Oocytes From Live Mare Produce Healthy Cloned Foal

A Lipizzaner foal born on May 5 is the first cloned horse produced by using oocytes (immature egg cells) harvested from a live mare. Previously, oocytes recovered from live mare donors were used to clone mules, but horses were cloned using oocytes harvested from deceased animals.

The cloned foal was produced by a team led by Katrin Hinrichs, DVM, PhD, professor of veterinary physiology and pharmacology and Patsy Link Chair in reproductive studies at Texas A&M University. The team paired the oocytes with skin cells taken from a 30-year-old Lipizzaner stallion.

In a process identical to that used to recover eggs from women for in vitro fertilization, Hinrichs recovered oocytes from all the follicles present on donor mare ovaries, then matured the oocytes in vitro.

The use of oocytes harvested from live mares is a milestone in part because it allows researchers greater control over the clone's cell composition, Hinrichs said.

"This (process) makes it possible to select the mares you want to use as oocyte donors, which is important if you want to control some aspects of the cytoplasm of the resulting clone," she said.

The surrogate carrying the foal was later transferred to the University of Florida College of Veterinary Medicine where a team of specialists including Margo Macpherson, DVM, Malgorzanta Posor, DVM, PhD, and Dr. Rob MacKay, BVSc, PhD, monitored the pregnancy's progress and provided post natal care for the foal.

Owner Kit Knott asked Hinrichs' team to produce the foal, later named Mouse, after failing to find an animal comparable to her stallion.

"I not only wanted to reproduce the stallion's physical build, but its temperament as well," said Knott. "Mouse is just the cutest, sweetest foal; he's all we hoped for."

About the Author

Pat Raia

Pat Raia is a veteran journalist who enjoys covering equine welfare, industry, and news. In her spare time, she enjoys riding her Tennessee Walking Horse, Sonny.

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