Academic Review: 25-Hydroxycholecalciferol in Poultry Nutrition

This article summarises publicly available research on 25-hydroxycholecalciferol in poultry nutrition. It is intended as a technical reference for nutritionists evaluating vitamin D sources in layer and broiler diets. Compared with cholecalciferol, the 25-hydroxy metabolite is absorbed more efficiently and does not require hepatic hydroxylation before entering circulation. In published layer trials this has been associated with improvements in eggshell thickness and specific gravity, particularly in the late production phase. In broiler studies, researchers have reported better leg soundness scores and bone mineralisation parameters when the metabolite was used in diets with reduced inorganic phosphorus or high phytase loading. Several factors influence the magnitude of the response, including baseline vitamin D status, calcium and phosphorus balance, bird age and housing conditions. Readers should therefore treat published values as directional rather than as guaranteed outcomes. Our technical team can provide the underlying trial summaries and a recommended starting inclusion level for specific diet types on request.