Vitamin D is the primarily sourced from whole milk, liver oils, and sun-dried green fodder. Vitamins D2 and D3 are the two most important forms; the former is derived from ergosterol in plants transformed by sunlight, while the latter is produced in animals from 7-dehydrocholesterol under ultraviolet light. Vitamin D helps regulate calcium and phosphorus absorption, excretion, and bone mineralization, particularly crucial when calcium and phosphorus supply is insufficient or improperly balanced. Vitamin D deficiency can lead to calcium and phosphorus metabolism disorders, resulting in issues such as rickets, osteoporosis, skeletal and joint deformities, growth disorders, brittle bones, and inadequate eggshell strength.