A lion at a zoo in the Netherlands has been given a vasectomy after he fathered five cubs last year.
The 11-year-old lion, named Thor, impregnated two lionesses. The first gave birth to twins, while the second had triplets."Why are we doing it? Because he's a proven breeder," the chief vet at the Royal Burgers' Zoo in Arnhem said.
The World Wildlife Fund says lion populations in the wild have decreased by 30-50% in the past 20 years.
But vet Henk Luten, who performed the surgery on Thursday, said the zoo now had enough of Thor's DNA.
"We have a lot of offspring and we don't want to have him overpopulating the genetic pool," he told the Reuters news agency.
While not unheard of, performing vasectomies on lions is rare.
"It's the first time in the 35 years that I've been a veterinarian here that I have done this operation on lions," Mr Luten said.He opted for a vasectomy instead of castration because the latter procedure would have caused Thor's mane to fall out. His lack of testosterone after castration would have also seen Thor lose his place in the pride's social hierarchy as a dominant male.
Lions are classified as vulnerable by the WWF, which means they are facing a high risk of extinction in the wild.