Synthesis, characterization, and therapeutic evaluation of neem-extract stabilized zinc oxide nanoparticles against avian pathogenic Escherichia coli in broilers

Abstract Colibacillosis is a significant problem in poultry production and a major contributor to antimicrobial resistance because of widespread antibiotic administration. This study evaluated the therapeutic effect of the neem-extract stabilized zinc oxide nanoparticles as an alternative treatment of colibacillosis in broiler chickens. One hundred one-day-old Cobb broiler chicks were randomly assigned to five groups ( n = 20). The negative control group was not challenged, but all the other groups were intraperitoneally challenged with avian pathogenic Escherichia coli (3 × 10 ⁸ CFU/0.25 ml) at the age of 10 d. Group G3 was treated with colistin sulphate (1 g/5L drinking water), Groups G4 and G5 were orally treated with 50 mg kg ⁻¹ and 70 mg kg ⁻¹ of neem-extract stabilized ZnO-NPs, respectively, over a period of five days. The agar-well diffusion assay was used to determine the antibacterial activity; furthermore, growth performance, mortality, serum biochemistry, and histopathology were evaluated. ZnO-NPs had excellent in vitro antibacterial properties against avian pathogenic E. coli with inhibition zones comparable to colistin sulphate. Body weight gain and mortality were significantly better in the treated groups than in the untreated infected group ( p < 0.001). Biomarkers of the liver and kidney were also normalized after the treatment, showing better hepatic and renal functioning. There was histopathological evidence of significant liver and kidney tissue recovery and a decrease in congestion and leukocytic infiltration, especially in the 70 mg kg ⁻¹ ZnO-NP group. The ZnO nanoparticles stabilized with neem extracts exhibited strong antibacterial and organ-protective effects against avian pathogenic E. coli infection in broilers, and were found as effective as colistin sulphate, making them a promising alternative to antibiotics in the treatment of poultry.