Relationship between phenotype, carcass characteristics and the incidence of dark cutting in heifers

- Slow growth and reduced slaughter weight related to dark cutting in heifers
- Dark cutting probability reduced in heifers with slaughter weights greater than 550 kg
- Marbling score had no effect on dark cutting incidence in beef heifers.
- Dark cutting carcasses most similar to USDA Select/Canada AA carcasses

Previous research has suggested that cattle predisposed to dark cutting can be identified from live animal or carcass characteristics. This hypothesis was tested using production and phenotype data from an existing data set collected from heifers (n = 467) on study at three farms. Carcasses in the data set graded Canada AAA (n = 136), AA (n = 296), A (n = 14), and B4 (dark cutting, n = 21). Farm was identified as significant (P = 0.0268) by CATMOD analysis and slaughter weight and carcass weight accounted for the variation in dark cutting frequency across the farms. Analysis of variance indicated that dark cutting heifers had reduced weight at weaning (P < 0.0001) and at slaughter (P < 0.0001), and produced reduced weight carcasses (P < 0.0001). Results of logistic regression indicated that the probability of dark cutting was decreased in heifers slaughtered at live weight greater than 550 kg and in carcasses weighing greater than 325 kg.