Smallstock farmers should watch out for animals showing signs of anaemia and bottle jaw, and learn to use the FAMACHA system, according to the Ruminant Veterinary Association of South Africa.
This system (FAffa MAlan CHArt) was developed by South African scientists Drs Francois Malan, Gareth Bath and Jan van Wyk. It allows a farmer to estimate the level of anaemia in sheep and goats from wireworm (Haemonchus contortus) infection and use this information to make the right deworming decisions.
To properly implement FAMACHA, a user should get practical instruction on how to use it properly and be sure to understand the information supplied.
Wireworm is the most important gastrointestinal nematode parasite affecting sheep and goat production on pasture in the warm regions of the world, particularly in the subtropical and tropical areas.
The worm has a small ‘tooth’ that cuts the animal’s stomach (abomasum) wall, and then feeds on the blood released. This can result in anaemia, a reduction in the number of red cells in the blood.
Major production losses and death occur where the worm is not adequately controlled with dewormers (helminthicides).
However, resistance to helminthicides is an ever-increasing problem. The FAMACHA system counters this with a diagnostic test that helps a smallstock farmer separate animals that require deworming from those that do not. The tool is simply a card that matches eyelid colour to anaemia levels.
Deworming only those animals that require treatment greatly decreases the development of resistance, because the eggs produced by the few resistant worms that survive treatment will be greatly outnumbered by the eggs produced by the animals that did not receive treatment.
If, on the other hand, all the animals are treated and moved to ‘clean’ pastures, only resistant worms that survive treatment will produce the eggs that form the next generation of worms.
Both resistance (the ability to prevent or suppress infection) and resilience (the ability to withstand the effects of parasites) are moderately heritable. This means that sheep and goats can be culled or selected for these traits.
In the long term, by culling animals that cannot cope with a moderate worm burden, you will breed a more resistant and resilient flock, genetically suited to the environment.
- You will see a significant drop in the amount and frequency of deworming for most of the animals in your flock, saving you money spent on chemicals.
- Because fewer animals are treated, the development of resistance in worm populations is slowed down.
- If the flock is examined regularly, animals can be treated before the symptoms and effects of anaemia become too severe.
- Individual animals that repeatedly fail to cope with Haemonchus in spite of an effectively designed control programme can be identified and culled.
- Animals that missed treatment or were under-dosed or improperly drenched (due to a faulty drenching syringe, for example) can be identified before severe problems occur.
- If the helminthicide is effective, pale mucous membranes should become noticeably redder within a week or so, provided that protein intake is sufficient and body condition is adequate. If many anaemic sheep are seen after treatment, the helminthicide is ineffective.
- A sudden increase in the number of anaemic animals is an early warning that there is a severe build-up of infective larvae on the pasture.
- Paddocks, pens and pastures that repeatedly present problems can be identified and treated.
A simple procedure to carry out
Inspecting the eyes is a quick and easy procedure that can be readily integrated with other management activities such as vaccination, weighing, condition scoring or counting. With practice and adequate facilities, it is possible to inspect up to 500 sheep an hour.
Another advantage of regular FAMACHA testing is that other unrelated problems are discovered in good time and
can be treated accordingly.
The frequent testing also means that the animals become tamer and easier to handle.
Information guide compiled by the Faculty of Veterinary Science, University of Pretoria, the Onderstepoort Veterinary Institute, the Worm Workshop of the South African Veterinary Association and Intervet South Africa, with the support of the Food and Agriculture Organization of the United Nations, the National Wool Growers’ Association and the National and Provincial Departments of Agriculture in South Africa.