There are more than 30 types of Cecropin, which has a broad-spectrum antibacterial effect. Cecropin P1 was the first peptide isolated from the porcine small intestine. It is a peptide sequence consisting of 31 amino acids. Antimicrobial peptides play an important role in maintaining the balance of intestinal flora, regulating body immunity and defending against pathogenic bacteria. Cecropin P1 is mainly against Gram-negative bacteria (Escherichia coli, Salmonella typhimurium, Haemophilus parasuis) and some Gram-positive bacteria (Staphylococcus aureus), with good antibacterial activity.