Effects of Group Size and Space Allowance on Performance and Behavior of Swine

Abstract

Two experiments were conducted to determine the effects of number of pigs per pen and amount of space per pig on the rate and efficiency of gain and behavior patterns. Exp. 1 involved 189 pigs and consisted of three replications of four factorial treatments—(1) five pigs/pen, 1.64 m²/pig; (2) five pigs/pen, .82 m²/pig; (3) 20 pigs/pen, 1.64 m²/pig; (4) 20 pigs/pen .82 m² /pen—and a fifth intermediate treatment of 13 pigs/pen with 1.25 m² of floor space/pig. The pigs averaged 21.6 kg initially and were housed in an open front, concrete-floored building. Growth rate to 89.5 kg was not affected by group size, but decreased linearly (P<.05) as the space allowance per pig decreased. Crowding the pigs by reducing their space allowance tended to increase the level of aggressive behavior. Exp. 2 consisted of three replications of four factorially arranged treatments which compared .66 vs .33 m² of floor space/pig and five vs 10 pigs/pen. The pigs, averaging 15.9 kg initially, were maintained in an environmentally regulated building with 50% slatted floors for the 41-day test. Rate and efficiency of gain to 41.5 kg were not affected by group size. However, crowding of the pigs tended to reduce daily gain (600 vs 644 g/day, P<.08) and increase feed/gain (2.47 vs 2.39). Crowding also tended to increase aggressive behavioral patterns. Performance traits were not correlated to level of aggression or type of activity in any consistent pattern. Within the limits of the two experiments, space allowance had a greater effect on performance and behavioral patterns than did group size. Space allowance and group size appeared to affect performance independently. Copyright © 1981. American Society of Animal Science . Copyright 1981 by American Society of Animal Science