Cattle ticks are a major cost to dairy farmers on the eastern side of the tick line. As temperatures begin to increase into the spring months so do tick populations. Interestingly, there have been some farmers reporting high tick loads through the current winter months which will result in increased tick loads moving into spring and summer this year.
The cattle tick life cycle will vary depending on humidity and temperature, and is outlined in the diagram below. Generally, the cycle will speed up as ideal temperature and humidity levels are reached. Needless to say we generally see higher tick loads in the warmer, wetter months of the year. Usually the popualtion is at it’s lowest in late winter and this is a crucial time to manage tick numbers for the season ahead. Developing a tick management program and being ready to treat the whole herd upon the sight of the first wave of ticks in the spring will reduce numbers of viable breeding females going forward, this is referred to as “treating on the spring rise”. Repeated treatments throughout the year before the next lifecycle has completed is essential to keep populations down.
There are many treatment options available, however, withhold periods do restrict some chemicals on dairy animals, particularly lactating stock. No matter what option is employed, correct dosing and application is paramount to ensure an effective and desirable result, treatment is expensive don’t waste it. Additionally, sub-optimal dose rates build resistance in the tick population and ultimately deem chemicals ineffective which will have significant economic impacts on the business and industry as a whole. Cattle ticks may be tested for resistance to particular chemicals through the Department of Agriculture and Fisheries. This test takes a couple of months to be performed as a whole life cycle of the tick needs to be completed for assessment for resistance, however, if ticks are not dying after treatment it is a worth while test. Weighing cattle before treating with pour-ons and injectables is also advised.
Paddock rotations are common practice for the milking herd, this does help manage tick numbers to some degree and where possible having some form of paddock rotation for the other classes of stock on the farm is useful. One strategy that has worked well is to treat young stock with a “long acting” chemical, there are a couple on the market registered for dairy cattle, then move these cattle through as many paddocks as possible on the farm to essentially “vaccum” ticks. The long acting mode of action keeps killing ticks as they attach and go through their lifecycle for many weeks, helping to reduce populations further. There are many chemical options, having a plan around tick management will help reduce numbers.
Vaccinating young cattle with trivalent vaccine (three germ blood) is also recommended. Just because cattle are reared in ticky country does not ensure they are immune to tick fever. There were cases of tick fever in young cattle in the Gympie area in the summer of 2018, vaccinating calves at 3-9 months of age is recommended. Cattle ticks are costly to manage, however, the ramifications to production and animal health are enormous if left unmanaged. Having a plan and treatment strategy going into the spring will help keep tick populations under control and should reduce overall costs for the season.
Ross Warren, Dairy Extension Officer, DAF.