title: Do lambs perceive regular human stroking as pleasant? Behavior and heart rate variability analyses.
abstract: Stroking by humans is beneficial to the human-animal relationship and improves welfare in many species that express intraspecific allogrooming, but very few studies have looked at species like sheep that do not express such contact except around parturition. This study investigated the way lambs perceive regular human tactile contact using behavioral and physiological responses. Twenty-four lambs were reared and bucket-fed in groups of four. All were stroked daily by their familiar caregiver. At 8 weeks of age, the lambs were individually tested in their home pen but in a 1×1m open-barred pen after a 15 h period of habituation to physical separation from peers while remaining in visual and auditory contact. Half of the lambs received stroking by their caregiver for 8 min and half were exposed to their caregiver's immobile presence. Heart rate and heart rate variability were recorded and analyzed by 2-min slots over the same interval based on three measures: mean heart rate value (HR), root mean square of successive differences (RMSSD) and standard deviation of all intervals measured between consecutive sinus beats (SDNN). Behavioral responses (ear postures of the lamb and time spent in contact with the familiar caregiver, on the knees of the familiar caregiver, and moving) were recorded throughout the test. Lamb HR decreased continuously while in the presence of their caregiver. Lambs being stroked showed slower HR and higher RMSSD which reflected positive emotional states compared to lambs left unstroked. All behavioral variables were highly correlated with the main component axis of the PCA analyses: the more the animals stayed in contact with their caregiver, the less they moved and the more their ears were hanging. This first component clearly differentiates lambs being stroked or not. Behavioral and physiological observations support the hypothesis that gentle physical contact with the caregiver is perceived positively by lambs.
authors.affiliation: INRA, Unité Mixte de Recherche 1213 Herbivores, Site de Theix, 63122 Saint-Genès-Champanelle, France; Clermont Université, VetAgro Sup, Unité Mixte de Recherche Herbivores, BP 10448, 63000 Clermont-Ferrand, France.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Coulon
authors.affiliation: INRA, Unité Mixte de Recherche 85 Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France; CNRS, Unité Mixte de Recherche 7247, 37380 Nouzilly, France; Université François Rabelais de Tours, 37041 Tours, France; Institut Français du Cheval et de l'Equitation, 37380 Nouzilly, France.
authors.forename: Raymond
authors.initials: R
authors.lastname: Nowak
authors.affiliation: INRA, Unité Mixte de Recherche 1213 Herbivores, Site de Theix, 63122 Saint-Genès-Champanelle, France; Clermont Université, VetAgro Sup, Unité Mixte de Recherche Herbivores, BP 10448, 63000 Clermont-Ferrand, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Peyrat
authors.affiliation: INRA, Unité Mixte de Recherche 1213 Herbivores, Site de Theix, 63122 Saint-Genès-Champanelle, France; Clermont Université, VetAgro Sup, Unité Mixte de Recherche Herbivores, BP 10448, 63000 Clermont-Ferrand, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Chandèze
authors.affiliation: INRA, Unité Mixte de Recherche 1213 Herbivores, Site de Theix, 63122 Saint-Genès-Champanelle, France; Clermont Université, VetAgro Sup, Unité Mixte de Recherche Herbivores, BP 10448, 63000 Clermont-Ferrand, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Boissy
authors.affiliation: INRA, Unité Mixte de Recherche 1213 Herbivores, Site de Theix, 63122 Saint-Genès-Champanelle, France; Clermont Université, VetAgro Sup, Unité Mixte de Recherche Herbivores, BP 10448, 63000 Clermont-Ferrand, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Boivin
mesh_terms: D000367:Age Factors; D000818:Animals; D001522:Behavior, Animal; D005260:Female; D006339:Heart Rate; D006801:Humans; D012756:Sheep