González-Vega, J. C., C. L. Walk, M. R. Murphy, and H. H. Stein. 2016. Requirement for digestible calcium by 25 to 50 kg pigs at different dietary concentrations of phosphorus as indicated by growth performance, bone ash concentration, and calcium and phosphorus balances. J. Anim. Sci. 94:5272-5285. Link to full text (.pdf)

González-Vega, J. C. and H. H. Stein. 2016. Digestibility of calcium in feed ingredients and requirements of digestible calcium for growing pigs. Anim. Prod. Sci. 56:1339-1344. Link to full text (.pdf)

González-Vega, J. C., Y. Liu, J. C. McCann, C. L. Walk, J. J. Loor, and H. H. Stein. 2016. Requirement for digestible calcium by eleven- to twenty-five–kilogram pigs as determined by growth performance, bone ash concentration, calcium and phosphorus balances, and expression of genes involved in transport of calcium in intestinal and kidney cells. J. Anim. Sci. 94:3321-3334. Link to full text (.pdf)

González-Vega, J. C., C. L. Walk, and H. H. Stein. 2016. Digestible calcium requirements for 25 to 50 kg pigs. J. Anim. Sci. 94(Suppl. 2):101 (Abstr.) Link to abstract (.pdf)

An excess of calcium in swine diets may increase excretion of phosphorus due to formation of Ca-P complexes. Therefore, when formulating diets for pigs, it is important to consider the ratio of calcium to phosphorus. The proper ratio should ensure that both minerals are maximally utilized in the bodies of the pigs.

González-Vega, J. C., C. L. Walk, and H. H. Stein. 2015. Digestible calcium requirements for 25 to 50 kg pigs. Memorias XVII Congreso Bienal AMENA. Puerto Vallarta, Jal. Mexico. Link to full text (.pdf)

It is important to include calcium and phosphorus in the diets in the proper proportions because the excess or deficiency of one mineral may affect the utilization of the other. Calcium requirements in the 2012 NRC are based on a model, which used a 2.15 ratio of total calcium to standardized total tract digestible (STTD) phosphorus. An optimal ratio of STTD calcium to STTD phosphorus has not been reported because not enough data exist on the standardized total tract digestibility of calcium. However, recent studies conducted by the Stein Monogastric Nutrition Lab have determined values for STTD calcium for several calcium sources. With these data, it is possible to determine the requirement for STTD calcium. Therefore, an experiment was conducted to determine the requirement of STTD calcium to maximize growth performance and bone ash in 11 to 25 kg pigs.