Update 1/16/2018: A spokesperson for Borås Djurpark recently contacted The Dodo with the following statement: "We follow EAZA’s Code of Ethics and the Culling Statement, which are also reflected in the WAZA policy for the same issue. The euthanasia takes place at a biologically relevant junction, such as weaning, leaving the family unit or any other social group. We are very transparent about this concept, both in our communication with our visiting guests and students, as well as in our communication with the media."
In August 2012, four healthy lion cubs — Simba, Nala, Sarabi and Rafiki — were born at Borås Djurpark, a zoo in southern Sweden, after the zoo let their parents breed. By fall 2013, the zoo had killed all four cubs for a reason many people are now calling unacceptable.
According to Swedish media site SVT, zoo documents reveal that the four cubs were in excellent health at the times of their death, but the zoo simply considered them to be "surplus" animals.