A man who tried to breed enormous hybrid sheep using genetic material from endangered animals so he could sell them to trophy hunting ranches has been sentenced to six months in prison, the US Department of Justice said Monday.

Arthur Schubarth, 81, illegally imported parts of the world’s largest species of sheep from Kyrgyzstan, which he used to create cloned embryos in the United States.

The resulting embryos were then implanted in ewes on his Montana ranch, resulting in the birth of a genetically pure Marco Polo argali, an endangered species that can weigh more than 300 pounds (135 kilograms) and has horns more than five feet (1.5 meters) wide.

Schubarth then used semen from this specimen to impregnate various species of sheep in an effort to create never-before-seen hybrids, with the goal of breeding even larger sheep.

He hoped to sell the resulting animals to “canned” hunting ranches, facilities where customers pay to shoot captive animals, and where bigger animals can command higher prices.