4 September 1998

Ensure choice is right

By James Garner

FIND out which ectoparasites are a concern in your flock and treat accordingly this autumn.

Linda Mitchell, SAC Aberdeen sheep specialist, warns that OP dip is used less frequently now, and since the end of compulsory dipping skin damage has increased.

Thats confirmed by the British Leather Confederation. Its recent survey found an increase in skin damage since compulsory dipping regulations were abandoned in 1992. Philip Hadley, research officer at the BLC, says that skin damage because of ked infection has become particularly noticeable recently.

While the need to prevent ectoparasite damage increases, the rising number of products giving ectoparasite control means choosing the right one is vital.

The OP dips are still Dr Mitchells favoured option. "These kill all types of ectoparasites and control blowfly. This is not the case for non-OP dips and the injectibles," she explains.

"When treating scab, use a product with a long-lasting action which will prevent re-infection when manufacturers guidelines are followed correctly When dipping, ensure sheep are immersed for at least a minute.

"The average length of time a sheep spends in the dipper is 12 seconds. This does not kill off scab infection and would be a risk later.

"It is also important to co-operate with your neighbours, and co-ordinate protection measures within a period of two to three weeks," she says.

Spray-on products

While it appears that more producers are using a spray-on product to prevent blowfly strike, they will need to use an injectible for scab control where required, warns Lesley Stubbings, independent sheep adviser.

"Dipping still gives the best persistency and treatment against scab and the method means that sheep are hardly ever missed. This may not be the case with injectibles. Some of these are becoming more expensive for scab treatment as they require two doses 10 days apart, which may make it prohibitive for some producers.

"It is important that lowland producers assess risk of ectoparasites, particularly scab, to their flock and take appropriate action. This may mean quarantine and treatment of brought in stock," she continues.

Dr Mitchell agrees, and warns against complacency. She urges producers to remember that even where the vendor has a certificate guaranteeing animals have been dipped against scab , this does not necessarily mean the parasite will have been killed.

"The best way of avoiding buying in infection is to quarantine and treat animals as they arrive on the farm. Any problems will be spotted and infections can be dealt with before mixing," says Dr Mitchell.

Scab control products

Dips with long lasting action

These were approved scab dips when the compulsory dipping regulations were in force. They kill mites and provide protection against re-infection. About four weeks protection from a single dipping.

Group Chemical Trade name Manufacturer MWP*

Organophosphorus Diazinon All Seasons Fly & Scab Dip Coopers Schering-Plough 35

Diazinon Diazadip All Seasons Sheep Dip Bayer 35

Diazinon Deosan Diazinon Dip DiverseyLever 35

Diazinon Topclip Fly & Scab Dip Novartis 35

Propetamphos Ectomort Centenary Youngs 14

Propetamphos Flyte 1250 Youngs 21

Propetamphos Seraphos Crown 21

Non-organophosphorus Flumethrin Bayticol Scab & Tick Dip Bayer Nil

High-cis-cypermethrin Ecofleece Bimeda 12

Dips with a short action

These kill mites but offer no protection against reinfection. Double dipping 14 days apart required to eliminate scab mites.

Group Chemical Trade name Manufacturer MWP*

Non-organophosphorus High-cis-cypermethrin Crovect Dip Crown Nil

High-cis-cypermethrin Robust Youngs Nil

High-cis-cypermethrin Provinec Dip C-Vet Nil

Injection with a short action

This is a licensed product which kills mites but offers no protection against reinfection. Two subcutaneous injections seven days apart are required. Only mix with flock after a further seven days.

Group Chemical Trade name Manufacturer MWP*

Avermectin Ivermectin Ivomec Injection for Sheep Merial 42 days (+ Panomec) after 2nd injection

Injection with long lasting action

This is a licensed product which kills mites and provides protection against reinfection. One intramuscular injection is required but treated sheep must not be mixed with untreated sheep for 14 days.

Group Chemical Trade name Manufacturer MWP*

Avermectin Doramectin Dectomax Pfizer 56

Milbemycin Moxidectin Cydectin Fort Dodge 70

*Meat withdrawal period (days).

Source: SAC.