Developing alternatives to antibiotics is an urgent need in livestock production. Antimicrobial peptides (AMPs) are regarded as powerful antibiotic substitutes (ASs) because AMPs have broad-spectrum antimicrobial activities and growth-promoting ability. Here, we aimed to comprehensively assess the effects of AMPs on the growth performance, diarrhea rate, intestinal morphology and immunity of healthy or challenged piglets, compared with an antibiotics group or negative control group. We performed a set of meta-analyses of feeding trials from database inception to 27 May 2019. Among the 1379 identified studies, 20 were included in our meta-analyses (56 arms and 4067 piglets). The meta-analyses revealed that (1) compared with the negative control group, AMPs significantly improved the healthy piglets’ average daily gain (ADG), average daily feed intake (ADFI), gain : feed ratio (G/F), levels of immune globulin (Ig) IgM and IgG, and intestinal villus height : crypt depth ratio (V/C) (P < 0.05). Meanwhile, AMPs significantly increased the challenged piglets’ ADG, ADFI, G/F and V/C of the jejunum and ileum, and notably deceased the diarrhea rate (P < 0.05); (2) compared with antibiotics group, the effects of AMPs were slightly weaker than those of antibiotics in the healthy piglets, but AMPs have similar effects to those of antibiotics in challenged piglets. In a higher purity, the optimal dose of AMPs may be approximately 0.01%. Our findings indicate that AMPs can improve piglet growth performance, enhance immunity, benefit intestinal morphology and decrease the diarrheal rate. AMPs could be great ASs especially under infection conditions.

开发抗生素的替代品是畜牧生产的迫切需要。抗菌肽 ( AMPs ) 被认为是强大的抗生素替代品 ( ASs) 因为 AMP 具有广谱抗菌活性和促进生长的能力。在这里，我们旨在全面评估与抗生素组或阴性对照组相比，AMPs 对健康或受攻击仔猪的生长性能、腹泻率、肠道形态和免疫力的影响。我们对从数据库建立到 2019 年 5 月 27 日的喂养试验进行了一系列荟萃分析。在 1379 项已确定的研究中，20 项被纳入我们的荟萃分析（56 只手臂和 4067 头仔猪）。荟萃分析显示：（1）与阴性对照组相比，AMPs显着提高了健康仔猪的平均日增重（ADG）、平均日采食量（ADFI）、增重比（G/F）、免疫球蛋白（Ig ) IgM 和 IgG，以及肠绒毛高度：隐窝深度比 ( V/C ) ( P < 0.05)。同时，AMPs显着提高受攻击仔猪空肠和回肠的ADG、ADFI、G/F和V/C，显着降低腹泻率（P < 0.05）；(2)与抗生素组相比，AMPs对健康仔猪的作用略弱于抗生素，但AMPs对攻击仔猪的作用与抗生素相似。在更高的纯度下，AMP 的最佳剂量可能约为 0.01%。我们的研究结果表明，AMPs 可以改善仔猪生长性能、增强免疫力、有益于肠道形态并降低腹泻率。AMP 可能是很好的 AS，尤其是在感染条件下。