Some simple husbandry changes and practical midge control measures may help break the livestock infection cycle of Bluetongue Disease, Schering-Plough livestock vet adviser Paul Williams has told Farmers Weekly.
“It may be difficult on some farms, but aim to reduce vector access to susceptible livestock. Housing livestock during times of maximum midge activity – from dusk until dawn – will significantly reduce biting rates and potential likelihood of infection,” he says.
“In addition, protecting livestock housing openings with fine mesh netting or coarser material impregnated with insecticide may also help.”
Experts say that it is virtually impossible to eliminate populations of the biting midge, but tackling potential midge breeding grounds and use of pour on insecticides approved for use on sheep and cattle may reduce risk of infection to some degree in certain circumstances.
“As far as possible, midge breeding sites should be identified and destroyed,” Mr Williams adds. “The Culicoides midges that carry the Bluetongue virus usually breed on animal dung and moist soils, either bare or covered in short grass.
“So turning off taps, mending leaks and filling in or draining damp areas will all help dry up breeding areas. And dung heaps and straw bedding should be removed at least weekly to break the immature midge breeding cycle.”
Mr Williams also recommends applying insecticides approved for use on sheep and cattle.
“The DEFRA technical review on Bluetongue maintains that targeted use of synthetic pyrethroids – such as deltamethrin, applied weekly in and around animal housing and directly onto the target animals – should be effective as a practical disease defence strategy,” he points out.
However, he does stress that farmers need to speak to their vet about using insecticides as their use for midge control is off label and meat withdrawal periods will need modification. “If you are using Coopers Spot On at weekly intervals, observe a 29 day withdrawal period for cattle and 63 days for sheep. The zero withdrawal period for milking dairy cows is unchanged,” he says.