Driving slaughter pigs for electrical stunning - A comparison of systems

The access for the stunning system is one of the most stressful procedures slaughter pigs experience in the abbatoir. Investigations on two batches of 25 pigs each were carried out to characterize two different access systems for electrical stunning by physiological response such as heart frequency (HF) and the blood constituents lactate and cortisol. All animals were of the same hybride breeding programm. The access race in system A, where the animals are separatet was 11 m long. The personell used different equipments including electrical prods to move the pigs forward. The lairage time after transport was between 1 to 2 h. In system B the animals arrived the evening before slaughter. In system B the access race was 3.5 m long. In the access race the HF were at about 205 beats/min (system A) and 161 beats/min (system B). Blood samples were taken immediately after stunning. The lactate concentration differed by 6 mmol/l (8.6 mmol/l in System A, 2.6 mmol/l in system B). Cortisol was distinctly higher in the blood of the animals from system A (166 ng/ml) compared to system B (126 ng/ml). The results show that the used techniques are suitable to examine stress indicators of pigs under practical conditions. Access systems with long race seem to pose a higher stress than short access ways. The influence of handling (human factor) and management is equally important. The role of longer resting times in the lairage should be investigated in more detail. This should also include the keeping conditions on the farm where the animals are raised.