PIG BEHAVIOR STUDIES APPLIED TO SLAUGHTER-PLANT DESIGN

Market pigs weighing 90-113 kg and mature sows were observed while being handled in commercial slaughter plants. In abattoirs slaughtering 500 or more pigs per hour, jamming at the single-file race entrance was reduced by installing two single-file races side by side, with a wedge-shaped partition centered between the two single-file race entrances. The wedge was 66 cm long and 25 cm wide at the base. It induced one pig to step aside and prevented three animals from jamming the entrance. Redesigned crowd pens also reduced excitement and jamming because the handler could direct the leaders into the single-file race instead of pushing a group of pigs from the rear. The center fence in a twin single-file race should be constructed so that the pigs can see each other, to encourage following behavior. The entrance gate to the crowd pen and the pen itself must have solid sides, to prevent pigs from attempting to return to the stockyards. Pigs moved more readily in single-file races with solid side fences and open barred tops than in races with partially solid tops. Crowd pens should have level floors and ramps should be avoided. Pigs have 310” panoramic vision, and puddles and shadows should be eliminated. Pigs tended to move from a darker area to a brightly illuminated area under artificial lighting. Animals raised in dimly illuminated confinement buildings refused to move towards direct sunlight.