title: Artificially Increased Yolk Hormone Levels and Neophobia in Domestic Chicks.
abstract: In birds there is compelling evidence that the development and expression of behavior is affected by maternal factors, particularly via variation in yolk hormone concentrations of maternal origin. In the present study we tested whether variation in yolk hormone levels lead to variation in the expression of neophobia in young domestic chicks. Understanding how the prenatal environment could predispose chicks to express fear-related behaviors is essential in order to propose preventive actions and improve animal welfare. We simulated the consequences of a maternal stress by experimentally enhancing yolk progesterone, testosterone and estradiol concentrations in hen eggs prior to incubation. The chicks from these hormone-treated eggs (H) and from sham embryos (C) that received the vehicle-only were exposed to novel food, novel object and novel environment tests. H chicks approached a novel object significantly faster and were significantly more active in a novel environment than controls, suggesting less fearfulness. Conversely, no effect of the treatment was found in food neophobia tests. Our study highlights a developmental influence of yolk hormones on a specific aspect of neophobia. The results suggest that increased yolk hormone levels modulate specifically the probability of exploring novel environments or novel objects in the environment.
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, Nouzilly 37380, France. aline.bertin@tours.inra.fr.|Centre National de la Recherche Scientifique (CNRS), UMR7247, Nouzilly 37380, France. aline.bertin@tours.inra.fr.|Université François Rabelais de Tours, Tours 37000, France. aline.bertin@tours.inra.fr.|Institut Français du Cheval et de l'Equitation (IFCE), Nouzilly 37380, France. aline.bertin@tours.inra.fr.
authors.forename: Aline
authors.initials: A
authors.lastname: Bertin
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, Nouzilly 37380, France. cecile.arnould@tours.inra.fr.|Centre National de la Recherche Scientifique (CNRS), UMR7247, Nouzilly 37380, France. cecile.arnould@tours.inra.fr.|Université François Rabelais de Tours, Tours 37000, France. cecile.arnould@tours.inra.fr.|Institut Français du Cheval et de l'Equitation (IFCE), Nouzilly 37380, France. cecile.arnould@tours.inra.fr.
authors.forename: Cécile
authors.initials: C
authors.lastname: Arnould
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, Nouzilly 37380, France. chantal.moussu@tours.inra.fr.|Centre National de la Recherche Scientifique (CNRS), UMR7247, Nouzilly 37380, France. chantal.moussu@tours.inra.fr.|Université François Rabelais de Tours, Tours 37000, France. chantal.moussu@tours.inra.fr.|Institut Français du Cheval et de l'Equitation (IFCE), Nouzilly 37380, France. chantal.moussu@tours.inra.fr.
authors.forename: Chantal
authors.initials: C
authors.lastname: Moussu
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, Nouzilly 37380, France. maryse.meurisse@tours.inra.fr.|Centre National de la Recherche Scientifique (CNRS), UMR7247, Nouzilly 37380, France. maryse.meurisse@tours.inra.fr.|Université François Rabelais de Tours, Tours 37000, France. maryse.meurisse@tours.inra.fr.|Institut Français du Cheval et de l'Equitation (IFCE), Nouzilly 37380, France. maryse.meurisse@tours.inra.fr.
authors.forename: Maryse
authors.initials: M
authors.lastname: Meurisse
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, Nouzilly 37380, France. paul.constantin@tours.inra.fr.|Centre National de la Recherche Scientifique (CNRS), UMR7247, Nouzilly 37380, France. paul.constantin@tours.inra.fr.|Université François Rabelais de Tours, Tours 37000, France. paul.constantin@tours.inra.fr.|Institut Français du Cheval et de l'Equitation (IFCE), Nouzilly 37380, France. paul.constantin@tours.inra.fr.
authors.forename: Paul
authors.initials: P
authors.lastname: Constantin
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, Nouzilly 37380, France. christine.leterrier@tours.inra.fr.|Centre National de la Recherche Scientifique (CNRS), UMR7247, Nouzilly 37380, France. christine.leterrier@tours.inra.fr.|Université François Rabelais de Tours, Tours 37000, France. christine.leterrier@tours.inra.fr.|Institut Français du Cheval et de l'Equitation (IFCE), Nouzilly 37380, France. christine.leterrier@tours.inra.fr.
authors.forename: Christine
authors.initials: C
authors.lastname: Leterrier
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique (INRA), UMR85, Nouzilly 37380, France. ludovic.calandreau@tours.inra.fr.|Centre National de la Recherche Scientifique (CNRS), UMR7247, Nouzilly 37380, France. ludovic.calandreau@tours.inra.fr.|Université François Rabelais de Tours, Tours 37000, France. ludovic.calandreau@tours.inra.fr.|Institut Français du Cheval et de l'Equitation (IFCE), Nouzilly 37380, France. ludovic.calandreau@tours.inra.fr.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Calandreau
keywords: behavioral development; fear; maternal effects; neophobia; yolk hormones