WITH sheep lice being more widespread than they have been for a number of years, a new product is good news for sheep producers.

Unfortunately, it isn’t going to rid all properties of lice, but it does provide another treatment option.

The new chemical comes with the brand name “Avenge”. The chemical it contains is called imidacloprid, which has been used previously as a crop pesticide and now has been adapted for use on animals.

We constantly need new chemicals to fight parasites in animals because of resistance development. This is a particular problem with sheep worms and with sheep lice.

The big challenge when treating a mob of sheep is to treat them all thoroughly. You must deliver the right dose to all the animals in the mob. With sheep worms, it’s relatively simple, dose to the heaviest in the mob and check that your drench gun is delivering the full dose with a measuring cylinder.

It’s harder with lice. The dose rate is important and we use bodyweight of sheep as an estimate of the surface area of the sheep. You really need to dose sheep to the weight that they would be if they were in at least condition score 3 - their skin is just as big, whether it’s pulled tight over a fat frame or hanging off a drought affected sheep.

And it’s harder still. You have to make sure that the chemical can spread to all parts of their body. So you need to make sure that the chemical hasn’t all gone off to one side, or you don’t miss the back half or absolutely critically, don’t miss the neck. Around the neck, where there is a bit of wrinkle, usually a few longer bits of wool and some shade is where lice will survive best.

Grown sheep need a double stripe of Avenge to aid spread. It can be applied to wet sheep and can handle rain after application.

The Insect Growth Regulators (Magnum, Zapp), when they were first released, had the great advantage of sustained action, preventing reinfestation with lice for some months.

Unfortunately, resistance to these chemicals is quite widespread, so they are not as reliable as they used to be.

Avenge offers one months protection from reinfestation and if you want to get rid of lice, it’s important that you use that month to your advantage.

Make sure that you find and treat any stragglers or strays within that month and wean any lambs. If you get them out, then you just might clean up the lice with one treatment.

Stray sheep, stragglers and odds and ends need to be kept away from treated sheep. The killer mob is a good place for them. If you get lice in your killers, it shouldn’t be too big a problem. You can always get sheep back out of the killer mob and return them to their mob after the next shearing and lice treatment.

All backlines take time to kill lice - time to spread around the sheep and contact the lice. After 6 weeks, sheep treated with Avenge should have no live lice. Make the point of checking so that you know whether or not the chemical worked. Check sheep any time you have them in the yards because the sooner you realise lice are present, the sooner you can limit the damage.

LHPA staff across the State are keen to get more involved with lice control. We need to know what treatments are working and what are failing and can then talk to the chemical companies about what might be happening.

Certainly we have seen more lice through the Cooma saleyards this year, though not many from Bombala have been amongst them. If you would like a mob checked, or want to talk about lice control, please give me a call on 0429 946 441 or through the Bombala office on 6458 3055.