Divergent genetic selections for an early behavioural reactivity in meat sheep

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Hazard, Dominique | Morisset, A. | Foulquie, Didier | Delval, Eric | Douls, Sebastien | Carriere, Fabien | Pradel, J. | Boissy, Alain

Edité par CCSD ; Wageningen Academics Publishers -

International audience. Including behavioural traits in genetic selection could be an advantageous strategy for improving the autonomy of animal to extensive farming systems in an agroecological perspective. More particularly, farm animals are social and gregarious, and relational behaviours are essential for ensuring social cohesion, social facilitation, offspring survival and docility. Breed differences and genetic variation within breed have been reported in sheep for social behaviour and found to be heritable, suggesting such behaviour could be selected. The aim of the present study was to investigate in sheep the efficiency of an early selection for social attractiveness or tolerance to the human. For 7 years, four divergent lines were produced according to the reactivity of lambs to social separation or towards a human. Each year, in average 300 female and male lambs from 250 dams were individually exposed just after weaning to two behavioural tests. The arena test aims at assessing the motivation of the lambs towards conspecifics and the corridor test aims at assessing the reactivity of the lambs to an approaching shepherd. Several behaviours were measured and individual estimated breeding values (EBV) were calculated for selected behaviours for each lamb using an animal mixed model. Extreme animals were chosen according to their high or low EBV either for the frequency of their vocalisations for social reactivity (high vs low frequency), or for the flight distance towards human (short vs long distance). After two generations of selection, the divergent selection led to highly significant line differences for social reactivity or reactivity towards the human. Differences between high and low lines reached 1.8 and 1.0 genetic standard deviation for social reactivity and reactivity towards a human, respectively. Such divergent selections affected significantly locomotor and vigilance behaviours and proximity to flock-mates or the human depending on the lines. Present results confirm that early selection for behavioural traits is feasible. The expected effects on performances and facility to handle flocks will be investigated to assess relevance of such selection for contributing to improve sustainability of livestock.

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