Emotional states and emotional contagion in pigs after exposure to a positive and negative treatment

After-effects of events that elicit an emotional state on both the animals that experienced these events and on their group members have only scarcely been studied. We investigated effects of a positive vs. negative treatment on the behaviour and emotional state of pigs and their naive pen mates afterwards. Behaviour of 96 pigs was observed in the home pen for 5. min on two different days (day 2 and 18), directly after two pigs per pen (N = 16) had been subjected to a positive or negative treatment in a test room. On day 2, treated pigs lay down more (30.78. ±. 4.07 vs. 15.25. ±. 3.74% of time, P = 0.01), walked less (17.91. ±. 2.82 vs. 26.87. ±. 2.32% of time, P = 0.02) and explored the pen less (12.30. ±. 1.34 vs. 18.29. ±. 1.71% of time, P = 0.01) after the negative compared to the positive treatment. Naive pigs simultaneously also lay more (45.67. ±. 6.00 vs. 18.79. ±. 5.88% of time, P = 0.003), walked less (6.33. ±. 0.80 vs. 12.83. ±. 1.74% of time, P. <. 0.001) and explored the pen less (6.80. ±. 1.23 vs. 13.47. ±. 2.34% of time, P = 0.02) after their pen mates' negative treatment. After their pen mates' positive treatment, in contrast, naive pigs showed more nosing behaviour, nose-nose (0.83. ±. 0.14 vs. 0.40. ±. 0.06 freq./min, P = 0.004) and nose-body contact (0.73. ±. 0.10 vs. 0.47. ±. 0.06 freq./min, P = 0.02), and tended to play more (0.10. ±. 0.03 vs. 0.01. ±. 0.01 freq./min, P = 0.09). On day 18, treated pigs were only found to eat longer after the negative than the positive treatment (10.75. ±. 3.73 vs. 0.96. ±. 0.79% of time, P = 0.02), whereas their naive pen mates, similar to day 2, lay more (45.01. ±. 5.16 vs. 22.59. ±. 5.52% of time, P = 0.006), stood (40.73. ±. 3.84 vs. 57.32. ±. 4.29% of time, P = 0.007) and walked less (7.00. ±. 1.21 vs. 10.88. ±. 1.04% of time, P = 0.01). After their pen mates' positive treatment, at day 18, they still nosed the nose (0.52. ±. 0.06 vs. 0.21. ±. 0.04 freq./min, P. <. 0.001) and body of their pen mates more (0.68. ±. 0.06 vs. 0.29. ±. 0.05 freq./min, P = 0.002) than after their pen mates' negative treatment, and they tended to wag their tails more (2.30. ±. 0.95 vs. 0.68. ±. 0.41% of time, P = 0.08). Thus, pigs still appeared to be in a negative emotional state for some time after the negative treatment had ended. Furthermore, their pen mates also seemed to be (emotionally) affected even though they were not subjected to the treatment themselves. Negative and positive events may thus have consequences that extend beyond the duration of these events, for both the welfare of the exposed animals and their group members

Vocalisations in farm animals : A step towards positive welfare assessment

Public concern for farm animal welfare is increasing. Animal welfare is defined as the balance of positive and negative emotions, where positive emotions are key to a good animal life. Emotion is defined as an experience that varies in valence and arousal. Many methods developed to identify positive emotions in animals involve disadvantages. For example, they require training the animals, are age specific or invasive. Vocalisations are a promising indicator of positive emotions. We aimed to review current knowledge on farm animal vocalisations putatively associated with positive emotions and discuss the potential of vocalisations as an on-farm tool to assess positive emotions in farm animals. Vocalisation types and acoustic structures that can potentially be used to identify positive emotions depend upon species. In pigs, lower frequency vocalisations are produced more in positive situations, however, within grunts, higher frequencies reflect positive situations. In horses, more snorts and shorter, lower frequency whinnies could be linked to positive situations. In cows, closed-mouth vocalisations (lower in frequency) might be more common in positive emotions. Food calls and fast clucks may be linked to positive emotions in chickens. In goats, the fundamental frequency shows less fluctuations during positive compared to negative situations. A link between vocalisations and positive emotions has not been shown yet in sheep. Overall, a combination of vocalisations and other measures of emotions could be a promising on-farm tool to monitor positive emotions.</p

Temporal niche switching and reduced nest attendance in response to heat dissipation limits in lactating common voles (<i>Microtus arvalis</i>)

According to the heat dissipation limit theory, maximum metabolic turnover is limited by the capacity of the body to dissipate excess heat. Small mammals, including common voles (Microtus arvalis), face a heat dissipation limitation during lactation. Pup growth and milk production are reduced under higher ambient temperatures. Heat dissipation problems might in part be alleviated by modifying behavior, such as reducing nest attendance and being active at energetically optimal times of day. According to the circadian thermo-energetics hypothesis, animals can make use of daily ambient temperature fluctuations to alter their energetic expenditure. In this study we test whether heat challenged (housing at 30 °C compared to 21 °C) lactating common voles allocate their time differently among behaviors and whether their ultradian and circadian behavioral rhythmicity are altered. Behavior was scored every 13 min from automated picture recordings, while general locomotor activity was measured by passive infrared detectors to assess ultradian and circadian organization. The effects of ambient temperature on the ultradian organization of behavior were assessed by determining the ultradian period length and the distribution of activity within the ultradian bout. Changes in circadian organization were assessed by the distribution of activity over the light and dark phase. As a complementary measure nest temperature recordings were used to quantify nest attendance distribution between day and night. Lactating dams at 30 °C reduced the fraction of time spent on the nest while increasing the fraction of time resting without pups away from the nest. The ultradian period of locomotor activity was longer in voles housed at 30 °C during pregnancy and lactation, but not after weaning when the pups were removed. No differences in the distribution of activity within the ultradian bout could be detected. The circadian organization was also modulated by ambient temperature. Lactating voles housed at 30 °C became more day active and a loss of day–night differences in nest temperature suggests a shift of nest attendance towards the night. Reducing the time attending the nest can reduce the risk of hyperthermia, and may be the behavioral component resulting in lower milk production and hence reproductive output. Becoming more day active allows feeding and nursing of the pups during the rest phase to occur during the night at which lower ambient temperatures are expected in the field. In natural situations this strategy will increase heat dissipation and lactation capacity. Whether there are similar benefits associated with a longer ultradian period is currently unknown, but these are likely to result from decreased energy turnover at 30 °C. In conclusion, our study shows that lactating common voles facing heat dissipation problems re-organize their behavior in a way that can maximize heat dissipation capabilities and thereby optimize lactation capacity

Effects of early and later life environmental enrichment and personality on attention bias in pigs (Sus scrofa domesticus)

We investigated effects of early and later life housing on attention bias, as an indicator of affective state, in pigs differing in coping style [reactive (LR) vs. proactive (HR)]. Pigs (n = 128) in barren or enriched housing from birth (B1 vs. E1) that experienced either a switch in housing at 7 weeks of age or not (creating B1B2, B1E2, E1E2, and E1B2 treatments), were studied in a 180-s attention bias test at 11 weeks. Pigs exposed to a 10-s-auditory-and-sudden-motion threat in the test arena paid more attention to the location of the threat, were more vigilant, showed less eating, more walking and were more likely to utter high-pitched vocalisations than non-threat pigs. During threat presence, HR pigs from post-switch enriched housing (E2-HR, i.e., B1E2 + E1E2) showed more vigilance but less exploration than others. After threat removal, no effects were found on time spent paying attention to the threat, vigilance, and eating, but E2-HR pigs paid attention to the threat more frequently, were more likely to utter high-pitched vocalisations and walked more compared to (part of) other groups, suggesting the most negative affective state in these animals. E2 pigs grunted more than B2 pigs. Thus, current housing, but not early life housing, affected behaviour in a personality-dependent manner in this attention bias test. Housing effects were opposite to expectation, possibly due to the short-term effect of the relative contrast between the home pens of the pigs and the test room. This potentially overruled putative long-term effects of environmental conditions on attention bias.</p

Soiling of pig pens : A review of eliminative behaviour

This is a comprehensive review on the pigs’ normal eliminatory behaviour (i.e., defaecation and urination) and pen soiling. This review is aimed primarily at solving issues with pen soiling in current systems, and ultimately at the future design of a well-functioning pig toilet, which we intend to elaborate on in a subsequent publication. In this paper, first, normal elimination is described in relation to what is known about its phylogeny, ontogeny, causation, and function, i.e., according to Tinbergen’s four why questions concerning animal behaviour. Then, pen soiling is described as if it were a medical disorder, highlighting its importance, aetiology, symptoms, diagnosis, pathogenesis, treatment, and prevention. Due to its negative consequences in terms of animal welfare, health, workload, and environmental emissions, possible methods to address pen soiling in current systems are described. Probably, pigs do not choose a specific place to eliminate but rather choose the most comfortable place for resting, and avoid eliminating there. We identified four main strategies to reduce pen soiling: (1) reducing the suitability of the designated elimination area to be used for other functions, especially resting or thermoregulation; (2) improving the suitability of other functional areas in the pen to be used for their specific function, such as resting and activity; (3) reducing the suitability of other functional areas to be used for elimination; and (4) improving the suitability of the elimination area for elimination. These prevention strategies and the encompassing disease framework provide a structured approach to deal with pen soiling in existing systems and to support the future design, development, and implementation of a well-functioning pig toilet that can help to achieve some of the main goals of modern pig production, namely reducing environmental emissions as well as substantially improving pig welfare.</p

Soiling of Pig Pens: A Review of Eliminative Behaviour

This is a comprehensive review on the pigs\u2019 normal eliminatory behaviour (i.e., defaecation and urination) and pen soiling. This review is aimed primarily at solving issues with pen soiling in current systems, and ultimately at the future design of a well-functioning pig toilet, which we intend to elaborate on in a subsequent publication. In this paper, first, normal elimination is described in relation to what is known about its phylogeny, ontogeny, causation, and function, i.e., according to Tinbergen\u2019s four why questions concerning animal behaviour. Then, pen soiling is described as if it were a medical disorder, highlighting its importance, aetiology, symptoms, diagnosis, pathogenesis, treatment, and prevention. Due to its negative consequences in terms of animal welfare, health, workload, and environmental emissions, possible methods to address pen soiling in current systems are described. Probably, pigs do not choose a specific place to eliminate but rather choose the most comfortable place for resting, and avoid eliminating there. We identified four main strategies to reduce pen soiling: (1) reducing the suitability of the designated elimination area to be used for other functions, especially resting or thermoregulation; (2) improving the suitability of other functional areas in the pen to be used for their specific function, such as resting and activity; (3) reducing the suitability of other functional areas to be used for elimination; and (4) improving the suitability of the elimination area for elimination. These prevention strategies and the encompassing disease framework provide a structured approach to deal with pen soiling in existing systems and to support the future design, development, and implementation of a well-functioning pig toilet that can help to achieve some of the main goals of modern pig production, namely reducing environmental emissions as well as substantially improving pig welfare

Factor scores of victims and non-victims of tail biting at time of weaning.

<p>Behavioural and physiological responses of pigs to novelty (pre- and post-weaning) were summarized in five factors using a PCA. Factor scores are presented per type of pig, i.e. victim (with tail wound) or non-victim (without tail wound) at time of weaning. <b>A:</b> Barren housing. <b>B:</b> Enriched housing. +P<0.10, *P<0.05.</p

Blood 5-HT measures at 8 (T1), 9 (T2), and 22 (T3) weeks of age in barren or enriched housed pigs^a.

a<p>Untransformed LSmeans ± SEM.</p>b<p>Whole blood 5-HT level in nmol/ml; Platelet 5-HT level in nmol/platelet 10⁹; Platelet 5-HT uptake velocity in pmol/platelet 10⁹/min.</p><p>+P<0.10.</p><p>*P<0.05.</p><p>Blood 5-HT measures at 8 (T1), 9 (T2), and 22 (T3) weeks of age in barren or enriched housed pigs^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107040#nt101" target="_blank">a</a>}.</p

Effect of enriched housing on levels of natural (auto-)antibodies in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae

Abstract Housing of pigs in barren, stimulus-poor housing conditions may influence their immune status, including antibody responses to (auto-)antigens, and thus affect immune protection, which will influence the onset and outcome of infection. In the present study, we investigated the effects of environmental enrichment versus barren housing on the level of natural (auto-)antibodies (NA(A)b) and their isotypes (IgM and IgG) binding keyhole limpet hemocyanin (KLH), myelin basic protein (MBP), and phosphorycholine conjugated to bovine serum albumin (PC-BSA) in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae). Pigs (n = 56) were housed in either barren or enriched pens from birth to 54 days of age. They were infected with PRRSV on 44 days of age, and with A. pleuropneumoniae 8 days later. Blood samples were taken on 7 different sampling days. Housing significantly affected the overall serum levels of NA(A)b binding KLH, MBP and PC-BSA, and before infection barren housed pigs had significantly higher levels of NA(A)b than enriched housed pigs, except for KLH-IgM and PC-BSA-IgG. Infection only affected the IgM, but not the IgG isotype. Moreover, changes in MBP-IgM and PC-BSA-IgM following infection were different for enriched and barren housed pigs. These results suggest that the effect of infection on NA(A)b is influenced by housing conditions and that NA(A)b, especially IgM may be affected by infection