Renal Endocytic Regulation of Vitamin D Metabolism during Maturation and Aging in Laying Hens.

Egg-laying hens undergo a specific and dramatic calcium metabolism to lay eggs with eggshells composed of calcium carbonate. Calcium metabolism is mainly regulated by vitamin D. Although vitamin D metabolism is closely related to the deterioration of eggshell quality associated with aging and heat stress, the details of the mechanisms regulating vitamin D metabolism are not clear.