Planning an effective parasite control strategy relies upon establishing specific management systems for individual farms and pastures. The type of parasite and the level of challenge will vary from location to location and animal to animal.
The most common parasites in cattle are Ostertagia ostertagi, Cooperia oncophora, Haemonchus contortus and Dictyocaulus viviparus, which can inhibit an animal’s growth and reduce productivity, in addition to producing clinical disease. Thus identifying, monitoring and managing for the exact challenges of your farm is vital.
As conditions on individual farms are variable, a general one-sizefits-all blueprint will not be effective. Planning an integrated approach, which identifies risks and utilises both anthelmintic treatments and pasture management to control a specific parasite threat, will reduce the risk of outbreaks of clinical disease and loss of productivity.
Reducing reliance on anthelmintic treatments alone also reduces selection for resistant parasites.
The following guidelines outline key areas for consideration. However, your local vet or animal health adviser can support you to understand and plan a parasite management strategy which is right for your farm.
To plan effective pasture management, it is important to know which parasites are on-farm and when and how they will impact cattle. Dedicate some time at housing, at turnout and in mid-summer to reflect on the effectiveness of parasite control over previous months and plan for the next six months.
It is important to understand parasite larvae which survived winter will become active at around the time when grasses turn green in spring. Cattle can potentially become infected with parasites from every bite of forage they take through the grazing season.
When developing a parasite control programme for the grazing season, consider the type and age of cattle, farm topography and facilities, and the farm’s objectives and capabilities.
Climatic conditions will inevitably impact on grass growth, parasite epidemiology, cattle husbandry, farm management and housing, and thus parasite control approaches may need to be adapted to take this into account.
Parasite populations typically increase from spring into summer, resulting in an increasing risk of parasitic gastroenteritis (PGE), while clinical lungworm disease usually occurs from July onwards.
Planned ahead, grazing management can be used to reduce the risk of PGE, particularly in young cattle at highest risk of disease.
Map the farm at the start of the grazing season to determine the use of pastures, particularly in terms of parasite risk, when aftermaths will become available and which classes of stock will be moved there.
Treating the right animals at the right time is critical to the success of gutworm control.
Each spring, decide whether the parasite control plan for youngstock will be a preventive strategy, using anthelmintic and grazing management, or whether a targeted approach, based on ongoing risk assessment, is more appropriate for the farm.
To be effective, strategic anthelmintic treatments need to begin early in the grazing season, at or shortly after turnout. Thereafter, this approach will help minimise pasture contamination up to mid-July, by which time the over-wintered population should have declined to insignificant levels.
If a targeted approach is implemented, ensure effective regular cattle growth monitoring is carried out to assess the risk of parasite exposure.
Diagnostic testing may also be useful. Faecal egg counts can provide some indication of worm burdens early in the grazing season and can be a useful tool for monitoring trends and infection dynamics as the season progresses.
Grazing management will have a bearing on parasite control. Being proactive and adapting to seasonal variations in grass growth will allow the most efficient use of pasture. However, remember most larvae on the pasture are very close to the ground, so grazing hard may increase the likelihood of parasite consumption.
Parasite control should be a key consideration when management decisions are being made, since failure to effectively control the risk in growing cattle will compromise health and growth.
Monitoring is also vital. Regular weighing of cattle will allow the performance of individual animals to be tracked and ensure they do not fall behind targets.
It also allows an indirect assessment of gutworm control to take place, since impaired growth in the face of good nutrition is often associated with a high parasite burden.
Targeting anthelmintic treatments at individuals which are failing to thrive can control gutworms effectively. When anthelmintic treatments are administered, it is critical that best practice is observed. Accurate dosing can only be achieved if you have assessed the weights of animals to be treated.
It is also important to make an assessment of the risk periods for different parasites on-farm. Targeting the right parasites at the right time will give predictable results and may mean re-treatment is less likely to be needed.
The efficacy of a gutworm treatment can be accurately assessed using a faecal egg count reduction test. To do this, faecal samples are collected from cattle before treatment and follow-up samples are taken from the same animals 10-14 days later, depending on the product used.
Faecal egg counts are compared and, when a treatment has been fully effective, a reduction of 95 per cent or more is expected. A lesser reduction could be a sign of resistance, but could also reflect poor treatment technique or under-dosing and this should be investigated further.
Knowing the resistance status of your farm will allow the most appropriate treatment choices to be made.
Understanding the parasite dynamic on-farm, and using this information to develop a season-long parasite control programme, will ensure the productivity and health of your cattle are maximised, while allowing sustainable effective treatment decisions to be made and helping to safeguard future performance.
To ensure any anthelmintic products you use to treat cattle are as effective as possible, you should:
Beat The Parasites is the new series from Boehringer Ingelheim which will offer information, advice and best practice guidance on all aspects of parasite control - as well as asking you, the farmers, how you deal with the parasite burden on farm.
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An educational service from Boehringer Ingelheim Animal Health UK Ltd (“BI”). Further information available from BI, RG12 8YS, UK. ©2019. All rights reserved. Date of preparation: January 2019. AHD 11982. Use Medicines Responsibly.
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