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Lice principles of control

Proper Application is Imperative to Success

The key to lice control is to plan a well-timed annual treatment of all sheep. Lice prevention requires planning in terms of timing and method of application. For backline treatments, it is best to treat lice off-shears, and for saturation dipping, when the wool is short e.g., 2-4 weeks off-shears with a flat comb. Lice can reduce the quality and yield of the fleece, and in fine woolled breeds, body lice are considered to be a major factor in affecting fleece quality and wool value.

Proper application is imperative to success.

Pour-on: Apply off-shears within 24 hours of shearing i.e., Pour-ons are best applied off-shears to skin level. They move over the skin killing lice on contact. Therefore, it is very important that the product is applied in a wide band down the midline of the back from the ears to the tail. Use of any pour-on products in long woolled sheep is never going to be fully effective and is generally considered a salvage operation until the next time sheep are shorn. Remember that shearing will only remove around 80% of the lice on a sheep.

Saturation: For shower dipping, the standard recommendation is 1 minute in a shower dip for every week off-shears. This is only a guide so use an indelible pen to check if your sheep are saturated to skin level.

Regardless of whether you are using a conventional or constant replenishment shower, the sump should be drained and cleaned regularly. The ‘1 sheep to 2 L’ rule applies here e.g., 1000 L sump will allow 500 sheep to be dipped, after which should be drained and cleaned before the next 500 sheep are dipped.

Hand jetting is widely accepted as first choice for fly control but only a supplementary treatment for lice control. Set pump @ 70 psi and apply a minimum 2 L of wash to adult sheep and 1 L minimum of wash to lambs. Tip: time how long it takes to run 1 L of wash into a bucket to work out how long it takes to pass the jetting wand over a sheep to deliver the right amount of wash.

Note: Automatic jetting races are principally used for fly control despite manufacturers promoting them as being capable of applying lice treatments effectively. There is limited information regarding the efficacy of this application method with respect to lice control.

The advantage of AJRs is that a large number of sheep can be treated over a shorter period compared to hand jetting. Volumes delivered are usually lower than hand jetting (400-500 ml). Therefore, where practical, running lambs through the AJR twice is recommended. Expect shorter periods of flystrike protection especially if a low volume has been applied.

Learn more about the 10 point lice management plan.

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