Lagos, L. V., C. L. Walk, and H. H. Stein. 2018. Requirement for digestible calcium at different dietary concentrations of digestible phosphorus indicated by growth performance and bone ash of 50 to 85 kg pigs. J. Anim. Sci. 96(Suppl. 2):130-131 (Abstr.) Link to abstract (.pdf)

Abelilla, J. J. and H. H. Stein. 2018. Degradation of dietary fiber in the stomach, small intestine, and large intestine of growing pigs fed corn- or wheat-based diets without or with microbial xylanase. J. Anim. Sci. 96(Suppl. 2):81 (Abstr.) Link to abstract (.pdf)

Last month's newsletter included a research report on research into a novel E. coli phytase expressed in corn, called GraINzyme. Results of that research indicated that adding GraINzyme phytase to diets fed to young growing pigs increased growth performance, digestibility of calcium and phosphorus, and bone mineralization. The comparative effects of GraINzyme and a commercial phytase was not tested in the previous study. Therefore, an experiment was conducted to compare effects of addition of GraINzyme phytase to the commercial phytase AxtraPhy in diets fed to growing pigs.

Navarro, D. M. D. L., E. M. A. M. Bruininx, L. de Jong, and H. H. Stein. 2018. Analysis for low-molecular-weight carbohydrates is needed to account for all energy-contributing nutrients in some feed ingredients, but physical characteristics do not predict in vitro digestibility of dry matter. J. Anim. Sci. 96:532-544. Link to full text

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.

Fiber in feed ingredients used in diets for pigs is mainly used for energy, which is synthesized by microbes in the hindgut of the pig and absorbed in the form of short chained fatty acids. To estimate the energy that a pig can obtain in a particular fibrous ingredient, a digestibility experiment is usually conducted and the digestible energy (DE) and the metabolizable energy (ME) in the ingredient is determined. However, it is not known if the obtained DE and ME values are accurate for all inclusion rates of the feed ingredient in diets.

There are two reasons that differing inclusion rates of high fiber ingredients in diets fed to pigs might result in variable DE and ME values. Because energy from dietary fiber is obtained via hindgut fermentation, there may be a saturation point in the fermentation capacity in the hindgut of growing pigs. In addition, increasing dietary fiber increases the passage rate of feed through the digestive tract and thus reduces time for fermentation. However, it is not known if these potential issues affect the DE and ME in fibrous ingredients fed to pigs. An experiment was conducted to determine effects of inclusion rate of four commonly used high fiber dietary ingredients on the concentration of DE and ME by growing pigs.

Abelilla, J. J., Liu, Y., and H. H. Stein. 2018. Digestible indispensable amino acid score (DIAAS) and protein digestibility corrected amino acid score (PDCAAS) in oat protein concentrate measured in 20- to 30-kilogram pigs. J. Sci. Food Agric. 98:410–414. Link to abstract

Espinosa, C. D., R. S. Fry, J. L. Usry, and H. H. Stein. 2017. Copper hydroxychloride improves growth performance and reduces diarrhea frequency of weanling pigs fed a corn–soybean meal diet but does not change apparent total tract digestibility of energy and acid hydrolyzed ether extract. J. Anim. Sci. 95:5447-5454. Link to abstract

Calmin is a calcium supplement produced from sea minerals. It also contains 6% magnesium, which may increase calcium absorption. Calmin has been used as a rumen buffer in dairy cows, but limited data are available for pigs. Therefore, two experiments were conducted to test the effect of feeding diets containing Calmin on calcium, phosphorus, and nitrogen balance, energy balance, and growth performance of weanling pigs.