Copenhagen Zoo has killed a healthy giraffe because of rules imposed by a European zoo association to deter inbreeding despite a wave of online protests to save it.

Zoo spokesman Tobias Stenbaek Bro says it put down the male giraffe, named Marius, on Sunday using a bolt pistol and will feed its meat to carnivores in the zoo.

Stenbaek Bro says the zoo was recommended to put down the giraffe by the European Association of Zoos and Aquaria because there were already a lot of giraffes with similar genes in the organisation’s breeding program.

Stenbaek Bro said EAZA membership isn’t mandatory but most responsible zoos are members of the organisation, which works to conserve global biodiversity.

An online explanation of the decision to kill the giraffe said it was “insurance that we in the future will have a healthy giraffe population in European zoos”.

The zoo continued to defend the kill on Facebook: “We would like to stress, that we do not consider it cruelty to animals to first euthanize a giraffe and then feed it to the lions. Lions are predators and thus they eat meat. In this case the lions were fed a giraffe, which lions also eat in nature. If we hadn’t fed them with the giraffe, they would have had to be fed with the meat of some other animal, which would have been put down instead.”

This post, and others by the zoo, received a severe backlash, with many calling the zoo “a disgrace”.

An online petition to save Marius had received more than 20,000 signatures.