A horse put down after breaking a leg during a tornado in Colorado produced progeny almost a year after her death through surrogate mothers, her owner says.

Two foals were born in April, KUSA-TV in Denver reported. They were conceived through in vitro fertilization at the Colorado State University Equine Reproduction Laboratory and carried by surrogate mares.

Jennifer Mears, who owned the foals' mother, brought them back to her ranch in Lucerne in northern Colorado this Tuesday.

Tuesday, an American quarter horse, was behind a shed that collapsed on May 22 last year, Mears said. She took the horse to the CSU veterinary hospital where eggs were harvested and Tuesday was put down.

The foals, both males, are described as healthy.

"The outcome is the result of a decade's worth of work," said Dr. Pat McCue, director of the laboratory.

Mears, who describes Tuesday as having been her "best friend," is thrilled.

"I'm totally ecstatic," she told KUSA. "I have two beautiful babies who make a name for Tuesday."