Antibiotic resistance of pathogens, which is caused by the abuse of in-feed antibiotics, threatens the sustainable development of livestock production. The present study aimed to investigate the efficiency of porcine intestinal antimicrobial peptide (PIAP) as an alternative to in-feed antibiotics in terms of growth performance, intestinal morphology, digestive enzymes and immunity, and microbiota community of the post-weaning piglets. A total of 204 piglets (Duroc × Landrace × Yorkshire, weaned at 28 d age) with a similar body weight of 7.97 ± 1.04 kg were randomly allocated to 4 groups (51 piglets per group): (1) control group: basal diet; (2) AB group: antibiotic, basal diet + chlortetracycline (1000 mg/kg from d 1 to 24; 500 mg/kg from d 25 to 37); (3) P1 group: basal diet + a relatively low dose of PIAP (400 mg/kg from d 1 to 24; 300 mg/kg from d 25 to 37); (4) P2 group, basal diet + a relatively high dose of PIAP (600 mg/kg from d 1 to 24; 500 mg/kg from d 25 to 37). The results showed that serum indicators of hepatocyte damage and relative organ weight were not affected by these treatments (P > 0.05). Compared with the AB treatment, the P1 treatment remarkably decreased jejunal crypt depth and increased jejunal and ileal villus height:crypt depth ratio (P < 0.05). The values of jejunal maltase, lactase, sucrase, intestinal alkaline phosphatase, and secretory immunoglobulin A (SIgA) in the P1 group were sharply increased compared with those in the control and P2 groups (P < 0.05). Compared with the control group, the P1 group decreased serum concentrations of D-lactate, diamine oxidase, and endotoxin (P < 0.05), and increased the abundance of Lactobacillus reuteri (P < 0.05) in the colonic feces. Furthermore, there was a positive correlation between the abundance of L. reuteri and the concentrations of maltase, lactase, sucrase, and SIgA (P < 0.05). Collectively, dietary supplementation with a relatively low dose of PIAP (400 mg/kg from d 1 to 24; 300 mg/kg from d 25 to 37) demonstrates beneficial effects on intestinal morphology, digestive enzymes, immunity, and permeability by shaping the gut microbiota composition in weaned piglets. This study will provide a valuable reference for using PIAP as an in-feed antibiotic alternative in swine production.

饲料中抗生素的滥用导致病原菌产生耐药性，威胁着畜牧生产的可持续发展。本研究旨在从断奶仔猪的生长性能、肠道形态、消化酶和免疫力以及微生物群落等方面研究猪肠道抗菌肽 (PIAP) 作为饲料中抗生素替代品的效率。将体重相近的7.97±1.04kg仔猪（杜洛克×长白×约克夏，28日龄断奶）204头随机分为4组（每组51头）：（1）对照组：基础日粮；(2)AB组：抗生素、基础饲料+金霉素(1000 mg/kg d 1-24；500 mg/kg d 25-37)；(3) P1组：基础饮食+相对低剂量的PIAP（400 mg/kg，第1~24天；第 25 至 37 天 300 毫克/千克）；(4)P2组，基础饮食+较高剂量的PIAP(第1-24天600 mg/kg；第25-37天500 mg/kg)。结果表明，肝细胞损伤和相对器官重量的血清指标不受这些治疗的影响（P  > 0.05）。与AB处理相比，P1处理显着降低了空肠隐窝深度，增加了空肠和回肠绒毛高度：隐窝深度比值（P  < 0.05）。P1 组空肠麦芽糖酶、乳糖酶、蔗糖酶、肠道碱性磷酸酶和分泌性免疫球蛋白 A（SIgA）值较对照组和 P2 组显着升高（ P < 0.05 ）  。与对照组相比，P1 组降低了血清 D-乳酸、二胺氧化酶和内毒素浓度（P < 0.05），增加了 结肠粪便中罗伊氏乳杆菌 的丰度（P < 0.05）。此外，丰度之间存在正相关关系L. reuteri与麦芽糖酶、乳糖酶、蔗糖酶和 SIgA 的浓度（P  < 0.05）。总的来说，膳食补充相对低剂量的 PIAP（第 1 至 24 天 400 mg/kg；第 25 至 37 天 300 mg/kg）通过塑造肠道对肠道形态、消化酶、免疫和通透性产生有益影响断奶仔猪的微生物群组成。本研究将为在猪生产中使用PIAP作为饲料中抗生素替代品提供有价值的参考。