Cactus pear: an oasis in dry Africa

Anyone searching for a wonder fodder crop for semi-arid regions need look no further than the cactus pear
Issue date 26 October 2007

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Anyone searching for a wonder fodder crop for semi-arid regions need look no further than the cactus pear. During drought, when little else is available, cactus cladodes alone can be fed to ruminants allowing them to survive for many months – even without drinking water. So says Ernst Erasmus who experienced this first as a mixed farmer and then as an adviser in the Gauteng agriculture department where he works with commercial and emerging producers. Wonder of cactus pears While conceding that cactus cladodes are not a balanced feed but rather a good, inexpensive source of energy, he believes the plant has unbelievable versatility and production potential. “But farmers unfortunately don’t see this. Instead, they continue to spend money and time on thirsty crops such as lucerne or buy in feed during droughts,” Erasmus says. “Sure, animals prefer veld and other food when conditions are good, but come winter or drought and you won’t be able to keep the animals away from the cactus. You can feed a big cow a 14kg pure cactus diet supplemented only with dry hay for saliva and rumination, and protein. You’ll need about 1t a day to maintain a flock of 250 sheep, again with a dry supplement added. The beauty is that you won’t need more than about 4ha, planted at 80cm x 80cm (giving you 40 000 plants per hectare).” A dense stand of cactus pear can yield 400t of feed per hectare per year under ideal conditions. If you only produce 250t/ ha you’ll still be beating sugarcane, the next best producer, by 150t. In dry areas, even without irrigation and fertiliser, the crop can yield five times more dry matter (DM) than natural veld. Under rainfed conditions yield may vary from 2t to 10t DM per hectare per year if harvested every two to three years. Contour plant to reduce rainfall runoff, especially where rainfall is only 250mm per year. Fears and fallacies O ne of the reasons why farmers don’t plant cactus pear is because of their fear of cochineal. But Erasmus contends that this is not a serious problem. “In most stands the pest is easy to control using Cypermetrine on a spot treatment basis. Just inspect your plantation regularly,” he advises. Another problem is that the pads are low in crude protein. Any ration for non-reproductive sheep and cattle should contain at least 8% crude protein. A sheep with a liveweight of 35kg requires about 50g crude protein per day. The average 500kg of DM from the daily ration of cactus cladodes contains only 20g of crude protein, so cactus cladodes must be supplemented. Erasmus says the crude protein content of cactus pear fodder can be raised from between 3,5% and 4,5% to 8% and 10% by applying nitrogen. Supplement cactus rations with one-third bonemeal, one-third common salt and one-third urea. Another possibility is a ration consisting of cactus meal and 6,5% fishmeal, which will meet the needs of sheep. There’s also the question of laxative action in ruminants. “This is not a disease symptom and has no detrimental effect on the animal’s health,” Erasmus says. “It is merely the result of a fast passage through the digestive system. The laxative effect can be curtailed by feeding fodder lime (3% of the total intake) to counteract acidosis; adding lime to the drinking water; and feeding hay with the cladodes.” He says the best variety to plant for fodder is Gymno Carpo obtained from established plantations at about R4 per treated cladode. “If that’s too expensive for you, cut the cladode into 10 pieces and grow your own plants from these.” For direct browsing, grow dense stands with short plants. The cut-and-carry system requires a wider space to accommodate a tractor and trailer. In this case a 1m x 6m layout is preferred, giving a mean planting density of about 1 666 plants per hectare. Contact Ernst Erasmus on (012) 548 7268 or 082 573 9273. |fw