Soybean meal (SBM) is one of the protein ingredients fed to commercial pigs. With recent increases in cost of this ingredient, evaluation of quality is critical. This study evaluated a total of 122 SBM samples collected from commercial feed mills, from 9 different states, 6 different SBM suppliers, 4 different regions and included two separate harvest years (2019 and 2020). Samples were sent to two separate labs (University of Missouri agricultural experiment station chemical laboratories, and Eurofins) and analyzed for amino acids, digestibility factors, anti-nutritive factors and trypsin inhibitors. The model was a factorial in an 9 x 6 x 4 x 2 arrangement, consisting of 9 states, 6 suppliers, 4 regions, and 2 harvest years where all samples were tested. Data was analyzed by ANOVA JMP PRO 15 (SAS Institute Inc, 2019) and means were separated by Tukey HSD with significance level set at P< 0.05. Results showed state was significant (P < 0.05) for trypsin inhibitor, protein dispersibility index (PDI), and protein solubility. While SBM supplier and region was significant for trypsin inhibitor and PDI only. For those parameters that were significant, northeastern region were of the highest (P < 0.05) for trypsin inhibitor, PDI and protein solubility. Typical benchmark of urease activity to evaluate SBM quality was not significant for supplier, region or state. However, the coefficient of variation (CV) of urease activity ranged from 31% to 70%, indicating this parameter is too variable to utilize as an indicator of SBM quality. Total oligosaccharides (stachyose+raffinose+verbascose) was analyzed and indicated a significant (P < 0.05) difference for state, with samples from Mississippi being the lowest, while samples from the Midwest region had the highest (P < 0.05).
This study indicates the significant differences between supplier, the state in which supplier resides and the region the soy comes from can play a role in the overall quality.