In Vitro Screening of Antibacterial Efficacy of <i>Moringa oleifera</i> and <i>Thymus vulgaris</i> Methanolic Extracts Against Different <i>Escherichia coli</i> Strains and Their In Vivo Effects Against <i>E. coli</i>-Induced Infection in Broiler Chickens.

Abstract

This study evaluated the antibacterial efficacy and growth-promoting potential of <i>Moringa oleifera</i> and <i>Thymus vulgaris</i> methanolic extracts in broiler chickens challenged with <i>Escherichia coli</i> O78. In vitro antibacterial screening using agar well diffusion and disc diffusion assays revealed that ciprofloxacin exhibited the strongest inhibitory effect, followed by tetracycline and enrofloxacin, whereas among plant extracts, <i>T. vulgaris</i> was more effective than <i>M. oleifera</i>. The optimal combination (M100T150; 100 mg <i>M. oleifera</i> + 150 mg <i>T. vulgaris</i>) produced the largest inhibition zones against <i>E. coli</i> strains. For the in vivo trial, 540 Ross-308 broiler chicks were distributed into six treatment groups in a completely randomized design and reared for 42 days. Parameters assessed included growth performance, carcass traits, gut pH, ileal microbial counts, and intestinal histomorphology. Results showed that <i>E. coli</i> challenge significantly reduced feed intake, weight gain, carcass yield, and villus integrity while increasing FCR and <i>E. coli</i> counts (<i>p</i> < 0.05). Addition of plant extracts, particularly M100T150, significantly improved weight gain, FCR, Broiler Performance Efficiency Factor (BPEF), and Broiler Farm Economy Index (BFEI) compared to the positive control (<i>p</i> < 0.05). Extracts reduced duodenal and jejunal pH (<i>p</i> < 0.001), suppressed <i>E. coli</i> counts (<i>p</i> = 0.003), and enhanced <i>Lactobacillus</i> populations (<i>p</i> = 0.0004). Histological analysis revealed that extract-supplemented groups had greater villus height and surface area with shallower crypts than the positive control, indicating restoration of gut integrity. These findings suggest that methanolic extracts of <i>M. oleifera</i> and <i>T. vulgaris</i>, particularly in combination, can serve as natural alternatives to antibiotics in broiler production under pathogenic challenge.