Diurnal rhythm of bar-biting in relation to other behaviour in pregnant sows

Abstract

Instantaneous observations of behaviour were made with video once every sixth minute around the clock (in 20-s recordings at each interval) during the first 3 days following the introduction of pregnant sows into one of the following three environments: (1) loose housing in groups of five with a common lying area, a dunging area and individual feeding stalls (20 sows); (2) semiconfinement in groups of four in individual feeding stalls with access to a common dunging area (16 sows); (3) confinement in individual stalls (16 sows). In addition, direct observations of straw-directed behaviour after feeding were made. Bar-biting was most frequent in confinement and least in loose housing (22.5% of observations when the sows were active in confinement, 7.5% in semi-confinement and 3% in loose housing). Bar-biting was mainly performed during ∼2 h following feeding. At the time when confined and semi-confined sows performed most bar-biting, the loose-housed sows moved a lot and performed complex straw-directed activities, including several of the normal nest-building behaviours. It was concluded that the differences in frequencies of stereotypies cannot be explained only by frustration at feeding, but depend on the housing system of the sows. Many of the movements in the stereotyped sequences of the confined sows resembled elements in the nesting sequences of loose-housed sows, supporting the hypothesis that a thwarted movement pattern can develop into a stereotypy, which then may bear resemblance to the normal movements.