Sheep management: worm control

This week’s sheep feature, touches on the measure of parasite control and using faecal egg counts to determine the need for worm treatment.

Product selection and correct administration is also a critical component of efficient worm control, with significant resistance identified to white, yellow and clear drenches in the sheep technology adoption programme.

Benzimidazoles, or white drenches, were the worst offenders followed by levamisoles (yellow drench) and macrocyclic lactones (white drench), with some farms recording resistance to all three. Where there is doubt that resistance is an issue, then it is advisable to get a faecal egg count reduction test completed.

This consists of collecting a faecal sample, treating lambs and carrying out another faecal sample seven days later for levamisole products, and 14 days later for benzimidazoles and macrocyclic lactones.

An egg count reduction of less than 95% conveys resistance could be an issue.

Appropriate selection of products can reduce the rate of resistance developing. Treatments should be alternated between products with a different active ingredient.

Where resistance is an issue, then there may be no choice but to use one of the new wormers, Zolvix or Startect, which are prescription-only medicines.

These products are also recommended for quarantine treatment to reduce the risk of importing resistant worms onto the farm, where purchasing sheep.

Care should be taken to accurately treat animals for their weight and where a dosing gun is used, to ensure the gun is calibrated and delivering the correct amount.