Carcass and meat quality of Bos indicus x Bos taurus and Bos taurus cattle in northern Australia

Abstract

Liveweights, carcass characteristics, bruising and muscle properties of Bos indicus x Bos taurus (BiX) and Bos taurus (Bt) cattle (1070 steers and 394 cows) were compared from 7 experiments throughout Queensland. In general, the cattle were weighed (unfasted), transported as mixed genotype groups to an abattoir and given access to water from arrival until slaughter. Access to feed varied between experiments. Mustering to slaughter periods varied from 4 to 9 days. For steers, mean liveweight at slaughter and carcass characteristics (weight, dressing percentage, liver weight and rib fat depth) were generally similar for BiX and Bt. In 1 of the 5 experiments with steers, BiX had a greater (P<0.05) mean liveweight, carcass weight, dressing percentage and liver weight. In both of the experiments with cows, BiX had greater (P<0.05) mean carcass weight but in only 1 experiment greater (P<0.05) mean liveweight and dressing percentage. There were no consistent differences between BiX and Bt in bruise score. Meat properties were compared in 1 experiment each for steers and for cows. BiX cows had a greater (P<0.05) mean initial yield(YI) shear value and tended to have a greater peak force (PF) for M. longissimus dorsi (LD) muscle than Bt cows. BiX had a lower (P<0.05) PF - IY value. Genotype had no significant effect on shear values and sarcomere length in steers or on cooking loss in steers and cows. Over all experiments, there was a higher (P<0.05) percentage of Bt than BiX carcasses ( 8.5 v. 3.7%) with high pH (> 6.0) values 24 h post mortem (pH24) for LD muscle. Genotype had no significant effect on mean pH24 and ultimate pH in cows or steers. Significantly more (P<0.05) cow than steer carcasses had high pHz4 values (10.9 v. 5.0%). In 2 experiments, more (P<0.05) heads and tongues were condemned for BiX than Bt steers, but there was no significant difference for the percentage of burst rumens. We conclude that the belief held by producers, butchers and others that BiX cattle have more bruising and produce darker meat than Bt cattle is unfounded. The overall toughness of meat from cattle slaughtered in northern Australia is of much greater concern than minor differences between genotypes.