Growth performance, carcass traits and meat quality of bulls and heifers slaughtered at different ages

The effects of sex and slaughter age on growth, feed intake, carcass composition and meat quality attributes of musculus longissimus lumborum were investigated in Charolais × Simmental bulls (n = 12) and heifers (n = 12) reared and finished under identical management conditions. The animals entered the experiment at similar age (251 days) and were slaughtered at 14 or 18 months of age. Bulls gained more rapidly (P < 0.001), consumed more dry matter daily (P < 0.05), and had a higher killing-out proportion (P < 0.05). The sex × slaughter age interaction was significant (P < 0.01) for feed conversion ratio, which deteriorated markedly more in heifers than in bulls as slaughter age increased. Bulls produced leaner carcasses with a higher proportion of total meat (P < 0.001). While bulls contributed to high-priced meat by a higher proportion of meat from the shoulder (P < 0.01), heifers had higher proportions of meat from the rump and loin (P < 0.05). Older animals were generally fatter and their carcasses contained lower proportions of high-priced meat (P < 0.01) and bones (P < 0.05). Bulls exhibited lower contents of dry matter (P < 0.001), protein (P < 0.05) and intramuscular fat (P < 0.001), and a higher content of collagen (P < 0.001) in musculus longissimus lumborum than hei-fers. The meat from heifers was assessed by the sensory panel as more tender and, when aged for 11 days, more acceptable than the meat from bulls. Older animals obtained higher scores for beef flavour intensity (P < 0.01), tenderness (P < 0.001), juiciness (P < 0.05), and overall acceptance (P < 0.001).