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| The Context |
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Trypanosomiasis, a protozoan disease transmitted by tsetse flies, is one of the top 3 animal diseases in sub-Saharan Africa. It prevents, or seriously curtails, the keeping of ruminants and equines over 10 million square km of potentially productive land. Over 40 million cattle are affected by poor productivity and many die. The most dangerous trypanosome species affecting cattle in Africa are the blood trypanosomes Trypanosoma congolense and T. vivax. Rural development and livelihoods are severely damaged in these areas through the absence of cattle to provide draught power, milk, manure and meat.
Much research and extension effort has been devoted to the control of this disease through the use of drugs and control of the fly vector. But it's been a loosing battle as only 5 % of the affected area has been cleared of tsetse flies in the last 100 years. Attempts to control the disease are compromised by the vast areas involved and the ability of the trypanosome itself to evade the immune systems of their hosts. Livestock owners have reacted by only keeping cattle and other ruminants in areas where tsetse flies are less common. But these are often semi-arid or desert areas where the supplies of water and feed are frequently difficult to find.
The only exception to this general rule is in West Africa where a number of breeds of cattle, like the N'Dama and West African Shorthorn and small ruminants have developed a degree of innate or natural resistance (trypanotolerance) to the pathogenic effects of trypanosomes. As a result those breeds can at least survive in areas with high tsetse populations. However, even in these areas, feed supplies can be severely restricted and trypanotolerance can break down through the prolonged dry season.
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| Methods |
A solution - Better Feeding Practices If drugs to treat animals are too expensive, unavailable or drug resistance has appeared farmers can help their animals resist and recover from the threat of trypanosomosis by opting to feed stock better. Scientists have come up with a number of feeding options to counter the effects of trypanosomiasis:
| Anaemia |
This is the principal characteristic of trypanosomiasis and common when the disease first strikes. It is caused by lack of red blood cells that are killed off by the parasite when it gets into the blood. Better feeding will not halt the disease but protein levels eaten can influence the rate at which anaemia develops and higher energy intake helps recovery. So feeding a high protein supplement as found in concentrates or a leguminous fodder or just letting grazing stock access to a wider range of forage will help slow anaemia. Goats and sheep, if allowed, will even self-select higher value protein forage like tree leaves and scrubs if infected with trypanosomosis. |
| Fever |
Common at the start of the disease, fever is associated with increased energy demands, needed to maintain body weight. Fevered animals will show less voluntary activity and poorer productivity like lower milk yields. Feeding more protein and energy will again help. |
| Weight changes |
Animals generally lose weight if they get trypanosomiasis. Feeding high levels of protein will slow this loss and mean a speedier recovery and quicker return to productivity. A thinner animal is weaker and takes much longer to get back to full health. |
| Growing |
High food intakes allow infected animals to grow at the same rate as uninfected ones as long as energy intake is adequate. This means, for example, supplementing the normal poor quality forage grazed in the dry season. Low energy levels will just increase body weight losses. |
| Feed intake |
Trypanosomiasis normally reduces the amount an animal eats through loss of appetite. As ruminants have to eat lots of poor quality forage to get sufficient protein this is a problem. Giving high protein diets helps compensate for this loss. Where the disease limits intake, animals will often exhibit preferential selection of higher quality browse. So allowing them to range or giving a selection of fodder will all help. |
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| Resources Required and Support |
Farmers are usually well able to identify when their animals are sick or ill but they sometimes need assistance in identifying exactly which disease is present. With the loss of many state veterinary organizations in Africa farmers now have less advice from government in keeping animals in good health. There is thus a role for both the non-government (NGO) and commercial organizations to assist in giving good advice to farmers in identifying both disease problems and cost effective feeding practices to keep animals healthy. |
| Costs and Benefits |
Obtaining high protein or high-energy feedstuffs especially if they have to be bought in from off the farm, can be costly. It is important therefore that the farmer calculates the benefits of extra feeding. Often with trypanosomiasis there is a significant benefit in taking action to avoid unhealthy or dead animals. If however, the threat of the disease is ever-present then costs are on-going and will make keeping animals ultimately more expensive when compared to those kept in areas without tsetse flies.
In Africa the disease threat varies through the year depending on the season and better quality food is often available, for example, during the wet season. The most dangerous period is likely to be at the start of the rainy season when animals may be in poor condition following lack of availability of good quality forage. An upsurge in fly numbers at this time is brought about by climatic conditions and so the disease threat is high. Strategic feeding of high energy and high protein feeds in the latter part of the dry season will enable animals to gain better physical condition to counter any threats. |
| Risks |
The major risks associated with better feeding of livestock to avoid or reduce the effect of trypanosomiasis is the cost of feeds being too expensive for the farmer to purchase or obtain. If climatic conditions in these semi arid areas are poor, as in a drought, then the price of purchased concentrates and cereals may well be too expensive to feed to animals. The danger then is that the farmers will have to suffer the catastrophic losses the disease may cause. |
| Alternatives |
The strategic use of drugs or fly traps have been shown to give protection to a herd or flock of animals. Where cash is limited it is possible to treat only the larger males in a herd with a systemic insecticide drug. The large males are selected, as these are the animals that the tsetse flies usually target and when the flies take a blood meal the insecticide kills them. This reduces the fly population overall so there are less flies to attack other animals and so the incidence of trypanasomosis is reduced. Flies can also be lured into traps using colours and smells where they are killed with insecticides. Using drugs in this way is effective but requires cash, cooperation with community groups and a constant campaign, all of which may be beyond the capabilities of poor farmers. |
| Impacts |
In Africa good nutrition has always been associated with keeping animals healthy. Better fed animals are usually able to tolerate both diseases and parasites. If farmers can be encouraged to feed their animals with higher protein and higher energy level feedstuffs then their stock would be more disease tolerant and more productive. This has obvious implications for improving the livelihoods of poor farmers. Better feeding of the animals will ultimately lead to a better lifestyle for the farming family. |
| Policy Implications |
Scientists still have more work to do in identifying the minimum levels of protein and energy supplementation required to halt the negative effect of trypanosomiasis, and the nature and quality of protein supplements to achieve sustainable benefits.
Such research needs to be encouraged and supported. Veterinary and Livestock extension services should also be made more aware of these findings. |
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| References and Further Reading |
If you would like further information on the implications of the original DFID project then the scientists involved would be happy to help.
- P.H. Holmes, J.J. Bennison, and J. J. Parkins,
University of Glasgow Veterinary School,
Bearsden Road,
Glasgow, G61 1QH, UK.
- E. Katunguka-Rwakishaya,
Makere University Veterinary Faculty,
P.O. Box 7062,
Kampala,
Uganda.
Akinbamijo, O.O., Bennison, J.J., Romney, D.L., Wassinak, G.J., Jaitner, J., Clifford, D.J., & Dempfle, L. (1997). An Evaluation of food intake, digestive physiology and live-weight changes of N'Dama and Gobra zebu bulls following experimental Trypanosoma congelense infection. Animal Science 65, 151-158 |
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| Related Research Projects |
This information is part of a series on small stock that cover disease-nutrition interactions.
| R6140 |
Controlling trypanosomosis in Sheep & Goats is more important than extra feeding |
| R6342 |
Best Feeding Practices to help animals fight Trypanosomosis |
| R6358 |
The Decision Tree that Helps counter the threat of Trypanosomosis |
| R6561 |
Helping lambs to control stomach worms before they get sick |
| R6608 |
Feeding Tree Fodder to beat liver Fluke |
| R7424 |
Farmers can use Tannins to kill parasitic worms |
| R8151 |
Sensible use of drugs and feeding to stop roundworms killing sheep & goat |
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