UNIVERSITY PARK, Pa. — In a surprising agricultural breakthrough, researchers at Penn State have discovered that metformin, a widely used medication for type 2 diabetes and polycystic ovary syndrome (PCOS) in humans, can significantly boost egg production in broiler breeder hens — the parent birds of the chickens we eat.
This discovery, recently published in Biology of Reproduction, reveals how metformin not only helps older hens lay more fertile eggs, but also improves their metabolic health and reproductive hormone levels, extending their productive lifespan.
Broiler breeder hens have long been bred for offspring that grow rapidly, meeting the global demand for affordable chicken meat. However, as these hens age, their fertility declines — mirroring symptoms of PCOS in women. In humans, PCOS is a common hormonal disorder affecting up to 12% of women, and a leading cause of female infertility, according to the National Institutes of Health.
“Metformin’s ability to regulate reproductive hormones and reduce body fat in hens is remarkably similar to its effects in humans with metabolic disorders,” said Dr. Ramesh Ramachandran, senior author and professor of reproductive biology at Penn State’s College of Agricultural Sciences.
In a controlled 40-week trial published in Reproduction, hens receiving a small daily dose of metformin laid more fertile eggs, had healthier hormone profiles, and accumulated less fat compared to those that didn’t receive the medication.
Researchers then used advanced RNA sequencing to investigate how metformin interacts with the liver — a key organ in egg production due to its role in synthesizing yolk precursors. They found that metformin activated genes involved in yolk protein production and glucose regulation, while suppressing genes linked to fat accumulation — mechanisms that mirror its action in PCOS treatment.
“Essentially, metformin helps aging hens remain metabolically younger, allowing them to lay eggs longer than expected,” explained Dr. Evelyn Weaver, lead author and postdoctoral researcher.
The findings offer promising implications for the poultry industry. By prolonging the egg-laying capacity of broiler breeder hens, farms could reduce flock turnover, improve animal welfare, and enhance production efficiency — all while using a cost-effective and food-safe drug. Weaver also confirmed that metformin is rapidly metabolized in chickens, eliminating concerns over drug residues in meat or eggs.
This cutting-edge research was conducted by the Ramachandran Lab at Penn State’s Department of Animal Science, in collaboration with Dr. Tae Hyun Kim and undergraduate researcher Nathan Connolly. The project was funded by the U.S. Department of Agriculture (USDA) and the National Institutes of Health (NIH).
