Current weather conditions are creating an ideal environment for flystrike in sheep, prompting an advisory for producers.
Flystrike imposes a significant financial burden on the Australian sheep industry, amounting to approximately $320 million annually. This cost stems from production losses, treatment expenses, and sheep mortalities. Effective flystrike reduction strategies are beneficial for both animal welfare and productivity.
The Primary Culprit: Green Blowfly (Lucilia cuprina)
The primary culprit behind 90% of flystrike cases is the green blowfly, Lucilia cuprina. This species becomes active when temperatures exceed 15 °C and exhibits peak activity between 26 °C and 36 °C in calm weather.
A single female can produce up to 300 offspring. With an optimal 21-day life cycle, fly populations can rapidly escalate. Flies are drawn to odor and moisture, indicating an increased risk of flystrike with consistent rainfall that keeps sheep's skin damp.
Identifying Vulnerable Sheep
Sheep with certain characteristics are more vulnerable to flystrike. These include those with:
- Breech wrinkles
- Long wool
- Dags
- Urine stain
- Fleece rot
- Dermatitis
- Existing wounds
Additionally, sheep that have previously experienced flystrike are at a higher risk of recurrence.
Integrated Approach to Flystrike Prevention
An integrated approach is required for flystrike prevention, encompassing several key strategies:
- Flock Management: Selecting sheep and marking lambs to develop a flock with reduced susceptibility to flystrike.
- Timing of Practices: Scheduling shearing and crutching to occur before periods of high flystrike risk.
- Chemical Application: Using preventative chemicals correctly and at opportune times to ensure protection during peak risk periods.
- Diet and Worm Control: Implementing worm control measures and dietary management to lessen the prevalence of dags.
- Paddock Selection: Utilizing open, windy, and dry paddocks.
- Environmental Cleanup: Removing infective materials and animal carcasses that could attract flies.
Monitoring and Response
As conditions become more favorable for flystrike, sheep require more frequent monitoring.
If a flystruck sheep is identified, the affected area should be closely clipped and dressed to prevent secondary infections.
The sheep should then be isolated in a hospital paddock to mitigate the risk of wider flock infection. Collected maggots should be destroyed to help control fly population growth.
Producers seeking further guidance can contact their local veterinarian, rural merchandise reseller, or Agriculture Victoria veterinary or animal health officer.