The behaviour of pigs weaned at 12 and 21 days of age from weaning to market

Abstract

Segregated early weaning (SEW) of piglets at less than 21 d of age is becoming an increasingly common procedure in North America. Such early weaning has become commercially feasible through the use of highly palatable nursery diets, which increase intake during the week following weaning. A study was conducted to determine the effects of such early weaning on the behaviour of piglets. Thirty-two litters were weaned at either 12 or 21 d of age. During the subsequent 48 h, pigs were videotaped and the tapes used to determine the development of eating behaviour using scan sampling. Pigs weaned at 21 d of age spent more time eating than those weaned at 12 d of age (P < 0.05). Although both age groups ate little (<3% of time) during the initial 12 h, those weaned at 21 d of age began increasing time spent eating during the subsequent 12 h and reached a normal level of approximately 9% of time spent eating by 36 h post-weaning. No noticeable increase in eating occurred among those weaned at 12 d of age until after 36 h, at which point the level quickly increased to 10% of time. During the subsequent 6 wk, live scan sampling revealed that pigs weaned at 12 d of age spent more time eating (11.6 vs. 10.5%; P < 0.05), drinking (1.65 vs. 1.22%; P < 0.01), nosing other pigs (1.23 vs. 0.74%; P < 0.01), and chewing on objects (2.48 vs. 2.33%; P < 0.01) than did those weaned at 21 d of age. Nosing of other pigs peaked during the 2nd and 3rd weeks after weaning in both weaning age groups, but the maximum level was approximately twice as high for piglets weaned at 12 as for those weaned at 21 d of age. Piglets weaned at 12 d of age continued to nose and chew other piglets more during the growing/finishing period than did those weaned at 21 d of age (P < 0.05). Partial, within-pen, correlations indicated that less-active pigs grew faster (r = 0.18) and were less likely to nose or chew other pigs (r = –0.15 and −0.26, respectively). Nosing other pigs and being nosed were negatively correlated (r = −0.17), but neither was correlated with rate of gain (P < 0.05). The delay in eating and the higher incidence of anomalous behaviours by the earlier weaned pigs suggest that additional improvements in early weaning management are desirable. Key words: Pigs, behaviour, weaning, age