Study on the relationship between pre-slaughter handling and carcass bruising in calf and bull carcasses

The pre-slaughter handling of 105 calves and 142 bulls was examined in a commercial situation with the aim to investigate the potential causes of bruising on cattle carcasses. Calves were supplied by one farm, while bulls were supplied by 12 different farms. During handling, the time needed to load and unload the group of animals and the time spent in the truck before unloading, in lairage, and in the race before stunning were recorded. Moreover, the number of falls, reversal, heads, mounts, balks, jumps, slips, evacuations and vocalizations were noted during loading, unloading, resting and before stunning. All animals were slaughtered in the same plant. About 30 minutes after slaughter, carcass bruising was assessed on the basis of photographic standards using a 3-point scale (1 = none, 2 = slight, 3 = severe). The frequencies of the different behavioural occurrences, their distribution within the bruising score classes, and the relationship between handling time and bruises were evaluated. Slip was the most frequent event during loading, unloading and waiting before stunning for both calves and bulls. The distribution of veal carcasses within the bruising score classes was significantly affected by the unloading time and the duration of resting. Both faster and slower unloading, as well as a short resting period, led to an increase in the percentage of severely bruised carcasses. Slight and severe bruises were found on carcasses of calves that showed a higher frequency of falls and mounts during pre-slaughter handling. The distribution of bull carcasses within the bruising score classes was affected significantly only by the waiting time before stunning, showing a positive relationship between short duration and severe bruising. The latter was also associated with a higher balk frequency and a reduction in evacuation.