关键词: 竹丝鸡；第益肽；生长性能；产气荚膜梭菌群；短链脂肪酸

Abstract: The advantages of antimicrobial peptides， including broad antibacterial spectrum， immune regulation，stable biological activity，and low resistance development，are well recognized. In this study，the effect of the antimicrobial peptide product Youtide on the growth performance of Silkie chickens was evaluated，aiming to provide a scientific basis for its application in Silkie chicken production. A total of 2，889 one?day?old female Silkie chickens were selected and assigned into three groups：a production control group （Group A），a Youtide ? supplemented group（Group B），and a blank control group（Group C），with three replicates per group and 321 chickens per replicate. At 55 days of age，production performance indexes，including marketing rate，feed intake， body weight，and feed?to?gain ratio，were recorded. During the middle and late feeding stages（35 and 55 days of age），samples were collected for the observation of intestinal tissue morphology，and the levels of short-chain fatty acids as well as the load of Clostridium perfringens in the cecum were measured. In addition，cecal contents obtained from 55 ? day ? old birds were subjected to high-throughput 16S rRNA gene sequencing to analyze the microbial community structure. At 55 days of age，the average body weight and slaughter rate of Silkie chickens in the Youtide test group were found to be significantly higher than those in the blank control group （P<0.05），while the feed-to-meat ratio in the test group was observed to be significantly lower（P<0.05）. At 55 days of age，the ratio of jejunal villus height to crypt depth in the Youtide group was shown to be significantly greater than that in the blank control group（P<0.05）. At 35 days of age，the cecal contents of acetic acid，propionic acid，butyric acid，and isovaleric acid in the test group were found to be significantly elevated compared with those in the blank control group （P<0.05）. At 35 days of age，the counts of Clostridium perfringens group in the jejunum and cecum of the Youtide test group were significantly reduced relative to the blank control group（P<0.05）. No significant differences in cecal microbial community composition at the phylum or genus level were observed among the groups. Therefore，Youtide can be recommended for large?scale Silkie chicken production，as it improves intestinal morphology，inhibits harmful pathogenic bacteria，and achieves the dual benefits of promoting growth and reducing the feed?to ?meat ratio.

Key words: Silkie Chicken；Youtide；Growth performance；Clostridium perfringens group ；Short?chain fatty acids