Farm Ireland

Tuesday 23 January 2018

Protect your flock by developing an accurate parasite programme


Peadar O Scanaill

Each year, the Department of Agriculture produces an extensive report on all animal diseases found in the samples sent to the regional veterinary laboratories around the country. This year's report was sent to all vets in practice and makes for some very interesting reading indeed.

First and foremost, in recent years, the report is an all-island report involving all 32 counties. It takes all the information from Stormont and Omagh laboratories as well as the seven laboratories run by the Department of Agriculture across the rest of the island. That is because diseases do not recognise land borders.

Thankfully, diseases do respect island borders and we are blessed in that respect, having a water boundary between ourselves and the landmass that is Eurasia. We must covet that sea border and only move livestock onto our island once the livestock has passed through rigorous quarantine testing for any disease that may wish to get a foothold on Irish farms.

Back to the report itself, and it is a very accurate read on sheep diseases in particular. For instance, when it comes to mortality, the biggest single killer on Irish farms still remains grassland parasites. That includes both intestinal worms and liver fluke, and the picture is very similar north and south of the border.

Anywhere up to 25pc of sheep deaths on Irish farms is due to worm or fluke infestation. This is despite all the different wormers available throughout the country and the extensive knowledge we all have on how prevalent worms and fluke are in this country.

Several problems in sheep husbandry may affect this figure. Firstly, we all know that the early grass worms that cause extensive damage in grazing lambs can creep up very quickly after turnout. Nematodirus is a specific parasitic infestation that will cause farm deaths in young lambs before any faecal sample will begin to show evidence of parasites. Within a couple of weeks after turnout, the lambs may show one or two cases of ill-thrift before a sudden explosion of parasitic problems occurs. This can lead to increased sheep mortality despite very close observation of the flock.

Next on the list is anthelmintec resistance. It is known that resistance to many common wormers on sale in this country is a growing problem. The disease surveillance report tells us that some evidence emerged from a 2005 questionnaire in Northern Ireland, suggesting significant levels of resistance to Benzimadoles, Levamisole and the lactones group of wormers. The Department of Agriculture is conducting its own study to give an accurate read on resistance to common wormers all around the island. To help in this, we need to do our own bit of research.

We should all keep good records of the dose we use and the amounts given to the different batches. Most importantly, follow up with faecal samples sent via your own vet to the regional veterinary laboratory. This is to test if the wormer has worked in the first place and also to focus the correct worming interval to avoid overuse or underuse of our products. The regional veterinary laboratory is often forgotten about, but it is by far the single biggest asset our Government supplies to sheep farmers in their battle against diseases. It costs money to keep them there but without the regional labs, we would never get an accurate up-to-date read of on-farm sheep diseases.

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As well as faecal samples, we should also encourage more and more sheep and lamb carcasses to be sent to the labs. A post-mortem is a very inexpensive and heavily subsidised way of giving early warning indicators of growing diseases on sheep farms. I've often heard the adage, "a sick sheep is a dead sheep," but we should quickly reply, "a dead sheep tells us how to save the live sheep."

Another reason we continue to have up to 25pc of sheep mortality caused by parasites is because liver fluke falls into that category. Liver fluke in sheep has become one serious problem in lamb production here. In the first instance, it causes ill thrift throughout the entire batch. It quickly leads to the death of many lambs and can cause extensive liver damage within a few weeks of turnout. Tackle this problem with good veterinary advice as control involves many forms of approach. It is further complicated with flukicide resistance as well as some flukicides only killing adult fluke and others killing different stages of fluke larvae.

As a final note on fluke, it must be a continuous drain on sheep farmers to have up to 70pc of lamb livers deemed unfit for human consumption because of fluke infestation. The butcher trade must cringe at such high waste levels.

Returning to the surveillance report, thankfully the report indicates that less than 5pc of laboratory submissions found clostridial diseases to be the cause of sheep mortality. With excellent vaccination products available at a reasonable price, we must all ensure that the national flock is adequately protected.

To finish with this week, we'll touch on abortion findings in the annual report. It must be emphasised again that samples of aborted foetus and placenta should be sent to the regional laboratory whenever noted. This is because the two most common causes of abortion in this country remain the infectious diseases toxoplasmosis and enzootic abortion. These are largely preventable by vaccination, although vaccine availability has varied in the past. We'll discuss sheep abortion in the next article, but in the meantime consult your vet on your own vaccination programme.

Get the dosing done and never shirk from sampling before or afterwards in order to accurately focus your parasite programme.

Peadar O Scanaill is a vet based in Ashbourne, Co Meath, and a member of the Food Animal Group of Veterinary Ireland. Email:

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