Effect of growth intensity of bulls on the microstructure of musculus longissimus lumborum and meat quality.

摘要

Effects of growth rate (growing or rearing intensity) of bulls were investigated on the microstructure and physicochemial properties of beef. Beef samples (longissimus lumborum) were taken from 43 bulls with different growth rates (<900 and >=900 g/day). Commercial crosses of Polish Lowland black-and-white cows with Charolais and Limousin bulls were used; the 2 hybrids had similar slaughter wt. (447.6 and 517.2 kg) and age (526 and 606 days). Beef from intenstively reared (high growth rate) animals contained smaller proportions of fibres with tetrazole dehydrogenase activity. For fibres with myofibrillar ATPase activity, intensively reared animals exhibited higher s.d. values than the other groups. Further analysis of muscle tissue from this group revealed that out of the 24 muscles, 9 contained giant fibres. In comparison with less intensively reared animals, meat from bulls that gained >900 g/day in wt. contained significantly less glycogen (P <= 0.01) and, consequently, the meat was less acidic. Meat from intensively reared animals demonstrated relatively high pH variability; pH₂₄ and pH₄₈ values, as well as pH variability, indicated that beef from these animals would be dark, firm and dry.