Blowfly strike risk is becoming increasingly unpredictable due to changing weather patterns.

We are now seeing strike as early as March and as late as December meaning the old ‘predictable fly season’ is a thing of the past.

As well as the welfare impact, strike will also affect your bottom line. It’s estimated struck lambs might suffer a £10 production loss each and with more than 75% of farms affected annually, the costs quickly add up .

The adult fly lays eggs in the fleece which then hatch into maggots. Those maggots produce enzymes which digest the host’s skin tissue and also have abrasive mouth parts to further damage the skin surface.

In addition to the trauma caused, the maggots also produced ammonia as a waste product which can be absorbed, by the sheep through open wounds, leading to shock and death. If they survive this, they risk secondary bacterial infections and the potential for further strike.

While strike can occur on the clean, dry wool of any sheep, there are risk factors which increase the likelihood of strike occurring including organic matter in the fleece, open wounds, thick fleeces and environmental conditions such as prolonged hot weather.

Due to the number of factors involved, fly prevention products are only part of the solution. Other precautions include:

  • Annual shearing and regular dagging/crutching of soiled fleeces. Shearing results in a 95% reduction in the incidence of strike .
  • Docking – where appropriate, and when done in conjunction with the law. Docked lambs are five times less likely to suffer from fly strike.
  • Check animals frequently during high-risk periods, of course, and remove any carcasses promptly.
  • Reduce scouring (gastrointestinal parasite management, good nutrition).
  • Reduce the incidence of footrot and monitor any wounds closely.

There are a number of factors to consider when choosing a fly prevention product for your flock.

The withdrawal period and duration of action are important, particularly when drawing lambs for sale.

Discuss treatment options in detail with your vet or SQP, taking into account which other parasites can be targeted and the timing of treatment, to help decide which product is most appropriate for you.

This information was provided by Bimeda, makers of Ectofly 12.5 mg/ml Pour-on Solution for Sheep

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