Prepartum behavior in swine: effects of pen size.

Gravid Yorkshire sows assigned to one of three pen sizes on d 109 of gestation, were continuously observed for 72 h before parturition. Pens included a 2.1- x .7-m rectangular farrowing crate (n = 6), a small, square pen 2.1 x 2.1 m (n = 5), and a large, square pen 4.2 x 4.2 m (n = 5). Body positions were recorded at 30-s intervals. Other behaviors were recorded using the one-zero method of sampling at 1-min intervals. Sows became more active as they approached farrowing. They stood, sat, lay with legs under, changed positions, drank, urinated, defecated, rooted the floor and pipes, mouthed the waterer and pipes, and pawed the floor more (P < .05) during the 24 h before the birth of the first pig than during the previous 2 d. Position changes, rooting the floor, and pawing frequency peaked during the 6 h preceding parturition and show promise as predictors of parturition. During the 24 h preceding the birth of the first pig, farrowing crate sows stood, rooted the floor, and pawed less and sat, lay, and changed positions more than sows in either pen (P < .05). No differences (P > .05) among pens were noted for lying with legs under or out, eating, drinking, urinating, defecating, rooting the pipes, mouthing the pipes. or mouthing the waterer. Pipe biting and other behaviors commonly thought to be caused by confinement stress occurred in all three pen sizes and seem to be components of nest-building, expressed inappropriately, in a barren environment.