DVUR KRALOVE NAD LABEM, CZECH REPUBLIC — A Czech zoo will dehorn its rhinos after poachers last week killed a white rhino at a French zoo and attempted to hack its horn off with a chainsaw.

The zoo in the central town of Dvůr Králové nad Labem said it will first administer an anaesthetic before cutting the horns off 18 adult black and southern white rhinos, the Guardian reported. Three calves will not undergo surgery.

With the rhino’s eyes and ears covered, zookeepers will use a chainsaw to cut horizontally into the horn to remove it. When the horns are removed, the zoo will file the sharp edges to smooth them down.

Last week, poachers killed Vince the white rhino at a zoo near Paris, but failed to get away with his horn.

Rhino horn is made of a fibrous protein called keratin, the same substance humans produce in our nails and hair. Rhino horn sells for around $60,000 per kilo on the black market, making it more expensive than gold or cocaine.

Most of the demand comes from China and Vietnam, where rhino horn is prized for its supposed value as an aphrodisiac and ingredient in traditional medicine. Such medicinal properties of rhino horn has not been proven.