This study aims to determine the influence of silver nanoparticles (Ag-NPs) on performance, clinical and pathological pictures, virulence gene expression, and electron microscopy of experimentally induced Escherichia coli infection (colisepticemia) in broiler chickens. One-day-old chickens (n = 120) were segregated into 4 equal groups (1–4) with 3 replicates of 10 birds each. Birds were fed mash diet in 3 phases: starter (1–14 d), grower (15–28 d), and finisher (29–35 d). Chickens of the first 3 groups (T1, T2, T3) were fed Ag-NPs in the following dietary levels: 4, 6, and 8 g/kg diet, respectively, while chickens of the fourth group (C) were fed a basal diet. All groups were individually infected by crop gavages with 0.5 mL/bird of PBS containing 3 × 10⁸ CFU/mL of E. coli serogroup O78 for 2 successive days. In vitro Ag-NPs had a potent inhibitory effect against E. coli growth in pure form only (2,000 ppm). In vivo study revealed that treatment of colisepticemic broiler chickens at a low dose (4 g/kg diet) improved performance, reduced both gross and histopathological lesion scores, and virulence genes. It also altered the electron microscopic profile of the inoculated E. coli in the examined liver tissue. Severe negative effect was recorded on supplementation of the higher dose of Ag-NPs (8 g/kg diet) that resulted in major effects on all the measured parameters except the gene expression analysis. Ag-NPs treatment with a dose of 4 g/kg diet could play an optimistic role in the impedance of colisepticemia in broiler chickens.

这项研究旨在确定银纳米颗粒（Ag-NPs）对肉鸡实验性诱导的大肠杆菌感染（大肠杆菌败血症）的性能，临床和病理图片，毒力基因表达以及电子显微镜的影响。将一天大的鸡（n = 120）分成4组，每组10只鸡，分为3组，每组1-4个。分为三个阶段为禽类饲喂饲料：初学者（1-14 d），生长者（15-28 d）和育成期（29-35 d）。前三组（T1，T2，T3）的鸡以以下饮食水平喂食Ag-NP：分别为4、6和8 g / kg饮食，而第四组（C）的鸡则以基础饮食喂食饮食。所有组均通过农作物分别用0.5 mL /只含3×10 ⁸的PBS鸟感染。CFU / mL大肠杆菌O78血清群连续2天。体外Ag-NP仅以纯形式（2,000 ppm）对大肠杆菌的生长具有有效的抑制作用。体内研究表明，低剂量（4 g / kg饮食）的大肠埃希杆菌病肉鸡治疗可提高性能，降低总体和组织病理学损害评分以及毒力基因。它还改变了接种大肠杆菌的电子显微图在检查的肝组织中。补充高剂量的Ag-NPs（8 g / kg饮食）会产生严重的负面影响，这对除基因表达分析之外的所有测量参数均产生了重大影响。以4 g / kg剂量的日粮进行Ag-NPs处理可对肉鸡的败血症抵抗力起乐观作用。