Digestibility of Amino Acids and Concentration of Metabolizable Energy Are Greater in High-Oil Corn Than in Conventional Corn when Fed to Growing Pigs

Two experiments were conducted to test the hypothesis that the coefficient of standardized ileal digestibility (CSID) of amino acids (AA), concentrations of digestible energy (DE) and metabolizable energy (ME), and the coefficient of standardized total tract digestibility (CSTTD) of phosphorus (P) in high-oil corn is greater than in conventional corn. In experiment 1, 9 pigs (81.5 +/- 5.9 kg) that had a T-cannula installed in the distal ileum were allotted to a triplicated 3 x 3 Latin square design with 3 diets and 3 periods for 9 replicates per diet. A nitrogen-free diet and 2 diets that contained conventional corn or high-oil corn as the only source of crude protein (CP) and AA were formulated. Results indicated that the CSID of CP and most AA was greater (P < 0.05) in high-oil corn than in conventional corn, which consequently resulted in greater concentrations of standardized ileal digestible AA in high-oil than in conventional corn. In experiment 2, 64 pigs (18.75 +/- 2.2 kg) were housed in metabolism crates and allotted to a 2 x 4 factorial arrangement with 2 sources of corn (conventional corn or high-oil corn) and 4 levels of microbial phytase (0, 500, 1000, or 2000 phytase units/kg). Feces and urine were collected using the marker-to-marker approach with 5-day adaptation and 4-day collection periods. The digestibility of gross energy (GE) was not different between diets containing high-oil corn and diets containing conventional corn. However, because of the greater GE in high-oil corn than in conventional corn, concentrations of DE and ME in high-oil corn were greater (P < 0.01) than in conventional corn. Addition of microbial phytase to diets increased (P < 0.01) the CSTTD of P in both corn sources, and the CSTTD of P was greater (P < 0.01) in high-oil corn than in conventional corn. In conclusion, high-oil corn contained more standardized ileal digestible AA, DE, and ME than conventional corn. The CSTTD of P in high oil corn, regardless of phytase supplementation, was also greater than in conventional corn. These results indicate that high-oil corn has greater nutritional value than conventional corn when fed to pigs.