1-ONAB : who are we

Genetic diseases emerge recurrently in all livestock populations. Their onset is pratically unavoidable. They are due to DNA mutations that we cannot control.

If they are not expressed in the heterozygous state (in this case the mutation is recessive), they can diffuse silently in a population over several generations without being identified. An active surveillance is therefore necessary to detect their emergence as early as possible, bearing in mind that the first cases observed are late and always largely posterior to the original mutation and its spread in the population.

However, if on the contrary a disease is expressed in the heterozygous state (in this case the mutation is dominant), it will spread through an animal's descendants from the first generation onwards, sometimes in only one herd. Disease  declaration and rapid progeny follow-up can help to sort and keep non-carrier animals, limiting losses.

Searching for the mutation responsable requires several steps:

• Demonstrating the emergence of a mutation,
• Clinical description of the disease. This step is crutial to guarantee the uniqueness of the pathology studied and to guide genetic research,
• Sample collection (blood-EDTA tubes, ear biopsies, ...) of affected individuals to obtain DNA,
• Genetic analyses via genotyping and sequencing.

Progress in genomic tools in recent years have made the isolation of the genes implicated much more rapid. A diagnostic DNA test that can distinguish sick animals, carriers and non-carriers, is the only effective tool for a proactive policy to eradicate diseases in the population.

The first steps of the observation of the emergence of a disease, the clinical characterization and sampling are the most complicated to do since they require the coordination and intervention of the different actors on the field.

This coordination is organized by the National Observatory for Bovine Diseases (ONAB) and ensured by Cécile Grohs (INRAE), Rachel Lefebvre (INRAE) and Stéphanie Minery (French Livestock Breeding Institute (IDELE)).

To find out more about our partners

References

• Capel C., Duchesne A. 2010 Du nouveau au sein de l’Observatoire National des Anomalies Bovines. BTIA, 132, 40.
• Boichard D., Floriot S., Capel C., Duchesne A. 2010. Abord des anomalies génétiques bovines. Le Point Vétérinaire, 311, 66-69.
• Ducos A., Manciaux L., Malafosse A., Eggen A. 2008. L'observatoire national des anomalies bovines : objectifs, actions mises en œuvre et premiers résultats. Journées Nationales GTV, Nantes, 29 mai 2008, 491-494.
• Duchesne A., Ducos A., Manciaux L., Eggen A. 2006. Des marqueurs génétiques pour l’éradication des anomalies. BTIA, 120, 19-21.
• 5 articles in a special issue of Production Animales on genetic anomalies in 2016 https://productions-animales.org/issue/view/348