Ameliorating effects of antibiotic alternatives on the performance and pathological parameters of Salmonella Typhimurium infected broiler chickens.

Abstract

The purpose of this study was to investigate the effects of thyme oil (TO), chitosan nanoparticles (CS-NPs), and TO-loaded-CS-NPs on controlling Salmonella Typhimurium (S. Typhimurium) infection in broiler chickens when compared to ciprofloxacin (Cip) antibiotic treatment. The CS-NPs and TO-loaded-CS-NPs were initially characterized using a transmission electron microscope. Two hundred and forty broiler chicks were divided into six equal groups. Group 1 was given TO (1ml/4L of the drinking water). However, group 2 and group 3 were given CS-NPs and TO-loaded-CS-NPs in a 2 ml/chick dose by oral gavage. Group 4 was given a Cip (0.5 g/mL of drinking water). Treatments started on the 20th day of age and continued for 5 successive days. Each chicken in groups 1-5 was orally infected with 1 ml of 1 × 10 CFU/ml S. Typhimurium 14 days old. Chickens in group 6 were kept as blank control negative without treatment or infection. All groups were kept for 4 weeks post-infection to record clinical observations, performance parameters, the shedding rate of S. Typhimurium, and the histopathological parameters of different organs. Results showed that the infected untreated group had the lowest performance (BWT: 2164.60 ± 31.90), with the highest bacterial count (BC) (8.56 ± 0.14) and lesion scores. The best results were obtained in response to TO-loaded-CS-NPs (BWT: 2422.70 ± 51.15 and BC: 6.62 ± 0.32) and Cip (BWT: 2431.50 ± 40.01 and BC: 5.32 ± 0.16). Therefore, it is recommended to use TO-loaded-CS-NPs as an alternative antibacterial agent in controlling S. Typhimurium infection without taking the risk of developing resistant bacterial strains as with antibiotics.