Parasites are a natural part of the ecology in which cattle, sheep and goats have evolved.
Parasites need their host to survive, so most successful parasites do not usually kill their host. Instead, there is usually equilibrium between hosts and parasites and the incidence of disease due to parasite infestation is low.
Human management, production requirements or environmental manipulation alter the equilibrium, allowing parasites to flourish. Successful and sustainable parasite control can only be achieved when the impact of these factors on parasites is recognised.
Parasites are not the sole cause of the problem. Relying on chemical control options alone may produce only short-term results and will probably be unsustainable.
Principles of parasite control
Producers should adopt an integrated approach to parasite control, recognising that the problems caused by parasites are usually a combination of the parasite, the age and condition of the animals, the environment the animals live in and other management factors.
Parasite control approaches
Planning as part of a farm animal health or biosecurity plan
This should include planning how to control parasites in livestock already on the farm, as well as options for treating and quarantining introduced livestock prior to releasing them onto the property.
Always request an animal health statement when purchasing livestock so you are aware of the disease status level of assurance that is being provided by the livestock vendor.
Knowing the parasites that occur in the region
Some parasites are adapted to the tropical and subtropical regions of northern Australia, whereas others occur mainly in the temperate southern regions.
Reducing parasite challenge
This is particularly important in more intensive production systems in high rainfall regions where substantial numbers of parasites can accumulate on pastures.
Aiming to prevent rather than cure
By the time animals are showing clinical signs of parasite infestation, substantial productivity losses will have already occurred.
Animals affected by drought or on a low plane of nutrition are more susceptible to parasites.
Parasite levels in these animals must be carefully monitored, especially if environmental conditions favour parasite development.
Protecting susceptible livestock
Examples of this include having low-worm pastures available for young and pregnant livestock and not introducing tick-naive animals to tick-infested pastures unless they can be carefully monitored.
Using breeding to improve parasite control
This includes activities such as using breeds more resistant to cattle ticks in tick-endemic regions or integrating selection for resistance to worms into sheep breeding objectives.
Monitoring livestock and only using chemicals when required
For example, in regions where buffalo fly is a problem for cattle, monitor fly numbers and only treat when there are more than 200 flies per beef animal (100 per side) or more than 30 per dairy animals.
Using drenches, pour-ons and other chemicals strategically as part of an overall parasite control program
When using drenches, pour-ons and other chemicals, only use products registered for use in the livestock being treated. Read the label thoroughly before use and follow all label directions or restrictions, including directions for dose rates, safety precautions, personal protective equipment, withholding periods (WHPs), export slaughter intervals (ESI), re-handling intervals and disposal of empty containers and unused product. Record the appropriate information and include on the LPA NVD/Waybill if the livestock are sold.
- Cattle Parasite Atlas
- Department of Agriculture and Fisheries, Queensland
- Module 6: Herd health and welfare from MLA's More Beef from Pastures
- Module 11: Healthy and contented sheep from the Making More From Sheep manual
- Module 9: Parasites and Module 6: Husbandry of the MLA publication Going into Goats: profitable producers' best practice guide