Lagos, L. Vanessa, Mike R. Bedford, and Hans H. Stein. 2021. Increased microbial phytase increased phytate destruction, plasma inositol, and feed efficiency of weanling pigs, but reduced dietary calcium and phosphorus did not affect gastric pH or fecal score and reduced growth performance and bone ash. J. Anim. Sci. 99: 12, 1-13. doi.org/10.1093/jas/skab333.

Lee, S. A., M. R. Bedford, H. H. Stein. 2021. Comparative digestibility and retention of calcium and phosphorus in normal- and high-phytate diets fed to gestating sows and growing pigs. Animal Feed Science and Technology 280 (2021) 115084. doi.org/10.1016/j.anifeedsci.2021.115084. Link to full text.

Lee, Su A, L. Vanessa Lagos, Mike R. Bedford, and Hans H. Stein. 2021. Quantities of ash, Ca, and P in metacarpals, metatarsals, and tibia are better correlated with total body bone ash in growing pigs than ash, Ca, and P in other bones. Journal of Animal Science, 2021, Vol. 99, No. 6, 1–6. doi:10.1093/jas/skab149.

Lagos, L. Vanessa, Su A Lee, Mike R. Bedford, and Hans H. Stein. 2021. Formulating diets based on digestible calcium instead of total calcium does not affect growth performance or carcass characteristics, but microbial phytase ameliorates bone resorption caused by low calcium in diets fed to pigs from 11 to 130 kg. Journal of Animal Science, 2021, Vol. 99, No. 3, 1–11. doi:10.1093/jas/skab057.

Lee, Su A, Hans H. Stein. 2020. Young Scholar Presentation: Digestibility of calcium and phosphorus in feed ingredients fed to gestating sows and growing pigs. J. Anim. Sci. 98(Suppl. 3): 111. doi.org/10.1093/jas/skaa054.188. (Abstr.). Link to abstract.

Absorption of Ca and P by active transport in the small intestine is regulated by calcitriol, which is the active form of vitamin D (1,25-dihydroxycholecalciferol) and the hormones calcitonin and PTH. One-alpha-hydroxycholecalciferol (1-α-OH-D₃) is an active vitamin D₃ analog that does not require the second hydroxylation step for vitamin D₃ to be active. It is possible that supplementation of 1-α-OH-D₃ may increase absorption of Ca and P.

The requirement for Ca and P by gestating sows increases in late gestation compared with early- and mid-gestation because of increased needs by the developing fetuses. It is also possible that dietary concentrations of Ca and P affect the rate of absorption of Ca and P in sows but data to demonstrate this have not been reported. Therefore, the objective of this experiment was to test the hypothesis that the Ca and P concentrations in diets fed to gestating sows in late gestation and supplementation of 1-α-OH-D₃ affect apparent total tract digestibility (ATTD) and retention of Ca and P as well as the ATTD of GE and concentration of DE in diets. The second hypothesis was that there is an interaction between dietary Ca and P concentrations and supplementation of 1-α-OH-D₃ in diets fed to gestating sows.

Lee, Su A, and H. H. Stein. 2019. Balance calcium effect on phosphorus in late-gestation sows’ diets. National Hog Farmer. August 29, 2019. Link to full text

McGhee, Molly L., Hans H. Stein. 2019. Effects of microbial phytase on standardized total tract digestibility of phosphorus in hybrid rye, barley, wheat, corn, and sorghum fed to growing pigs. Transl. Anim. Sci. 2019.  Volume 3, Issue 4, Pages 1238–1245. Link to full text.

Lee, Su A, L. Vanessa Lagos, Carrie L. Walk, and Hans H. Stein. 2019. Basal endogenous loss, standardized total tract digestibility of calcium in calcium carbonate, and retention of calcium in gestating sows change during gestation, but microbial phytase reduces basal endogenous loss of calcium. J. Anim. Sci. 2019.97:1712–1721. Link to full text.