Pre-slaughter factors affecting the incidence of severe bruising in cattle carcasses

Animal transportation and pre-slaughter procedures are major components of the beef production system, but cattle are especially susceptible to stress during those events. In addition to stress-induced meat quality problems that might occur, such as higher pH and DFD meat, stressed animals are more prone to carcass bruising, which represents negative impact for the beef industry, from producers to meat packing plants. Therefore, this study was conducted to identify and quantify some risk factors for severe bruising in cattle carcasses. A total of 154,100 carcasses from 5028 loads of cattle purchased by a commercial slaughterhouse were assessed, and the following antemortem bruise-related variables were analyzed: sex, cattle handling procedures, loading facilities on the farm, type of vehicle used for transportation, distance traveled from the farm to the slaughterhouse, journey duration, truck load density, and season of the year at slaughter. Data were analyzed using the binary logistic regression model and Poisson regression model, assuming the presence or absence of severe bruises and total number of severe bruises per load as response variables, respectively. All analyzed variables showed to be potential factors for severe carcass bruising. Cattle sex was the most influential variable, and the likelihood of severe carcass bruising was greater for females (P < 0.001), as was the mean number of severe bruises per load (P < 0.05), when compared to male cattle. When handling conditions during the loading process or farm facilities worsened from 'good' to 'poor', there was an increase in the likelihood of severe bruising (P < 0.001) and in the mean severe bruise counts per load (P < 0.05). The season of the year at slaughter was also a potential carcass-bruising factor, as the chances of severe bruising and mean severe bruise number per load were greater (P < 0.001) for cattle slaughtered in the fall. In general, the likelihood of severe carcass bruising and the mean number of severe bruises per load increased (P < 0.05) when cattle were transported in larger trucks or when load density was greater than 431 kg/m(2). Moreover, distances traveled on unpaved roads greater than 31 km increased the chances of severe bruising (P < 0.001), whereas total distance traveled greater than 151 km increased the mean number of severe bruises per load (P < 0.05). In conclusion, inadequate pre-slaughter conditions compromise carcass quality by increasing the susceptibility of cattle to bruising.