However, these issues have rarely been investigated on commercial pig farms. Therefore, we assessed how piglets play, fighting and biting behaviour before and after weaning were affected by the housing system and weaning age as well as how the three behaviours are related to each other and piglet post-weaning weight gain.
We recorded playing, fighting and biting behaviour in 5 GH farms (6–11 lactating sows and their litters kept in a large straw-bedded pen), and in 5 IH farms (each sow and litter kept in a pen with less straw) in Sweden. We observed 16 piglets (2 males and 2 females per litter) from 4 litters (in GH farms belonging to the same group) in each farm on the day before weaning (W − 1), the weaning day (W) and 5 days after weaning (W 5). Weaning was accomplished (without mixing litters) by removing the sows after on average 39 days of lactation (range 33–50 days). All statistics were based on farm averages.
There was no difference between GH and IH farms in the frequency of playing, fighting or biting behaviour, and weaning age did not affect any of the three behaviours (GLMM, p > 0.10). However, the frequency of playing and fighting differed significantly across the three observation days (GLMM, p < 0.05). Play was higher on day W − 1 and on day W than on W 5 (GLMM, p < 0.05 and p = 0.01), fighting was lower on W − 1 than on W or W 5 (GLMM, p < 0.05 and p < 0.05). On W − 1 and W 5, playing correlated with fighting (r = 0.785, p < 0.01; and r = 0.71, p < 0.05, n = 10 farms) but biting correlated with neither playing nor fighting. In farms with higher weight gain between W and W 5 days, piglets played and fought more on W 5 day (r = 0.809, p < 0.01; and r = 0.672, p < 0.05, n = 10 farms). We conclude that (i) social piglet behaviour around weaning was not different between GH and IH farms; (ii) play and fighting (but not isolated biting) seemed to form one continuum; (iii) playing and fighting in weaned (nonmixed) piglets seemed to indicate good adaptation.
J. Šilerová, M. Špinka, R. Šárová and B. Algers. Playing and fighting by piglets around weaning on farms, employing individual or group housing of lactating sows. Applied Animal Behaviour Science. 2010. Vol. 124 (3-4): 83-89.