What is the role of calcium particle size (coarse vs. fine) in brown layer feed?

The timing of calcium intake is a critical aspect of avian physiology. A layer hen forms her eggshell primarily during the 12-hour dark period of the night, when she does not consume feed. Fine calcium particles (limestone powder) are absorbed rapidly in the intestine during the day and excreted if not needed. In contrast, coarse calcium particles (2-4 mm grit) are retained in the gizzard, dissolving slowly overnight. This slow release provides a steady stream of calcium ions directly into the blood during the critical hours of shell calcification, preventing the hen from depleting her bone calcium reserves. This nutrition practice minimizes thin-shelled and soft-shelled floor eggs. Farmers can access mineral particle calculators in the Poultry Encyclopedia, buy quality grit on Poultry Plaza, and track daily feed ingredient rates on Poultry Rates.