Effect of Number of Dietary Phases Fed during the Wean-to-Finish Period on Growth Performance and Carcass Characteristics of Pigs Under Commercial Conditions.

This study evaluated the effect of number of dietary phases fed during the wean-to-finish period on growth performance and carcass characteristics of pigs using a RCBD (blocking factor being day of start on test) with 3 treatments. Treatment 1 was a standard phase-feeding program with 9 dietary phases, and Treatments 2 and 3 were achieved by combining dietary phases resulting in 7 or 6 dietary phases, respectively. Each dietary phase was formulated to meet the standardized ileal digestible lysine to energy ratio for the weight range over which the phase was fed and to meet or exceed NRC (2012) requirements for other nutrients. The study was carried out in a commercial facility using a total of 3,744 animals. Pigs were housed in single-sex (barrows or gilts) groups of 78 from weaning (5.9 ± 0.29 kg BW) to 11 wk post-weaning (42.9 ± 2.58 kg BW) at which point the groups were split into 2 groups of 38 until the end of the study (128.2 ± 1.92 kg). The pen of 78 pigs (16 replicates) was the experimental unit and data were analyzed using PROC MIXED of SAS; the model accounted for the effects of treatment, block, and replicate. Reducing the number of dietary phases had no effect (P > 0.05) on ADG (730, 726, and 726 g, for 9, 7, and 6 dietary phases, respectively; SEM 7.0), ADFI (1,682, 1,674, and, 1,665 g, respectively; SEM 19.1), G:F (0.436, 0.435, and 0.437 kg:kg, respectively; SEM 0.0010), or morbidity and mortality (9.1, 10.4, and 10.8 %, respectively). There was no effect (P > 0.05) of the number of dietary phases on carcass yield, backfat depth, or predicted carcass lean content. The results of this study suggest that the number of dietary phases can be reduced from 9 to 6 without affecting wean-to-finish growth performance or carcass characteristics.