Frustration in grower
pigs: the effect of toys
N.J. Lewis
University of Manitoba,
Winnipeg, Canada
Pigs acquire, through learning and evolution, expectations of their environment. Frustration of expectations results in altered behaviour, which can be ameliorated by toys.
Eighteen growers were fasted (1-h, 3-h) by removing feeders. On training days (2/wk), feeders were returned after the fast. On test days (3/wk), non-functional feeders were used, producing frustration. Pigs were videotaped for 2 h following feeder replacement. Training and test days were compared by split-plot-in-time analysis. Toys were randomised across test days and the effect of toy (ball, chain, none) was compared within weeks. Single and paired pigs were observed.
Frustrated pigs were more active as indicated by reduced lateral recumbency (-11.3%) and increased sternal recumbency (+8.2%), sitting (+2.5%) and moving (+1.1%). Frustration increased oral manipulation of feeders (+7.3%), pigs (+1.1%) and other objects (+9.8%). Single pigs (S) found balls, and pairs of pigs (P) found chains frustration reducing. With balls, frustration related behaviours were lower in single pigs: sitting (S 2.1%, P3.3%), object manipulation (S15.7%, P 16.8%) and feeder manipulation (S3.0%, P3.8%) while play-with-toys was higher (S11.8%, P 7.0%). The opposite occurred with chains (sitting S 5.5%, P 4.5%, object manipulation S 20.2%, P13.8%, feeder manipulation S 4.2%, P 3.5% and play-with-toys S 6.0%, P 10.0%).
When fasting increased (1-h to 3-h), standing increased in the no-toy pens (23.7% to 36.5%), a sign of frustration. However, with toys (balls, 30.4%, chains 34.1%) standing remained similar to 1-h fast levels (32.5%, 30.6%). Object manipulation followed a similar pattern. With limited frustration (1-h fast), balls (22.9%), chains (21.3%) and no-toys (22.7%) were similar. When frustration increased (3-h fast) pigs without toys increased manipulations (31.2%) while pigs with toys maintained 1-h levels (balls 20.5%, chains 21.4%). Resting (lateral) showed opposite pattern. When frustration increased (3-h fast), resting by pigs without toys dropped (22.9% to 9.8%) but was retained at close to 1-h levels (balls 14.9%, chains 18.2%) when toys were present (balls 17.0%, chains 12.5%). Novel toys appear to reduce frustration in growing pigs.