Effect of starting time of co-mingling non-littermates during lactation on performance and skin lesions of sows and piglets

Abstract

The natural weaning process of piglets is a gradual event, whereas in current commercial pig production weaning is a sudden, stressful phase in the pigs’ life. Management strategies such as co-mingling of non-littermates before weaning aim to mimic (semi)natural conditions and to stimulate social skills in piglets in order to minimize the adverse effects of stress around weaning. The present study investigated in which way timing of co-mingling non-littermate piglets during lactation in conventional farrowing units had implications for the sow and affected the performance and behaviour of piglets before and after weaning. In the experimental treatments, 3 litters were co-mingled either at day 16 before weaning (n = 27 sows and their litters), day 11 before weaning (n = 27) or day 6 before weaning (n = 27). In the control treatment, piglets were not grouped before weaning (n = 27). In total, 1294 piglets were weaned at 21 days of age. At weaning, piglets from 3 litters within each treatment were mixed. Piglets from the co-mingling system were housed with those they were co-mingled with during lactation, whereas control piglets were mixed with unfamiliar piglets. Co-mingling of non-littermate piglets did not affect sow body condition and lesion scores of udder and teats during lactation. Piglets co-mingled 6 days before weaning tended to gain less weight during d-6 – d-1 before weaning (P = 0.082), but piglet growth was not affected during d-16 – d-1. After weaning, the feed to gain ratio in piglets which were co-mingled 6 days before weaning tended to be lowest during the first week after weaning (P = 0.086), but no other treatment effects were observed in the post-weaning phase. Skin lesion score of the shoulders and flanks tended to be higher at day 11 before weaning in piglets co-mingled 16 days before weaning (P = 0.051) and was highest at day 6 before weaning in piglets co-mingled 11 days before weaning (P < 0.001). However, 1 day before weaning no differences in skin lesions were observed. After weaning, the socialized piglets had less skin lesions at the shoulders and flanks compared to control piglets (P < 0.001). In conclusion, pre-weaning co-mingling of non-littermates resulted in less aggression (i.e. lesions) at weaning, suggesting better social skills and a reduction of stress, consistent with a tendency for improved feed to gain ratio in the first week after weaning. Time of co-mingling seemed not crucial.