Immunomodulatory effects of a polyherbal formulation against experimental Eimeria tenella infection in Sonali chickens.

Coccidiosis caused by Eimeria tenella remains a major economic constraint in poultry production, and rising anticoccidial drug resistance has intensified interest in phytogenic alternatives. This study evaluated a polyherbal mixture (PHM) combining Moringa oleifera, Azadirachta indica, Psidium guajava, and Curcuma longa against experimental E. tenella infection in Sonali chickens. Thin-layer chromatography of the four extracts and their combination identified gallic acid, catechin, curcumin, and alkaloids as consistent phytoconstituents. 72 birds were allocated into six groups - uninfected and infected controls, a commercial anticoccidial group, and three PHM doses (1.0, 0.5, 0.25 mL/L drinking water) - and monitored for average weight gain (AWG), feed conversion ratio (FCR), and oocyst shedding as oocysts per gram (OPG) at 9 and 14 days post-infection (DPI). The 0.25 mL/L dose produced the most efficient FCR, lowest OPG at both time points, and highest AWG by 14 DPI despite the lowest early gain, consistent with a non-linear, inverse dose-response reflecting a shift from a beneficial to a less-tolerated phytochemical exposure level. Relative expression of interferon-gamma (IFN-γ), interleukin-10 (IL-10), and Toll-like receptor 4 (TLR4) in cecal tissue showed early IL-10 suppression and TLR4 downregulation at 9 DPI, followed by significant IFN-γ upregulation and IL-10 recovery by 14 DPI, while TLR4 remained suppressed. STRING-based protein-protein interaction analysis identified direct, high-confidence associations among the three genes and enrichment in defense-response and Toll-like receptor signaling pathways, supporting a functionally coordinated immune module. These findings indicate that low-dose PHM exerts anticoccidial efficacy through a time-resolved immunomodulatory mechanism, positioning it as a promising, sustainable alternative to conventional anticoccidials for commercial Sonali chicken production.