Abstract: This experiment was conducted to study the effects of antimicrobial peptide cecropin on production performance，immune function and serum biological parameters of weaner piglets.A total of 240 weaner hybrid piglets （Landrace×Large White×Duroc） with average body weight （8.35±0.12）kg were randomly divided into 4 treatments with 6 replicates of 10 each.The four treatments were control group （fed a basal diet），antibiotics group （fed basal diet＋140 mg/kg 50% kitasamycin＋100 mg/kg olaquindox ＋600 mg/kg 10% colistin sulfate），antimicrobial peptide group （fed basal diet＋350 mg/kg antimicrobial peptide cecropin），compatibility group （antibiotics + antibacterial peptide group）（fed basal diet＋250 mg/kg antimicrobial peptide cecropin＋50 mg/kg olaquindox ＋200 mg/kg 10% colistin sulfate），each group was half male and half female.The pre-test period lasted for 7 days，the trial period lasted for 34 days.The results showed that compared with control group，the average daily gain in compatibility group was significantly increased  （P＜0.05），the average daily feed intake in antibiotic group and antimicrobial peptide group was significantly decreased （P＜0.05），the feed conversion ratio and diarrhea rate in all three experimental groups were significantly decreased （P＜0.05）.The antibody blocking rate and serum IgG，IgA contents in antimicrobial peptide group and compatibility group were significantly increased （P＜0.05），the serum urea nitrogen and blood sugar contents in antimicrobial peptide group and compatibility group were significantly decreased （P＜0.05），but the serum total protein and albumin contents were significantly increased （P＜0.05）.In conclusion，dietary supplementation appropriate level of antimicrobial peptide cecropin could replace part of the antibiotics，and adding high dose of antimicrobial peptide cecropin could replace antibiotics used in feed completely.

Key words: antimicrobial peptide cecropin; weaner piglets; production performance; immune function; serum biological parameters