Abstract: 【Objective】 To study the effect of antibacterial peptide extracted from pig small intestine on the growth performance and growth mechanisms in chickens. 【Method】Sixty 7-day-old chickens with similar weight body were separated into experimental and control groups at random. One-tenth ml (100 μg·ml-1) of antibacterial peptide (ABP) was administered intramuscularly into each experimental group chicken at the age of 7, 14, 21, 28, 35, 42 days, One-tenth ml of sterile saline into control group's chicken at the same age, respectively. Two groups of chickens were fed under the same conditions for 6 weeks. The villus length, mucosa thickness and villus/crypt (V/C) value of duodenum and jejunum were determined at the age of 7, 49 days, respectively. 【Result】 The average daily weight gain of the experimental group chickens (13.54±0.20) g was significantly higher than that of the control group chickens (11.10±0.19) g (P<0.01), and the feed/weight-gain ratio of the experimental group chickens (2.27±0.04) was significantly lower than that of the control group chickens (2.60±0.05) (P<0.01). The villus length and V/C value of duodenum and jejunum of the experimental group chickens were higher than those of the control group chickens at the age of 49 days (P<0.05). The mucosa thickness of duodenum and jejunum of experimental group was of no significant difference compared with the control group (P>0.05).【Conclusion】The antibacterial peptides could improve the structure of duodenum and jejunum and enhance the growth performance and feed conversion ratio.

Key words: Antibacterial peptide, Small intestine of pig, Growth-enhancing, Mechanism, Chicken