Determination of calcium and phosphorus digestibility and relative calcium bioavailability in limestone sources from different countries and interactions with phytase

Two experiments were conducted to evaluate 18 limestones varying in country origin and calcium (Ca) solubility for Ca digestibility and utilization in broiler chickens. The 18 commercial limestones came from several different countries (Asia, United States, South Africa, and Europe). Sources varied in Ca concentration (32.1 to 40.9%) and solubility (45.7 to 92%), and were evaluated for apparent ileal digestibility (AID) of Ca and phosphorus (P), and relative bioavailability of Ca. The first experiment was conducted on male 308 Ross broilers to determine if the different limestones impact AID of Ca and P, in the presence and absence of phytase. Chickens were randomly allotted and were fed 1 of 36 corn soybean meal-based diets containing 1 of 18 limestones sources at 2 different phytase levels of 0 FYT/kg and 1000 FYT/kg. Results from experiment 1 indicated there was a significant (P < 0.05) main effect of limestone source, phytase inclusion and the interaction of both factors, on AID of Ca and P, with higher values for chickens fed the limestone sources from South Africa and lower values for sources from Asia. There was a significant effect of limestone source, phytase inclusion and the interaction of both (P < 0.05) on digestible Ca and P concentrations, and values ranged from 0.182 to 0.542% for digestible Ca and from 0.131 to 0.393% for digestible P. For limestone solubility, phytase inclusion and the interaction of both factors had a significant effect (P < 0.05) on AID of Ca and P, with higher values generally obtained for the medium soluble limestones than for slow and fast soluble limestones. Overall, the results of experiment 1 indicate that AID of Ca, P, and the magnitude of the increase associated with phytase varied among limestone sources and limestone solubility. Experiment 2 was conducted to determine relative bioavailability of Ca in 4 limestones sources (2 sources with the lowest AID values and 2 sources with the highest AID values obtained in experiment 1) using bone ash as the response criterion. Ross 308 broiler males were fed 1 of 11 diets which consisted of a Ca deficient diet (0.3% Ca), and that diet supplemented with 0.15% or 0.30% Ca from either reagent grade Ca carbonate (CaCO3) or 1 of the 4 limestones sources for 13 days. Multiple linear regression of bone ash (mg/tibia) on supplemental Ca intake (mg) yielded slope-ratio relative Ca bioavailability values (relative to the reagent grade CaCO3 ranging from 74 to 89.3% for the 4 test limestones. The results of these studies indicate a slope-ratio bone ash assay can be used to measure relative bioavailability of Ca in limestones. One of the 2 low AID Ca limestones had a significantly lower (P < 0.05) relative Ca bioavailability value than the 2 high AID Ca limestones, whereas there was no significant difference for the other low AID Ca limestone. Thus, there was both agreement and disagreement between the AID values and the relative bioavailability values based on bone ash.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Animal Sciences

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Valencia Beltran, Juan Carlos

Contributors dc:contributor

• Parsons, Carl
• Emmert, Jason

• Limestone
• Calcium
• Phosphorus
• Digestibility
• Phytase

Statement dc:rights

• Copyright 2025 Juan Carlos Valencia Beltran

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132594

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132594