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Understand biological mechanisms associated with an appropriate adaptive response

According to Knap (2005) robustness may be defined as the ability of pig to “combine high production potential with resilience to external stressors”. However, adaptive mechanisms represent the integrated results of the complex relationships co-existing within different organism functions such as survival, growth, or reproduction capabilities. Consequently, an operational definition of animal robustness cannot be addressed in a simple way and it should encompass the biological mechanisms occurring during the mounting of an appropriate adaptive response (Sauvant et Martin, 2010).

Investigate the nutrient partitioning

The resource allocation theory states that genetic selection, which is solely based on some performance traits, may alter the metabolic and physiologic profiles of animals, which, in turn, prevent them to mount an appropriate adaptive response. Adding environmental disturbances is a way to demonstrate the trade-off between different functions competing for nutritional resources (Rauw et al., 2009).  According to such theory, it may be hypothesized that the most efficient animals are also the least able to cope with a sanitary challenge.

...to take advantage of natural adaptive abilities of pigs

The main objective of this thesis project is to investigate the nutrient partitioning between the two functions which allowing both the adaptive responses and the performances to be maintained.   Understanding the trade-off between adaptive capabilities and animal performances appears as a way to take advantage of natural adaptive abilities of pigs. In such sense, it is a perspective to elaborate strategies which may allow decreasing the use of medication in pig farming system by identifying the ideal trade-off between growth rate and defense functions.

Combine an experimental and a modelling approach

Classical experimental methods combined with a modelling approach will be performed during this project. The experimental protocol will be done thanks to the European project “Prohealth” dealing with poultry and swine production diseases.

• First, an experiment will be performed to characterize growth  performances as well as the physiologic and metabolic status of a divergent line selected for RFI (Residual Feed Intake) and which will be submitted (or not) to a sanitary pressure during the first growing weeks. Individual growth responses, metabolic and physiologic mechanisms at the origin of the adaptive response will be captured during and after the sanitary stress (degree of responsiveness and recovering).
• The second aim of this work is to generate a conceptual model in order to integrate the whole data set. Relative responses of challenged pigs (compared to the no challenged animals) should allow determining some key indicators able to describe a global sanitary stress response. The evolution of this response during time may give an indication and describe pig robustness in response of an environmental disturbance using the concept of flexibility, elasticity or resilience.

Alexandra Chatelet has been working on this subject of thesis since november 2014 for 3 years. She is supervised by Nathalie Le Floc’h in the team Physiology of Adaptation, Animal Nutrition and Health and co-supervised by Florence Gondret (team Physiology and Metabolisms of Growth) and Nicolas Friggens in the mixed research unit MoSAR (systemic modelling applied to ruminants).

Contacts

Nathalie.LeFloch[at]rennes.inra.fr (supervisor)
Florence.Gondret[at]rennes.inra.fr (co-supervisor)
nicolas.friggens[at]agroparistech.fr (co-supervisor)
Alexandra.Chatelet[at]rennes.inra.fr (PhD student)

Bibliography

Knap, P. W. (2005). "Breeding robust pigs." Animal Production Science 45(8): 763-773. (DOI)
Rauw, W. M. (Ed.). (2009). Resource allocation theory applied to farm animal production. Cabi. (DOI)
Sauvant, D., & Martin, O. (2010). Robustness, rusticity, flexibility, plasticity… the quality new criteria of farm animals: systemic and biological definitions of the various concepts. INRA Productions animales, 23(1), 5-10. (link)