Vitamin D3 is a key nutrient in animal feed. Its core function is to regulate calcium and phosphorus metabolism, promote intestinal absorption and bone deposition, thereby ensuring the health of animal bones and preventing rickets and chondrosis. It can simultaneously enhance growth performance and feed conversion efficiency, and strengthen immune regulation functions, helping animals resist diseases. In breeding animals, vitamin D3 helps maintain normal reproductive capacity and embryo development. However, it needs to be added precisely. A deficiency can lead to metabolic disorders, while an excess may cause poisoning. Therefore, it is necessary to scientifically proportion it based on the species and growth stage.