Voluntary food intake, live-weight gain, carcass quality and food conversion in contrasting genotypes of weaned suckler-bred bulls finished intensively on a cereal-based diet

Abstract

AbstractA bull beef finishing experiment was conducted with the objective of comparing physical performance of constrasting genotypes of suckler-bred bull beef animals finished intensively on a cereal-based diet at approximately 12 to 13 months of age. Nine bulls per genotype were drawn from weaned, bull calves born to one of two dam types (Belgian Blue×Holstein/Friesian (BB) or Simmental×Holstein/Friesian (SIM)) and which had been sired by one of two contrasting sire types (Aberdeen Angus (AA) or Charolais (CH)). Bull calves were weaned at approximately 8 months of age and the finishing experiment ran from approximately 9 months of age until slaughter at 12 to 13 months of age. Cereal-based concentrate diets were offered to all bulls on an ad libitum basis throughout the experimental finishing period. Dry matter intake (DMI), live-weight gain (LWG), food conversion ratio (FCR), and carcass slaughter characteristics were quantified.Average daily LWG was 2·07, 2·11, 2·34 and 2·65 kg/day, average FCR was 5·14, 5·06, 4·70 and 4·12 kg DMI per kg LWG and average age at slaughter was 387, 381, 374 and 366 days for the AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively. These figures showed that CH sired bulls grew faster ( P<0·001), finished at an earlier age ( P<0·01) and had better food conversion ratios ( P<0·01) than AA sired bulls. CH sired bulls also produced heavier carcasses (P<0·001) with better conformation ( P<0·001) than AA sired bulls. Average cold carcass weights (CCW) at slaughter were 309, 318, 348 and 365 kg and average conformation scores (15-point scale) at slaughter were 9·28, 10·28, 12·39 and 12·75 for the AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively. Finished bulls from SIM dams had higher LWGs (P<0·01) and produced heavier carcasses (P<0·05) than bulls from BB dams. No statistically significant differences in fat score (15-point scale) were seen between any of the breed combinations with fat scores of 7·50, 7·25, 6·75 and 6·75 for the AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively. No significant differences in average daily food intake were observed between breed combinations in the experiment with average daily DMI being 10·6, 10·6, 11·0 and 10·9 kg/day for AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively.Overall, there was little evidence to suggest that the rate of bull LWG declined to bring about any meaningful reduction in productivity as average bull live weight increased from approximately 9 months of age until slaughter at 12 to 13 months of age. When finished on a nutrient-rich, cereal-based concentrate diet, excellent animal performance and commercially acceptable carcasses can be produced from the UK suckler herd using genetically superior sires of either traditional UK or continental beef cattle breeds. Results from this study indicate that CH sired bulls out-performed AA sired bulls, especially when produced from SIM cows.