Vitamin D plays multiple physiological roles, including enhancing intestinal calcium and phosphate absorption, stimulating bone resorption, and promoting renal calcium reabsorption. 25-hydroxyvitamin D3 [25(OH)D3] is the secondary metabolite which is commercially available showed higher bioactivity than vitamin D3 in poultry. Research has examined its role in bone health and performance in broilers, but little is known about the role of 25(OH)D3 in broilers under hot weather stress or coccidiosis. The current experiments were conducted to evaluate 25(OH)D3 on broilers during hot weather and coccidiosis. Under hot weather, supplementing different 25(OH)D3 levels altered circulating metabolites, improved performance, and enhanced bone health. In coccidiosis-challenged broilers, infection reduced 25(OH)D3, growth, bone integrity, and immunity, while supplementing 25(OH)D3 restored circulating levels, bone health, acid-base balance, and showed cytokine modulation during immue responses, consequently reduced cecal lesions. Overall, 25(OH)D3 supplementation benefited broilers beyond their classical roles, improving growth, bone health, and immune response under environmental or disease-related stresses.
