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Controlling External Parasites

Solution name: Controlling external parasites

Aim: To present best practise for controlling external parasites


    The main external parasites are

    • flystrike
    • ticks
    • lice (biting and sucking)
    • scab

    External parasites can have negative impact on

    • animal – health, welfare and performance
    • labour requirement
    • overall profit on a sheep enterprise

      How to implement:

      • Good farm biosecurity is key for controlling lice and scab
      • Keep sheep clean by crutching when necessary
      • Chemical treatments can be administered via plunge dipping or pour-ons
      • Pour-ons have become popular due to their ease of application and being less labour intense than plunge dipping

      Plunge dipping to be effective requires:

      • correct dilution and replenishing of dip
      • immerse sheep for at least 60 seconds
      • submerge the head twice
      • use personal protection equipment (PPE) and in well ventilated area

      Key messages for using pour-ons:

      • apply in dry weather (i.e. dry fleece)
      • apply to clean wool – crutch excessively dirty sheep
      • treat lambs early before fly strike is anticipated as some products only prevent flystike (insect growth regulators)
      • be aware of the withdrawal period when selecting treatment
      • use correct nozzle (different for ticks and blowfly) for even distribution of treatment on the animal’s fleece

      Topic: Health

      Production:  Dairy / Meat

      Animal Category: Adult / Lamb / Replacement

      Issue: External Parasites

      Level of Solution: Knowledge, Practical

      Country: Ireland






      Expected benefits

      Expected benefits:

      • No reduction in animal performance or welfare
      • Reduced costs for animal remedies

      Prerequisites and/or limits (knowledge, training, capabilities, cost, management, facilities, equipment, etc.)

      • For plunge dipping, dipping facilities are required


      Cost Benefit analysis

      The control of external parasites reduces labour and veterinary/antibiotic costs from parasite damage, and improves animal welfare, performance and possibly lowers mortality rate.

      Sustainability analysis

      Controlling external parasites improves feed efficiency as the animals have an improved growth rate and are slaughtered earlier. There is a slight increase in effluent production and water use due to disposal of the dipping solution.
      A reduction in external parasites improves animal welfare, creates a better work environment and reduces physical labour, all of which have a positive effect on farmer image.

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