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The Way Humans Behave Modulates the Emotional State of Piglets.

Brajon S, Laforest JP, Schmitt O, Devillers N - PLoS ONE (2015)

Bottom Line: Simultaneously, they were individually trained on a go/no-go task to discriminate a positive auditory cue, associated with food reward in a trough, from a negative one, associated with punishments (e.g. water spray).The presence of an observer during CBT did not modulate the percentage of go responses following an ambiguous cue (P > 0.10).However, regardless of the treatment, piglets spent less time in contact with the trough following positive cues during CBT in which the observer was present than absent (P < 0.0001).

View Article: PubMed Central - PubMed

Affiliation: Agriculture and Agri-Food Canada, Dairy and Swine Research and Development Centre, 2000 College Street, Sherbrooke, Quebec, J1M 0C8, Canada; Université Laval, Department of Animal Science, 2325 Rue de l'Université, Quebec city, Quebec, G1V 0A6, Canada.

ABSTRACT
The emotional state can influence decision-making under ambiguity. Cognitive bias tests (CBT) proved to be a promising indicator of the affective valence of animals in a context of farm animal welfare. Although it is well-known that humans can influence the intensity of fear and reactions of animals, research on cognitive bias often focusses on housing and management conditions and neglects the role of humans on emotional states of animals. The present study aimed at investigating whether humans can modulate the emotional state of weaned piglets. Fifty-four piglets received a chronic experience with humans: gentle (GEN), rough (ROU) or minimal contact (MIN). Simultaneously, they were individually trained on a go/no-go task to discriminate a positive auditory cue, associated with food reward in a trough, from a negative one, associated with punishments (e.g. water spray). Independently of the treatment (P = 0.82), 59% of piglets completed the training. Successfully trained piglets were then subjected to CBT, including ambiguous cues in presence or absence of a human observer. As hypothesized, GEN piglets showed a positive judgement bias, as shown by their higher percentage of go responses following an ambiguous cue compared to ROU (P = 0.03) and MIN (P = 0.02) piglets, whereas ROU and MIN piglets did not differ (P > 0.10). The presence of an observer during CBT did not modulate the percentage of go responses following an ambiguous cue (P > 0.10). However, regardless of the treatment, piglets spent less time in contact with the trough following positive cues during CBT in which the observer was present than absent (P < 0.0001). This study originally demonstrates that the nature of a chronic experience with humans can induce a judgement bias indicating that the emotional state of farm animals such as piglets can be affected by the way humans interact with them.

No MeSH data available.


Related in: MedlinePlus

The nature of the experience with the handler biases the judgement of piglets towards AM cues.Average proportion of approach (i.e. “go” response) in response to the five cues during cognitive bias tests (A) in which the human observer was absent; (B) in which the human observer was present; (C) or the combination of the two conditions, for piglets from gentle (GEN, light grey squares), rough (ROU, black triangles) and minimal contact (MIN, dark grey diamonds) treatments (back-transformed least square means; P, trained positive cue; AP, ambiguous cue nearest positive cue; AM, ambiguous median cue; AN, ambiguous cue nearest negative cue; N, trained negative cue) († P < 0.10; * P < 0.05).
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pone.0133408.g002: The nature of the experience with the handler biases the judgement of piglets towards AM cues.Average proportion of approach (i.e. “go” response) in response to the five cues during cognitive bias tests (A) in which the human observer was absent; (B) in which the human observer was present; (C) or the combination of the two conditions, for piglets from gentle (GEN, light grey squares), rough (ROU, black triangles) and minimal contact (MIN, dark grey diamonds) treatments (back-transformed least square means; P, trained positive cue; AP, ambiguous cue nearest positive cue; AM, ambiguous median cue; AN, ambiguous cue nearest negative cue; N, trained negative cue) († P < 0.10; * P < 0.05).

Mentions: The number of CBT sessions required to play all the ambiguous cues was not influenced by treatment (GEN: 4.5 ± 0.5 sessions; ROU: 4.3 ± 0.5 sessions; MIN: 3.4 ± 0.4 sessions, per set of sessions with or without an observer, F2,26 = 1.63, P = 0.21). The main effects on behavioural variables following each cue are summarised in Table 1. The results show that the interaction between cue and treatment had an impact on behavioural responses of piglets during CBT. In addition, the interaction between observer and treatment tended to have an impact on the proportion of approach. Fig 2A and 2Bdescribe the mean percentage of approach to the trough of piglets from each treatment for both trained and ambiguous cues during CBT in absence or presence of the human observer. Analyses showed that differences between treatments in the proportion of approach, regardless of the cue, were significant in the absence of the human observer (F2,21.37 = 3.32, P = 0.05). Specifically, GEN piglets approached more often following playback of the AM cues than ROU piglets when the observer was absent (0.25 ± 0.56 vs -1.83 ± 0.67, t263.3 = -2.40, P = 0.04), whereas MIN piglets were intermediate (-1.11 ± 0.54) and tended to differ from GEN (t198.8 = -1.76, P = 0.08) and did not significantly differ or even tend to differ from ROU (t237.4 = 0.84, P = 0.40) piglets (Fig 2A). Although there were no overall treatment effect in presence of the human observer (F2,12.89 = 0.31, P = 0.74), an effect of the interaction between treatment and cue was observed (F8,748.8 = 2.00, P = 0.04). Indeed, when the handler was present, GEN piglets tended to approach more often following playback of AM cues than MIN piglets (0.57 ± 0.64 vs -1.30 ± 0.61, t90.72 = -2.15, P = 0.08), whereas ROU piglets were intermediate (-0.49 ± 0.59) and did not significantly differ from GEN (t79.7 = -1.23, P = 0.43) and MIN piglets (t63.47 = -0.97, P = 0.59) (Fig 2B).


The Way Humans Behave Modulates the Emotional State of Piglets.

Brajon S, Laforest JP, Schmitt O, Devillers N - PLoS ONE (2015)

The nature of the experience with the handler biases the judgement of piglets towards AM cues.Average proportion of approach (i.e. “go” response) in response to the five cues during cognitive bias tests (A) in which the human observer was absent; (B) in which the human observer was present; (C) or the combination of the two conditions, for piglets from gentle (GEN, light grey squares), rough (ROU, black triangles) and minimal contact (MIN, dark grey diamonds) treatments (back-transformed least square means; P, trained positive cue; AP, ambiguous cue nearest positive cue; AM, ambiguous median cue; AN, ambiguous cue nearest negative cue; N, trained negative cue) († P < 0.10; * P < 0.05).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4526664&req=5

pone.0133408.g002: The nature of the experience with the handler biases the judgement of piglets towards AM cues.Average proportion of approach (i.e. “go” response) in response to the five cues during cognitive bias tests (A) in which the human observer was absent; (B) in which the human observer was present; (C) or the combination of the two conditions, for piglets from gentle (GEN, light grey squares), rough (ROU, black triangles) and minimal contact (MIN, dark grey diamonds) treatments (back-transformed least square means; P, trained positive cue; AP, ambiguous cue nearest positive cue; AM, ambiguous median cue; AN, ambiguous cue nearest negative cue; N, trained negative cue) († P < 0.10; * P < 0.05).
Mentions: The number of CBT sessions required to play all the ambiguous cues was not influenced by treatment (GEN: 4.5 ± 0.5 sessions; ROU: 4.3 ± 0.5 sessions; MIN: 3.4 ± 0.4 sessions, per set of sessions with or without an observer, F2,26 = 1.63, P = 0.21). The main effects on behavioural variables following each cue are summarised in Table 1. The results show that the interaction between cue and treatment had an impact on behavioural responses of piglets during CBT. In addition, the interaction between observer and treatment tended to have an impact on the proportion of approach. Fig 2A and 2Bdescribe the mean percentage of approach to the trough of piglets from each treatment for both trained and ambiguous cues during CBT in absence or presence of the human observer. Analyses showed that differences between treatments in the proportion of approach, regardless of the cue, were significant in the absence of the human observer (F2,21.37 = 3.32, P = 0.05). Specifically, GEN piglets approached more often following playback of the AM cues than ROU piglets when the observer was absent (0.25 ± 0.56 vs -1.83 ± 0.67, t263.3 = -2.40, P = 0.04), whereas MIN piglets were intermediate (-1.11 ± 0.54) and tended to differ from GEN (t198.8 = -1.76, P = 0.08) and did not significantly differ or even tend to differ from ROU (t237.4 = 0.84, P = 0.40) piglets (Fig 2A). Although there were no overall treatment effect in presence of the human observer (F2,12.89 = 0.31, P = 0.74), an effect of the interaction between treatment and cue was observed (F8,748.8 = 2.00, P = 0.04). Indeed, when the handler was present, GEN piglets tended to approach more often following playback of AM cues than MIN piglets (0.57 ± 0.64 vs -1.30 ± 0.61, t90.72 = -2.15, P = 0.08), whereas ROU piglets were intermediate (-0.49 ± 0.59) and did not significantly differ from GEN (t79.7 = -1.23, P = 0.43) and MIN piglets (t63.47 = -0.97, P = 0.59) (Fig 2B).

Bottom Line: Simultaneously, they were individually trained on a go/no-go task to discriminate a positive auditory cue, associated with food reward in a trough, from a negative one, associated with punishments (e.g. water spray).The presence of an observer during CBT did not modulate the percentage of go responses following an ambiguous cue (P > 0.10).However, regardless of the treatment, piglets spent less time in contact with the trough following positive cues during CBT in which the observer was present than absent (P < 0.0001).

View Article: PubMed Central - PubMed

Affiliation: Agriculture and Agri-Food Canada, Dairy and Swine Research and Development Centre, 2000 College Street, Sherbrooke, Quebec, J1M 0C8, Canada; Université Laval, Department of Animal Science, 2325 Rue de l'Université, Quebec city, Quebec, G1V 0A6, Canada.

ABSTRACT
The emotional state can influence decision-making under ambiguity. Cognitive bias tests (CBT) proved to be a promising indicator of the affective valence of animals in a context of farm animal welfare. Although it is well-known that humans can influence the intensity of fear and reactions of animals, research on cognitive bias often focusses on housing and management conditions and neglects the role of humans on emotional states of animals. The present study aimed at investigating whether humans can modulate the emotional state of weaned piglets. Fifty-four piglets received a chronic experience with humans: gentle (GEN), rough (ROU) or minimal contact (MIN). Simultaneously, they were individually trained on a go/no-go task to discriminate a positive auditory cue, associated with food reward in a trough, from a negative one, associated with punishments (e.g. water spray). Independently of the treatment (P = 0.82), 59% of piglets completed the training. Successfully trained piglets were then subjected to CBT, including ambiguous cues in presence or absence of a human observer. As hypothesized, GEN piglets showed a positive judgement bias, as shown by their higher percentage of go responses following an ambiguous cue compared to ROU (P = 0.03) and MIN (P = 0.02) piglets, whereas ROU and MIN piglets did not differ (P > 0.10). The presence of an observer during CBT did not modulate the percentage of go responses following an ambiguous cue (P > 0.10). However, regardless of the treatment, piglets spent less time in contact with the trough following positive cues during CBT in which the observer was present than absent (P < 0.0001). This study originally demonstrates that the nature of a chronic experience with humans can induce a judgement bias indicating that the emotional state of farm animals such as piglets can be affected by the way humans interact with them.

No MeSH data available.


Related in: MedlinePlus