Vitamin B9 (folic acid) is an important water-soluble vitamin in animal feed. As a key coenzyme for one-carbon unit transfer, it is involved in the synthesis of nucleic acids (DNA/RNA), protein metabolism, as well as cell division and proliferation. In aquaculture production, it is crucial for maintaining the rapid growth of animals (especially young ones), normal hematopoietic function (preventing anemia), and good reproductive performance. Specifically, folic acid can effectively support the early development of embryos and reduce the rate of malformations. Improve the egg-laying rate and hatching rate of breeding poultry; And maintain the health of the fur. Deficiency can lead to growth retardation, anemia, reproductive disorders (such as embryo death, decreased sperm quality), and poor feather or hair development. Although rumen microorganisms in ruminants can synthesize some folic acid, monogastric animals (such as pigs and poultry) cannot do so on their own, and the demand increases during high-intensity production, poor intestinal health or the use of antibacterial drugs. Therefore, additional supplementation is required in complete feed, especially in the diets of breeding, gestation and fast-growing animals.