Prepartum nesting opportunities may improve maternal characteristics and welfare of sows during parturition and lactation. We investigated the effects of provision of space and nesting material prior to parturition on circulating oxytocin concentrations, maternal characteristics and their interrelation in early lactating sows. A total of 33 sows were kept in: 1) CRATE: the farrowing crate closed (210 × 80 cm) with provision of a bucketful of sawdust, 2) PEN: the farrowing crate opened with provision of a bucketful of sawdust, 3) NEST: the farrowing crate opened with provision of abundant nest-building materials. Sow blood samples were collected for hormonal assays via indwelling ear vein catheters on days -3, -2, -1, +1, +2, +4, and +7 from parturition, twice a day. Pigs were video-recorded for 24 h on days 3 and 6 of lactation to assess nursing and maternal behaviour. During the periods from days -3 to -1 and from days -3 to +7, NEST brought about an increase in sow oxytocin concentrations compared with CRATE and PEN (P < 0.05), and prolactin concentrations in NEST sows were also greater than for CRATE sows during those periods (P < 0.05). From days 1 to 7 of lactation, prolactin concentrations were positively correlated with oxytocin concentrations (r = 0.39, P < 0.0001). The average duration of all nursings (P < 0.05) and of successful nursings only (P < 0.01) were longer for CRATE than for PEN and NEST sows. The incidence of carefulness behaviour towards offspring for NEST sows was greater than for sows from the other treatments for the mean of days 3 and 6 of lactation (P < 0.001), and was correlated with oxytocin concentrations during the 7 days after parturition (rs = 0.26, P < 0.01). In conclusion, provision of abundant nesting materials to sows prior to parturition could increase plasma oxytocin concentrations. This would result in improved nursing performance and maternal behaviour during early lactation.
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