239 Effects of Increasing Soybean Meal in Corn- or Corn-Ddgs-Based Diets on Growth Performance of Early Finishing Pigs

Abstract With the recent renewable fuels initiative, demand for soybean oil is expected to reach a record high. Consequently, there will be unprecedented amounts of soybean meal (SBM) produced and available. As a result, the opportunity will arise for increased usage of SBM in swine diets at the expense of feed-grade amino acids. Therefore, this study aimed to determine the maximum amount of SBM that can be added to early finishing pigs fed corn- (Exp. 1) or corn-DDGS- (Exp. 2) based diets. Experiment 1 used 625 pigs [initial body weight (BW) = 43.2 ± 0.68 kg], 70 pens with 9 or 10 pigs per pen, and 5 added SBM levels, 19.1, 22.6, 26.3, 29.9, and 33.4%, corresponding to crude protein levels of 13.1, 14.1, 15.2, 16.2, and 17.3%, respectively, with 14 replicate pens per treatment. Experiment 2 used 1,053 pigs (initially 39.1 ± 0.78 kg), 40 pens with 26 or 27 pigs, and 4 added SBM levels, 18.2, 23.5, 28.9, and 34.3%, corresponding to crude protein levels of 18.2, 23.5, 28.9, and 34.3%, respectively, with 10 replicate pens per treatment (Table). The diet with the highest level of SBM in each experiment contained no feed-grade amino acids. Minimum levels of Ile, Met & Cys, Thr, Trp, and Val were 58, 60, 65, 19.8, and 72% of lysine, respectively. The experimental diets were corn-SBM-based, and in Exp. 2, 20% DDGS was added to all diets. In both experiments, diets were isocaloric and formulated considering SBM NE at 100% of Corn NE. In Exp. 1, no differences were observed for BW (P = 0.42) and ADFI (P = 0.46); however, increasing SBM linearly increased ADG (P = 0.04), though the greatest change was from increasing SBM from 19.1 to 22.6%, and tended to quadratically improve feed efficiency (P = 0.09). In Exp. 2, with the inclusion of DDGS, no differences (P > 0.32) were observed for any growth performance criteria. In conclusion, increasing levels of SBM (up to 33.4%) in early finishing pig diets linearly improved growth performance and feed efficiency in corn-soybean meal-based diets. However, when DDGS were included in the diet, pig performance was not affected regardless of the amount of SBM within the range from 18.2 to 34.3%. Replacing feed-grade amino acids by increasing the level of SBM in early finishing diets can improve growth performance, but this effect was not observed when DDGS were added to the diets.