SynthesisVeterinary medicine and science2025
Effects of Dietary Thymus vulgaris on Laying Hens: A Systematic Review and Meta-Analysis of Productive Performance and Egg Quality.
Synthesis in Veterinary medicine and science, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
2 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Effects of Dietary Thymus vulgaris on Laying Hens: A Systematic Review and Meta-Analysis of Productive Performance and Egg Quality.Veterinary medicine and science · 2025Pooled it
- A meta-analysis ofVeterinary and animal science · 2026Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
4 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectivesNatural alternatives to synthetic additives are being explored as a means to enhance laying hen performance and egg quality. The study conducted a systematic review and meta-analysis to evaluate the effect of dietary supplementation with Thymus vulgaris (thyme) on productive performance and egg quality in laying hens.
methodsA comprehensive search of databases identified 18 eligible studies. Data were analysed using random-effects models, with subgroup analyses based on the thyme form (powder, essential oil, extract) and supplementation duration (≤ 8 weeks, > 8 weeks). The unstandardized mean difference was used to calculate the effect size, and confidence intervals were generated to estimate the range of the true effect size.
resultsThyme significantly improved egg weight, egg mass, yolk colour, yolk index and shell thickness (p < 0.05), with very large effect sizes for egg weight and mass. However, albumen quantity decreased, while egg production rate, Haugh unit, and shell weight remained unchanged. Powdered thyme was particularly effective at enhancing egg weight and mass, while essential oils and extracts improved yolk colour. Longer supplementation periods (> 8 weeks) yielded greater benefits for egg mass and weight, whereas shorter durations (≤ 8 weeks) improved shell thickness.
conclusionsThese findings suggest that thyme supplementation, particularly in powdered form and over extended periods, can enhance egg quality, offering a natural alternative to synthetic additives. This research demonstrates thyme's efficacy as a phytogenic feed additive, offering a natural solution to improve egg quality and meet the rising demand for sustainable and high-quality poultry products. SUMMARY: Thyme supplementation improves egg weight, egg mass, yolk colour and shell thickness in laying hens. Powdered thyme shows the most significant benefits for egg weight and mass. Longer supplementation periods (> 8 weeks) enhance yolk colour and egg quality traits. Thyme offers a natural, sustainable alternative to synthetic feed additives in poultry production.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.