# Effects of dietary supplementation with a thymol-carvacrol blend on growth performance and intestinal health of poultry

## TL;DR

This study explores using a thymol-carvacrol blend as a natural alternative to antibiotics in poultry, showing improved growth and gut health.

## Contribution

The study introduces a composite thymol-carvacrol essential oil blend as a potential antibiotic substitute in broiler production.

## Key findings

- Supplementing with 600 g/t or 1200 g/t EO significantly increased average body weight and average daily feed intake.
- EO supplementation reduced serum total protein, albumin, globulin, and cholesterol levels.
- Histological analysis showed improved intestinal morphology with increased villus height and V:C ratios.

## Abstract

Antibiotic resistance has intensified the search for alternatives in poultry production. Essential oils (EOs), particularly blends of carvacrol and thymol, have shown potential as natural growth promoters and antimicrobials. This study evaluated a composite carvacrol-thymol EO as an antibiotic substitute in broiler production, focusing on growth performance, serum biochemistry, intestinal morphology, and gut microbiota.

A total of 672 Aibayi-Yijia broilers were randomly assigned to seven treatment groups: control (CK), EO1 (200 g/t feed), EO2 (600 g/t feed), EO3 (1200 g/t feed), EO1+AG (EO 200 g/t + FON 0.15 g/kg feed), EO3+AG (EO 1200 g/t + FON 0.15 g/kg feed), and AG (FON 0.15 g/kg feed). Growth performance, serum biochemistry (TP, ALB, GLB, GLU, AST, GGT, CHOL, TG, IL), jejunal histology (villus height, crypt depth, V:C ratio), and cecal microbiota (16S rRNA sequencing) were assessed.

Supplementation with EO (600 g/t) or florfenicol followed by 1200 g/t EO significantly increased ABW and ADFI (p < 0.05). EO (200 g/t or 1200 g/t) supplementation after antibiotics reduced serum TP, ALB, GLB, and CHOL (p < 0.05). Histological analysis showed increased villus height and V:C ratios with 1200 g/t EO. Cecal microbiota shifted, with increased Bacteroidetes and decreased Firmicutes.

The composite carvacrol-thymol EO blend showed promise as an antibiotic alternative, improving growth performance, supporting intestinal health, and modulating the gut microbiota. Further research is needed to optimize dosing, assess long-term safety, and explore EO interactions for scalable use.