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Guest Question – Why Do Giraffes Chew Bones?

23 Jan 2020 | By Author Thornybush | Wildlife

Picture this, you’re out on a game drive during your South African safari and you come across a herd of giraffe. Most of them are contentedly munching on camel thorn leaves but one of the herd appears to be chewing on an old bone. There must be a reason, right? Well here it is.

Nutritional Necessities

Giraffe can consume up to 34 kilograms of foliage a day but even that’s not enough for them. The spindly leaves that they love so much are high in protein, fibre, carbohydrates and most minerals but can be lacking in a few essentials.

Giraffe’s huge bodies need a substantial skeleton to keep them upright and these big bones need calcium and phosphorus to remain healthy. Unfortunately, leaves are slightly lacking in the amounts of calcium and phosphorus that are so essential for bone density. This is especially true during the dry season.

A deficiency in phosphorus can also cause serious issues with mammals’ reproductive systems, growth, protein synthesis, cell signalling, lactation and energy metabolism.

Meal Plan B

Fortunately, giraffes and other large ungulates such as kudu, have a Plan B. They simply pick a bone up off the ground, move it into a comfortable position using their tongue, and away they go.

Chewing on bones is a way to supplement their diet and stay healthy. By sucking and chewing on bones, giraffe can extract small quantities of minerals from the surface of bones.

This phenomenon is called osteophagia and simply means ”feeding on bone”. The bones are never swallowed but simply dropped when the animals’ craving for nutrients has subsided.

Osteophagia and phosphorus

Studies have proven the link between osteophagia and phosphorus deficiency in a rather roundabout way.

During the 1900s South Africa underwent an epidemic of botulism among cattle. While this illness is not linked to a nutritional imbalance and is caused by a bacterium, a lack of phosphorus in the grazing lands turned out to be behind the epidemic.

Due to this deficiency, cattle were eating the bones of decomposing carcasses and inadvertently ingesting the bacteria that cause botulism. Once bone meal was introduced into their diets, the incidences of botulism stopped.

Apart from cattle, giraffe and kudu; red deer, camels, wildebeest, tortoises, and grizzly bears are also partial to snacking on bones when the mood takes them.

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Book a South African safari with Thornybush, and you could get to witness this natural phenomenon and many others during your stay.