Equine scientists in the United States believe they have produced the first ever foals, Ethyl and Vitreous, using frozen eggs from donor mares.

The technique is being hailed as a breakthrough as it can provide flexibility in reproduction specifically for female genetic lines.

Surrogate mothers were implanted with freeze-thawed eggs from the donor mares. The recipients were then inseminated with semen from the donor stallion.

The technique was carried out at the Colorado State University which has done several other studies using eggs from mares.

“It has taken several years to establish conditions that have led to the birth of Vitreous and Ethyl,” says Lisa Maclellan from the equine team at the university.

“Despite the wonderful success of this project, further studies will be required to optimise the conditions so that the cryopreservation of eggs will be a commercially offered procedure.”

Lisasays the technique could offer horses owners more reproductive options.

“Mares that have competition careers can have eggs frozen for future transfer when they are older and have established performance records.”

Both foals born are said tobe normal and healthy. The university says they will be adopted to “knowledgeable horsepeople”, so that the university can monitor their growth and development.