Fatores pré-abate relacionados às contusões em carcaças bovinas.

Abstract

Carcass injury originates mainly during pre-slaughter. In this period animals are submitted to na unifamiliar chain of factors, causing stress, as result of a forced adaptation tentavive. Factors related to injuries were evaluated in bovine carcasses, from animal loading management until unloading at slaughterhouse. Management conditions and transport data were collected in a packing plant in Southern Brazil. Dependent variables correspond to the proportion of injured animals and the total number of injuries, for each animal lot. Independent variables were: sex of animals, animal density in trucks, time (minutes) and travel distance (kilometers), unloading time,handling facilities conditions and management and ti me and type of vehicle used for transport. Through logistic regression a Family binomial model was adjusted for data of injury frequencies, in which carcasses were separated in bruised and not bruised and a Poisson Family model for data of total count of injuries. To determine the probability of an animal be injured the test “odds ratio” (OD) was performed and, for data of countings Tukey test was applied to compare means predicted by the model. Sex presented the highest effect in the results of the two models, with females being more susceptible to injuries. Higher frequencies of injury (P<0.05) were caused by longer travel time. However, when evaluated by the distance this relationship was not obeserved. Lower chances of injuries were observed with a shorter time of unloading and, in relation to animal densities, results show that very low or very high animal density caused less injuries, when total number of injuries was considered. In relation to management and handling facilities conditions, a reduction of injuries was observed for regular grade to good, being lower values for bad grade. Better results were observed in lots transportated in trailer type trucks. Despite the fact that injuries occur in several pre-slaughter phases, sex was the more determinant factor,with females being more susceptible.