Bononbos in Planckendael
Foto: Jonas Verhulst

Antwerp Zoo puts great apes on a diet

The great apes at Antwerp and Planckendael zoos are being served less fruit and more green vegetables. Thanks to this vegetable diet, the monkeys live healthier lives and there is less aggression in the group. "The animals had to get used to it, but we’ve seen a lot of progress," says coordinator Nicky Staes of Antwerp University.

The great apes are not getting less to eat but are being put on a different diet. By eating less fruit and more green vegetables, the animals have a healthier and more natural diet. "In the wild, monkeys also eat a lot of fruit, but the fruit here contains much more sugar," says research coordinator Nicky Staes (Antwerp University). Moreover, the monkeys get more food than before, so there is less aggression and competition for all the goodies. "We noticed that the higher-ranking monkeys eat more and have put on weight," Staes adds.

The great apes have been on their new diet since January. There was an eight-week transition period giving the monkeys time to adjust to the new diet. They have been fully on the vegetable diet since March.

Nicky Staes has already noticed a lot of progress. "Aggression has reduced, but we also see more activity in the monkeys, which means they scratch themselves less as a result of stress," she says. The diet change is benefiting the animals. However, not all the monkeys are equally enthusiastic about every vegetable. "Spinach was less to their liking, so we removed that from their diet."

To track the weight of the great apes, the zoo needs special animal scales. "We are asking visitors to help sponsor the purchase so that we can install scales in the monkey enclosures," says Staes. "Right now, we don't know how much the monkeys weigh. We can hardly put them on ordinary scales."

You are what you eat

In the future, Staes wants to take her research a step further. "We would like to see whether the vegetable diet alters the microbes in the gut, which are very important because they influence behaviour. You are what you eat."

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