Dietary essential oils improves the growth performance, antioxidant properties and intestinal permeability by inhibiting bacterial proliferation, and altering the gut microbiota of yellow-feather broilers Original paper

What was studied?

This experimental study investigated the antibacterial properties of essential oils (EOs) and their effects on growth performance, intestinal morphology, antioxidant capacity, and gut microbiota of yellow-feathered broilers. A total of 720 male chicks were divided into four groups receiving different EO doses over 48 days. The study aimed to determine whether EOs could inhibit bacterial proliferation, improve gut health, and enhance overall poultry production performance. The researchers combined in vitro antimicrobial testing with in vivo assessments of intestinal structure, biochemical markers, and gut microbial shifts.

Who was studied?

The study focused on yellow-feathered broiler chickens, which are commonly used in poultry farming. These birds were fed either a control diet or diets supplemented with varying concentrations of EOs, which contained thymol and carvacrol as active ingredients. Their growth, intestinal morphology, antioxidant responses, serum biochemistry, and cecal microbiota were closely monitored. The microbial focus included pathogenic species like E. coli and Salmonella, along with beneficial genera such as Lactobacillus and Faecalibacterium, enabling a clear view of how the EO interventions reshaped gut microbial communities.

What were the most important findings?

The study demonstrated that EOs significantly inhibited the proliferation and biofilm formation of E. coli O78 and Salmonella pullorum, with minimum inhibitory concentrations (MICs. In vivo, EO supplementation enhanced average daily gain (ADG) and feed efficiency across multiple growth phases. Antioxidant markers such as superoxide dismutase (SOD) and catalase (CAT) activity improved, while intestinal permeability markers (villus height and tight junction protein expression) were positively affected. Gut microbiota analysis revealed that EO supplementation increased beneficial microbes, particularly Lactobacillus and Faecalibacterium, while reducing harmful genera such as Negativibacillus and Flavonifractor. Notably, the EO400 group showed the highest microbial diversity and upregulated pathways for chemoheterotrophy and fermentation. Correlation analysis linked improved gut microbiota profiles to better growth performance, suggesting that EO-driven microbial shifts were central to the observed production benefits.

What are the greatest implications of this study?

This study provides robust evidence that essential oils can serve as effective natural alternatives to antibiotic growth promoters (AGPs) in poultry farming. By reducing pathogenic bacteria and fostering beneficial microbiota, EOs improve gut health and production performance while mitigating risks associated with antibiotic resistance. The findings are particularly relevant as global regulations increasingly restrict AGP use. However, the dose-dependent effects and variable long-term impacts highlight the need for precise formulation and further research to optimize EO-based interventions in commercial settings.