Limestone

Standardized total tract digestibility of calcium in 14 sources of calcium carbonate produced in Latin America fed to growing pigs

Most cereal grains and grain co-products contain very low concentrations of Ca, and the majority of Ca in commercial diets for pigs is, therefore, provided by Ca carbonate. Excess dietary Ca can reduce digestibility of P, and it is, therefore, important that digestibility of Ca in Ca carbonate is determined to allow formulation of diets based on digestible Ca.

Concentration of Ca in Ca carbonate may vary among sources depending on raw materials, geological origin, and processing methods. Differences in apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of Ca among sources produced in the USA have been observed, and Ca carbonate produced in Europe, Asia, and South Africa may have different STTD of Ca than Ca carbonate produced in the USA. However, no values for STTD of Ca in Ca carbonate produced in Latin America have been reported, and it is unknown if STTD of Ca differs among sources produced in different countries within this region. Therefore, the objective of this experiment was to test the hypothesis that there are differences in the STTD of Ca among sources of Ca carbonate obtained from different countries in Latin America.

Keywords: 
Calcium, Digestibility, Limestone, Phytase, Standardized total tract digestibility
Authors: 
Guerrero, Lee, Stein
Publication Type: 
Research Reports

Why limestone becomes important: Practical implications of supplemental phytase for increased calcium digestibility of limestone in growing pigs

Lee, S. A, and H. H. Stein. 2026. Why limestone becomes important: Practical implications of supplemental phytase for increased calcium digestibility of limestone in growing pigs. Book of abstracts. IFTC 2026. 3rd International Feed Technology Congress. Victam. Utrecht. The Netherlands, June 2-3, 2026. Page 94 - 95 Link to full text.

Keywords: 
Limestone, Phytase, Calcium digestibility, Growing pigs
Authors: 
Lee, Stein
Publication Type: 
Conference proceedings

Digestibility of calcium in calcium carbonate varies among origins, but is increased by microbial phytase regardless of origin

Nelson, Megan E., Su A Lee, Carrie L. Walk, April Zhang, Heng-Xiao Zhai, Hans H. Stein. 2025. Digestibility of calcium in calcium carbonate varies among origins, but is increased by microbial phytase regardless of origin. Animal Feed Science and Technology 320 (2025) 116230. doi.org/10.1016/j.anifeedsci.2025.116230 Link to full text.

Keywords: 
Calcium, Calcium carbonate, Digestibility, Limestone, Phytase, pig
Authors: 
Nelson, Lee, Walk, Zhang, Zhai, Stein
Publication Type: 
Peer-reviewed journal articles

Effects of source of calcium carbonate and microbial phytase on digestibility of calcium

It is important that the digestibility of Ca in Ca sources is known to formulate diets based on values for digestible Ca rather than total Ca. Only a small amount of the Ca required by pigs is provided by plant-based ingredients and supplementation of Ca from Ca phosphates and Ca carbonate, is usually required to meet the requirement by pigs. In addition, use of microbial phytase increases Ca digestibility in Ca carbonate, which is one of the major sources of Ca in pig diets.

Differences in Ca digestibility in 4 sources of Ca carbonate produced in the United States have been observed, but it is unknown if there are differences in the ATTD of Ca in calcium carbonate sources produced outside the United States. Therefore, the objective of this experiment was to test the hypothesis that there are differences in the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of Ca and in the response to microbial phytase among 20 sources of Ca carbonate obtained from different parts of the world.

Keywords: 
Calcium, Digestibility, Limestone, Standardized total tract digestibility, Phytase
Authors: 
Nelson, Lee, Stein
Publication Type: 
Research Reports