Polypeptide antibiotics have strong antibacterial effect on gram-positive bacteria, a few Gram-negative bacteria, spirochaeta and actinomyces and even penicillin-resistant staphylococcus. The antibacterial mechanism is to inhibit the formation of bacterial cell wall and damage the bacterial cytoserous membrane. It can promote intestinal microbial growth, increase intestinal mucosal permeability, and promote the absorption of nutrients. It is mainly used to promote the growth of Chemicalbook livestock and poultry, prevent and control bacterial diarrhea of livestock and swine blood dysentery caused by treponema. Bacitracin zinc is almost not absorbed by internal administration, and most of it is excreted with feces within 2 days, so it is not easy to remain in livestock and poultry products. Bacteria rarely develop resistance to bacitracin, and have no cross-resistance with other antibiotics, and have synergistic effects with penicillin, streptomycin, neomycin, aureomycin, polymycin, etc