Gradually reducing sow contact in lactation is beneficial for piglet welfare around weaning

This study tested whether a gradual reduction in sow contact during lactation, achieved through housing the sow in a 'sow only' area, would influence piglet stress responses to weaning. Gradual reduction in sow contact was achieved by separating the sow from her piglets (SP, n = 30) for 5, 7, and 9 h per day on days 10-15, 16-20 and 20 to weaning, respectively. Litters from 20 sows were followed as controls (CON), remaining in full contact with one another until weaning. Weaning occurred on day 28 +/- 1.3 of lactation. Piglet body weight, injury scores and evidence of creep ingestion were measured throughout lactation and after weaning. Continuous video footage was collected for 6 h on the days following weaning for behavioural analyses. After weaning, SP piglets were lighter than CON piglets (6.8 +/- 0.22 versus 7.6 +/- 0.16 kg); however, by day 7 post-weaning piglet weights were similar (P > 0.05) for the CON (8.6 +/- 0.22 kg) and SP (8.4 +/- 0.15 kg) treatments, possibly reflecting a reduced growth check in SP piglets. There was a significant effect of treatment (CON versus SP) on the duration of aggressive (6.5 +/- 1.1 versus 4.2 +/- 0.8 s) and belly nosing (6.3 +/- 2.0 versus 2.4 +/- 1.3 s) events post-weaning. Injury scores were higher for CON piglets on almost all days examined (P < 0.05). Plasma circulating cortisol concentrations following weaning were increased in CON piglets (18.7 +/- 13.3 nmol/L), and decreased in SP piglets (-12.3 +/- 14.1 nmol/L; F-1,F-127 = 4.425, P < 0.05). These findings imply sow separation during lactation provides welfare benefits for piglets around the highly stressful weaning period.