Effect of transport stress on physiological responses of male bovines

Forty-eight slaughter bulls were transported by road in groups of eight for approximately 30 min, 3 h and 6 h in two replicates. Animal welfare during the transport process was assessed. Loadings and unloadings were evaluated with a scoring method. Heart rates were monitored at the farm before loading and during all stages of transport. Blood samples were taken from all animals a week before transport and at sticking and analysed in terms of haematological values: hematocrit, haemoglobin, red and white blood cells (RBC and WBC), differential WBC counts and neutrophil:lymphocyte ratio. Glucose, creatine kinase, lactate and cortisol were also determined. To evaluate differences in meat quality, pH and water-holding capacity (WHC) were measured 24 h after slaughter. The loading and unloading scores were very low (low stress) but were associated with changes in heart rate, especially loading. Animals recovered their resting heart rate during the journey in medium and long transports. On the other hand, animals transported around 30 min maintained an elevated heart rate during the whole journey. All animals showed a stress response with significantly higher (p < 0.05) levels of erythrocyte series, N:L ratio, glucose and lactate. Animals transported for 3 and 6 hours had significantly (P<0.05) higher levels of cortisol than controls or 30 min transports, without differences between control and the shortest journey. Different transport times did not influence meat quality. Under good conditions, the transport had a slight effect on welfare, meat quality or physiological parameters related with stress.