Mitigating Effect of Phytogenic Plant Extracts on Heat Induced Stress in Broilers

Background: This study was aimed to evaluate the effectiveness of a phytogenic blend composed of extracts from Mangifera indica, Citrullus lanatus, Cymbopogon citratus, Allium cepa, Rosmarinus officinalis and Allium sativum, against induced heat stress in commercial broilers. These were studied by examining their effects on growth performance, haematological parameters and stress biomarkers. The biomarkers used were HSP70 and cortisol (COR) in feathers and blood serum. Methods: A total of 1760 one day-old Cobb 430Y broiler chicks were randomly allocated into four treatment groups, consisting of 440 birds in each group. A phytogenic plant extract, referred as PPE, was used in this study. The experimental groups were as follows: Normal Control (NC, 36.05±0.32oC at 2 PM, no PPE), NC+PPE (36.05±0.32oC at 2 PM, with PPE), Heat Stress (HS, 42.20±1oC at 2 PM, no PPE), HS+PPE (42.20±1oC at 2 PM, with PPE). Heat stress was induced using portable electric heater for the HS groups. After a 14-day acclimatization period, PPE was administered through drinking water. Feed was withdrawn from 12:00 hrs. and 16:00 hrs, while water was provided ad libitum for all the birds. Result: The NC+PPE and HS+PPE groups showed significantly higher (P less than 0.05) body weight and body weight gain compared to their respective control groups. The cumulative weekly mortality percentage was lowest in the NC+PPE group (1.36%, 6 birds). Feather HSP70 levels on day 41 were lowest (P less than 0.05) in the HS+PPE group. No significant differences were observed in the haematological parameters between the treatment groups. The NC+PPE and HS+PPE both groups performed comparatively better than other treatment groups. Both the groups had a comparatively better reduction of stress biomarkers, viz., feather HSP70, as compared to the respective control groups.