No, monkeys don’t eat bananas!

The image of a monkey eating a banana is deeply anchored in the collective imagination, blame it on the cartoons and illustrated books that shaped our childhood. While it is true that fruits are eaten by wild primates (although in quantities that vary depending on the species), they contain 5 times less sugar than fruits cultivated by humans that are on the menu of the daily intake of primates housed in zoos. However, too much sugar due to the excessive consumption of cultivated fruits can cause physical problems (obesity, diabetes, diarrhea, heart disease, dental abscesses, etc.) as well as behavioral problems by increasing competition or aggression between individuals for example. Removing fruits, associated with an increase in fiber intake, has on the contrary, beneficial effects on the health and welfare of our animals: reduced risk of obesity and cavities, lower blood sugar, increased time spent searching for food and eating, reduced social stress and aggression between individuals, etc.

Even if the nutrition of zoo-housed animals has evolved considerably in recent decades, providing food that is nutritionally and structurally adapted to each species and promotes the expression of natural behaviors remains a real challenge. However, getting as close as possible to the natural diet of our animals is essential if we want to preserve their health and meet their physiological and behavioral needs.

This is why last spring, as part of our collaboration with the research organization Akongo to improve the welfare of our great apes, we began the dietary transition of our groups of gorillas and orangutans in order to get them with a fruit-free and high-fiber diet.

The process lasted about 3 months, their ration being modified every two weeks in order to gradually change the proportion of each food item. Little by little, the fruits were reduced and replaced by a greater portion of vegetables classified into 3 categories: root vegetables (turnip, black radish, sweet potato, parsnip, celeriac, etc.), stem vegetables (broccoli, avocado, artichoke, eggplant, celery, zucchini, etc.) and leafy vegetables (cabbage, lettuce, chard, endive, etc.). At the same time, we started to give them alfalfa either during the day or in the evening. Browse is also given as regularly as possible.

An ethology student, present throughout the transition period, was responsible for collecting data on food intake (weighing rations and leftovers, observing behavior at mealtimes, highlighting food preferences), with the veterinarians ensuring the nutritional (preparation of rations) and health monitoring of the individuals. Fecal samples were regularly collected and analyzed to monitor the composition of the microbiota, which can be significantly modified by a change in diet.

The assessment carried out approximately 2 months after the end of the food transition showed that our gorillas and orangutans have adapted rather well to their new diet, both from a behavioral and physiological point of view. The animals' weight has stabilized, and some new food items are particularly appreciated, such as artichokes, asparagus and avocados, now very popular with almost all individuals in these two species.

Our two groups of chimpanzees will undergo the same transition process in 2025. This will probably be spread over a larger number of weeks, the proportion of fruits in their ration being higher than that of gorillas and orangutans before the transition operated in these two species. Other primates in the zoo (pig-tailed macaques, buff-cheeked gibbons, cercopithecus...) are also currently undergoing a dietary transition. The other primate species will follow in 2025.

By the end of next year, no primates at La Palmyre Zoo will eat bananas or other fruits anymore! A small revolution that is, however, at the forefront of the current scientific recommendations on the nutrition of animals in zoos.