Farm Ireland
Independent.ie

Sunday 23 September 2018

Are 'very affordable' drugs leading to incorrect dosing of cattle?

Why tailored dosing programmes are required to combat animal drug resistance

The Teagasc sc team get set for action at last week's animal health on Alan McDonnell's farm. Photo: Jeff Harvey/HR Photo
The Teagasc sc team get set for action at last week's animal health on Alan McDonnell's farm. Photo: Jeff Harvey/HR Photo
Paul Gibney, Teagasc; Vivienne Silke, Teagasc; Alan McDonnell, beef farmer/host; Bernadette Early, Teagasc and Catherine Carty, UCD AHI at the AHI/Teagasc Beef Farmer event on the farm of Alan McDonnell in Westmeath. Picture: Jeff Harvey/HR Photo
Ann Fitzgerald

Ann Fitzgerald

Stern warnings about the incorrect use of both anthelmintics and antibiotics were issued at the Animal Health Ireland/Teagasc/Meat Industry Ireland animal health event held on Alan McDonnell's farm in Streamstown, Mullingar, Co Westmeath.

Teagasc drystock advisor Paul Gibney said under-dosing and over-dosing are both occurring and each cause different problems.

He said there are currently three classes of anthelmintics available for the treatment of gut worms in cattle, benzimidazoles (white drenches), levamisoles (yellow drenches) and the avermectins (clear drenches).

The first two are about 40 years old; the avermectins 10 years younger. All are now off patent and have become "very affordable", he said.

Paul Gibney, Teagasc; Vivienne Silke, Teagasc; Alan McDonnell, beef farmer/host; Bernadette Early, Teagasc and Catherine Carty, UCD AHI at the AHI/Teagasc Beef Farmer event on the farm of Alan McDonnell in Westmeath. Picture: Jeff Harvey/HR Photo
Paul Gibney, Teagasc; Vivienne Silke, Teagasc; Alan McDonnell, beef farmer/host; Bernadette Early, Teagasc and Catherine Carty, UCD AHI at the AHI/Teagasc Beef Farmer event on the farm of Alan McDonnell in Westmeath. Picture: Jeff Harvey/HR Photo

The Teagasc man suggested that this may contribute to animals sometimes being dosed when it's convenient rather than when it is required.

If someone has cattle in for the TB test, for example, they might say to themselves, "I might as well give 'em a little bit of Pour-On."

On the other side of the coin, "if you under-dose, you will get rid of some worms but others will get a taste for it and only come back stronger; it's nothing personal, just survival of the fittest."

He emphasised the need to know the correct weight of the animal being dosed and suggested that greater use be made of weighing scales.

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Mr Gibney reiterated the "five rights" of drug administration: the right (correctly identified) animal; the right product for what's being treated; the right dose for the animal's weight; the right route; and the right juncture in the parasite's life cycle.

While more research needs to be done, he warned that we are starting to see resistance to all three groups of products.

He pointed to a Teagasc study last year which looked at 16 farms operating dairy calf to beef system and was reported on in these pages last month.

A fully effective anthelmintic dose reduces egg count to zero after administration. If the egg count reduction is less than 95pc, then anthelmintic resistance is present.

The study found that, on all 16 farms, the ivermectin treatment failed to reduce the egg count by >95pc.

The Teagasc man said the situation is compounded because of the lack of research in this area. Gut parasites are really only an issue in Ireland, Britain and France, which is not big enough a market to attract a lot of investment.

He advised that faecal sampling is a very useful way of determining egg burdens.

He demonstrated one kit, which costs €28 for two tests and showed how simply it can be done - just gather up fresh dung samples (from a maximum of five dungs in each container) and send it off to the lab (midweek, so it's not sitting in the post over the weekend). If dosing is required, re-sample two weeks later.

Both Gibney and UCD bovine health specialist Catherine Carty urged that faecal counting be used in conjunction with the AHI Beef HealthCheck reports, which are currently issued by the meat factory when an animal is slaughtered.

She said the hope long-term is to roll out these reports back down the line, so that all handlers of a particular animal would be provided with feedback on their health status.

In response to a question from one of the 70-plus farmers who attended the event as to what constitutes a proper dosing programme, she replied that there is no one simple answer.

"It is very farm specific. It depends on what part of the country you are in, whether an animal is spring-born or autumn-born, whether there were calves on the pasture last year, etc.," adding, "your own vet would be well placed to help".

Ms Carty presented liver fluke figures for Westmeath for the year to date, which show the county to be "slap bang" in the middle of the table, as would be expected, with close to 4pc of livers showing signs of liverfluke damage with live fluke observed and 20pc of livers showing fluke damage but without live fluke.

Both faecal sampling and these HealthCheck reports can be used to build up a picture of the prevalence of the various parasites on your farm and be used to assess the effectiveness of your dosing programme, the vet said.

Teagasc Knowledge Transfer specialist west and midlands, Vivian Silke, who is based in Athenry, quoted England's chief medical officer who recently said, "if antibiotics lose their effectiveness, it would spell the end of modern medicine."

He pointed out that Anti-Microbial Resistance is causing the deaths of 37,000 people in Europe every year and it is of concern to us as farmers as we are supplying into the food chain.

In response to a comment that, "farmers are being blamed for everything", Mr Silke conceded that the situation in considerably worse elsewhere, especially in the pigs and poultry sectors but said now is the time for us in Ireland to take action to prevent it from becoming a problem.

If microbes that cause disease in humans are becoming resistant to anti-microbials used in animals and crops, these anti-microbials will not be effective in treating that disease in sick humans, or animals.

In terms of preventing AMR, we need to use anti-microbials responsibly, and he said there are a number of points that need to be kept in mind: antibiotics do not kill viruses, antibiotics should be used for treatment not prevention, and they should be used as prescribed, ie always complete the course.

There also exists lists of first, second and last choice anti-microbials for certain microbes. By following the correct order in which they are administered and not, for example, using a last choice before trying a first choice, we can prevent microbes from acquiring resistance from the last choice (last resort!) anti-microbials.


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