Using Saccharomyces cerevisiae as a strain, obtained by liquid fermentation of bacteria, Autolyzed Yeast is rich in Mannan Oligosaccharides (MOS), nucleic acids, nucleotides, small peptides, digestive enzymes, free amino acids, and B vitamins. Nucleotides and amino acids together add umami to and improve the palatability of feed, so the feed intake of animals can be improved. Intestinal cell proliferation can be quickened by the nutrition of nucleic acids, so as to promote the development of the intestine in young animals. The functions of nucleic nutrition, small peptide nutrition, and yeast polysaccharides together help the development and recovery of the immune system.