The following information is informed by the April Parasite Forecast published by NADIS and is relevant for cattle producers in the UK only.
NADIS April Parasite Forecast
Liver Fluke
There is potential for greater levels of fluke infectivity this coming grazing season, so vigilance will be required in youngstock and susceptible animals. The mild and wet winter may have enabled liver fluke to continue development on pasture and in its intermediate host, the mud snail, later into the year and helped its survival on pasture.
Cattle that grazed high-risk pastures last year, such as areas of boggy or wet ground, or pastures next to ponds or rivers, and were not treated for all stages of liver fluke, may be affected by chronic fluke disease. This is caused by adult flukes which have migrated to the liver and are likely to now be producing eggs.
Cattle with chronic liver fluke disease may not show obvious signs of infection but a fluke burden can negatively impact productivity through reduced growth rates, milk drop, and impaired fertility.
If left untreated, chronically-infected cattle will contaminate pasture with fluke eggs in the coming grazing season, contributing to future infections.
Actions to take for Liver Fluke in April
- Monitor cattle for signs of chronic disease: weight loss or failure to meet weight gain targets, milk drop, anaemia, chronic diarrhoea, or weak calves born with little milk produced by the dam.
- Consider diagnostic testing through pooled faecal egg counts. These can provide a useful indication of fluke infection status within a group of animals.
- Consult abattoir reports for information on numbers of livers condemned due to the presence of live liver fluke or evidence of liver fluke damage.
- Consult your vet or animal health advisor for guidance on whether a treatment is necessary for some or all animals, according to the fluke status and individual requirements of your herd.
- If a treatment is recommended, consider an alternative to products containing triclabendazole, due to concerns over emerging resistance.
- Alternative products include TRODAX® (containing nitroxynil) and IVOMEC® Super (which contains clorsulon) which are effective against adult and late immature stages of fluke.
Gutworm
First or second-season grazing youngstock that have not been treated for gutworms over the housing period, may be at risk of type-2 ostertagiosis. This severe form of parasitic gastroenteritis (PGE) causes profuse, intermittent diarrhoea, loss of appetite, and rapid weight loss and, in some cases, cattle will die without prompt treatment.
After turnout, calves and youngstock are at greatest risk of gutworm infection and resulting parasitic disease, especially in their first or second grazing season.
Strategic treatments with a suitable wormer, usually within three weeks of turnout, will reduce the gutworm burden in young cattle. This must be followed by another treatment later in the grazing season, the timing of which will be guided by the first product used.
After July the population of parasite larvae on pasture will reduce and the risk of infection and resulting disease will be lower.
The strategic use of pastures to reduce parasite larval load in cattle is an alternative option, where strip grazing, paddock rotation and use of current season silage or hay aftermaths is available. Regular performance monitoring of animals is vital, since animals that are not meeting weight-gain or growth targets are likely to have worm burdens that need treating.
Worm egg counts can be a useful indicator of potential worm burden in a group of cattle, but cannot be relied upon for single-animal diagnosis.
Actions to take for Gutworm in April
- Check that all grazing youngstock received a housing treatment for gutworms. If they didn’t, assess the risk of type-2 ostertagiosis and treat accordingly. Wormers containing ivermectin (such as IVOMEC® Classic pour-on for cattle or IVOMEC Classic injection for cattle and sheep) or eprinomectin (such as EPRINEX® Pour-on for beef and dairy cattle) would be appropriate, as well as some group 1 benzimidazole products. Ask your vet or animal medicine advisor for guidance on the most appropriate product for your situation.
- Decide on your worming strategy for calves and youngstock, either using strategic treatments through the grazing season, or targeted selective treatment based on growth rates.
- Be careful with the use of bolus wormers where there is a risk of increasing on-farm selection pressure for wormer resistance.
- Regularly weigh growing cattle to track their average daily weight gain or growth against targets.
- Animals not meeting growth or weight targets are likely to be carrying a worm burden and should be selected for treatment.
Lungworm
Farms which have previously had lungworm outbreaks should consider vaccination of susceptible cattle pre-turnout. The live vaccine must be purchased fresh each season and both doses are required, given four weeks apart, with the second one administered at least two weeks before turnout.
Where vaccination is not used, or it is too late to administer it, a strategic approach should be considered on high risk farms.
Calves and youngstock are particularly at risk of lungworm-derived respiratory disease, which can cause severe ill-health and significant production loss.
Adult cattle with an unknown immune status to lungworm, or where they have failed to gain sufficient exposure in previous seasons, should also be considered at high risk of infection and disease.
Actions to take for Lungworm in April
- Consult your vet or animal medicine advisor if you think you may have had a lungworm outbreak last year, and do not have a plan to control it this year.
- If vaccination is being used, ensure you complete programmes at least two weeks before turnout.
- Where vaccination is not used, consider whether there are any high-risk cattle that need additional monitoring from July onwards.
- Consider if anthelmintics being used in any strategic worming programmes for gutworms in youngstock may also provide protection from lungworm infectivity.
- Regularly monitor cattle from July onwards when lungworm infectivity levels may start to increase.
