Guidelines (10 Commandments) for Maximising Profit- through effective management of worms

This article is one in a series on techniques and technologies which farmers can use to increase profit through better managing animal health

Sheepvet Australia veterinarians are contactable through: frontdesk@sheepvet.com.au

First commandment: Recognise that resistance occurs to all anthelmintics and is unique on each farm

• Some drenches including ivermectin & Rametin combinations are now ineffective on many farms
• Some farms have major resistance to every drench group and registered drench combination
• Every farm should have an effective biosecurity program which keeps highly resistant worms out

Second commandment: Test for worm resistance to drenches every 2 years- at the correct time- on each farm

• Each test should be customised and does not need to include all groups of drenches
• Can be major differences for some groups or off-label combinations if tested on green or dry feed
• For some off-label combinations, testing needs to be undertaken just before intended time of use

Third commandment: Monitor body score and condition, and faecal egg counts at appropriate times

• When to monitor may vary with class of sheep, time of lambing, stocking rate and management practices such as shearing, and should be worked out in consultation with your veterinary adviser

Fourth commandment: Develop triggers for additional monitoring or management changes

• Consult with your veterinary adviser to develop a system for recognising events and circumstances which require intervention and/or increased monitoring

Fifth commandment: Be aware of and avoid ineffective strategies which may increase resistance levels or economic loss

• Rotation of drenches of unknown effectiveness is likely to increase farm resistance
• Do not presume that diarrhoea in sheep or lambs requires treatment for worms or coccidiosis
• Do not presume that the absence of diarrhoea means that worms are not a significant problem

Sixth commandment: Do not drench sheep or lambs without a well-defined objective or reason

• Understand why a drench is to be given- is to remove worms or to prevent contamination?
• Except for barbers pole worm, faecal egg count monitoring provides a basis for the decision

Seventh commandment: Always treat with a drench with the appropriate level of effectiveness

• Treatments should be more than 95% effective as pasture dries off, or early in a new pasture season. Drenches during maximum pasture growth (June to September in south-west Western Australia) should generally be at least 75% effective
• Treat single parasite infestations (barbers pole, thin-necked intestinal worm, liver fluke) with the specific drug

Eighth commandment: Avoid dry-season drenching onto larva-free pastures & stubbles

• Treating worms during November to March in south west Western Australia provides high selection pressure for resistant parasites, and is the single most important cause of drench resistance emergence in this region

Ninth commandment: Use adult dry sheep with low egg counts or cattle to clean up larvae from pastures

• Wethers, dry ewes or in some situations, hoggets can be used
• To avoid further contamination, these should have a low faecal egg count
• This is particularly valuable to prepare paddocks for highly susceptible lambs
• Be aware that there are risks to this strategy including some worm species being favoured

Tenth commandment: Breed resistance to worms into the flock

• Buy replacement rams which utilise EBV's which include faecal egg count data
• Select hogget rams bred on-farm on the basis of individual faecal egg counts

ADOPT AN IPM (Integrated Pest Management) STRATEGY

Obtain competent independent advice & be able to change your practices - irrespective of what you have believed previously. A veterinarian experienced in sheep medicine can provide this advice,

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Telephone 61 8 9642 1311 or from rural Western Australia 1800 651 226