Test before autumn worm control

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“It is disappointing to see the message around responsible and sustainable use of anthelmintics is still not getting through."

Sioned Timothy

Knowledge gap

“Understanding key factors which can influence the risk of infection during the grazing season is an important part of effective monitoring.

“With this in mind, we recently conducted a number of polls through Farmers Guardian’s Facebook, Twitter and Instagram channels to determine awareness of some of these risk factors.

“The results have shown a concerning number of respondents are unaware of the approaches they could be taking to monitor and reduce parasite burdens in grazing cattle.” When asked whether it was true or false that reducing stocking density reduces parasite risk, most respondents to the poll chose the incorrect answer.

Only 104 out of 229 (45 per cent) replied correctly ‘true’.

When it came to understanding anthelmintic resistance, poll respondents were also lacking in knowledge.

Questions around best practice for resistance management, such as leaving some cattle unwormed and not adopting a ‘dose and move’ strategy, were asked twice each in different ways to test understanding.

In all cases most respondents selected the incorrect answer.

Sioned says: “It is disappointing to see the message around responsible and sustainable use of anthelmintics is still not getting through.

“For several years we have been advising cattle producers to adopt a more targeted approach to worm control, using various assessment techniques, and to avoid blanket-treating the herd.

“We have also been strongly advocating against using ‘dose and move’ strategies which are highly selective for resistant worms.

“The lessons of the sheep industry have not been learned by cattle producers yet, but anthelmintic resistance is a real threat.

“If we don’t implement some simple safeguards now, we could jeopardise the effectiveness of parasite control in the long-term.”

Identify the threat

Cattle are often infected by several parasite species at the same time.

So understanding which species you have on-farm and their lifecycle will help identify the right testing and monitoring strategies and the most appropriate treatment.

The most common worms affecting grazing cattle are the gutworm species Ostertagia ostertagi and Cooperia oncophora and the lungworm Dictyocaulus viviparus.

A parasite control strategy should also take the threat posed by liver fluke (Fasciola hepatica) into account.

Without investigation and some diagnostic tests, it is not possible to tell which species are infecting the herd.

Grazing cattle can be assessed for worm burdens in a number of ways.

A simple method of identifying a potential gutworm burden is to weigh growing animals and benchmark them against target daily liveweight gain.

Ideally, animals should be weighed throughout the season, but an autumn stock check before housing is also a good time.

Calves and youngstock in their first and second grazing season which are receiving sufficient nutrition, but are not meeting growth targets, are likely to be facing a high gutworm challenge.

Selectively treating individual animals which are behind target removes the worm burden and its negative effect on production, while avoiding the high selection pressure for anthelmintic resistance associated with whole group treatments.

This strategy can also potentially reduce treatment costs.