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Robustness is defined as its capacity to adapt itself to different environment while maintaining good performances and without any changes on its health or welfare. Research of markers and predictors of robustness, on which animals could be bred or farm could be managed, are two major challenges. In pig production, mortality in post weaning phase are around 2% to 3% but this percentage is actually often only possible thanks to the frequent use of antibiotics in starter feed. Having some predictors and markers of piglets robustness would allow pig farmer to adapt his management and to secure, if needed, weaning time by adoption of specific measures (vitamins, antioxidants…). Up to date, the nature of these biological markers has to be determined.

These majors challenges leaded the French pig Cooperative COOPERL to fund a PhD project in collaboration with INRA (UMR PEGASE, Adaptation) and ONIRIS (UMR BIOEpAR).

This project aims at identifying

• descriptive markers during the post-weaning period that correlate with clinical expression of health problems, and could be used as markers of robustness at weaning
• a set of predictive markers that could be observed in steady-state conditions and that would be predictive of the ability of individuals to cope with future challenges (respiratory and digestive diseases, growth performances…). In addition, this project aims at establishing basis for a diagnostic tool which would allow identifying pig farms where stopping the use of antibiotics after weaning could increase or not risks to have health problems.

Identify and confirm the physiological markers of robustness

1. Some pertinent physiological markers (immune, endocrine, metabolic, nutritional…) to assess robustness of piglets will be identified through bibliographical studies. Those markers will be then tested on field. Sixteen pig production farms will be selected in order to have maximal variability according to the respect of general requirements of pig production (biosecurity, density, air quality…) and exposition to health problems during post-weaning phase. In each farm, zootechnical and sanitary results of 18 piglets will be recorded from birth to end of post-weaning. Some blood samples will be done before and after weaning, on which the biological analysis identified in the bibliographical study will be carried out. Correlation between biological measures before and after weaning and performances will allow identifying markers to describe and predict robustness at individual scale.
2. The relevance of the markers selected during part 1 will be validated in another study, to determine if they can be generalized to other animals (and farms). This study will be carried out on a smaller number of farms, but on pigs of known genealogy, in order to estimate markers’ heritability, and evaluate if they could be used as relevant markers for genetic selection.

Arnaud Buchet has been working on this subject of thesis since the 1st September of 2014 for 3 years. He is supervised by Elodie Merlot and Nathalie Le Floc'h in the team Physiology of Adaptation, Animal Nutrition and Health.

Contact

Elodie MERLOT : elodie.merlot@rennes.inra.fr,  Tel : +33 223 487 055 (thesis supervisor)
Catherine BELLOC: catherine.belloc@oniris-nantes.fr, Tel: + 33 240 687 791 (co-supervisor)
Arnaud BUCHET: arnaud.buchet@rennes.inra.fr, (Phd student)