Effects of stocking density on growth performance, carcass grade and immunity of pigs housed in sawdust fermentative pigsties

This study determined the effect of space allowance on performance, carcass grade and physiological variables of pigs reared in sawdust fermentative pigsties. A total of 699 crossbred (Landrace x Yorkshire x Duroc) pigs were housed in sawdust fermentative pigsties and assigned to one of three treatments at different growth stages, namely early grower pigs (EGP), weighing 15 - 40 kg; late grower pigs (LGP), weighing 40 - 75 kg; and finisher pigs (FP), weighing 75 - 110 kg, with three replicates. The three space allowances for each growth stage were 0.40, 0.55 and 0.70 m(2)/head for EGP; 0.55, 0.70 and 0.85 m(2)/head for LGP; and 0.85, 1.00 and 1.15 m(2)/head for FP. The feed intake in EGP was significantly decreased with increased stocking density. In LGP, the average daily gain (ADG) of pigs reared at high stocking density decreased linearly, whereas the feed conversion ratio increased significantly. The final bodyweight, ADG and feed intake in FP were lower with restricting space allowance. The carcass weight and backfat thickness were significantly higher with increased space allowance. The serum immunoglobulin G levels declined significantly with increased stocking density in all growth stages. The results of this study suggest that the space allowance for maximizing the growth performance and stabilizing immune response of pigs in sawdust fermentative pigsties is 0.55, 0.70, and 1.00 m(2)/pig for the bodyweight ranges of 15 - 40 kg, 40 - 75 kg, and 75 - 110 kg, respectively.