Research was conducted to compare the apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) of amino acids (AA) in soybean meal (SBM) produced in different regions of the United States. Twenty-two sources of SBM were procured from soybean crushing plants located throughout the United States. The crushing plant locations were separated into the following three geographical 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).

In this experiment, 22 barrows weighing about 26kg were fitted with a T-cannula and allotted to a 22×8 Youden square design experiment. The 22 dietary treatments were composed of a mixture of cornstarch, sucrose, and SBM as the sole source of crude protein.Results indicated similar concentrations of most indispensable and dispensable AA in SBM among zones. The level of a few AA varied between zones when expressed as a percentage; however, if concentrations of AA were calculated as a percent of the crude protein, there were no differences among the three zones. Likewise, the AID and SID for crude protein and the AID of indispensable and dispensable AA were not different among SBM from the three zones. The SID of most AA was also not different among SBM from the three zones. However, some variation was observed in SID values when expressed as a percent by weight between the three zones; if the concentrations of SID for crude protein and AA were calculated as grams per kilogram/SBM among the three zones were not different with the exception that there was a tendency (P = 0.07) for SBM from zone 2 to contain more SID threonine and SID tyrosine than SBM from zone 3. The authors concluded that only a few differences in concentrations and digestibility of crude protein and AA exist among sources of SBM from different zones in the United States. These observations support the general conclusion that the protein value is not different among SBM produced in the United States regardless of the location of the crushing plants.