PROTECTIVE ROLE OF PHYTOGENIC COMPOUNDS AGAINST OXIDATIVE STRESS INDUCED BY MYCOPLASMA GALLISEPTICUM IN POULTRY

Mycoplasma gallisepticum (MG) is a significant respiratory pathogen of poultry which may negatively affect productive performance and cause oxidative and inflammatory damage to tissues. The protective effects of a diet supplemented with curcumin, thymol and quercetin against respiratory injury, pathogen burden, inflammation and oxidative stress associated with the MG in broiler chickens were evaluated in this study. A total of 120 1-day-old male Ross 308 broilers were divided into five dietary treatments with six replicate pens per dietary treatment as follows: non-challenged control (CON), MG-challenged control (MG), MG + curcumin (200 mg/kg), MG + thymol (150 mg/kg), and MG + quercetin (200 mg/kg). Growth performance, oxidative stress biomarkers, inflammatory cytokines, MG DNA abundance and respiratory histopathology were assessed after MG challenge on day 21. Final body weight, body weight gain and feed conversion were significantly depressed for MG challenge birds compared to CON birds. Moreover, the malondialdehyde content was elevated with a simultaneous decline in the levels of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase in MG challenge. Levels of pro-inflammatory cytokines were elevated, while anti-inflammatory cytokine levels were decreased (IL-10). Partial recovery of these changes occurred with phytogenic supplementation, which increased antioxidant defenses and decreased inflammatory responses. The treatment also decreased the amount of MG DNA and mitigated the severity of the lesions in the trachea and lungs. Quercetin exhibited the greatest numerical improvement on a number of integrated endpoints. The dietary treatment with curcumin, thymol, and quercetin as a whole reduced several pathological effects caused by the MG challenge, indicating their potential for use as nutrition strategies to enhance the antioxidant system, inflammatory homeostasis and respiratory health of broilers.