Sows show increased activity during the pre-parturient period and if given the opportunity will express nest-building behaviour (Haskell and Hutson, 1993). It has been suggested that farrowing crates by closely confining sows and preventing this pre-parturient behaviour induce behavioural stress. The aim of this work was to test this hypothesis by measuring the effect of parturition environment on plasma levels of Cortisol a commonly used physiological indicator of behavioural stress in pigs.
Twenty-three Large White x Landrace gilts (Cotswold Pig Development Co Ltd, UK; average weight 187 kg ± 3) were implanted with Jugular catheters approximately 10-14 days before their expected farrowing date (EFD). After surgery the animals were moved to 2 x 2 m strawed pens, before being transferred on day 5 before EFD, either into a standard farrowing crate without bedding (Treatment C; n = 11) or into a strawed farrowing pen (2.1 x 3.1 m; Treatment P; n = 12). The animals were blood sampled on the day before (Pre/In) and the day after introduction (Post/In) to the treatments. Blood sampling was resumed 48 hours before EFD and continued until 5 hours post-commencement of farrowing. Samples were generally taken every 4 hours over 24 hour periods, expect for day Post/In, when more rapid sampling took place over the 2 hours post-introduction (Post/lni), before sampling returned to every 4 hours for the rest of the 24 hour period (Post/ln2). More rapid sampling also occurred from approximately 24 hours pre- to 5 hours post-parturition. The plasma was assayed for Cortisol and the data averaged over the following time periods: Pre/In; Post/lni; Post/ln2 -48 to -24 hours (-48/-24); -23.30 to -12 hours (-24/-12); -11.30 to 0 (parturition) hours (-12/0); 0.30 to 2 hours (0/2); 2.30 to 5 hours (2/5). The data were transformed by log and analysed by analysis of variance.