PHOTO: Chris Gordon
Whilst the La Niña may have run its course, wet season worm woes continue in many regions. The drier conditions for many will mean that gaining the upper hand on the worms that are in paddocks and inside sheep will be a little less complex, however the risks remain, and vigilance will be essential for staying ahead of the worms and getting back on top of them if they have become out of control.
Internal parasites are a massive cost to the industry, through both production losses, and the cost of control. Therefore, effective management, preventative strategies and effective control are key to minimising on-farm impacts.
For areas that have experienced flooding, there are no rules of thumb regarding the life span of worm larvae on flood inundated pasture. Testing is the key to building knowledge that will assist with decision making post flood.
A well thought out, planned and comprehensive campaign will be the best strategy for winning the war on worms. This will involve using as many of the tools available to gain the upper hand on the tricky parasites.
An integrated parasite management plan involves consideration of a number of factors:
- Which worms are inside the sheep (and how many): Know your enemy!
- What worms are on the pasture: Think about pasture contamination, and how your pasture management can help decrease the pressure that contaminated pastures are placing back on your production – what spelling length do you need for your lambing ewes this Autumn?
- What stage of management the animals are up to in the production cycle: Which ones are the most and least susceptible – think pre-lambing ewes, weaners being very susceptible, dry ewes less so.
- Test – don't guess! Your worm egg counts are a key tool in the war on worms – do not underestimate their power to give you crucial information.
As many autumn lambing flocks approach lambing, woolgrowers will need to step up monitoring programs, and their pasture management and preparation should be well and truly under way. Timely spelling of lambing paddocks will help set the lambing up to be less pressured by internal parasite burden from the paddock. Use the opportunity to increase your knowledge of estimated longevity of worm larvae on pastures at different temperatures. This knowledge will help refine spelling periods to minimise the worm loading in pastures. This information is available on the WormBoss website.
This leaves the sheep worm environment to take care of. Testing and using thresholds that are applicable for the age and status of the sheep in the production cycle are essential to ensure minimal pick up of worms from pasture. Using cattle if available may also help with cleaning up of paddocks.
Once a worm test result has been returned – and you know the number of worms in the sample (measured as eggs per gram or epg) – knowledge of which worms are present (or not) is key to making an appropriate choice of product to drench with. A larval culture will help you understand which worms you are dealing with. Remember: Barbers pole, black scour and brown stomach worm eggs all look the same under a microscope, so culturing them to hatch is the only way to know for sure which worms are present. Do not make assumptions of what's present – those rules of thumb will increase your risk of ineffective management, or unnecessary expense.
Use of the ParaBoss Drench Decision Guide will help decide when to drench or when not to drench. These guides have been developed by technical experts and apply to different areas. Your local advisor will also be key to implementing an effective control strategy.
Best practice drenching
Best practice drenching starts with the planning
Testing and knowing which parasites are targeted is the first step.
Selection of the correct product for the job
Don't use products that target worms that you do not have. Some actives are effective on some worms and not others; know which ones these are and use them for the worm species present. Combination drenches that contain a mixture of actives are considered best practice. Use the ParaBoss Product Search Tool to help understand the range of products that target the worm species present. This tool will also allow consideration to be given to the Witholding Period and Export Slaughter Interval (WHP and ESI) of the products.
Calibrate your drench gun
Take the time to check the calibration, and ensure your equipment is in good working order.
Right dose rate
Whilst it sounds simple, estimation of weight is often a significant source of both underdosing or overdosing at drenching time. Weigh a sample of animals and dose to the heaviest in the mob. If there is a large variation in weight, it may be preferable to weigh and draft into heavy and light to ensure that dose rates are correct. Remember, underdosing will help speed up the development of drench resistance. Overdosing costs money, and in some cases, depending on the class of stock and active, may cause toxicity to the sheep and this may lead to residue in meat or milk.
Read the label and adhere to the WHP and ESI
These are in place to ensure that food safety is maintained. Product labels are easily found on the Product Search Tool on the ParaBoss website.
Buying in stock? – Don't buy in someone else's worm problems!
All farms should have a biosecurity plan in place that helps protect the farm from introducing parasites or disease. When purchasing stock from anywhere, they should be treated with a quarantine drench upon arrival. If they have come a long distance, they may need to remain in a yard, and fed/watered to allow them to fill up and recover from the trip prior to treatment. Read the direction of the products that will be used for the quarantine drench before administering – do the stock need to be off feed for a period or full? Keep the introduced stock in a containment paddock for a few days to allow them to be free of worms before they are released to pasture.
Consider unfamiliar parasites in this space
For example, are the introductions coming from a barber's pole worm area, or a liver fluke area, or a black scour worm area? Do you have problems with any of these?
Quarantine drenches should contain four actives
This includes one of the newer products (monepantel or derquantel). This may seem extreme, but some pre-emptive treatment at introduction may prevent long term parasite induced headaches later on.
