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