Immunopathological studies on Escherichia coli infected broiler chickens fed on Aloe vera leaf extract

Escherichia coli infection is the major bacterial disease affecting the poultry industry and the continuous use of antibiotics in poultry farming has resulted in antibiotic resistance. So this study was planned to evaluate the use of an ecologically safe alternative to fight against infections. The leaf gel of the Aloe vera plant was selected based on its antibacterial activity assessed in in-vitro tests. The objective of the present study was to evaluate the effect of A. vera leaf extract supplementation on the severity of clinical signs and pathological lesions, mortality rate, levels of antioxidant enzymes, and immune response in experimentally E. coli-infected broiler chicks. Broiler chicks were supplemented with aqueous Aloe vera Leaf (AVL) extract @ 20 ml per liter of water from day one of age. After seven days of age, they were experimentally infected with E. coli O78 @ 10⁷ CFU/0.5 ml intraperitoneally. Blood was collected at weekly intervals up to 28 days and assayed for antioxidant enzyme assays, and humoral and cellular immune response. The birds were observed daily for clinical signs and mortality. Dead birds were examined for gross lesions and representative tissues were processed for histopathology. The activities of antioxidants, Glutathione reductase (GR), and Glutathione-S-Transferase (GST) were significantly higher than the control infected group. The E. coli-specific antibody titer and Lymphocyte stimulation Index were comparatively higher in the AVL extract-supplemented infected group as compared to the control infected group. No considerable change was noted in the severity of clinical signs and pathological lesions, and mortality. Thus, Aloe vera Leaf gel extract enhanced the antioxidant activities and cellular immune responses of infected broiler chicks to combat this infection.