Comparative immunomodulatory efficacy of rosemary and fenugreek against Escherichia coli infection via suppression of inflammation and oxidative stress in broilers

Broiler chickens are frequently infected with Escherichia coli ( E. coli ) bacteria, which often leads to the emergence of many diseases and high economic losses. Hence, the current study was conducted to assess the relative efficacy of dietary rosemary and fenugreek, under E. coli infection in broilers and their ability to replace antimicrobials without any loss of productivity or negative influence on broiler health, via evaluation of growth performance, biochemical indices, immune response and histo-morphological changes. Eighty Cobb broilers were allotted to four equal groups ( n = 20 chicks/group): control non-infected (CN), control infected (CI), rosemary infected (RI) and fenugreek infected (FI) groups. The RI and FI groups revealed a significant elevation in their body weight and body weight gain compared with the CI group. However, both groups showed a significant decline in serum aspartate and alanine aminotransferase activities, as well as uric acid and creatinine levels. A significant decrease in total antioxidant capacity, catalase and superoxide dismutase activities was noted among CI chicks. Moreover, distinctly higher activities were evident in both RI and FI groups. Assessment of immunomodulatory markers showed a significant increase in immunoglobulin G along with a significant decline in interleukin-6 level in both RI and FI groups, with the lowest IL-6 value within FI group. Histopathological evaluations focused on the deleterious effect associated with E. coli infection of broilers’ liver, kidney, intestine, spleen, bursa of Fabricius and thymus. Partial histological improvement was noticed among RI group, and nearly normal tissues were recorded in FI group. Overall, the obtained findings suggest the ability of fenugreek to mitigate the adverse effects of E. coli infection on broiler performance and tissue profiles, by improving the general health status of the broiler chickens. Graphical abstract