While debate continues about the phasing out of mulesing in 2010, sheep producers still need to act to reduce the incidence of flystrike.

While hopes exist for effective alternatives to surgical mulesing by that time, there are already several strategies available to manage flystrike susceptibility, including flock husbandry practices, chemical and non-chemical pest management and breeding and selection.

Sheep in short wool are less susceptible to flystrike.

The timing of crutching and shearing are husbandry practices that play a large role in reducing the risks associated with both breech and body strike.

Many wool producers currently crutch twice a year as part of their normal wool management program.

There may be opportunities to modify the current sheep management schedule but it is important to consider the calendar of operations for all on-farm activities, including the availability of shearers.

Tail length is a critical consideration in reducing flystrike, as well as the incidence of tail and vulva cancer.

The correct place to dock the tail is immediately below the third palpable joint or in line with the tip of the vulva in ewes.

A three joint tail allows the sheep to lift its tail well away from urine or faeces which are the main attractant for breech strike.

Managing struck animals is critical to minimising flystrike.

Culling them reduces strike incidence in the short-term and in the long-term improves the flystrike resilience of the flock.

Integrated parasite management can incorporate use of flytraps to determine when the over-wintering blowflies emerge from the soil.

They emerge when soil temperatures exceed 15 degrees.

These temperatures occur from spring until at least autumn in many areas.

If the flies that emerge in spring find susceptible sheep, flystrike will occur unless remedial action is taken.

Blowflies are particularly attracted to sheep odours such as fleece-rot damage in damp fleece, and dags.

Flytrap results and the frequency of significant rainfall - enough to wet sheep to skin level - can be used to estimate the flystrike risk to susceptible sheep.

If the risk is significant, act quickly to reduce flystrike susceptibility.

This might mean applying insecticides, crutching or drenching if internal parasite levels are high.

If your sheep are not susceptible the risk is low.

When considering breeding and selection, the key traits to breed out are breech wrinkle, breech cover and fleece rot.

Of these traits, breech wrinkle is the most important for breech strike; fleece rot is the most significant for body strike.

Some producers worry that if breech wrinkle and body wrinkle are reduced, sheep will lose fleece weight.

But both can be achieved quickly and fleece weight maintained. How quickly will depend on a producer’s starting point.

The genetic solution will be permanent and cost effective as we are not relying on costly measurements.

So where to start?

Breech wrinkle correlates highly with body wrinkle.

To measure, use the scoring sheets used for Estimated Breeding Values (EBV).

Score 100 ewes hoggets at random or a good cross section of your flock for body wrinkle and breech cover.

Marking is a good time to do this if you are still mulesing or using an alternative measure such as breech clips.

Score the rams you have on hand.

Discuss the issue with your ram breeder and find out what direction they are heading on body wrinkle and breech bareness.

Selection strategies that can be implemented now include purchasing rams with breech Estimated Breeding Values which should be available in the coming spring; cull ewes with heavy body wrinkle (for example into a meat breeding group) and ones that have been struck.

No single solution will fit all.

Consulting your sheep classer and other sheep advisers will be important.

Breeding will be part of the solution in future, however, an integrated approach using the management options mentioned will still be required.

Notably, tail length has a noticeable effect on reducing the incidence of flystrike.

Contact Sally Martin, Young, (02) 6382 1077 or your local NSW DPI sheep and wool officer.

Further reading

Common blowflies that strike sheep in NSW, Australia

Dressing for flystrike and wounds

Chemicals registered to treat lice and flystrike on sheep, September 2004