Deal a death blow to killer blowflies, urges Downland

Farming health company Downland is urging UK sheep farmers to ensure they are ready for action against blowfly strike. The disease is potentially at its worst from June until September-October.

It poses a serious welfare challenge to animals and, left unchecked, sheep die an agonising death. Strike can significantly affect farm profitability. More than 80 per cent of sheep flocks are hit by blowfly strike every year – compromising the welfare of more than 500,000 animals.

Figures from Eblex show the total cost to the sheep industry is £2.2 million a year. As well as animal deaths there are losses from damaged wool and fleeces, plus the cost of treatment and strike control.

A challenge for many farmers is that treating ewes with long-lasting insecticides at the start of the season means much of the product is lost when sheep are sheared, and the treatment of early-season lambs may delay getting them to market.

Basing strike control on a pour-on product such as Vectocert 1.25% provides more cost-effective protection for up to eight weeks and it has a withdrawal period for meat and offal of just eight days. There are no restrictions for use during pregnancy or lactation.

Rachel Clarry, Downland’s marketing co-ordinator, says with so many lambs going for slaughter at six to eight weeks it doesn’t make good economic sense for farmers to pay for 16 weeks’ protection.

In a bid to reduce the serious impact of blowfly strike, she is urging farmers who are looking for more information on the disease to contact the specialist in their relevant Downland independent distributor. There are 28 companies in the network, giving total UK coverage.

Blowfly strike is caused mainly by the maggots of greenbottle and bluebottle flies infecting sheep and lambs. Dirty areas of fleeces are a big attraction to the flies, which is why most strikes are at the back end of animals.

Pregnant female flies can lay up to 3,000 eggs in 10 batches over three weeks. Eggs hatch in about 12 hours and in the next three days the maggots use enzymes to digest and break through the skin. The enzymes release toxins which get into the blood stream of animals.

Risk of strike can be reduced by good husbandry, says Rachel Clarry, such as inspecting sheep twice a day in the fly season, removing dags from early April, and shearing – which will reduce susceptibility.

She adds: “It takes constant vigilance to keep on top of the problem. Female flies can travel several miles in their search for suitable victims, and they are attracted by the smell of sweat or fleeces contaminated with decaying organic matter such as urine or faeces. But vigilance and a good treatment programme will help to reduce the industry’s £2.2 million annual losses.”

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