Opuntia spp.

Prickly-pear cactus

One of the largest genera of cactus, comprising at least three hundred species which are highly variable in habit and size. The stems and branches have flat cylindrical or globular joints, usually very fleshy. Some species are almost spineless. The opuntias are commonly large and rampant. They are sometimes cultivated as hedge or for the edible fruits, but they are more commonly regarded as a weed in arid and semiarid areas.

The prickly pears are sometimes used as an emergency feed for animals during droughts, but the spines must first be destroyed with a gasoline torch by passing a flame over the surface of the plant. The spines are dry and burn easily, especially if they are abundant and close. If large quantities are used, the material can be chopped so that the spines are thoroughly broken up. If they can still cause harm, the broken spines should be winnowed out. Other methods of making the spines harmless are soaking in water, steaming or washing with soda. Because of its high water content and high average salt content, prickly-pear cactus is laxative when fed in large quantities. The opuntias are fairly palatable and when fed in liberal amounts can replace drinking water; however, the nutritive value is not sufficient to maintain weight in animals receiving only cactus. Sheep in good condition are known to survive up to eight months on a diet consisting entirely of opuntia. Preferably the feed should be supplemented by other less succulent dry feeds, such as 1-2 kg of straw or dry grass and 0.5 kg of cottonseed daily. Prickly-pear cactus is sometimes combined with poor quality straw or hay in silage.