Worming strategies re-assessment advised

Adult hoose worms, highlighted by the black arrows, in the airways of a weanling submitted for post mortem to the Veterinary Laboratory Service. Wormer treatments at or during housing are recommended.

Q&A: Animal Health Ireland

Department of Agriculture sources have warned that the mild, humid autumn was ideal for development of cattle parasites.

The Department’s Regional Veterinary Laboratory Service has advised all sheep and cattle farmers to re-assess their worming strategies this autumn and to speak to their local vets or Teagasc adviser about any concerns.

According to Animal Health Ireland (AHI), economic losses due to parasites such as stomach worms and liver fluke in cattle are universally accepted.

And the scouring or coughing animal with severe weight loss and maybe ‘bottle jaw’ is only the ‘tip of the iceberg’.

Sub-clinical parasitic infection, with its potential impact on growth rate, milk yield and fertility lies ‘beneath the surface.’

According to AHI, housing of cattle for the winter provides a good monitoring opportunity to assess the parasite status of your farm.

¦ Why should I control parasites at housing?

>> Cattle can pick up infections with worms and liver fluke only while grazing at pasture.

When cattle are housed, they can no longer pick up new worm and liver fluke infections until they are turned out onto grass the following spring. This means that effective anthelmintic (wormer) treatments at or during housing should keep the animals virtually free of worms and liver fluke until they return to pasture.

¦ How well is my herd performing?

>> Before considering the parasites themselves, it is valuable to consider the performance of the stock over the previous grazing season and how it compared with expectations and/or targets. Measurable on-farm performance indicators that can be affected by parasites are growth rate in calves in their first grazing season and second grazing season fattening cattle.

Check age/weight and preg-nancy rate in second grazing season breeding heifers. Check milk yield, milk composition, condition score and fertility in adult dairy cows. Check body condition score and fertility in adult beef cows.

If there has been no clinical parasitic disease during the year and if the stock are all performing to expectations/ targets, it may well be that your parasite control has been successful.

However, it is still time well spent to review any parasite control undertaken.

What was done, when was it carried out, how easy was it, how much did it cost and is there scope for improvement?

¦ How do I investigate my herd parasite status?

>> If parasites are suspected of having affected performance, diagnostic sampling is recommended.

Contact your vet for parasite investigation advice.

The results will help you plan parasite control for the next grazing season as well as deciding the optimal treatment at housing. Tests should be done on 10-15 samples of faeces from all cattle, plus the same number of blood samples from calves in their first grazing season and second grazing season fattening cattle, plus one bulk milk sample from adult dairy cows.

¦ What are the target parasites and treatments at housing?

>> Target parasites in cattle of all ages at housing are stomach worms, lungworms, liver fluke, chewing lice, sucking lice and mange mites. The number of parasites carried by cattle at housing can vary according to several factors, including their age, health status, previous grazing management and level of previous anthelmintic treatment.

These, plus inhibited larvae of stomach worms, are common in Ireland and the chances are that all are present on your farm (with the possible exception of liver fluke). They affect all ages of cattle, although it’s mainly young, first grazing season cattle that are affected by sucking lice.

Using an anthelmintic effective against inhibited larvae of stomach worms can be specifically targeted at housing in order to eliminate the risk of potentially serious dis-ease towards the end of the housing period. Many of the treatments are available as combinations, usually a flukicide and a general wormer or an endectocide. Thus, with some externally applied and injectable combination products, it is possible to effectively treat almost all the different types and stages of the target parasites.

Whatever is used, it is time well spent for farmers and their vets to discuss the treat-ment options and whether broad or narrow treatment options are required.

These parasites are difficult, if not impossible, to eliminate (with the possible exception of mange).

All are in some part responsible for both clinical disease and sub-clinical production losses, thus the rationale for their control is strong and housing provides a unique opportunity to simply and simultaneously treat a broad spectrum of potentially pathogenic parasite species.

¦ For full information, see the www.animalhealthireland.ie website


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