How is Copenhagen Zoo still functioning? Now they kill off 4 lions?

According to this article

The Copenhagen Zoo now killed the 4 lions, of which were fed the remains of the baby giraffe due to “overcrowding” in their zoo. In a nutshell they are making way for a new younger soon to be dominant male Lion and had to put down the 4 lions who earlier feasted on the mutilated giraffe (in public mind you for “teaching purposes” to “humans”)

Isn’t there some sort of international zoology committee that has some sort of say in all of this that speaks for the greater good?

Or is this how it is when strictly business minded higher ups make these decisions in the name of science?