Effects of space allowance on productivity, welfare, and blood constituents of group-housed gestating sows

This study aims to evaluate the effects of space allowance during gestation on productivity, welfare, and blood constituents of group-housed primiparous sows. A total of 48 primiparous sows (Landrace × Yorkshire; 220.68 ± 17.29 kg initial body weight, mean ± SD) were randomly assigned to four space allowance treatments (1.9, 2.1, 2.3, and 2.5 m²; 12 sows per treatment) in a half-stall group housing system from day 42 to day 106 of gestation. The following parameters were measured in sows: reproductive performance, welfare indicators, and blood constituents. Space allowance did not affect sow body weight, backfat thickness, or reproductive performance, including litter size, litter and piglet weights, average daily gain, or survivability. However, the colostrum total solids and protein concentrations were higher (p < 0.05) in sows housed at a space allowance of 1.9 m² than those housed at 2.5 m². For the welfare indicators, skin injury scores were higher (p < 0.05) in sows allocated 1.9 and 2.1 m² than those allocated 2.5 m² during the first week after mixing, but lameness scores of sows were not different among space allowance treatments. Sow metabolic and stress-related blood indicators, including blood urea nitrogen, creatinine, triglycerides, free fatty acids, glucose, and cortisol concentrations, were not affected by space allowance treatments. In conclusion, space allowances ranging from 1.9 to 2.5 m² per sow did not affect sow productivity or metabolic status, indicating that productivity and metabolic status were maintained at 1.9 m² under commercial half-stall group housing conditions. However, larger space allowance was associated with progressively fewer skin injuries, suggesting that farms with greater facility capacity may improve sow welfare benefits by adopting space allowances toward the upper end of this range (2.3–2.5 m²).