The Impact High Soyhull and Soybean Meal Diet Formulations on Grow-Finish Pig Performance

Abstract The objectives of this study were two-fold in evaluating the effects of soybean meal and soyhulls inclusion level in diets fed to grow-finish pigs on growth performance. Firstly, we compared high soybean meal (minimal crystalline amino acids) vs. crystalline amino acids diet formulations. Secondly, we evaluated the addition of soyhulls and soyhulls plus xylanase to diet formulations. In a complete randomized design, a total of 463 grower pigs (BW of 28.4 ± 5.6 kg) were randomly assigned to one of four dietary treatments (n = 12 pens/treatment; 9 – 11 pigs/pen). Within each phase, dietary treatments were formulated to the same SID Lys:ME, and to meet or exceed nutrient recommendations (NRC, 2012) and were fed over three phases consisting of: 1) corn soybean-meal based diet formulated with crystalline amino acids (CON); 2) corn soybean-meal based diet formulated to meet AA requirements via soybean-meal with limited crystalline amino acids (HSBM); 3) As diet #1 with 15% soyhulls (SH); and 4) As diet #3 + commercial xylanase enzyme (SH+X). Diets were formulated with to a SID Lys:ME of 3.26, 2.46, and 1.95 in phase 1, 2, and 3, respectively. Pig BW and pen feed disappearance were recorded at phase change to calculate ADG, ADFI, and feed efficiency (G:F) over the study duration of 95 days. All data were analyzed using the PROC MIXED of SAS 9.4 with pen as the experimental unit and the model included the fixed effect of treatment with least squares means reported. There were no differences (P > 0.05) amongst treatments in phase 1 for any growth performance measures. There was an increase in ADFI of pigs fed SH and SH+X when compared with CON and HSBM (P < 0.05) in phase 2 (P2; 2.89 and 2.82 vs. 2.75 and 2.73 kg/d, respectively) and phase 3 (P3; 3.42 and 3.40 vs. 3.18 and 3.28 kg/d, respectively). However, no differences in ADG or G:F (P > 0.05) compared with CON were reported in P2 or P3. Overall, there were no differences in ADG (P > 0.05) between treatments. Pigs fed SH and SH+X had an increase ADFI compared with CON and HSBM (2.84 and 2.83 vs. 2.68 and 2.71 kg/d, respectively; P < 0.05) and a decrease in G:F when fed SH; however, no differences between CON, HSBM, and SH+X (0.38 vs. 0.40, 0.40, and 0.39, respectively; P > 0.05). In conclusion, there were no negative growth performance effects of feeding a diet containing minimal crystalline amino acids and meeting the requirement of the pigs via soybean meal. Further, there was an increase in feed intake when pigs were fed a diet containing 15% soyhulls, regardless of if there was an addition of xylanase.