Dr Jeff Cave, Senior Veterinary Officer
With the current weather conditions, sheep producers should be aware conditions are ideal for flystrike.
Flystrike is a condition that costs the Australian sheep industry approximately $320 million annually, because of lost production, treatment costs and deaths.
Reducing the risk of flystrike has great benefits to the health and wellbeing of sheep – as well as their productivity. The major fly responsible for flystrike in sheep in the green blowfly, Lucilia cuprina, which is believed to be the cause of 90% of flystrike cases.
Lucilia cuprina begins to become active when temperatures are above 15 °C and is most active when temperatures are between 26 °C and 36 °C and conditions are calm.
Each female fly can have up to 300 viable offspring and with a 21-day life cycle when conditions are optimal, fly numbers can increase rapidly. The fly is attracted to odour and moisture, so the risk of flystrike increases when there is regular consistent rainfall that keeps the sheep's skin moist.
Sheep most susceptible to flystrike are those with breech wrinkles, long wool, dags, urine stain, fleece rot, dermatitis and/or wounds. Sheep that have been previously flystruck have a higher likelihood of being restruck.
The prevention of flystrike requires an integrated plan and includes the following:
- Selection of sheep and marking of lambs to produce a flock with low susceptibility to flystrike
- Shearing and crutching timed before the peak flystrike risk period
- Correct use of preventative chemicals timed to give protection during the peak flystrike risk period
- Worm control and dietary management to help reduce the prevalence of dags
- Selection of open, windy, dry paddocks
- Removal of infective material and carcasses that may attract flies.
As conditions become more conducive to flystrike, sheep should be monitored more regularly for flystrike.
If a flystruck sheep is found, the affected area should be clipped close to the skin and dressed to prevent reinfection, and the sheep should be moved to a hospital paddock to reduce the risk of infecting the rest of the flock. Any maggots should be collected and killed to help reduce the build-up of fly populations.
