Drinking-water Chinese herbal formula as an antibiotic alternative for broiler necrotic enteritis: efficacy and mechanism

Necrotic enteritis (NE) triggered by Clostridium perfringens severely impairs broiler productivity, and stricter antibiotic limitations urgently demand feasible substitutes. Herein, 40 herbal raw materials were screened via inhibition zone and MIC assays; synergistic combinations determined by FICI values yielded a six-component compound Chinese herbal formula (CHF) ( Phellodendri Cortex : Berberidis Radix : Lignum Sappan : Chebulae Fructus : Caryophylli Flos : Glycyrrhizae Radix et Rhizoma = 2.5:2.5:1.5:1.5:1:1). CHF produced a 22.17 ± 0.29 mm inhibition zone against the pathogen, with MIC of 15.63 mg/mL and MBC of 31.25 mg/mL. In vitro tests revealed CHF barely damaged bacterial membrane (unchanged extracellular AKP and intact ultrastructure) but markedly suppressed hemolysis, biofilm formation, motility and epithelial adhesion. Meanwhile, CHF was safe to Caco-2 cells below 1/2 MIC. For the in vivo trial, 150 SPF chicks were split into blank, NE model, amoxicillin control and three CHF groups (1.5, 2.5, 3.5 g/L, drinking water). Relative to diseased controls, 3.5 g/L CHF elevated ADG by 1.90 g and lowered FCR by 0.33, accompanied by relieved jejunal lesions. Moreover, high-dose CHF normalized spleen and bursa indices, downregulated pro-inflammatory TNF-α and IL-6 while elevating anti-inflammatory IL-10, and upregulated intestinal tight junction proteins (MUC2, Occludin, Claudin-1, ZO-1). Collectively, CHF mitigates C. perfringens -provoked NE via restraining bacterial virulence and reinforcing intestinal barrier. Under the conditions of this study, supplementation with CHF at 3.5 g/L showed the most pronounced protective effect and may provide a basis for the development of alternative strategies for necrotic enteritis control in poultry.