Impact of plant-based antibiotic alternative supplemented feed on the gut microbiota of Bábolna Tetra-SL chickens experimentally infected with Salmonella enterica and Escherichia coli

BACKGROUND: Salmonella enterica and Escherichia coli-associated enteric disturbances contribute to health and productivity losses in poultry and pose zoonotic concerns. In the context of antimicrobial resistance, phytogenic feed additives may offer antibiotic-sparing strategies by modulating the intestinal microbiota. We evaluated a fenugreek (Trigonella foenum-graecum) and turmeric (Curcuma longa) extract combination for its microbiota-modulating effects in a controlled dual-challenge model. MATERIALS AND METHODS: A total of 270 Bábolna Tetra-SL chicks were allocated to six groups: low-, medium-, or high-dose phytobiotic; enrofloxacin; infected control; and non-infected control. Birds were orally challenged on days 3-4 post-hatch with clinical isolates of S. enterica and E. coli (both phenotypically susceptible to enrofloxacin). Cloacal swab samples were collected on days 1, 7, and 42 and profiled by V3-V4 16 S rRNA gene amplicon sequencing. Alpha diversity and beta diversity were assessed in QIIME2 using non-parametric and permutation-based approaches. RESULTS: Alpha diversity increased with age across groups. On day 42, the medium-dose phytobiotic group exhibited the most balanced community profile among treated groups, whereas enrofloxacin was associated with the strongest early community disruption followed by partial recovery by day 42. Beta diversity ordinations and clustering indicated clear time-driven separation, with treatment-associated differences observed within time points and supported by permutation-based multivariate statistics. CONCLUSIONS: A fenugreek-turmeric phytobiotic modulated cloacal microbiota structure in chickens under a controlled dual-challenge model. Medium-dose supplementation was associated with the most balanced community configuration at the end of the trial, while enrofloxacin induced marked early perturbation. These findings support further evaluation of phytogenic additives as components of antibiotic-reduction strategies in poultry production.