Variation in the eating quality of M. longissimus dorsi from Holstein-Friesian bulls and steers of New Zealand and European/American descent, and Belgian Blue x Holstein-Friesians, slaughtered at two weights

The aim of this experiment was to determine the extent of variation in the eating quality of beef from light or heavy steers and young bulls from extreme dairy or beef cross dairy breeds of cattle. High genetic merit New Zealand Holstein-Friesian dairy progeny (NZ), high genetic merit European/North American Holstein-Friesian dairy progeny (EU) and Belgian Blue beef cross Holstein-Friesian progeny (BB) (32 per genotype) were reared from birth to slaughter as light (620 kg) steers, heavy (720 kg) steers, light young bulls or heavy young bulls. Quality assessments of M. longissimus dorsi were: pH, Warner Bratzler shear force (WBSF), sensory attributes, cooking loss and chemical composition. Variances were compared using Bartlett's test. Bulls were more variable than steers for ultimate pH, WBSF after 2 and 7 days postmortem, flavour after 14 days postmortem and cooking loss after 2, 7 and 14 days postmortem. Within genotype, the BB breed was less variable for moisture and intramuscular fat concentration than the dairy breeds, but the variance for eating quality characteristics was similar for the three breeds. Within weights, the heavy animals were more variable for ultimate pH and cooking loss after 2 and 7 days postmortem. Within each factor, more than 81% of samples were considered acceptably tender after 14 days ageing postmortem. Further work should focus on reducing this residual variation.