THE INFLUENCE OF LEVEL OF FEEDING AND LIVE WEIGHT ON FEED CONVERSION AND CARCASS COMPOSITION IN FRIESIAN BULLS

Feed conversion and carcass quality in relation to feeding level were investigated using 75 bulls of the Swedish Friesian breed. The experim ent was carried out using a factorial design with three feeding levels (H, L, and F) and three slaughter stages. The bulls were fed concentr ate and hay to gain 1100 g/day (H) or 850 g/day (L). The third group ( F) was fed to gain 850 g/day until 18 months of age and 1100 g/day the reafter. On each feeding level the bulls were slaughtered at three dif ferent ages (H: 13, 18 and 23 months; L and F: 18, 23 and 28 months) a nd when reaching treatment mean carcass weights of 240, 325, 418, 277, 363, 422, 275, 372 and 454 kg, respectively. The relative amounts of fat, lean and bone were strongly affected by both feeding level and ag e or weight. The carcasses became fatter and the relative weight of th e bone decreased as the carcasses grew heavier and as feeding level in creased. The feed conversion ratio to the same degree of fatness, expr essed as metabolizable energy consumed per kg carcass weight gain, was similar irrespective of feeding level. The conversion of feed into li ve weight and carcass weight gains increased sharply with increasing l ive weight.