibres and collagen at slaughter that favour meat tenderness. For do uble-muscled bovines, it has been shown that these characteristics originat ed during foetal life. However, no studies have been done to determine the origin of muscle growth superiority in bovine with high muscle growth capac ity compared to those with a low muscle growth capacity. Therefore, the obj ective of this study was to examine the proliferation and differentiation p hases of myoblasts in primary culture taken from high and low muscle growth capacity foetuses at 110 days post-conception. These cultures were analyse d on 1, 2, 3, 4, 6, 8, 10 days of culture. The proliferation phase was moni tored by appropriate marker antibodies. The differentiation was studied by immunocytochemistry with specific antibodies for foetal, I, II (IIa and IIb ), I and IIb, I and IIa myosin heavy chains (MHCs) and connectin respective ly, and by immunoblotting with desmin antibody. A higher proliferation, a l ower fusion and a delayed differentiation of the 'late markers' namely MHCs fast (IIa and IIb) and connectin were shown in high muscle growth capacity foetuses compared to low capacity ones. The results indicate that the musc le growth superiority of high muscle growth capacity bovines seems, therefo re, to have a similar foetal origin to that of double-muscled ones.