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Do lambs perceive regular human stroking as pleasant? Behavior and heart rate variability analyses.

Coulon M, Nowak R, Peyrat J, Chandèze H, Boissy A, Boivin X - PLoS ONE (2015)

Bottom Line: 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.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).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.

View Article: PubMed Central - PubMed

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.

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.

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Distribution of the 8-week-old tested lambs on the two components of the PCA.Lambs were exposed to human stroking (n = 11) or just motionless human presence (n = 11) in the 8-min phase.
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pone.0118617.g006: Distribution of the 8-week-old tested lambs on the two components of the PCA.Lambs were exposed to human stroking (n = 11) or just motionless human presence (n = 11) in the 8-min phase.

Mentions: Behavioral responses. Lambs approached their familiar caregiver in 14.3 ± 4.7 sec when she entered the small pen. At this time, two lambs tried to escape and none of the lambs vocalized. Principal Component Analysis on behavioral variables recorded during the 8 min revealed that the first two components explained 80% of total variance, where the first component explained 62%. Load of each variable, indicating the variance explained by each component and with their eigenvalues are presented in Table 2. All variables are highly correlated with the first component (rp > 0.6, P < 0.01). The more the animals stayed in contact with the human, the less they moved and the more their ears were hanging or in axial positions. The first component was interpreted as an evaluation of calmness of the animals while in contact with the human (Table 2). The lambs appeared much calmer during stroking than when left unstroked by the passive motionless human (t20 = 10.98; P < 0.001; Fig. 6).


Do lambs perceive regular human stroking as pleasant? Behavior and heart rate variability analyses.

Coulon M, Nowak R, Peyrat J, Chandèze H, Boissy A, Boivin X - PLoS ONE (2015)

Distribution of the 8-week-old tested lambs on the two components of the PCA.Lambs were exposed to human stroking (n = 11) or just motionless human presence (n = 11) in the 8-min phase.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340872&req=5

pone.0118617.g006: Distribution of the 8-week-old tested lambs on the two components of the PCA.Lambs were exposed to human stroking (n = 11) or just motionless human presence (n = 11) in the 8-min phase.
Mentions: Behavioral responses. Lambs approached their familiar caregiver in 14.3 ± 4.7 sec when she entered the small pen. At this time, two lambs tried to escape and none of the lambs vocalized. Principal Component Analysis on behavioral variables recorded during the 8 min revealed that the first two components explained 80% of total variance, where the first component explained 62%. Load of each variable, indicating the variance explained by each component and with their eigenvalues are presented in Table 2. All variables are highly correlated with the first component (rp > 0.6, P < 0.01). The more the animals stayed in contact with the human, the less they moved and the more their ears were hanging or in axial positions. The first component was interpreted as an evaluation of calmness of the animals while in contact with the human (Table 2). The lambs appeared much calmer during stroking than when left unstroked by the passive motionless human (t20 = 10.98; P < 0.001; Fig. 6).

Bottom Line: 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.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).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.

View Article: PubMed Central - PubMed

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.

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.

Show MeSH
Related in: MedlinePlus