Abstract
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 mg/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 mg). In vivo study revealed that treatment of colisepticemic broiler chickens at a low dose (4 mg/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 mg/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 mg/kg diet could play an optimistic role in the impedance of colisepticemia in broiler chickens.