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| Author | Christensen, J.W.; Ahrendt, L.P.; Lintrup, R.; Gaillard, C.; Palme, R.; Malmkvist, J. | ||||
| Title | Does learning performance in horses relate to fearfulness, baseline stress hormone, and social rank? | Type | Abstract | ||
| Year | 2012 | Publication | Applied Animal Behaviour Science | Abbreviated Journal | App Anim Behav Sci |
| Volume | 140 | Issue | 1 | Pages | 44-52 |
| Keywords | Horse; Learning; Fearfulness; Stress; Reinforcement; Social rank | ||||
| Abstract | The ability of horses to learn and remember new tasks is fundamentally important for their use by humans. Fearfulness may, however, interfere with learning, because stimuli in the environment can overshadow signals from the rider or handler. In addition, prolonged high levels of stress hormones can affect neurons within the hippocampus; a brain region central to learning and memory. In a series of experiments, we aimed to investigate the link between performance in two learning tests, the baseline level of stress hormones, measured as faecal cortisol metabolites (FCM), fearfulness, and social rank. Twenty-five geldings (2 or 3 years old) pastured in one group were included in the study. The learning tests were performed by professional trainers and included a number of predefined stages during which the horses were gradually trained to perform exercises, using either negative (NR) or positive reinforcement (PR). Each of the learning tests lasted 3 days; 7min/horse/day. The NR test was repeated in a novel environment. Performance, measured as final stage in the training programme, and heart rate (HR) were recorded. Faeces were collected on four separate days where the horses had been undisturbed at pasture for 48h. Social rank was determined through observations of social interactions during feeding. The fear test was a novel object test during which behaviour and HR were recorded. Performance in the NR and PR learning tests did not correlate. In the NR test, there was a significant, negative correlation between performance and HR in the novel environment (rS=-0.66, P<0.001, i.e. nervous horses had reduced performance), whereas there was no such correlation in the home environment (both NR and PR). Behavioural reactions in the fear test correlated significantly with performance in the NR test in the novel environment (e.g. object alertness and final stage: rS=-0.43, P=0.04), suggesting that performance under unfamiliar, stressful conditions may be predicted by behavioural responses in a fear test. There was a negative correlation between social rank and baseline stress hormones (rS=-0.43, P=0.04), i.e. high rank corresponded to low FCM concentrations, whereas neither rank nor FCM correlated with fearfulness or learning performance. We conclude that performance under stressful conditions is affected by activation of the sympathetic nervous system during training and related to behavioural responses in a standardised fear test. Learning performance in the home environment, however, appears unrelated to fearfulness, social rank and baseline FCM levels. | ||||
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| ISSN | 0168-1591 | ISBN | Medium | ||
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| Notes | Approved | no | |||
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Equine Behaviour @ team @ S0168-1591(12)00168-2 | Serial | 5769 | ||
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| Author | Heitor, F.; do Mar Oom, M.; Vicente, L. | ||||
| Title | Social relationships in a herd of Sorraia horses: Part II. Factors affecting affiliative relationships and sexual behaviours | Type | Journal Article | ||
| Year | 2006 | Publication | Behavioural Processes | Abbreviated Journal | Behav. Process. |
| Volume | 73 | Issue | 3 | Pages | 231-239 |
| Keywords | Horse; Equus; Affiliative relationship; Rank; Kinship; Aggressiveness | ||||
| Abstract | The influence of age, dominance rank, kinship and aggressiveness over affiliative relationships and sexual behaviours were analysed in a herd of Sorraia horses, Equus caballus, kept under extensive management. Subjects were 10 adult mares 5-18 years old that had known each other since birth, and a stallion introduced into the group for breeding for the first time. Kinship coefficient and dominance rank were the most important factors affecting affiliative relationships. Bonds were reciprocal and stronger among mares with higher kinship. Mares spent more time in proximity to close-ranking and lower-ranking females. Mares with stronger affiliative relationships or higher relatedness were not less aggressive towards each other. Affiliative relationships between the stallion and the mares were not reciprocal: lower-ranking mares formed stronger bonds with the stallion but he preferred the less genetically related mares for proximity. However, the stallion was involved in sexual behaviours more frequently with the mares that were more genetically related to him. These results suggest that kinship beyond close relatives may affect affiliative relationships both among familiar and among unfamiliar horses. However, the influence of kinship does not imply that horses possess a kin recognition system and alternative explanations are discussed. | ||||
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| Notes | Approved | no | |||
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refbase @ user @ | Serial | 462 | ||
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| Author | VanDierendonck, M.C.; de Vries, H.; Schilder, M.B.H. | ||||
| Title | An Analysis of Dominance, Its Behavioural Parameters and Possible Determinants in a Herd of Icelandic orses in Captivity | Type | Journal Article | ||
| Year | 1995 | Publication | Netherlands Journal of Zoology | Abbreviated Journal | Netherl. J. Zool. |
| Volume | 45 | Issue | 3-4 | Pages | 362-385 |
| Keywords | Dominance; rank order; horses; Icelandic horses. | ||||
| Abstract | Th e applicability of the concept of dominance was investigated in a captive herd of  Icelandic horses and  ponies of diff erent breeds. Eight out of  behaviours possibly related to dominance occurred frequently enough to be investigated in detail. For these eight agonistic behaviours the coverage, the unidirectionality in the exchange, and the degree of transitivity (Landau`s linearity index) were calculated. Four off ensive behaviours, together with avoidance, were suitable for further analysis with regard to dominance. Th e patterns of asymmetries with which these behaviours were exchanged were suffi ciently similar as to justify the application of the dominance concept and to construct a (nearly) linear dominance hierarchy. Th e rank order of the castrated stallions was completely linear, the hierarchy of the mares was almost completely linear. Th e results suggest that off ensive and defensive aggressive behaviours should be treated separately and that the concept of dominance is applicable. However, ritualized formal dominance signals between adult horses appear to be (almost) absent. Th e rank positions of the individuals were correlated with age and residency in the herd but not with height. Middle ranking horses tended to be more frequently in the close vicinity of another horse than high ranking or low ranking horses. Over and above this correlation at the individual level, it was found that pairs of horses close in rank to each other were more often also spatially close to each other. Being in oestrus did not infl uence the dominance relationships between mares. For castrated stallions the rank positions were correlated with the age at which they were castrated. Th is suggests that in male horses experience prior to neutering infl uences the behaviour afterwards. |
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| Language | English | Summary Language | Original Title | ||
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| Notes | Approved | no | |||
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refbase @ user @ | Serial | 440 | ||
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| Author | Hemelrijk,C. K.; Wantia,J.; Gygax,L. | ||||
| Title | The construction of dominance order: comparing performance of five methods using an individual-based model | Type | Journal Article | ||
| Year | 2005 | Publication | Behaviour | Abbreviated Journal | Behaviour |
| Volume | 142 | Issue | 8 | Pages | 1043-1064 |
| Keywords | dominance order, ranking method, agent-based model, statistical method, aggression | ||||
| Abstract | In studies of animal behaviour investigators correlate dominance with all kinds of behavioural variables, such as reproductive success and foraging success. Many methods are used to produce a dominance hierarchy from a matrix reflecting the frequency of winning dominance interactions. These different methods produce different hierarchies. However, it is difficult to decide which ranking method is best. In this paper, we offer a new procedure for this decision: we use an individual-based model, called DomWorld, as a test-environment. We choose this model, because it provides access to both the internal dominance values of artificial agents (which reflects their fighting power) and the matrix of winning and losing among them and, in addition, because its behavioural rules are biologically inspired and its group-level patterns resemble those of real primates. We compare statistically the dominance hierarchy based on the internal dominance values of the artificial agents with the dominance hierarchy produced by ranking individuals by (a) their total frequency of winning, (b) their average dominance index, (c) a refined dominance index, the David`s score, (d) the number of subordinates each individual has and (e) a ranking method based on maximizing the linear order of the hierarchy. Because dominance hierarchies may differ depending on group size, type of society, and the interval of study, we compare these ranking methods for these conditions.We study complete samples as well as samples randomly chosen to resemble the limitations of observing real animals. It appears that two methods of medium complexity (the average dominance index and David`s score) lead to hierarchical orders that come closest to the hierarchy based on internal dominance values of the agents. We advocate usage of the average dominance index, because of its computational simplicity. |
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| Notes | Approved | no | |||
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refbase @ user @ | Serial | 445 | ||
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