Susceptibility and Management of Ticks in Cattle

Ticks are a stressor of cattle that can impact animal production and welfare. Their impact is made worse if the animal already deals with other physiological demands, such as pregnancy or lactation.

Traditional management targeted ticks on animals using chemical control. This approach was limited by residues and withholding periods for meat and milk and has rapidly led to increased chemical resistance. Acaricides alone do not offer a permanent solution for tick control. Vaccines have also had limited success. The Bm86 anti-tick vaccine was withdrawn from the Australian market because it required at least 2 doses and a booster to be effective. Current research is underway to develop new anti-tick vaccines but it is unlikely that vaccines will confer total efficacy against ticks.

Therefore, modern management of ticks uses an integrative approach that targets ticks on animals, as well as aiming to reduce seed ticks contaminating pastures. In addition, the choice of breed is important. Choosing breeds that are adapted to the environment (tropical or temperate), and breeds that have a natural resistance to ticks, will maximise the general health of the cattle and reduce the costs of tick control. The following links provide more information on ways to reduce ticks on your property.

Susceptibility to ticks

Certain cattle breeds are more resistant to cattle tick infestation than others. Typically, Bos indicus (tropical breeds) are more resistant than Bos taurus cattle (European breeds). Selecting a resistant cattle breed for tick infected areas will naturally reduce tick populations and is a low cost, permanent solution to control ticks.

Both animal and environmental factors can impact on an individual animals susceptibility to cattle tick, see Table 1. Within breed variability also exists at a genetic level (heritable traits), however, measuring a resistance score for a single animal is difficult. This constraint applies in both beef and dairy cattle. As described in the ‘Within breed selection’ and ‘EBVs’ sections, research is underway to find simpler, more cost-effective measures to identify cattle that are resistant to ticks, with the aim of genetically improving cattle breeds grazed in tick-endemic regions of the world.

Table 1. Animal and environmental factors (excluding breed) that can impact on resistance to cattle ticks.

Grazing management

• Grazing management alone is unlikely to achieve complete cattle tick control.
• Rotational grazing management in conjunction with planned chemical treatment is an effective means of cattle tick control.
• A reduction in cattle tick burden of over 80% with fewer treatments is achievable.
• Grazing management is not effective for controlling bush or paralysis ticks.

Rotational grazing management can be practiced to get rid of cattle tick seed-ticks, i.e. tick offspring on the pasture that have dropped at various times of the year. Destocked tick-infested paddocks should be left long enough for the seed-ticks to die. The length of survival of seed-ticks will depend on local climatic conditions, but it is never longer than 8-9 months. Under hot, dry conditions 90% of seed-ticks may die after one month. This form of management works well but may be difficult to apply in areas with limited fencing and without a water network.

Alternatively a spelling period of 3 months over summer, or 5 months over winter, will reduce tick numbers. Grazing management combined with chemical treatment of animals prior to re-introduction to paddocks provides an effective, quick clearance of ticks and a useful residual protective period to keep tick numbers low, with a reduced number of treatments.

Paddock spelling can be combined with a rotational grazing strategy, where treated cattle are moved into a paddock that is likely to only have a small tick burden. This will further reduce the number of chemical treatments needed. Cattle are kept in their original paddock for 3-5 days after treatment, before being moved to the lower tick burden paddock.

Grazing management is ineffective for reducing 3-host ticks, such as bush and paralysis ticks, because when the cattle are de-stocked, the ticks remain active in the paddock completing their life cycle on native hosts instead.

Feedpad management

Feedpad management offers a non-chemical means of reducing cattle tick numbers on cattle. The use of an intensive feedlot can eliminate ticks from cattle if the engorged ticks are all crushed after they drop from the cattle or the eggs and larvae all perish in the feedlot environment. Using a feedpad in conjunction with pasture or crops may help to reduce tick numbers if used strategically. Over 90% of fully engorged female ticks drop from cattle before 5 am to lay eggs on the pasture. If animals are brought in to a feedpad between 2 am and 6 am, the majority of engorged cattle ticks will drop onto ground unsuitable for tick and egg survival (too dry and no grass) and they will be crushed underfoot if the feedpad area is restricted and not too large. This will keep the tick burden off pastures. A feedpad management strategy needs to be optimised farm by farm. Although there are no chemical costs, there could be an increase in feed costs and feedpad related issues such as mastitis or foot problems may increase.