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General principles concerning endoparasites
Afrikaans | Xhosa
Endoparasites can be classified into three main groups, namely roundworms, tapewurms and flukes, and will be found on every farm, regardless of the type of animal that is being kept. Endoparasites are in competition with the animal for the available nutrients that have been ingested. Therefore losses are for the most part inconspicuous, and they are mainly of an economic nature. Initially production and reproduction are affected negatively. Endoparasites can, however, also result in mortality if conditions are favourable, in particular for threadworm (a roundworm).
Unless a scale is used, or accurate records are kept - particularly of production and reproduction losses - indications of the presence of endoparasites are not easy to observe. The following are among the losses that occur:
- weight loss or reduced weight gains (slow growth and retarded market readiness)
- decline in milk production
- decline in wool production
- decline in the quality of wool
- decline in the quality of carcases
- an increase in blowfly infestations (diarrhoea and therefore dirty backside)
- poor reproduction in animals with a low condition score (one or two)
If any of the following signs are observed in animals, the problem has already reached an advanced stage:
- loss of appetite
- emaciation
- pale to yellowish pale mucous membranes
- diarrhoea
- kwakkeel (a swelling beneath the chin)
- general feebleness and poor growth
- mortality
Consequently it is essential that the stock farmer should seek answers to the following questions:
Which are the endoparasites that occur on the farm?
At what time of the year are they in evidence?
When can losses be expected?
- Every farm is different, and there are even differences between camps on the same farm.
- Predetermined available dosing programmes do not provide instant solutions - the problem is too complex for this, and
- neither does the cheapest available medication provide the answer.
- Different groups of worm medicines are commercially available.
- Alternative methods of controling endoparasites do exist, but endoparasites can not be controlled effectively without the expert help of an animal health technician or a veterinarian.
The following general control measures apply:
- Dry land pasture is unfavourable for threadworm, but for brown stomach worm and bankrupt worm it is ideal.
- Irrigated pastures, especially kikuyu, are conducive to threadworm.
- Tapeworms require an intermediate host, while flukes require an intermediate host as well as stagnant water.
- Identifying the problem and determining its extent require post mortem examinations, larval cultures and egg counts.
- Use the correct medicine for the parasites occurring on the farm, and also vary medication.
- Do regular tests for parasite resistance to medicines (egg reduction test).
- Apply alternative endoparasite control, such as varying the animal species that utilise a camp, and allowing rest periods for fields and pastures. If practically possible, the fencing off of earth dams and wetlands can also be considered.
The most important alternative is the breeding and selection of animals for resistance to endoparasites, but especially for the ability to keep up production in spite of a burden of endoparasites. Due to their protracted exposure, wild animals do have this ability.
LJ Hon
ELSENBURG / SWELLENDAM Veterinary Services
