FACTORS INFLUENCING THE COMMERCIAL INCIDENCE OF DARK CUTTING BEEF

Data collected on 170 534 head of Saskatchewan cattle slaughtered over a period of 12 consecutive months were used to evaluate the importance of some factors influencing the incidence of dark cutting (DC) beef (Canada B2 grade based on a visual assessment of muscle color and texture). The variables examined included carcass weight, gender of animal, daily temperature and precipitation, month of slaughter, distance from farm to abattoir, mixing of loads during transportation and slaughter plant. DC beef compared to normal beef was associated with a slightly warmer daily temperature (5.4 vs. 4.8 °C), a lighter carcass weight (283 vs. 286 kg), but was not influenced by daily precipitation. The incidence of DC beef increased as distance between farm and slaughter plant increased (0.78–0.98%), and was higher in loads of cattle that were mixed during transportation than in those loads that originated from the same farm (1.11 vs. 0.79%). Steers recorded a higher frequency of DC beef than heifers (0.99 vs. 0.77%). There were large differences in the frequency of DC beef among slaughter plants after adjustment of the data for the effects of other variables (gender, mixing, trucking distance). Of the six slaughter plants in this study, the frequency of DC beef ranged from 0.27–1.79%. Month of shipment had a significant effect on the incidence of DB beef, with March and April recording the highest frequencies (1.54 and 1.24%), and December the lowest (0.45%). It was concluded that the mixing of loads and the slaughter plant were the two most important predisposing factors for DC beef. Key words: Beef, carcass, stress, dark cutting