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Cattle sired by Piedmontese or Wagyu bulls were bred and grown within pasture-based nutritional systems followed by feedlot finishing. Effects of low (mean 28.6 kg, n = 120) and high (38.8 kg, n = 120) birth weight followed by slow (mean 554 g/day, n = 119) or rapid (875 g/day, n = 121) growth to weaning on carcass, yield and beef quality characteristics at about 30 months of age were examined. Low birth weight calves weighed 56 kg less at 30 months of age, had 32 kg lighter carcasses, and yielded 18 kg less retail beef compared with high birth weight calves. Composition of carcasses differed little due to birth weight when adjusted to an equivalent carcass weight (380 kg). Calves grown slowly to weaning were 40 kg lighter at 30 months of age compared with those grown rapidly to weaning. They had 25 kg smaller carcasses which yielded 12 kg less retail beef than their counterparts at 30 months of age, although at an equivalent carcass weight yielded 5 kg more retail beef and had 5 kg less fat trim. Neither low birth weight nor slow growth to weaning had adverse effects on beef quality measurements. No interactions between sire-genotype and birth weight, or growth to weaning, were evident for carcass, yield and beef quality traits. Although restricted growth during fetal life or from birth to weaning resulted in smaller animals that yield less meat at about 30 months of age, adverse effects on composition due to increased fatness, or on indices of beef quality, were not evident at this age or when data were adjusted to an equivalent carcass weight. |
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