Worms in cattle: Sustainable control plan

A successful worm control plan integrates various management actions such as monitoring, effective quarantine and grazing management to reduce our reliance on anthelmintics and improve animal health.

A successful worm control plan includes:

• A worm control strategy integrated into the herd health plan that is adaptable to changing patterns of worm challenge and regularly reviewed by a vet or advisor
• The use of regional warnings and forecasting tools
• Methods to monitor parasite burden such as regular weighing of stock to check growth rates are on target
• Grazing management and identifying high-risk pastures
• Effective quarantine of bought-in cattle
• A targeted approach to treatment for those who need it – only use when necessary
• Anthelmintic efficacy checks
• Allowing cattle, particularly breeding replacements, to develop immunity to worms

Vigilance for any clinical signs of parasitic worms – for example, scour, ill-thrift and performance monitoring form the backbone of parasite control. Specific dung and blood tests can also help with diagnosis and the choice of optimal control in terms of both management and anthelmintics.

Ongoing monitoring of youngstock is important for controlling parasites:

• Daily vigilance for any clinical signs of worms such as coughing, scouring, anaemia or weight loss
• Monitoring growth rates, particularly in weaned calves – aim for 0.7 kg/day
• Faecal sampling and worm egg counting can provide an idea of how heavily pastures are being contaminated

How to take a good dung sample:

• Collect fresh dung (less than one hour old)
• Put in an airtight container or plastic bag
• Keep cool but not frozen
• Deliver to the lab within 48 hours
• If the sample is for lungworm, deliver to the lab as quickly as possible

However, faecal egg counts are poor indicators of the impact of gut worms on health and performance and should not be used alone as triggers for anthelmintic treatment.

Regional weather forecasts and parasite risk assessments such as the service run by the National Animal Disease Information Service (NADIS) can also be consulted before deciding if treatment if needed.

Three steps for successful quarantine:

1. Incoming or returning stock should be treated with an anthelmintic to minimise the risk of introducing resistant roundworms to the farm. The choice of appropriate products requires specialist knowledge, so seek advice from the vet or Suitably Qualified Person (SQP) at the retailers.
2. Dung samples can be taken two to three weeks after treatment to establish if the treatments have successfully removed all the parasites. If worm counts are negative, then cattle can be turned out. If not, they can be treated again with a different class of anthelmintic.
3. If possible, cattle should then be moved to pasture with a low/moderate parasite burden.