An experiment was conducted to determine the effects of soybean meal (SBM) inclusion rate on growth performance of growing pigs. A total of 1,722 pigs (initial BW = 41.1 kg), placed in pens with 20 or 21 pigs each, were used in a 49-d trial. There were 2 treatments consisting of different SBM inclusion rates. Experimental diets were fed in 3 phases. Treatment 1 (low SBM) contained 18, 14, and 12% SBM and Treatment 2 (high SBM) contained 26, 22, and 19% SBM in phases 1, 2, and 3, respectively. The different SBM levels were obtained by adjusting the inclusion rate of synthetic amino acids. Both treatments were formulated to the same SID Lys (1.00, 0.92, and 0.85% in phases 1, 2, and 3, respectively) and net energy levels (2,565, 2,575, and 2,581 kcal/kg in phases 1, 2, and 3, respectively). The net energy of SBM used in diet formulation was equivalent to 90% of corn net energy. There were 42 replicates per treatment. Pigs were weighed approximately every 2 weeks to calculate ADG, ADFI, G:F, and caloric efficiency. Data was analyzed with SAS MIXED procedure. Overall (d 0 to 49), there was no evidence for differences (P > 0.10) on ADG, ADFI, or final BW. Pigs fed the high SBM diets had improved (P < 0.01) G:F and caloric efficiency. The removal and mortality rate was 1.05% (9 pigs) on the low SBM treatment and 0.46% (4 pigs) on the high SBM treatment.
In conclusion, increasing levels of SBM resulted in improved G:F and caloric efficiency of growing pigs.