Image copyright AP Image caption Marius was said to be physically healthy, but the zoo said it followed recommendations

A young giraffe at Copenhagen Zoo has been euthanised - in the words of officials - to prevent inbreeding. The BBC examines the reasons for the action, which caused an outcry.

The zoo says this was done because the genes of the giraffe, named Marius, were too similar to those of other giraffes in a breeding programme run by the European Association of Zoos and Aquaria (EAZA).

Breeding closely related animals increases the chances that rare, harmful genes are expressed in offspring.

Two copies of a gene are inherited - one version from each parent. One of these copies might be harmful (deleterious), but if the other parent carries a non-harmful version of the gene, pairing them up might not result in any adverse consequences for offspring.

If you take away their ability to procreate, you are taking away even more of their natural life Prof Peter Sandoe, University of Copenhagen

When parents are closely related, it increases the chances that two harmful copies of a gene will pair up.

A spokesman for EAZA stressed that, as an individual, Marius was not particularly inbred, nor was the giraffe suffering from any identifiable health problem. But the spokesman explained that Marius' parents had produced other offspring, so there were already giraffes with similar genes in the organisation's breeding programme.

"That means that the giraffe Marius, unfortunately, cannot add anything further to the breeding programme that does not already exist," an EAZA spokesman told BBC News.

The programme aims to make the most of the genetic diversity that exists, avoiding matings between the most closely related animals available.

He said all alternatives were looked at, but none were found to be viable, describing euthanising animals as a "last resort". When the future survival of a species was at stake, he said, unpalatable decisions sometimes had to be made.

"We need to prioritise - wherever possible - individuals who can help safeguard that future over the long term," said the spokesman.

According to the European stud book for giraffes, which dates back to 1828, only five giraffes have been euthanised for conservation reasons.

Image copyright Reuters Image caption Marius was dissected as part of an educational event

According to EAZA, giraffes born in zoos generally need to be moved away from their family group once they reach sexual maturity.

Giraffe breeding groups in zoos are made up of a single bull together with a group of females. So female offspring must be removed to prevent inbreeding, and bulls must be removed around the age of 18-24 months to prevent fighting.

Contraception is in its infancy for giraffes and there are significant side-effects with certain drugs, such as irreversibility EAZA spokesman

Joerg Jebram, who oversees the European endangered species programme for giraffes, told the AP news agency: "Zoos could design new giraffe facilities, but many don't have that option.

"A young bull could theoretically be sent to an all-female group as stud, but experts prefer a larger, more mature male for that, and Marius didn't fit that bill.

"A final option is sending the giraffe to a zoo that doesn't participate in the EAZA-led breeding programme, but that could leave the giraffe or its offspring being sold into worse circumstances, such as those of a circus or private collection."

Copenhagen Zoo had turned down offers from at least two other zoos to take Marius and an offer from a private individual who wanted to buy the giraffe for 500,000 euros ($680,000).

Why not move Marius?

Bengt Holst, Copenhagen Zoo's scientific director, said it had turned down an offer from Yorkshire Wildlife Park in the UK, which is a member of EAZA, because Marius' older brother lives there and the park's space could be better used by a "genetically more valuable giraffe".

The EAZA spokesman said it stood fully behind the decision by Copenhagen Zoo to euthanise Marius.

In one respect, Marius may have been a victim of giraffe-breeding success by European zoos.

"Historically, many of the 347 zoos that belong to [EAZA] were eager to have giraffes of any kind," said Mr Jebram.

"But in the past several years zoo breeding programmes have produced enough of some sub-species."

Image copyright Other Image caption Longleat Safari Park also said that it had destroyed five lions due to "odd aggressive behaviour"

So why not prevent closely related animals from breeding in the first place?

Contraception and castration have been raised as possibilities, but both would require sedation. This is a relatively high-risk procedure in the case of giraffes, as they are liable to break their necks when they fall while sedated.

Mr Jebram told AP that in the past few years a contraceptive has been developed that can be injected into females from a distance.

But the EAZA spokesman said: "Contraception is in its infancy for giraffes and there are significant side-effects with certain drugs, such as irreversibility. This means we would lose vital animals in terms of breeding.

"We have to weigh up all the considerations, but we have a limited amount of space in which to conduct this endangered species breeding programme."

This week also saw news that five lions were put down at Longleat Safari Park in the UK because of genetic problems caused by inbreeding.

In a statement, the Wiltshire park said it had no choice but to put down a lioness and her cubs because they displayed "odd aggressive behaviour".

Ethical question

In a statement on the death of Marius the giraffe, the Royal Society for the Prevention of Cruelty to Animals (RSPCA) said it was "extremely saddened to hear the story of this poor giraffe".

"What a shame another home could not be found for him, especially as it sounds as if there were suitable offers."

A post-mortem examination of Marius was broadcast live on the internet.

A crowd of visitors, including children, watched as the carcass was skinned, cut up and fed to the zoo's lions.

Peter Sandoe, professor of bioethics at the University of Copenhagen, who is well acquainted with the zoo, said he sympathised with the decision to put down the giraffe.

"When small children can go and see this giraffe and see it being turned into lion food, it's a very good picture of what nature is like," he said.

On the savannah, Prod Sandoe explained, "many will die young, killed by lions, killed by diseases, killed by accidents, by lack of food".

On the question of contraception as an alternative, he said: "You're already taking away a lot of the natural behaviour by putting them behind a fence.

"If you take away their ability to procreate, you are taking away even more of their natural life."

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