From: Allison Winter, ENN
Published September 20, 2012 11:23 AM

Goats and sheep learn to avoid eating olive and grape leaves

Researchers from the Research Group on Ruminants led by Elena Albanell, lecturer in Animal and Food Science, have successfully thwarted sheep and goats from eating olive tree and grapevine leaves. By conditioning the species' palettes, researchers redirected their food preferences making them more willing to eat undesirable plants from pastures.


Olive trees, grapevines, fruit trees, and other woody plants make up about a quarter of the cultivated cropland in Spain. These cultivation systems allow plants to grow around the trees or vines, however, in order to prevent these plants from choking out the crop, they must be controlled with herbicides and farming equipment. These processes not only cost time and money for farmers, but they can cause environmental impacts due to the residues left behind from the chemicals and the compacted soil produced by farming equipment can lead to reduced rainfall infiltration and poor root penetration.

A more environmentally sound system would be to control these undesired plants with grazing sheep and goats. This system would reduce the use of herbicides and fertilizers and could also favor a more sustainable integration between the agricultural and farming sectors.

The downside to grazing is the damage caused by the animals, since sheep and goats would be free to eat leaves and sprouts from the plants farmers are trying to cultivate.

So how can we get these grazers to eat the undesirable plants that farmers don't want, yet avoid eating the good stuff?

Researchers at the UAB Faculty of Veterinary Medicine proposed the use of conditioned taste aversion to redirect the food preferences of these goats and sheep. A pilot plan revealed that sheep and goats could in fact be trained not to eat certain leaves.

Conditioned taste aversion is a natural defensive mechanism animals develop when learning which foods are healthy and which are potentially toxic. To achieve this aversion, researchers fed olive leaves and soft shoots laced with lithium chloride to individuals that never tasted the food before. Lithium chloride is used medically as a mood-stabilizing drug and in this case was used to modify eating habits in animals.

With one dose of lithium chloride, the sheep and goats rejected the olive leaves from the first day and their behavior differed greatly from the animals that were not given a dose of the compound.

While more research needs to be done, the results are very encouraging as the system has the potential to reduce the use of pesticides and farming equipment with the introduction of selective grazing.

Read more at the Universitat Autonoma de Barcelona

Goat image via Shutterstock. 

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