Lee Su A., Carrie L. Walk, Hans H. Stein. 2019. PSIV-13 Basal endogenous loss, standardized total tract digestibility, and retention of Ca in sows change throughout gestation, but microbial phytase reduces basal endogenous loss of Ca by gestating sows. Journal of Animal Science, Volume 97, Issue Supplement_2, July 2019, Pages 185–186. (Abstr.). Link to abstract.

Blavi, Laia, Cristhiam J. Muñoz, Jonathan N. Broomhead, and Hans H. Stein. 2019. Effects of a novel corn-expressed E. coli phytase on digestibility of calcium and phosphorous, growth performance, and bone ash in young growing pigs. J. Anim. Sci. 2019.97:3390–3398. Link to full text.

Soybean meal (SBM) is one of the most important protein sources in swine diets. However, most P in SBM is bound to phytate, which increases inclusion of inorganic P in diets for pigs. Use of microbial phytase may hydrolyze phytate and subsequently improve P absorption. Fermex 200 (Purina Animal Nutrition, Shoreview, MN, USA) is a new source of fermented SBM that may serve as an alternative to other protein sources in diets fed to pigs. However, there are at this point no data for effects of adding phytase to diets containing Fermex 200 and no data for digestible energy (DE) and metabolizable energy (ME) concentrations of Fermex 200.

Therefore, 2 experiments were conducted to test the hypothesis that inclusion of 1,000 phytase units (FTU)/kg of microbial phytase improves the standardized total tract digestibility (STTD) of P in conventional SBM and Fermex 200. The second hypothesis was that the STTD of P, as well as concentrations of DE and ME in Fermex 200 are greater than in conventional SBM.

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.

Arredondo Mónica A., Gloria A. Casas, Hans H. Stein. 2019. Increasing levels of microbial phytase increases the digestibility of energy and minerals in diets fed to pigs. Anim. Feed Sci. Technol. 248: 27 - 36. Link to full text.

Lee, S. A., G. A. Casas, and H. H. Stein. 2018. The level of feed intake does not influence digestibility of calcium and phosphorus in diets fed to gestating sows, but gestating sows have reduced digestibility of calcium and phosphorus compared with growing gilts. Can. J. Anim. Sci. 98:591-594. Link to abstract

Munoz Alfonso, C. J., L. Blavi, J. N. Broomhead, and H. H. Stein. 2018. Comparison between a novel phytase and a commercial phytase on growth performance and bone measurements in diets fed to growing pigs. J. Anim. Sci. 96(Suppl. 2):147-148 (Abstr.) Link to abstract (.pdf)

Most of the phosphorus in corn and other plant-based feed ingredients fed to pigs is bound to phytate. Pigs do not secrete phytase in adequate quantities to liberate significant amounts of phytate-bound phosphorus, meaning that most of the phosphorus in these ingredients is not biologically available. Calcium digestibility is also negatively affected by the presence of phytate in feed ingredients. One way for producers to ensure that pigs' requirements are met is to add supplementary phosphorus to diets. However, this adds to the cost of diets. The excretion of phytate-bound phosphorus also may contribute to algae overgrowth in waterways.

Another approach is to add supplemental phytase to the diets, to allow pigs to better utilize the phosphorus present in the ingredients. Phytases can be obtained from plants, animals, or microorganisms (bacteria, yeasts, and fungi).

GraINzyme is a source of phytase produced by genetically modified corn plants with genes derived from E. coli. In this experiment, the effect on growth performance, apparent total tract digestibility (ATTD) of calcium and phosphorus, and bone mineralization of adding GraINzyme to weanling pig diets was tested.

Long, C. J., L. B. Kondratovich, M. F. Westphalen, H. H. Stein, and T. L. Felix. 2017. Effects of exogenous phytase supplementation on phosphorus metabolism and digestibility of beef cattle. Transl. Anim. Sci. 1:168-178. Link to full text (.pdf)