Metformin, the common diabetes drug, enhances egg-laying in older hens by triggering liver genes that promote yolk production and reduce fat buildup — offering a major breakthrough for sustainable poultry farming.
It turns out chickens and humans share more in common than you might expect, especially when it comes to fertility. And the surprising connection? A widely used diabetes medication called metformin.
Researchers at Penn State have discovered that metformin, best known as a treatment for type 2 diabetes and polycystic ovary syndrome (PCOS) in people, can also help chickens lay more eggs. Specifically, it helps broiler breeder hens, the parent stock of meat chickens, stay fertile longer and produce more eggs as they age.
New Discovery: How Metformin Boosts Egg Production
While the scientists have known for a couple of years that metformin improves egg-laying in chickens, they recently uncovered how it works. The findings were recently published in Biology of Reproduction.
Broiler breeder hens have been selectively bred for decades to produce fast-growing offspring, helping supply affordable chicken meat across the globe. But there’s a downside: as these hens grow older, their fertility declines rapidly. This drop in egg production closely resembles what happens in women with PCOS, a hormonal disorder that also impacts fertility.
That’s where metformin comes in. The same medication that helps regulate hormones and improve fertility in women with PCOS is now showing promise in doing something remarkably similar for chickens.
Human Fertility Clues from Chicken Studies
PCOS, a hormonal disorder affecting women characterized by irregular menstrual cycles, is the most widespread endocrinological condition, affecting roughly 4% to 12% of women, and the main cause of infertility in women, according to the National Institutes of Health. Metformin is often used off-label to treat PCOS symptoms, improving insulin sensitivity, lowering excess hormone levels, and helping to regulate menstrual cycles, potentially aiding fertility.
In a 2023 study published in the journal Reproduction, researchers at Penn State gave a group of hens a small daily dose of metformin over 40 weeks. The results were striking: The hens laid more fertile eggs, had lower body fat, and showed healthier reproductive hormone levels than those not given the drug.
Improved Reproduction and Metabolic Health
“These findings suggest that metformin can significantly improve ovarian function in broiler breeder hens,” said Ramesh Ramachandran, senior author on the study, professor of reproductive biology in the College of Agricultural Sciences.
The researchers then dug deeper to find out what exactly was happening inside the birds’ bodies, and they found the answer in the liver. The liver plays a key role in bird reproduction, as it’s where egg yolk precursors are made. Using advanced gene sequencing techniques at Penn State’s Huck Institutes of the Life Sciences, the team analyzed RNA, genetic material that regulates many biological functions, from liver samples.
Genes Turned On and Off by Metformin
Their findings, published in their latest paper in Biology of Reproduction, revealed that metformin “switched on” several genes involved in producing yolk proteins and maintaining stable blood sugar. At the same time, it “switched off” genes linked to fat buildup — mirroring how metformin works in humans with metabolic disorders.
Implications for Poultry Farming and Food Safety
“Essentially, metformin helps older hens stay metabolically healthier, which lets them keep producing eggs well beyond their usual decline,” said Evelyn Weaver, a postdoctoral researcher and lead author on both studies.
This finding could have major implications for poultry farming, the researchers said. By extending egg production in broiler breeder hens, farmers may be able to reduce flock turnover, improve animal welfare, and increase efficiency — all while using a medication that’s affordable and safe. Metformin is quickly metabolized by these hens, Weaver pointed out, so it poses no risk of entering the human food supply.
Reference: “Metformin alters liver metabolism to sustain egg production in the reproductively aging broiler breeder hen” by Evelyn Anne Weaver, Nathan Patrick Connolly, Tae Hyun Kim and Ramesh Ramachandran, 28 March 2025, Biology of Reproduction.
DOI: 10.1093/biolre/ioaf072
The research was conducted in the Ramachandran lab in Penn State’s Department of Animal Science, with contributions from Tae Hyun Kim, assistant professor of avian biology, and undergraduate researcher Nathan Connolly.
The U.S. Department of Agriculture and the National Institutes of Health funded the research.
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4 Comments
JFC people, leave the poor chooks alone. It’s bad enough they have been bred to massively overproduce eggs, and are basically spent by the time they are 18 months old, and are then sent to slaughter. Any that are rescued end up with reproductive tumours after a year or two because of the way they have been selectively bred. It’s unusual for an ex-farm layer to make it much past 4 or 5 years of age, whereas the normal age for a chicken is up to 10 or more years. We’ve been rescuing ex-layers for many years and they all end up dying of tumours. And the roosters that are born, which are about half of all chicken hatched? They are thrown into meat grinders alive and conscious when just a few days old because they are no use to the egg industry. The egg industry is an appalling animal abusing industry and needs to end.
Interesting re-confirmation of Metformin role in longevity.
this sounds as creepy as driving up the milk production of cows
As then using this DRUG TO ENHANCE EGG PRODUCTION, that will no doubt enhance/increase , the chance of more humans having diabetes, wanna be [new study out, egss causing tne increase in people with diabetes]