What are the parasite risks for cattle in June?
The generally warm and dry weather during April and May means that many pastures will have lower numbers of over-wintered infective parasite larvae. But, infected adult cattle will continually shed eggs and, as the season progresses, there is an increased risk of higher parasite burdens on pasture which may pose a threat to youngstock.
This parasite alert describes the main parasite risks to cattle in June and actions that you can take.
The following information is informed by the June Parasite Forecast published by NADIS and is relevant for cattle producers in the UK only.
Will gutworm affect my cattle in June?
Cattle at greatest risk of parasitic gastroenteritis (PGE) caused by gutworms are calves and youngstock in their first and second grazing season. PGE can cause significant losses in production with up to 30% reduction in growth rates1.
Dairy heifers in their first season at grass, and weaned autumn-born beef suckler calves in their second grazing season are at highest risk, since they will not have been exposed to sufficient low-level gutworm challenge to have developed enough immunity.
Adult cattle are largely immune to gutworms and are less likely to show clinical signs of disease, however a gutworm burden can cause losses in milk yield in dairy cows. Infected adult cattle will also contribute low numbers of gutworm eggs to the pasture which pose a risk to any co-grazing or following youngstock.
It is recommended that cattle producers take action to reduce significant build-up of infective larvae on pasture to reduce the risk to calves and youngstock later in the season.
Actions to take against cattle gutworm in June
If your cattle are ‘set-stocked’ throughout the season:
- Assess the likelihood of pasture larvae burdens being high – were the fields grazed by calves and youngstock last year? If so, cattle may benefit from a strategic anthelmintic treatment with a 3-ML group product such as IVOMEC® Classic Injection or Pour-On, or EPRINEX® Pour-On from three weeks after turnout, with this being repeated after six to eight weeks.
- Consider leaving a part of the group untreated. Monitoring growth rates allows poorer performing animals to be identified and selectively treated. Leaving a proportion of the fitter animals within a group untreated reduces selection for anthelmintic resistance. The mixed population of worms carried by these individuals will dilute any resistant worms that survive in treated animals, helping to maintain the genetic diversity of worms on the farm and slowing the emergence of resistance.
- Moving young, more susceptible cattle to ‘safe pasture’ such as paddocks that were not grazed the previous season, or current season silage aftermath, will help to reduce the worm challenge in the latter part of the grazing season.
- Remember that if lungworm is a risk, calves and youngstock need sufficient exposure to this parasite over the early summer months to build enough immunity to protect them from disease outbreaks later in the year. Be aware that anthelmintics used to treat gutworms, may also treat lungworm.
Always consult your vet or animal health advisor for guidance on the most appropriate treatment plan for your herd.
If you adopt a targeted approach to treatment:
- Continue to regularly monitor cattle, through feacal egg counts, weight gain or condition score, and identify any individuals which are consistently not meeting targets. These cattle are most likely to have a production-limiting gutworm burden.
- Be alert for signs of PGE, including weight loss (or failure to gain weight), poor body condition score, and
- Considerable pasture larval burdens can build up, particularly later in the grazing season. Be ready to take action in high risk groups of animals if this situation is likely.
- Moving high-risk cattle to safe grazing later in the season, including pasture not grazed by cattle last year, or this season’s silage aftermath, can effectively reduce the challenge to cattle.
- Avoid implementing a 'dose and move strategy', where the entire group is treated and moved to clean pasture as this approach selects heavily for resistant worms. Instead consider leaving 10-20% of the fitter better performing animals in the group untreated, or delay treatment until a week after moving. The treat-delay-move approach recommended for sheep is not an effective way of managing resistance in cattle if products with persistent activity are used.
- Consider the risk posed by lungworm throughout the grazing season, particularly in cattle that have not been vaccinated, and ensure that any anthelmintic treatments are appropriate and targeted.
What is the risk of liver fluke in cattle this year?
Liver fluke infections appear to have been low last year, and conditions so far this year have not been favourable to fluke development on pasture. However, cattle farmers should not be complacent because it can result in costly production losses.
Some cattle may be carrying adult, egg-laying liver fluke without showing clinical signs of disease. Later in the year climatic conditions will be more suitable for fluke development, so reducing egg output in affected animals should be the priority.
Actions to take against liver fluke in cattle in June
- Consider testing groups of cattle for the presence of fluke eggs, as an indication of infection through the herd.
- If treatment is required, infected animals should be treated with a selective flukicide that only targets the later stages of liver fluke, such as TRODAX®.
- If a worm treatment is considered necessary at the same time, IVOMEC® Super is a suitable combination product.
Is there a high risk of lungworm in cattle this year?
The dry conditions in the early part of the grazing season will have hindered the ability of lungworm larvae to survive on pasture. However, periods of wet and warm weather later in the summer will rapidly increase pasture infectivity levels as larvae are released from dung pats. Cattle with no or low immunity will be at significant risk of disease.
Due to the low lungworm challenge on pasture this spring, youngstock will have struggled to build any early immunity to the parasite. This is essential to protect them against higher challenge later in the year. These cattle will require regular monitoring for signs of disease and producers should be prepared to act fast to control outbreaks of disease.
Actions to take against lungworm in June:
Monitor cattle from late June onwards when lungworm infectivity levels may start to increase, and particularly two to three weeks after periods of heavy rain.
- Investigate any signs of persistent coughing in cattle as soon as possible.
- Consider which animals need to build immunity to lungworm and remember that many products used for gutworm control also treat lungworm.
