Lee, Su A, Diego A. Lopez, and Hans H. Stein. 2023. Mineral composition and phosphorus digestibility in feed phosphates fed to pigs and poultry. Anim. Biosci. 36, 2:167-174. doi.org/10.5713/ab.22.0322. Link to full text.

The majority of P in most plant feed ingredients is bound to phytate. Pigs, however, do not synthesize adequate endogenous phytate to release the P bound to phytate, which results in low digestibility of P in field peas. Values for ATTD and STTD of P in field peas without and with phytase have been reported, but there are no comparative values for the ATTD and STTD of P in field peas adding different levels of phytase. The objective of this experiment is to determine the effect of increasing levels of phytase on the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of P in field peas fed to growing pigs.

Lee, Su A, Diego A. Rodriguez, Hans H. Stein. 2022. Effects of Different Watering Options on Standardized Ileal Digestibility of Amino Acids and net Energy in Diets fed to Growing Pigs. J. Anim. Sci. 100, (Suppl. 3) 118, doi.org/10.1093/jas/skac247.227. Link to full text.

Nelson, Megan E., Su A Lee, Yueming Dersjant-Li, Janet Remus, and Hans H. Stein. 2022. Microbial phytase reduces basal endogenous loss of calcium in pigs fed diets containing phytate phosphorus at commercial levels. Journal of Animal Science, 2022, 100, 1–7. doi.org/10.1093/jas/skac280. Link to full text.

Field peas have been produced mainly for human consumption, but lastly, the industry has been included in diets fed to livestock due to its content of starch and protein. In diets for swine, only peas that are harvested at maturity are used. Almost 80% of P in non-oilseed legumes is bound to phytate, and pigs do not synthesize an adequate amount of endogenous phytate to liberate the P bound to phytate. Therefore, the digestibility of P in field peas is relatively low. Values for apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of P in field peas have been reported, but there are no comparative values for the ATTD and STTD of P among different varieties of field peas at different particle sizes. Therefore, the objective of this experiment was to test the hypothesis that there are no differences in the ATTD and the STTD of P among different sources of field peas fed to young pigs and the second hypothesis was that there is a linear increase in the ATTD and STTD of P as the particle size of field peas increases.

Lee, S. A, and H. H. Stein. 2022. Vitamin D and vitamin D metabolites impact on calcium and phosphorus balance in gestating sows. Proc. 21th Annual Midwest Swine Nutrition Conf. Danville, IN, Sep. 8, 2022. Pages 39-43. Link to full text.

Lee, Su A, D. A. Rodriguez, and H. H. Stein. 2022. Determination of the net energy in soybean meal fed to group-housed pigs. 15th International Symposium on Digestive Physiology of Pigs. Animal - Science Proceedings 13(Issue 2): 178. Link to abstract.

Lee, Su A, L. Blavi, D. M. D. L. Navarro, and H. H. Stein. 2021. Addition of hydrogen chloride to collection bags or containers did not change basal endogenous losses or digestibility of amino acid in corn, soybean meal, or wheat middlings fed to growing pigs. Journal of Animal Science. 99(Suppl. 1):166-167. doi.org/10.1093/jas/skab054.281. Link to abstract.

There are several factors related to dietary Ca that may influence digestibility of amino acids (AA). By chelating to dietary phytate, dietary Ca can form non-digestible Ca-phytate complexes, and this may result in reductions of P and AA digestibility. However, adding Ca to diets may increase activation of proteases as co-factors, which could result in increased AA digestibility. In contrast, pH in the digesta may be increased by adding Ca to diets, which likely will have a negative effect on activation of protein digesting enzymes. However, to our knowledge, no data demonstrating effects of increasing dietary Ca on digestibility of AA in pigs have been reported. Therefore, the objective of this experiment was to test the hypothesis that the concentration of Ca in diets affects apparent ileal digestibility (AID) of AA by pigs.