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

Abstract

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; F1,127 = 4.425, P < 0.05). These findings imply sow separation during lactation provides welfare benefits for piglets around the highly stressful weaning period.