Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free:

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site:, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Google Analytics

Targeted advertising cookies


The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at or by post at:

24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

Menu Logo Principal Oniris

Home page

Merlin Aurélie

Optimizing the anthelmintic use in dairy cattle in order to prevent the emergence risk of resistant populations of gastrointestinal nematodes: development of sustainable selective treatment strategy

Abstract :

In first grazing season calves (FGSC), the anthelmintic (AH) treatments used to control the negative impact of gastrointestinal nematodes (GIN) on growth must be rationalized to preserve their long-term efficacy. The aim of this PhD thesis was to develop and assess targeted selective treatment (TST) strategies based on growth in FGSC, in order to preserve GIN populations in refugia i.e. not exposed to AH, and thus delay the emergence of AH resistance. Firstly, the relation growth/GIN infection at housing was demonstrated in different environments which allowed identifying groups, and within groups, the most infected animals. Then, a tree treatment decision at housing was proposed combing grazing management indicators to identify the groups at risk, and several average daily weight gain (ADWG) thresholds to identify, within groups, the animals suffering the most of infection. A TST strategy based on mid- season mean ADWG was assessed in field survey in comparison with whole group treatment (WT). No significant difference, in terms of growth and GIN infection, was observed at housing between the TST and the WT groups. Lastly, the veterinarians’ behaviors and perceptions about the control of GIN in dairy cattle farming, including a more rational AH management, were assessed. The veterinarians recognize the need to consider the sustainability of the AH treatment but identify serval obstacles
as the development of advices and the availability of simple, reliable and inexpensive tools.
The results of this thesis show that it is possible to target the use of AH in FGSC basing on individual and group indicators.

Key words :

Heifer, gastrointestinal nematodes, average daily weight gain, anthelmintic, targeted selective treatment, grazing management, veterinarian