Fertirelin
Acetate

The Discovery

The Farm Challenge

By the 1970s, dairy farmers faced a growing problem.

By the 1970s, dairy farmers faced a growing problem. As herds got larger, it became harder to know when each cow was ready to breed. Missing the right window meant lost months of milk production and wasted money. Artificial insemination had revolutionized breeding, but it only worked if you timed it right. Scientists knew that GnRH — the same hormone Schally and Guillemin had discovered in humans — also controlled reproduction in cattle. If you could give cows a precise dose of synthetic GnRH at the right time, you could synchronize their breeding cycles and take the guesswork out of reproduction.

The Breakthrough

The Synchronization Solution

Japanese pharmaceutical company Takeda developed fertirelin, a synthetic analog of GnRH specifica...

Japanese pharmaceutical company Takeda developed fertirelin, a synthetic analog of GnRH specifically designed for veterinary use. Fertirelin was slightly modified from natural GnRH to be more stable and predictable in cattle. When injected, it triggered the pituitary gland to release a surge of LH (luteinizing hormone), which caused ovulation. Veterinarians could now give an injection and know almost exactly when the cow would ovulate. This made artificial insemination schedules precise and predictable. Farmers no longer had to watch each cow for behavioral signs of heat — they could manage breeding on a calendar.

The Trials

The New Routine

Fertirelin became part of systematic breeding protocols used on dairy and beef farms.

Fertirelin became part of systematic breeding protocols used on dairy and beef farms. The most common approach combined fertirelin with prostaglandin injections in a timed sequence. First, prostaglandin synchronized the cows' cycles. Then fertirelin triggered ovulation at a predictable time. Finally, artificial insemination was performed at the optimal moment. This protocol, and variations of it, dramatically improved pregnancy rates in large herds. A farmer with a thousand cows could now breed hundreds of them in a single week, something that would have been impossible with traditional heat-detection methods.

The Crisis

Results Beyond Expectation

Clinical studies in Japan and other countries showed that fertirelin-based protocols improved fir...

Clinical studies in Japan and other countries showed that fertirelin-based protocols improved first-service conception rates by 10-20% compared to natural breeding. This had enormous economic impact. Each month a dairy cow wasn't pregnant cost the farmer money in lost milk production and feed costs. Fertirelin also proved useful for treating cystic ovarian disease, a common condition where fluid-filled cysts prevent cows from cycling normally. A single injection of fertirelin could burst these cysts and restore normal fertility. The drug became a standard tool in veterinary reproductive medicine across Asia.

The Legacy

Feeding the World

Today, fertirelin remains widely used in Japan and several other countries for reproductive manag...

Today, fertirelin remains widely used in Japan and several other countries for reproductive management in cattle. While other GnRH analogs like gonadorelin and buserelin dominate in North America and Europe, fertirelin holds a strong position in Asian markets. The broader impact of GnRH-based reproductive technologies in agriculture is staggering: they help feed billions of people by making livestock production more efficient. Fertirelin's story is less glamorous than Nobel Prize-winning human medicine, but it represents the practical application of the same fundamental science. The hormone that controls human puberty also helps ensure the world has enough milk and beef.