Ruiz-Arias, N. C., S. A. Lee, H. H. Stein. 2024. Standardized ileal digestibility of amino acids and metabolizable energy in three sources of high-protein corn distillers dried grains fed to weanling pigs. Animal Feed Science and Technology 313, 115985. doi.org/10.1016/j.anifeedsci.2024.115985 Link to full text.

Apparent ileal digestibility (AID) of amino acids (AA) is affected by dietary AA levels because of different contributions of endogenous AA to the ileal digesta from pigs fed diets with different levels of AA. Because of the influence of dietary protein and AA on calculated values for AID, values for AID obtained in individual feed ingredients are not always additive in mixed diets. Therefore, values for standardized ileal digestibility (SID) of AA, which are corrected for the basal ileal endogenous losses of AA, are used in diet formulations to avoid the influence of endogenous AA on digestibility values, and SID values are, therefore, additive in mixed diets.

When the direct procedure is used to determine AA digestibility, diets containing cereal grains are sometimes formulated to contain AA below the requirement. In contrast, if the SID of oilseed meals or other protein-rich ingredients are determined, concentrations of AA may be at or above the requirement. Because the influence of the basal endogenous losses of AA is eliminated in the calculations of SID values, it is assumed that values for SID are not influenced by dietary concentrations of AA. However, to our knowledge this hypothesis has not been experimentally verified, but it is an important question because it may influence how diets used in digestibility experiments are formulated. Therefore, four experiments were conducted to test the hypothesis that the SID of AA by growing pigs is not influenced by dietary AA levels.

Ruiz-Arias, N. C., S. A. Lee, and H. H. Stein. 2024. Is there a nutritional difference in full-fat soybeans fed to growing pigs? National Hog Farmer. On-line.

Particle size reduction in cereal grains often results in an improved digestibility of starch due to increased surface area of grains, which subsequently increases the interaction with digestive enzymes. Improvement in the apparent total tract digestibility (ATTD) of gross energy (GE) upon particle size reduction has also been demonstrated in corn and a number of other ingredients when fed to weanling or growing-finishing pigs.

Lee, S. A, and H. H. Stein. 2023. Advantages of Higher Soybean Meal Diets for Pigs. Proc. 22^nd Annual Midwest Swine Nutrition Conf. Danville, IN, Sep. 7, 2023. Pages 41-46. Link to full text.

Nelson, Megan E., Su A Lee, Hans H. Stein. 2023. Effects of Different Protein Sources Containing Highly Digestible Phosphorus on the Basal Endogenous Loss of Phosphorus. J. Anim. Sci., Volume 101, Issue Supplement_2, November 2023, Pages 80–81. doi.org/10.1093/jas/skad341.089. Link to abstract.

Cristobal, Minoy A., Su A. Lee, Hans H. Stein. 2023. Effect of Low Protein Diets Fed to Weanling Pigs on Growth Performance, Fecal Score, and Carcass Characteristics. J. Anim. Sci., Volume 101, Issue Supplement 2, Page 290, doi.org/10.1093/jas/skad341.330. Link to abstract.

Lee, Su A., Diego A. Rodriguez, Hans H. Stein. 2023. Interactive Effects of Pelleting and Particle Size Reduction of Corn on Ileal Digestibility of Starch and Amino Acids in Corn-Soybean Meal Diets Fed to Pigs. J. Anim. Sci. Volume 101, Issue Supplement, Pages 186–187, doi.org/10.1093/jas/skad341.205. Link to abstract.

Rodriguez, Diego A., Su A Lee, Hans H. Stein. 2023. Concentration of Net Energy in Corn without or with Microbial Phytase Fed to Group-Housed Pigs. J. Anim. Sci. Volume 101, Issue Supplement 2, Pages 151–152, doi.org/10.1093/jas/skad341.169. Link to abstract.