Effect of limestone particle size and inclusion level on duodenal and jejunal mucosal expression of Ca and P transporters and claudins in broilers was tested in a 2 × 3 factorial arrangement. Two limestone sources, coarse (mean particle size 1062 µm) vs. fine (mean particle size 160 µm), were separated from the same limestone limestone products via sieving. These two limestone sources were then added to a basal diet at three inclusion levels, resulting in Ca/P ratio 0.50, 1.00 and 1.75 in the experimental diets (dietary P content was fixed at 5.5 g/kg in the basal diet). Experimental diets were provided on day 14 onwards, and on day 20 and 21 three birds per replicate pen were randomly selected for collection of duodenal and jejunal mucosa. mRNA expression of Ca- and P-related transporters and claudins in the duodenal and jejunal mucosa were determined on individual bird level using RT-PCR.

For more details about the experimental design, please see the paper “Mucosal expression of Ca and P transporters and claudins in the small intestine of broilers is altered by dietary Ca:P in a limestone particle size dependent manner”.