Treatment Strategies to Control Parasitic Roundworms in Cattle

Moredun-logoSummary written by Dave Bartley BSc PhD and Jacqui Matthews BVMS PhD MRCVS

Taken from Moredun Foundation Newsheet Volume 5 No. 18 (2013)




Key points

  • There are a variety of roundworm species that can cause disease in cattle.
  • Grazing stock can take up to two grazing seasons to acquire adequate immunity and thus young calves are at greatest risk of succumbing to infection.
  • Anthelmintics (wormers) are the major control option available for the treatment of gastro-intestinal roundworms; however, the worms are developing resistance to some of these anthelmintics.
  • It is essential to conserve efficacy of existing wormers through correct usage.

General rules

  • Undertake post drench efficacy checks to determine whether the class of wormer is still effective or whether wormer resistance is present. Faecal egg count reduction tests can be used if there are concerns about wormer efficacy.
  • Treat bought-in stock and animals that have been grazed off farm with wormers from both the 1-BZ and 2-LV classes of drugs and where possible yard for at least 24-48 hours prior to turnout. See page 9 for a full description of wormer classes.
  • Turn out quarantine treated stock onto dirty pastures to ensure that any resistant surviving worms form a minor proportion of the total on pasture population.
  • Ensure best practice advice is followed (see page 11 for further details).
  • With your veterinary practitioner/health advisor, plan a strategic parasite control program that will reduce unnecessary treatments. Avoid frequent drenching by integration with grazing management.
  • The relationship between nutrition and parasitism is critical; poorly fed animals have difficulty in developing and maintaining immunity to worms.


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