Brahman and Brahman crossbred cattle grown on pasture and in feedlots in subtropical and temperate Australia. 2. Meat quality and palatability

Market demand for a reliable supply of beef of consistently high eating quality led the Cooperative Research Centre for Cattle and Beef Industry (Meat Quality) to initiate a crossbreeding progeny test program to quantify objective and sensory meat quality differences between straightbred and first-cross Brahman cattle. Brahman, Belmont Red, Santa Gertrudis, Angus, Hereford, Shorthorn, Charolais and Limousin sires were mated to Brahman females over 3 years to produce 1346 steers and heifers in subtropical northern Australia. Calves were assigned within sire by age and weight to one of three market endpoints (domestic, Korean or Japanese), one of two finishing environments (subtropical or temperate) and one of two finishing diets (pasture or feedlot). Average carcass weights were 227, 288 and 327 kg for domestic, Korean and Japanese markets respectively. Only steers were finished for the Japanese market. The effects of sire breed,finishing regime, market endpoint and sex on sensory meat quality of four attributes score (CMQ4), ossification score and Warner-Bratzler shear force (SF), instron compression (IC), ultimate pH and percent cooking loss (CL) on the M. longissimus thoracis et lumborum (LT) and M. semitendinosus (ST) were determined. Straightbred Brahmans had the highest SFLT (5.39 +/- 0.07; P < 0.001), ICLT (1.89 +/- 0.02; P < 0.05) and CL in both muscles (P < 0.05). Straightbred Brahmans were the only genotype that failed to meet minimum CMQ4 grading standards (38.3; P < 0.001). Progeny with up to 75% Brahman content successfully met minimum objective and sensory meat quality consumer thresholds for tenderness (IC < 2.2 kg, SF < 5.0 kg; CMQ4 > 46.5). There was little difference between crossbred progeny for most meat quality traits. All feedlot-finished animals were slaughtered at domestic, Korean and Japanese market weights by 24 months of age, with minimal differences in objective measures of meat quality between markets. The IC measures for all sire breeds were below 2.2 kg, indicating connective tissue toughness was not an important market consideration in feedlot-finished animals slaughtered by 24 months of age. Pasture finishing adversely affected all meat quality traits (P < 0.001) except CLST, with Korean and Japanese market animals having unacceptably tough SF, IC and CMQ4 measures. This was attributed to their older age at slaughter (31 and 36 months respectively), resulting from their seasonally interrupted growth path. While domestic animals slaughtered at 25 months of age off pasture had unacceptably high SF and IC, CMQ4 was acceptable. Subtropical feedlot animals had slightly more desirable (n.s.) SF and IC relative to temperate feedlot animals, whereas temperate feedlot animals had higher CMQ4 ( P < 0.001). Genotype x environment interactions were not important.