Amino acid digestibility in soybean meal sourced from different regions of the United States and fed to pigs

An experiment was conducted to determine the apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) by growing pigs of AA in soybean meal (SBM) produced in different regions of the United States. Twenty-two growing barrows (25.5 ± 1.73 kg) were fitted with a T-cannula near the distal ileum and allotted to a 22 × 8 Youden square design. Twenty-two sources of SBM were procured from soybean crushing plants located throughout the United States. For analysis, the crushing plant locations were separated into the following 3 zones: 1) Michigan, Minnesota, and South Dakota (n = 4); 2) Georgia, Illinois, Indiana, and Ohio (n = 11); and 3) Iowa, Missouri, and Nebraska (n = 7). Dietary treatments included 22 diets based on a mixture of cornstarch, sucrose, and each source of SBM as the sole source of CP. Results indicated that the concentration of most indispensable and dispensable AA in SBM were not different among zones. However, SBM from zone 2 had a greater (P < 0.05) concentration of Thr than SBM from zone 3 and a greater (P < 0.05) concentration of Gly than SBM from zone 1. The concentration of Tyr in SBM from zone 2 was also greater (P < 0.05) than in SBM from zones 1 and 3. However, if concentrations of AA were calculated as a percent of CP, there were no differences in the concentrations of indispensable and dispensable AA among SBM from the 3 zones. Likewise, the AID of CP and the AID of indispensable and dispensable AA were not different among SBM from the 3 zones. The SID of CP and most AA was also not different among SBM from the 3 zones. However, SBM from zone 3 had a greater (P < 0.05) SID of His, Asp, and Cys than SBM from zone 2, and SBM from zone 1 had a greater (P < 0.05) SID of Lys than SBM from zone 2. There was also a tendency (P < 0.10) for SBM from zone 3 to have a greater SID of Ile, Leu, Phe, Val, Ala, and Tyr than SBM from zone 2. If the concentrations of SID CP and AA were calculated as grams per kilogram, SBM among the 3 zones were not different with the exception that there was a tendency (P = 0.07) for SBM from zone 2 to contain more SID Thr and SID Tyr than SBM from zone 3. In conclusion, only a few differences in concentrations and digestibility of CP and AA exist among sources of SBM from different zones in the United States. These observations indicate that the protein value is not different among SBM produced in the United States regardless of the location of the crushing plants.