Calcium supplementation is important for swine diets because most commonly used feed ingredients have low concentrations of calcium. In a typical corn-soybean meal diet for a growing pig, the corn and soybean meal contribute only about 16% of the total calcium, with the rest coming from supplements. Apparent total tract digestibility (ATTD) values for calcium have not been reported for many common ingredients, and no values for the standardized total tract digestibility (STTD) of calcium have been reported. Therefore, an experiment was conducted to determine the ATTD and STTD of calcium in five calcium supplements.

An additional objective was to test the hypothesis that inclusion of microbial phytase in the diets increases the ATTD and STTD of calcium. Results of previous research has indicated that inclusion of microbial phytase in swine diets often increases the digestibility of calcium, but the effect of phytase on the STTD of calcium in individual ingredients has not been reported.

Baker, S. R., B. G. Kim, and H. H. Stein. 2013. Comparison of values for standardized total tract digestibility and relative bioavailability of phosphorus in dicalcium phosphate and distillers dried grains with solubles fed to growing pigs. J. Anim. Sci. 91:203-210. Link to full text (.pdf)

Petersen, G. I., C. Pedersen, M. D. Lindemann and H. H. Stein. 2011. Relative bioavailability of phosphorus in inorganic phosphorus sources fed to growing pigs. J. Anim. Sci. 89:460-466. Link to full text (.pdf)