Australian surveys on incidence and control of blowfly strike in sheep between 2003 and 2019 reveal increased use of breeding for resistance, treatment with preventative chemicals and pain relief around mulesing

Colvin, A.F.; Reeve, Ian; Kahn, Lewis; Thompson, L.J.; Horton, Brian J.; Walkden‐Brown, Stephen W.

doi:10.1016/j.vprsr.2022.100725

Cited by 3 publications

(2 citation statements)

References 33 publications

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“…The sheep farming community countered this campaign by pointing out the effectiveness of the approach and by trying to develop more humane alternatives, none of which has been extensively adopted (Wells et al 2011). Two significant advances have been the now widespread adoption of local analgesia during the procedure and the accreditation of mulesing practitioners (Colvin et al 2022). Forward-thinking farmers, seeing a time when the practice will be banned, have themselves decided to abandon it for their own flocks and, instead, use other means of prevention, including insecticides, more intense surveillance for early strike detection, and breeding for resistance to flystrike (Greeff et al 2018a) and for resistance to the helminths that cause diarrhoea in sheep (Karlsson and Greeff 2012).…”

Section: Box 1 Mulesingmentioning

confidence: 99%

Investigating the role of blow fly olfaction in flystrike in sheep

Yan,

Schlink,

Liu

et al. 2024

Anim. Prod. Sci.

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Breech flystrike is a painful, debilitating and potentially lethal disease caused by the larvae of the blowfly, Lucilia cuprina, and, despite many years of research, it remains a serious financial and animal-welfare issue for the Merino sheep industry in Australia. The common methods of prevention, namely insecticides, crutching and ‘mulesing’, are problematical, so alternative approaches are needed. Breeding for resistance to breech strike is a fundamentally attractive proposition, but the trait itself is difficult and expensive to quantify in large numbers of sheep in extensive production systems. Several indirect traits are correlated with susceptibility to flystrike, but a large proportion of the variation in susceptibility remains unexplained. The common thread through those indirect traits is odour, so we turned to the biology of insect olfaction and its role in fly–sheep interactions. L. cuprina uses odours to detect and locate potential hosts over long distances, to guide orientation and landing behaviour, and to select egg-laying sites. Preliminary studies demonstrated the importance of confining our work to gravid female L. cuprina, and also validated the use of flies reared in the laboratory for experimentation. Using laboratory-reared flies and a combination of gas chromatography–mass spectrometry with electroantennographic detection, we identified odouriferous compounds from sheep that the antenna of L. cuprina can detect. To determine whether the identified compounds were attractive or repulsive, we needed to use a behaviour test. In preliminary studies, we compared four behaviour bioassays (Y-tube, landing time, visiting frequency, and trap) and found the trap to be the most effective. We observed that L. cuprina was attracted by several compounds in Merino wool, including octanal, nonanal and dimethyl trisulfide. We also found that the wool levels of octanal and nonanal are heritable in Merino sheep, suggesting that these compounds might be useful as traits in selection for flystrike resistance. Another possibility is that these olfactory-active compounds might guide efforts to modify the genome of sheep, or perhaps even L. cuprina. Success in these endeavours could save as much as A$200 m per year for the Australian Merino-based industries, while also improving the image of wool in world markets.

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Section: Box 1 Mulesingmentioning

confidence: 99%

Investigating the role of blow fly olfaction in flystrike in sheep

Yan,

Schlink,

Liu

et al. 2024

Anim. Prod. Sci.

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“…Strategies to maintain blowfly susceptibility to currently used insecticides are critical, owing to producer reliance on chemical treatment (Levot 2001;Colvin et al 2022).…”

Section: Introduction Accepted: 31 January 2023mentioning

confidence: 99%

A model of flystrike pesticide resistance management on sheep: use of pesticide rotations

2023

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Context.In some regions of Australia, the Australian sheep blowfly (Lucilia cuprina) is resistant to some of the pesticides used to control flystrike in sheep. Few pesticide groups are available, so it is important to delay or prevent any increase in resistance. Aims. This study examined some of the assumptions in a previously developed model of pesticide resistance and tested the use of pesticide rotations as a means of limiting blowfly resistance to pesticides. Methods. A model of sheep blowfly pesticide resistance was added to a previous model of sheep blowfly strike, to allow simulation of a range of pesticide management options for control of flystrike in sheep that might avoid increasing pesticide resistance. Key results. The model requires some assumptions of settings that are uncertain, but the effects are not sensitive to a wide range of values for these settings. Resistance may not be obvious for some years after a new product is introduced, but once it has been detected, the frequency of resistance genes will increase rapidly if use of the same pesticide continues. The use of different pesticide groups each year is preferable to continuous use of the same product, but this risks losing efficacy of multiple products rather than one product at a time. However, rotations do provide a longer period of good protection from flystrike before all products used in the rotation fail. The number of years of successful protection against flystrike is extended if there is a fitness disadvantage for resistance to the products used. Conclusions. The model may be useful for examining interactions between genes for resistance to different pesticides and the effect of non-chemical methods of control of flystrike, to extend the useful life of the current range of pesticides. Implications. By the time resistance is detected on a farm, the level of resistance is high and will increase rapidly if the same pesticides continue to be used. Other non-pesticide methods such as breeding sheep for resistance to flystrike may be long-term solutions where resistance has reduced pesticide protection.

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Sheep producers report docking tails shorter than recommended, knowledge–practice gap, and inconsistent length descriptions: an Australian survey

Woodruff,

Munoz,

Coleman

et al. 2024

Anim. Prod. Sci.

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Context In Australia, it is a common practice to dock sheep tails, to reduce breech soiling and flystrike. According to research, for docking to provide the optimal benefit, tails should be left at a length that covers the vulva in ewes and to an equivalent length in males. Docking tails shorter than recommended increases the risk of perineal cancers, arthritis and prolapse. Research indicates that some producers dock tails shorter than recommended, up to 57% in surveys and up to 86% in on-farm data. Aims This study aimed to ascertain the current tail docking length, practices, knowledge and attitudes of Australian sheep producers. Methods A national survey was conducted using online, hardcopy and computer-assisted telephone interview (CATI) modes of delivery (n = 547). Key results Fifty-seven percent (205/360) of online and hardcopy survey participants chose short tail images to represent their practice, where the vulva was exposed. Although 88% (135/154) of CATI participants described their sheep tail lengths to be covering the vulva, participants equated the length to leaving two tail joints (40%, 54/134) and/or 50 mm (29%, 39/134), both of which have been previously found to be too short to cover the vulva. There was a high awareness of the recommended length (75.7%, 408/539) and 60% (234/390) of participants described it accurately. Significant associations were identified between choosing the short tail image and (1) describing the recommended length to be shorter than it is (P < 0.01), (2) being a producer in South Australia (P < 0.05), and (3) practicing mulesing (P < 0.01). Tail docking is important for producers to reduce flystrike, but docking at their chosen length held more importance than following the recommendation. Participants tended to agree that shearers preferred short tails. Docking tails with a hot knife or rubber rings were the most common methods used. Conclusions These results indicated that short tail docking remains a sheep-welfare issue for Australian sheep, and that a knowledge–practice gap exists for some producers. Implications Future research in the space of tail length could address the identified knowledge–practice gap, attitudes, and individual barriers to benefit sheep welfare and the industry.

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Australian surveys on incidence and control of blowfly strike in sheep between 2003 and 2019 reveal increased use of breeding for resistance, treatment with preventative chemicals and pain relief around mulesing

Cited by 3 publications

References 33 publications

Investigating the role of blow fly olfaction in flystrike in sheep

Investigating the role of blow fly olfaction in flystrike in sheep

A model of flystrike pesticide resistance management on sheep: use of pesticide rotations

Sheep producers report docking tails shorter than recommended, knowledge–practice gap, and inconsistent length descriptions: an Australian survey

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