A meta-analysis of <i>Origanum vulgare</i> impact on egg production and quality in laying hens.
Oregano supplementation can improve egg production and quality in laying hens, with specific benefits depending on the form used and duration of supplementation.
Where it sits
this study against the rest of the thymalin (thymus extract) corpusSummary and findings
This study meta-analyzed the effects of Origanum vulgare on laying hen performance and egg quality. Randomized controlled trials were evaluated, focusing on egg production, egg weight, shell thickness, yolk color, Haugh units, yolk index, and shell weight. Significant enhancements were observed in egg production and quality metrics with specific recommendations for supplementation duration and form.
Abstract
In response to the growing demand for natural feed additives in poultry production, this study systematically reviewed and meta-analyzed the effects of Origanum vulgare (oregano) on laying hen performance and egg quality. Six databases (PubMed, ProQuest, Scopus, Web of Science, SID, and MagIran) were comprehensively searched from database inception to May 10, 2026. Only randomized controlled trials evaluating oregano supplementation (as essential oil or powder) in laying hens were included. Outcome measures comprised egg production, egg weight, shell thickness, yolk color, Haugh units, yolk index, and shell weight. Data were analyzed using a random-effects model, with subgroup analyses based on oregano form and supplementation duration. Publication bias was also assessed. Oregano supplementation significantly enhanced egg production, egg weight, shell thickness, and yolk color, with biologically meaningful improvements for commercial production. Subgroup analyses revealed form-dependent effects: powdered oregano improved egg weight, yolk color, shell thickness, and shell weight but reduced Haugh units; essential oil increased Haugh units but decreased yolk index. Both forms increased egg production. Furthermore, improvements in shell quality and yolk color were only evident after more than nine weeks of supplementation. In conclusion, oregano effectively improves egg production and quality in laying hens, with outcomes dependent on the form and duration of use. Long-term supplementation (>9 weeks) is recommended, using powder for better shell and yolk characteristics or essential oil for firmer albumen. Meta-regression confirmed form-specific effects, with powder superior for production and shell traits, and essential oil for albumen quality.
Background
This paper addresses the impact of natural feed additives, specifically Origanum vulgare, on poultry production metrics. Prior research has suggested potential benefits of oregano on various performance indicators in laying hens, but systematic evaluations were lacking. The current study aims to fill this gap by providing a comprehensive meta-analysis of randomized controlled trials.
Methods
The study systematically reviewed six databases for randomized controlled trials evaluating oregano supplementation in laying hens. The outcome measures included egg production, egg weight, shell thickness, yolk color, Haugh units, yolk index, and shell weight. Data were analyzed using a random-effects model, with subgroup analyses based on the form of oregano and supplementation duration.
Results
Oregano supplementation significantly enhanced egg production, egg weight, shell thickness, and yolk color. Specific findings included that powdered oregano improved egg weight, yolk color, shell thickness, and shell weight but reduced Haugh units. Essential oil increased Haugh units but decreased yolk index. Improvements in shell quality and yolk color were only evident after more than nine weeks of supplementation.
Interpretation
The findings suggest that oregano can positively influence egg production and quality in laying hens, with effects varying by form and duration of supplementation. While statistically significant, the clinical relevance of these improvements should be carefully considered, particularly in commercial settings. Potential confounds include the reliance on randomized controlled trials and the need for further studies to confirm long-term effects.
Key findings
- Oregano supplementation significantly enhanced egg production, egg weight, shell thickness, and yolk color.
- Powdered oregano improved egg weight, yolk color, shell thickness, and shell weight but reduced Haugh units.
- Essential oil increased Haugh units but decreased yolk index.
- Improvements in shell quality and yolk color were only evident after more than nine weeks of supplementation.
- Meta-regression confirmed form-specific effects, with powder superior for production and shell traits, and essential oil for albumen quality.
Limitations
- Not all studies may have controlled for confounding variables.
- The analysis is limited to randomized controlled trials, which may not capture all relevant data.
- The effects of oregano may vary based on environmental and management factors not addressed in the meta-analysis.