Phosphorus is one of the most expensive nutrients in swine diets. Use of standardized total tract digestibility (STTD) of P, instead of apparent total tract digestibility (ATTD), may reduce the cost of diets because STTD values, unlike ATTD values, are additive in mixed diets. Values for STTD of P can be determined by correcting ATTD of P for the basal endogenous loss of P. The basal endogenous loss of P is estimated by using a P-free diet. Gelatin has been widely used in P-free diets because it does not contain any P and is a good source of protein. However, gelatin products can make diets dusty and sticky which can reduce the palatability of these diets and make them hard to work with. In addition, feeding pigs with diets containing no P may cause health issues in pigs. Blood plasma, casein, and potato protein concentrate are possible protein alternatives to gelatin because the P in blood plasma and casein is close to 100% digestible and potato protein concentrate provides very little P. Therefore, the objective of this experiment was to test the hypothesis that the basal endogenous loss of P from pigs fed a diet containing blood plasma, casein, or potato protein concentrate are not different from that of pigs fed a diet containing gelatin.

Lancheros, J. P., C. D. Espinosa, S. A. Lee, M. S. Oliveira, and H. H. Stein. 2022. Fiber in Swine Nutrition. L. I. Chiba, editor, Sustainable Swine Nutrition. 2nd rev. ed. doi:10.1002/9781119583998.ch14. Link to full text.

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.