Despite this increase in preventive treatment for unmulesed sheep, the predicted number of struck sheep was higher for Gunning and Inverell, but not for Flinders Island, where the model did not always require routine preventive treatment for mulesed sheep. In regions with a flystrike problem, avoiding any increase in strike after ceasing to mules was estimated to double the cost of preventive measures for most shearing dates.
The date of shearing had a significant effect on total costs related to flystrike and in some cases shearing during the fly season increased costs and increased strike by interfering with the most efficient use of preventive treatment.
Crutching reduced costs in some cases, but in other situations the timing of crutching interfered with the optimum timing of chemical treatment and the model sometimes predicted worse outcomes than with no crutching. The timing of shearing, crutching and treatment must be carefully managed if both costs and the number of struck sheep are to be minimised.
Control of flystrike was found to be most efficient when there was a single period of high risk of strike or two equal periods of strike risk, rather than one short and one long period. What is mulesing? Can the RSPCA prosecute farmers for performing painful husbandry procedures without anaesthetic or pain relief? How can I lobby government to improve animal welfare? What are the animal welfare issues with shearing of sheep? What is sheep freeze branding or steining and is it an acceptable alternative to mulesing sheep?
Why are livestock left in paddocks without shade? Why are painful procedures performed without anaesthetic? Why is it important to declare mulesing status on the National Wool Declaration? Home Farm Animals Sheep. Research report - Prevention and control of flystrike in sheep January KB. Was this article helpful? Yes No. Figure 2 clearly shows the large differences that were found between sires within each year. However, in every year there were sires whose progeny were highly resistant and highly susceptible.
All flocks are likely to have a similar distribution in sires for breech strike, and identifying the susceptible animals are very important. Culling sheep that have either been struck in the breech or, where records exist, have had significant numbers of progeny struck, is a simple way of reducing the incidence of breech strike in the flock. Figure 2 shows the large differences between sire progeny groups and Table 1 shows the incidence of breech strike of the un-crutched and un-mulesed progeny of the two most resistant and two most susceptible sires that were born in , over their lifetime in the flock.
The progeny of the two most resistant sires experienced a strike rate of 5. This is very low considering these sheep were not mulesed, crutched or jetted while strongly challenged and assessed in a high flystrike season prior to hogget shearing. It is clear that if sheep are struck early in life, then there is a high likelihood that they will be struck again at later ages.
Therefore, one can say with reasonable accuracy that any sheep that had been struck in the breech is very susceptible to future breech strike and that all such animals should be culled and not used for breeding in future.
However, a significant proportion of the daughters of the two most susceptible sires were again struck at 3, 4 and at 5 years of age. The differences in breech strike within the two groups from year to year were probably due to different environmental conditions from year to year.
Figure 3 shows the important indicator traits for breech strike up to weaner shearing and the amount of variation these indicators explain in un-crutched and un-mulesed weaner sheep. In ewes lambs dags was less important and instead, differences in urine stain and tail wrinkle contributed significantly to breech strike. Figure 4 shows the indicator traits for breech strike from weaner to hogget H shearing and the amount of variation they explained in crutched ewe hoggets.
It is clear that in crutched hogget ewes, breech wrinkle PBRWR was the most important factor in breech strike from weaner to hogget shearing. This implies that whilst the removal of the wool by crutching hogget ewes reduces breech strike, probably through preventing the wool from getting too wet from urine and enabling it to dry much quicker, the presence of wrinkles negates this drying out effect of the urine from crutching. This then increases the risk of being struck.
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