Diabetes Drug Metformin Boosts Egg Production in Chickens
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, the journal Biology of Reproduction reported.
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.
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.
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.
“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.
Their findings, 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.
“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.
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