Effect of calcium source, particle size, limestone solubility in vitro, and calcium intake level on layer bone status and performance.

Experiments were conducted to examine the effect on layer performance of dietary calcium source, particle size (average United States Screen Numbers 6, 8, 12, 18, 35, and 100) and calcium intake level (2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 g/day). Egg production and egg weight were not affected by any of the treatments. Size and calcium intake level significantly affected shell weight, shell weight per unit surface area, specific gravity, and shell thickness. Bone ash expressed as a percentage of fat-free dry weight was not affected by calcium intake level, but bone ash concentration (bone ash per unit volume) and bone-breaking strength were linearly related to calcium intake level. Regressed shell quality traits and various bone parameters related to solubility instead of particle size produced a better fitted line.