SP dips pose a risk of environmental damage
By James Garner
SHEEP producers considering dipping their flock with synthetic pyrethroid products this autumn are being warned by the Environment Agency to use them with care as they can cause severe environmental damage.
But with organophosphate dips still unavailable after the governments temporary ban in January 2000, there are few alternatives for producers requiring scab, lice, tick and blowfly control in one hit, say vets.
The situation is exasperated in hill, upland and common grazing areas where gathering sheep and shared grazing complicates methods of ectoparasite control.
SACs Brian Hosie reckons that SP dips, such as Bayticol or Ecofleece, can be used with more confidence where a complete gather is difficult and sheep are returned to the same pasture.
"Flockmasters concerned about reinfecting their flocks by not achieving a complete gather or who are returning sheep to the same grazing should use a product that controls scab and gives some protection against reinfection."
He adds that scab mites can survive for at least two weeks on pasture, fences and gorse bushes and will be a source of reinfection.
But there is no doubt that SP dips can cause environmental damage. SAC Thursos Sandy Clark says that diluted SP dips are 100 times more damaging to the environment that diluted OP dips.
Sheep farmers who can guarantee a 100% gather could inject against scab, but when one or two sheep are left behind these may reinfect others. "When injecting against scab, use the correct dose to the weight of the animal and follow manufacturers guidelines," he advises.
In an attempt to cut pollution risks, EA Wales has identified seven key areas – the first being to dip sheep only when necessary.
This may be naive, says NSA chief John Thorley. "The big difference with injectables and dips is that most dips usually do afford some protection against scab, kill lice and prevent blowfly attack.
"It is wishful thinking that producers will not dip sheep, particularly on common grazing land, where it is desperately important," he adds.
In response, EA Wales rural land use officer, Bob Merriman, says it is not advising flockmasters not to dip, but believes there is a habit of dipping sheep.
"Traditionally many flocks have dipped sheep in summer and autumn and do so because they always have done.
"In upland areas with communal land, producers will need to dip. In lowland areas, closed flocks without scab may not need to dip, but should inject replacements against scab to prevent introducing the infestation." He adds that animal welfare must come first and sheep should be treated on these grounds.
In an effort to stem dip pollution, Mr Merriman points to 1997 and 1998 when there were 34 and 24 incidents, respectively, mainly caused by SP dips.
The OP ban raises fears that similar levels of pollution incidents could recur this autumn. "Our advice to producers and contractors who really need to dip sheep is to do it carefully."
He outlines some common sense measures to help cut the risk of pollution and avoid maximum fines of £20,000.
Among other advice, he suggests checking drains in dip baths, as these can be a big risk through seepage. The drain pen must also run back into the dip.
Mobile dippers should be properly sited and not be used in farmyards where spillage, or drainage from sheep can run into surface water drains or ditches.
And freshly dipped sheep should be prevented from wandering through fresh water streams or wetlands. SPs are quickly washed off and will cause severe pollution, warns Mr Merriman. *
• Welfare of animal first.
• Dip when necessary.
• Care with dip disposal.