- Used to treat most ectoparasites including ticks, lice, buffalo flies and occasionally mites.
- Some sprays are high volume and require several litres be applied as a full body spray, all over the body for good effect, for example with ticks and lice, whereas others, usually for buffalo flies, may require lower volumes applied along the backline.
- Some insecticide spray products come as ready-to-use formulations, but most must be diluted with water before application.
- Sprays have the advantage that they give a rapid reduction in pest numbers. However residual effect is usually less than 2-4 weeks and frequent re-applications may be required.
- Experienced, careful management is important for effective application.
- Follow label instructions and ensure appropriate personal protective equipment is used.
A parasite population can develop resistance to a chemical through:
- repeated use of the same active.
- repeated overuse of a chemical (unnecessary treatments).
- wide-spread under-dosing of a chemical (e.g. under-estimating the weight of the animals being treated, poor application technique, uncalibrated dosing equipment).
- unintentionally exposing non-target parasites to chemicals (e.g. products to treat tick or lice can also affect worms).
What is resistance?
- On contact kill provides instant relief.
- Relatively cheap.
- Most products require dilution prior to application.
- Chemical concentration of spray fluid must be maintained.
- Repeat treatments may be required.
- May have longer export slaughter interval (ESI).
- Some products may be toxic to dung beetles.
- Risk of inadvertent chemical exposure. With hand spraying, close proximity of the operator to the spray wand and treated cattle presents a significant risk from deflected sprays and inhalation of aerosol droplets.
Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.
How it works
Spraying for parasites can be conducted with handheld sprayers, desirably powered by a fuel or electric pump, or with the use of a spray race where cattle walk through a ‘tunnel’ of spray nozzles strategically mounted to give complete body wetting of treated animals.
Hand spraying and race spraying is generally relatively inexpensive and can be used for opportunistic treatments, when cattle are in yards for other husbandry purposes, or where only low numbers of cattle are to be treated.
- Over-spraying with hand held sprayers may be most suitable in situations where infrastructure such as dips and spray races is not available or where only low numbers of cattle need to be treated.
- To ensure that all animals get full coverage cattle should be treated in a race or crush, NOT held in a holding yard and sprayed from a distance.
- Hand held spraying offers the advantage of being able to direct sprays to ensure that areas on cattle where parasites persist or are in highest numbers are properly treated.
- With lice and ticks, check that all predilection/preferred areas have been treated. In particular, check the tail, rump and escutcheon, under the front shoulder, the udder, ears and under the jaw as well as along the back and flanks to ensure these areas have been thoroughly wetted.
- Sprayers must be able to deliver a low-pressure high-volume output and for hand spraying the hand piece should be adjustable to control flow rates dependent on what part of the animal is being treated.
- Make sure that there is sufficient pressure to completely saturate the hair coat to skin level. Equipment that sprays a fine mist may only reach the outer layer of coat failing to penetrate to the skin. However, if spray pressure is too high much of the spray bounces off and is wasted and can cause a safety risk for both operators and animals.
- As lice eggs are not killed by most sprays, when spraying for lice it may be necessary to repeat the treatment after 2-3 weeks to kill any young lice that hatch from eggs before they are old enough to lay eggs themselves.
- Spray races usually consist a concrete base and metal walls, most commonly in a tunnel configuration, with spray nozzles strategically positioned to give complete body wetting of cattle as they walk through.
- The spray mixture is drawn from a sump and forced at pressure through the spray nozzles by means of a pump driven by either a stationary petrol engine, an electric motor or tractor power take-off.
Figure 1. Spray race. Image courtesy of Queensland Department of Agriculture and Fisheries
- Pumps that deliver high volumes of wash, operated at relatively low pressure e.g. 140 kpa give best effect. Check some treated animals to ensure that animals are completely wetted, particularly at body sites where the target pest is likely to be in highest numbers.
- Control the flow rates of cattle through the race so that they walk, not run and can be effectively wetted,
- Because the dip wash is recycled it is important to minimise the amount of dirt and other foreign material draining back into the sump. This is aided by having concrete feeder yards and entry races to the dip and keeping screens and filters clear. If possible, walk cattle through a footbath before they enter the spray area.
- Check spray nozzles frequently so that any that become blocked are quickly identified and cleaned out or replaced.
Figure 2. The spray race completely coats the animal as it walks through the race. Image courtesy of Queensland Department of Agriculture and Fisheries
- Spray fluid can become ‘stripped’ of its chemical leading to ‘exhaustion’ of the spray if counter measures are not taken. ‘Stripping’ occurs when chemical is preferentially adsorbed onto the skin and hair coat. This aids the efficiency of the spray, but leads to a progressive drop in concentration of the active chemical in the sump. The use of continuous replenishment, where fresh dip wash (using the starting concentration of chemical) is automatically added to the spray sump, or reinforcement where additional concentrated chemical is added when the level of the sump falls, can counteract the effects of stripping and ensure that all cattle are treated with effective levels of chemical.
- Check the product label for directions for ‘reinforcing’, ‘replenishing’, or ‘topping up’ the wash to counter the effects of stripping.