Interaction of swine nursery and grow-finish space allocations on performance

Two experiments were conducted to evaluate the possible interaction of nursery space allocations and grow-finish space allocations in swine. In Exp. 1, crowding was achieved by varying the number of pigs per pen. During the nursery phase, decreasing the space allocation (0.16 [m.sup.2]/pig vs 0.25 [m.sup.2]/pig; 8 and 12 pens per treatment, respectively) by increasing the number of pigs per pen (18 vs 12) resulted in a decrease in daily feed intake (0.609 vs 0.683 kg/d; P [is less than] 0.001) and daily gain (0.364 vs 0.408 kg/d; P [is less than] 0.001). Pigs were mixed within nursery treatment groups and reassigned to grow-finish pens (6 pens per treatment) at the end of the 35-d nursery period providing either 0.56 [m.sup.2]/pig (14 pigs/pen) or 0.78 [m.sup.2]/pig (10 pigs/pen). Crowding during the grow-finish phase decreased daily feed in-take (P [is less than] 0.003) and daily gain (P [is less than] 0.001). In Exp. 2, space allocations of 0.16 [m.sup.2]/pig vs 0.23 [m.sup.2]/pig during the nursery phase (24 pens per treatment) resulted in a decrease in daily feed intake (0.612 vs 0.654 kg/d; P [is less than] 0.005) and daily gain (0.403 vs 0.430 kg/d; P [is less than] 0.001). Pigs remained in the same (social) groups when moved to the grow-finish phase. Unlike Exp. 1, there was no effect of crowding during the grow-finish phase (0.60 [m.sup.2]/pig vs 0.74 [m.sup.2/pig) on daily feed intake or daily gain. The difference in results between experiments suggests that the response to crowding during the grow-finish phase may depend in part on whether pigs are mixed and sorted following movement from the nursery. Key Words: Mixing, Pigs, Spacing