Evidence map›Paper›PMID 42494492›Full record

ReviewVeterinary and animal science2026

A meta-analysis of

Hossein Hassanpour, Mehraban Salsali, Tahereh Karimi-Shayan, Mohammad-Saeed Heydarnejad, Aziz A Fallah

Abstract readReview
In one paragraph

Review in Veterinary and animal science, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from 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.

2 · The registry

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.

3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Hossein HassanpourDepartment of Basic Sciences, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran.
Mehraban SalsaliDepartment of Basic Sciences, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran.
Tahereh Karimi-ShayanDepartment of Biology, Faculty of Science, University of Mohaghegh Ardabili, Ardabil, Iran.
Mohammad-Saeed HeydarnejadDepartment of Animal Science, Faculty of Basic Science, Shahrekord University, Shahrekord, Iran.
Aziz A FallahDepartment of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

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.

Indexed as

Egg qualityEssential oilLaying hensOriganum vulgarePowder

Identifiers

PMID42494492
PMCPMC13393712

What Socratic holds

Textmetadata
LicenceCC BY-NC
Read underepoch 390

Registered trials

None linked

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 Socratic graph.