The product you choose to treat flies on cattle depends on the following factors:
1. Fly species
By far the majority of products available on the market will be targeted for use against buffalo flies. These products include insecticidal ear tags and strips, pour-ons, sprays, dips and compounds for application in backrubbers.
Where other biting or nuisance flies (for example stable flies, biting midges, houseflies) are to be controlled, products are usually applied as pour-ons, sprays or dips and may often act as repellents as well as insecticides.
A further group of products are registered for treating premises. They are applied to internal and external areas and surrounds of animal facilities, outbuildings and sheds. These insecticides target either fly larvae breeding in manure, or other accumulations of spilled feed and organic matter, or they target adult flies resting on buildings, structures or surrounding vegetation. These compounds should not be applied to cattle.
2. Impact on other parasites
Most common fly control compounds (for example, synthetic pyrethroids, organophosphates and macrocyclic lactones) will also affect other external parasites such as ticks, lice and mites. MLs have a particularly wide host range and can also impact on internal parasites. Where possible, choose a product to address only the parasites of concern at the time of treatment to reduce the risk of resistance developing from unnecessary overtreatment of non-target parasite species. However, in some instances with careful planning, strategic timing of applications to target multiple parasites with the same treatment can actually reduce the total number of treatments applied and reduce resistance selection.
3. Chemical resistance
Resistance to SPs is widespread, and resistance to OPs is common in buffalo fly populations and can reduce the efficiency of treatments. Resistance to MLs has not yet been detected in buffalo fly. To slow the development of resistance it is important to rotate chemical groups between treatments, taking into consideration of prior non-target exposure from other parasite treatments.
4. Long vs short acting products
While some products (e.g. insecticidal ear tags, backrubbers) can provide ongoing control for many weeks, other products (for example sprays) are more suited to immediate or short term control. Indiscriminate use of long-acting products can increase the risk of developing resistance, but may be the most efficient and practical approach where season-long protection is required, or where mustering and re-treatment is difficult. Short acting products may be more efficient when animals are soon to be sent to market or at the beginning, or near the end of the fly season to complement the use of ear tags. In this case, use a product from a different chemical group to that of the tags, this slows the rate of development of resistance.
5. Withholding periods (WHP), export slaughter interval (ESI) and retreatment intervals
It is essential to choose a product with an appropriate withholding period (WHP) and export slaughter interval (ESI) depending on the time left before the animals go to slaughter, or their milk is used for human consumption. Retreatment intervals may be important where frequent application of a product is required to ensure ongoing protection in high risk situations (e.g. calves exposed to paralysis ticks).
Using products
- Avoid unnecessary treatments, see when to treat cattle.
- Follow the label instructions to ensure correct dose and use of treatments and be aware of contra-indications (situations where a chemical might be harmful if used).
- Pour-ons and injectables—Calibrate applicators to ensure the correct dose is delivered. Calculate the dose based on the heaviest animals in the mob. It is difficult to estimate the body weight of cattle accurately without regular reference to a set of scales. Where possible, weigh the animals and treat according to individual weights. This will ensure that heavy animals are not under-dosed, and light animals are not overdosed.
- Sprays—Ensure spray races are operating at the correct pressure and that all nozzles are working. When using a spray pack, ensure the animal is completely wet. Avoid hand sprays. Preferably use liquid products in sprays, but if using powder products, ensure they are dissolved thoroughly.
- Dips—Ensure dips are charged and mixed appropriately, and all animals are thoroughly submerged. Stabilise dips if contents are to be used subsequently.
For help in selecting a product to treat ticks see the Flyboss cattle products search guide.
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