Effects of space allocation on finishing pig growth performance and carcass characteristics

A total of 405 pigs (PIC 327 × 1,050) were used in 2 experiments (Exp. 1, initially 66.1 ± 1.8 kg BW, Exp. 2 initially 60.8 ± 2.5 kg BW) to examine the effects of space allocation on finishing pig growth performance and carcass characteristics. Pigs were randomly allotted to pens on entry into the finishing facility. Pens of pigs were balanced by initial BW and randomly allotted to 1 of 3 treatments with either 7 or 8 replications per treatment (Exp.1 and 2, respectively). There were 9 pigs per pen and gates were adjusted to provide 0.84, 0.74, or 0.65 m² per pig. Each pen was equipped with a dry single-sided feeder with two 35.6 cm × 11.4 cm (length × width) feeder spaces and a cup waterer. In both experiments, as space allocation decreased, overall ADG and ADFI decreased (linear, P < 0.019) with no evidence for differences in G:F. In Exp. 2, there was marginal evidence for a linear improvement (P = 0.061) in G:F as space allocation decreased from d 42 to 56. Final BW was 3.8 and 5.3 kg greater (linear, P ≤ 0.005) in Exp. 1 and 2, respectively, when comparing the 0.65 to the 0.84 m² per pig space allocation treatments. Using a predicted k-value of 0.0336, ADFI and, subsequently, ADG should have begun to decrease when pigs reached 121.2, 101.7, and 83.3 kg at 0.84, 0.74, or 0.65 m² per pig, respectively. In Exp. 1, we found marginal evidence for a reduction in ADFI as space allocation decreased starting at a mean BW of 80.3 kg (d 14; linear, P = 0.072). In Exp. 2, ADFI and consequently ADG decreased linearly (P < 0.029) starting at a mean BW of 74 kg, as space allocation decreased, before pigs reached the k-value that should have influenced performance. It is unknown if growth performance was impacted for the 0.84 m² treatment group as this was the greatest space allocation treatment. Overall, these studies indicate that decreasing space allocation resulted in poorer ADG driven by a reduction in ADFI. The data suggests that the accepted k-value of 0.0336 might underestimate the impact of space restriction on finishing pig ADG and ADFI.