FACTORS AFFECTING POSTURE-CHANGING IN LOOSE-HOUSED AND CONFINED GESTATING SOWS

The time taken to lie down and stand up was determined for dry sows fr om different housing systems and related to physical and genetic param eters. In experiment 1, the times taken to lie down by 32 sows in two dry-sow housing conditions were measured. Sows housed long-term in sta lls took longer to lie down than group-housed sows (20.42 v. 9.28 s, P <0.001). Group-housed sows took longer to lie down in the open than t o lie down against a wall (11.07 v. 7.48 s, P=0.004). The length of ti me taken for stall-housed sows to lie down had strongest association w ith body length (P=0.033, R(2)=0.718). The length of time taken for gr oup-housed sows to lie down in the open had strongest association with the proportional weight of the extensor carpi radialis, (P=0.001, R(2 )=0.915). In experiment 2, the times taken for 30 sows in stalls to li e down and stand up were measured and genotype differences investigate d. There were no differences between genotypes in fetal times taken to stand up or lie down, but total times taken to stand tip quickly and lie down had strongest association with body length (P=0.032, R(2)=0.1 85, and P <0.001, R(2)=0.574 respectively). The results indicate that sows housed long-term in gestation stalls experience difficulty of mov ement when standing up quickly and lying down. Although the chronic ef fects of lack of exercise and the acute effects of floor type may cont ribute to this difficulty, the major factor is likely to be space rest riction as the times taken to lie down and stand up quickly both incre ase as body length, and hence dynamic space requirement, increases. Ly ing down in an unrestricted environment is under muscular control and the degree of control depends on the proportion of muscle weight to to tal body weight. The factors affecting lying down and standing up shou ld be considered when designing dry-sow and farrowing accommodation.