Soybeans grown in the northern United States are exposed to fewer growing days and hours of sunlight than soybeans grown elsewhere in the U.S. As a result, soybeans grown in the northern U.S. fix less nitrogen, and have a lower concentration of crude protein, than other U.S. soybeans. However, the concentrations of particular amino acids, particularly indispensable amino acids, are more important for the purposes of diet formulation than the concentration of crude protein. The concentration of amino acids in soybeans grown in different parts of the U.S. has not been determined.
The amount of amino acids in soybean meal that are available to the pig also depends on digestibility, but no research has been conducted to compare the digestibility of amino acids among soybean meal produced in different regions of the U.S. Therefore, an experiment was conducted to compare the standardized ileal digestibility (SID) of amino acids and the concentration of SID amino acids in soybean meal produced in different regions within the United States and fed to growing pigs.
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