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Ahmadinejad, S. M., & Asgari, Z. (2015). Facial expressions of the Caspian pony to its own picture, mirror and a combination of these two. In Proceedings of the 3. International Equine Science Meeting.
Abstract: Abnormal behaviors of the horses are among the most important problems, in the ridding clubs. Digestive and somatic abnormal behaviors are the two most important abnormal behaviors in the horses, with the loneliness and boredom the two most important causes of these abnormal behaviors. Many study showed that spending times ( increasing the exercise and training time) would stop such abnormal behaviors. The man power scarcity is the important reason many ridding clubs face and this is the reason why the abnormal behavior are mostly observed in such clubs.
Current study is the first report regarding facial expressions of the Caspian Pony to different objects. Totally 10 Caspian ponies were used in this study. The pictures were taken both in the calm and in the furious (nervous) situation The pony’s pictures were the alternatives we used in this research to combat the man power scarcity!. We also used mirror to compare the expressions of the ponies to the pictures and mirror. The results of this study showed that the ponies showed more attention to the picture in calm position when compared with the picture in nervous position. In the box with the mirror and the picture (in calm position) in it, the ponies paid much more attention to the mirror than the picture. We conclude that despite of resistant of ponies for leaving outdoor and entering to indoor (paddock to box), installing mirror can prevent (almost completely) the horse’s boredom and loneliness, a very cheap (but not wise! alternative for manpower). The results of this research were applicable and were suggested to many ridding clubs with the horses with stereotypic behaviors, received almost completely positive results. |
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Ahmadinejad, S. M., Pishkar, J., Anisi, T., & Babayee, B. (2015). Verbal expressions of the horses to the pain. In Krueger. K. (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: For communicating with the environment (other horses, foals, owner, etc.), horses have to use different methods. In contrast with the human, for whom talking is the most important way of communication, the horses can’t talk. In the years 1990s and before, the imagination was such that the infants do not express verbally to the pain either (like horses).
To communicate, horses use their body language. Vocalization (if not the body language), seems to be the most important way of communication in horses, though it seems they use the same tone when exposing to different events. In this study which was performed in collaboration with the electronic institute of Sharif technical university (the top most technical university of the country), totally 25 horses were used. The horses were exposed to different events (hunger, pain, loneliness, mating, parturition and separation of the 1-2 weeks old foals from their dams). The verbal expressions of the horses were studied using spectrogram. The results of this study showed that there were significant differences between the spectrograph of the voices of the horses, exposed to hunger, and the separation of the foals from dams. This was the same (no significant differences) when horses were exposed to loneliness, separation and hunger. There were no significant differences between the verbal expressions of the horses while exposed to mating, parturition. One of the most important reasons why the horses do not have verbal expressions when exposing to the pain, might be the absence of the part of the brain, responsible for the pain interpretation. Morse research has to be performed to prove this. |
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Ahmadinejad, S. M., Pishkar, J., & Bahmen, M. (2015). Comparisons of behavioral and physiological state in Caspian pony before and after stress. In Krueger. K. (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: Behavioral scores (BS) offer an non-invasive, objective and easy to use way of assessing welfare in horses. Their development has, however, largely focused on behavioral reactions to stressful events (often induced), and so far no use of physiological measures has been made to underpin and validate the behavioral measures in the Caspian ponies. This study aimed to develop a physiologically validated scale of behavioral indicators of stress for the purpose of welfare logically validated scale of behavioral and physiological data assessment in the stabled Caspian ponies. To achieve this , behavioral and physiological data were collected from 16 Caspian ponies that underwent routine husbandry procedures. The ponies were divided into two groups, a control and a treatment group (8 each). The ponies in the treatment group took part in a 700 meter race. Analysis of the behavioral data were undertaken by a panel of equestrian industry professionals. Physiological measures (salivary and serum cortisol level) were significantly correlated with the behavioral scores confirming that the scores were meaningful and reflected the physiological stress. The scores offer an easy to use tool for rapid, reliable non-invasive welfare assessment in Caspian ponies, and reduce the need for potentially invasive physiological measures.
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Baragli, P., Demuru, E., & Palagi, E. (2015). Mirror on the wall, who is the horsest of our all? Self-recognition in Equus caballus. In Proceedings of the 3. International Equine Science Meeting.
Abstract: Mirror Self-Recognition (MSR) is an extremely rare capacity in the animal kingdom that reveals the emergence of complex cognitive capacities (de Waal 2008). So far, MSR has been reported only in humans, chimpanzees (Gallup, 1970), bottlenose dolphins (Reiss and Marino, 2001) and Asian elephants (Plotnik et al, 2006), all species characterized by a highly developed cognition. There is growing evidence that domestic horses posses high cognitive abilities, such as cross-modal individual recognition (Proops et al, 2009), triadic post-conflict reunion to maintain social homeostasis (Cozzi et al, 2010), complex communicative systems (Whatan and McComb, 2014), flexibility in problem-solving (Lovrovich et al, 2015), and long-term memory (Hanggi and Ingersoll, 2009). All these capacities make horses a good candidate to test the ability of MSR in a domestic species. Through a classical MSR experimental paradigm (de Waal 2008) we tested eight horses living in social groups under semi-natural conditions (from the Italian Horse Protection rescue centre). Animals showing MSR typically go through four stages (Plotnik et al, 2006): (i) social response, (ii) physical mirror inspection (e.g., looking behind the mirror), (iii) repetitive mirror-testing behaviour (i.e., the beginning of mirror understanding), and (iv) self-directed behaviour (i.e., recognition of the mirror image as self). The final stage, known as the “mark-test”, is verified when a subject spontaneously uses the mirror to check for a coloured artificial mark on its own body which it cannot perceive otherwise. The horses underwent a three-phase “mark-test”: 1) with sham mark (transparent ultrasound water gel) positioned on both side at jaw level, 2) mark (yellow eye shadow mixed with ultrasound water gel) positioned on left side of jaw (with sham mark on the right), 3) mark (yellow eye shadow mixed with ultrasound water gel) positioned on right side of jaw (with sham mark on the left)
The mirror was one 0.5-cm-thick piece of 140x220-cm plexiglass glue on wood. Each test lasted one hour, horses were tested once a day, in consecutive days and at the same time. Our preliminary result on 1 horse shows some changes in self-directed behaviours which can be attributed to presence of the coloured mark. Firstly, the presence of the coloured mark significantly increased the frequency of scratching on both sides of the muzzle (p < 0.0001). The most intriguing result (p < 0.0001) comes from the comparison of the scratching rates directed towards the coloured mark side (N = 41) and the sham mark side (N = 23). Under the control condition (i.e. sham mark on both sides) no statistical difference was found for the scratching rates directed to the muzzle sides (dx N = 8; sx N = 5). Although further analyses are needed to confirm these preliminary results, our finding opens new scenarios about the evolution of Mirror Self-Recognition. The capacity of horses to recognize themselves in a mirror may be the outcome of an evolutionary convergence process driven by the cognitive pressures imposed by a complex social system and maintained despite thousands years of domestication. Keywords: Domestic horse · Mark test · Socio-cognitive skills · Self-awareness References De Waal FBM (2008) The thief in the mirror. PloS Biol 6(8):e201 Gallup GG Jr (1970) Chimpanzees: Self-recognition. Science 167: 86-87. Reiss D, Marino L (2001). Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. Proc Natl Acad Sci U S A 98:5937-5942. Plotnik J, de Waal FBM, Reiss D (2006) Self-recognition in an Asian elephant. Proc Natl Acad Sci U S A 103: 17053-17057. Proops L, McComb K, Reby D. (2009) Cross-modal individual recognition in domestic horses (Equus caballus). Proc Nat Acad Sci USA;106:947-951. Cozzi A, Sighieri C, Gazzano A, Nicol CJ, Baragli P. Post-conflict friendly reunion in a permanent group of horses (Equus caballus). Behav Process 2010;85:185-190. Wathan J, McComb K. The eyes and ears are visual indicators of attention in domestic horses. Curr Biol 2014;24(15): R677-R679. Lovrovich P, Sighieri C, Baragli P (2015) Following human-given cues or not? Horses (Equus caballus) get smarter and change strategy in a delayed three choice task. Appl Anim Behav Sci, in press. Hanggi EB, Ingersoll JF. (2009) Long-term memory for categories and concepts in horses (Equus caballus). Anim Cogn; 12:451-462. |
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Bartos, A., Bányai, A., Koltay, I., & Mándó, Z. (2015). Effect of mud treatment from Heviz Spa Lake on the joints and locomotion activities of horses. In Krueger. K. (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: Medical research on the effects of thermal mud in the human medical field already retrospect for many years (Gyarmati és Kulisch 2008). As a result, the thermal sludge product is successfully applied more widely, especially in the rehabilitation of rheumatic diseases (Gyarmati és mtsai., 2012). Research results related to the management of horses for the time being, however, are not available.
The aim of our study was to investigate how a mud treatment from Heviz Spa Lake affects the movement quality and flexibility of certain joints in horses. An experiment was carried out with 10 male and female school and sport horses. All of the horses had been ridden longer period than 3 years and had correct and healthy movement. Horses were treated with mud ten times, respectively, daily in the evenings. Wet sludge was blamed on the knee, hock, elbow, shoulder, back, stifle, front and hind cannons and fetlock joints. The sludge used for treatments was washed off in the morning. At the beginning of the experiment, after the treatment and 8 weeks following the average stride length and the longest distance between the print of hind and front foot during walking and trotting, maximal flexibility of knee, hock and fetlock joints were measured. To calculate the number of steps horses were lead straight during walking and trotting on 30 m flat distance. Following this the stride length was determined. To determine the longest distance between the print of hind and front foot on flat, sandy soil, the distance between hind and front prints was measured three times. The maximal flexibility of each joint was measured with a joint protractor. Statistical analysis was carried out with one way analysis of variance (ANOVA) with SPSS 7.0 program. According to the results (table 1.), the horses responded positively to the treatments. The most positive results were detected by the average stride lenght during walking, maximal flexibility of the front fetlock, knee and hock. This is partly explicable with the beneficial effects of sulphur on the joints, which is well-known in human field (Kovács és mtsai., 2012). The stride length and longest distance between the print of hind and front foot were lower but positively influenced by the mud treatment. Eight weeks after the treatments, most of the parameters similar to human therapeutic results (Kulisch és mtsai., 2012), compared to directly after the mud baths completion values ​​were further improved, a slight negative effect was observed only for a few test values, but the results obtained here were more favourable, as at the beginning of the experiment. The results seem to confirm that the treatment effects can be considered long term. This is also explained by the slurry preparation from which absorbed elemental sulphur and sulphur oxidizing hydrogen sulfide absorbed in the body may be another source of hydrogen sulphide formation at the skin (Gyarmati,1982). Our results show, that the mud treatment from Heviz Spa Lake may have benifical effects on the joints, playing an important role in the locomotion of horses. The results are remarkable as well, also because of the evidence of the chemical impact of mud also can help. Such modes of action are still under research and only partly demonstrated in human medicine (Odabasi és mtsai., 2008). Further veterinarian research has to be carried out to confirm the results. The results of the present experiment and the prospect of further research could be pioneer, as the Heviz mud, as well as the thermal effect of water even before in the equine medicine has not been demonstrated experimentally, only individual observations are aviable. So the veterinary use of Heviz mud, which has been proven many times in human medicine, seems to be a new research field. Key words: mud treatment, Heviz Spa Lake, maximal flexibility of joints, locomotion activities References Gyarmati, J. (1982): Experiences of Heviz mud treatments. FITEC Congress, Budapest Gyarmati N, Ms. – Kulisch Á., Ms. (2008): History and description of héviz spa with special emphasis on weight-bath. La Presse thermale et climatique 2008;145:233-242. Gyarmati N., Ms. – Mándó Zs., Ms. – Bergmann A., Ms. – Mózes M., Ms. (2012.): The role of mud treatment int he rehabilitation of reumatic illnesses. XXXI: Conference of The Hungarian Society for Medical Rehabilitation and Physical Medicine 6-8. september. Szombathely, Hungary Kovács C, – Pecze M, – Tihanyi Á, – Kovács L, – Balogh S, – Bender T. (2012): The effect of sulphurous water in patients with osteoarthritis of hand. Double-blind, randomized, controlled follow-up study. Clinical Rheumatology Oct;31(10):1437-42. Kulisch Á. and her medical team (2012): Survey of Heviz thermal-mineralwater on patienten suffering from primer knee-arthrosis. As medicinal declaration of human research. Essay, Saint Andrew Hospital for Reumatic Diseases, Heviz, Hungary Odabasi, Ersin; Turan, Mustafa; Erdem, Hakan; Tekbas, Faruk (2008): Does Mud Pack Treatment Have Any Chemical Effect? A Randomized Controlled Clinical Study. Journal of Alternative & Complementary Medicine; Jun, Vol. 14 Issue 5, p559 |
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Baumgartner, M., Frank, V., Gandorfer, J., Ramoser, A., Seiler, S., & Zeitler-Feicht, M. H. (2015). Feasible animal-based indicators for assessing equine welfare. In Krüger. K. (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: Introduction
Are horses doing well in their husbandries? For the first time the answer shall be given objectively by an integral on-farm welfare assessment system for horse husbandries. A current research project at the Technical University Munich evaluates indicators for well-being, pain and suffering in horses in order to develop a welfare assessment system (Baumgartner and Zeitler-Feicht 2013, 2014a, 2014b, 2015, Zeitler-Feicht et al. 2015). The research project is professionally supported by horse husbandry experts from academics, industries as well as leading organizations for horse owners and veterinarians. The aim of the project is to develop a welfare assessment system for all horse husbandry systems which can be applied both for sport horses and for leisure horses. It is based on national animal welfare standards (BMELV 2009) and does take sustainability into consideration. Animal-based indicators are completed with resource-based indicators if necessary. It is stipulated that indicators are valid, reliable and feasible. Welfare criteria were formulated for the two principles „good health“ and „behavioural demands“ (see figure 1 and 2). Each has to be represented by at least one indicator. The principle „behavioural demands“ aims at the possibility for horses to practise species-specific behaviour. It is gathered to what extent the housing conditions allow the horses to live out and show species-specific behaviour. Furthermore in the present studies the frequency of selected behaviours including abnormal behaviour were collected in precise timeframes. Potential indicators for assessing equine welfare on-farm were selected by study of literature and field tests. The field tests included direct observations on free-ranged horses, horses in group-housing systems and single-stabled horses. The following section presents selected indicators that are feasible for assessing equine behaviour on-farm. Feasible behavioural indicators for well-being The literature research revealed that „being together“ is linked with affiliative behaviour. It includes „resting together“, „foraging together“ and additionally „walking together“. Horses do have a strong need for social bonds. „Being-together“ amongst horses must be voluntary and not caused by bad weather conditions or lack of space. Therefore the context must be considered. For temporary direct observations the frequency in group-housing systems is sufficient (0.57 ± 0.67 per horse per 20 minutes). That´s why in our study „being-together“ is considered as a feasible indicator for well-being for horses in permanent or temporary groups. It is intended to conduct further studies on its validity. Other behaviours such as „social play“ is not only linked with positive emotional states in adult horses. Several studies showed that horses use „social play“ as a stress relief. However, it is too seldom to collect in an on-farm assessment system. Because of the lack of feasibility and validity we excluded „social play“ as an indicator for well-being. Feasible behavioural indicators for suffering Horses show „abnormal behaviour“ in distress, frustration, deprivation or conflict situations. The present studies showed a relatively high frequency in single-stabled horses (3.3 ± 6.45 per horse per 20 minutes). Hence „abnormal behaviour“ is a feasible and valid indicator for suffering. However, established stereotypes need to be excluded, because they may indicate a previous welfare status rather than the current welfare status. Horses use „agonistic behaviour“ to regulate social relations, to defend themselves or to defend resources. If husbandry or management is inadequate, „agonistic behaviour“ increases and thereby the frequency of injuries caused by social conflicts. A high frequency of „agonistic behaviour“ indicates a high aggression level in group-housed horses and therefore distress and suffering. The mean frequency of group-housed horses is sufficient for temporary observations (2.6 ± 2.26 per horse per 20 minutes). As a result „agonistic behaviour“ is a feasible and vaild indicator for suffering. Further studies need to be done on the scoring and severity. Key words Animal-based indicators Equine welfare Being-together Abnormal behaviour Agonistic behaviour References Baumgartner M. & M. H. Zeitler-Feicht (2013): Entwicklung eines Bewertungssystems zur Beurteilung der Tiergerechtheit von Pferdehaltungen als Bestandteil eines Nachhaltigkeitsmanagementsystems. KTBL Schrift: Aktuelle Arbeiten zur artgemäßen Tierhaltung 503, 226 – 227. Baumgartner M. & M. H. Zeitler-Feicht (2014a): Indikatoren für Tierwohl beim Pferd. 7. Pferde-Workshop Uelzen 2014. DGfZ-Schriftreihe Heft 64, 161 – 166. Baumgartner M. & M. H. Zeitler-Feicht (2014b): Entwicklung eines Bewertungssystems zur Beurteilung der Tiergerechtheit von Pferdehaltungen als Bestandteil eines Nachhaltigkeitsmanagementsystems. 9. Niedersächsisches Tierschutzsymposium in Oldenburg, Hrsg. Nds. Ministerium für Ernährung, Landwirtschaft und Verbraucherschutz, 37 – 42. Baumgartner M. & M.H. Zeitler-Feicht (2015): Eignung ausgewählter tierbezogener Indikatoren zur Beurteilung der Tiergerechtheit von Pferdehaltungen hinsichtlich Praktikabilität. In: Tagungsband der Deutschen Veterinärmedizinischen Gesellschaft e.V. (DVG), Fachgruppen „Ethologie und Tierhaltung“ sowie „Tierschutz“, Verlag der DVG Service GmbH, Gießen, S. 182 – 192. BMELV (2009): Leitlinien zur Beurteilung von Pferdehaltungen unter Tierschutzgesichtspunkten. Bundesministerium für Ernährung, Landwirtschaft und Verbraucherschutz. Sachverständigengruppe tierschutzgerechte Pferdehaltung. Zeitler-Feicht M.H., Frank V., Ramoser A., Seiler S., Girisch C., Baumgartner M. (2015): Anhand welcher Verhaltensweisen lassen sich Rückschlüsse auf das Wohlbefinden von Pferden ziehen? In: Tagungsband der Deutschen Veterinärmedizinischen Gesellschaft e.V. (DVG), Fachgruppen „Ethologie und Tierhaltung“ sowie „Tierschutz“, Verlag der DVG Service GmbH, Gießen, S. 148 – 156. |
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Berger, A. (2015). Evaluation of living conditions in free running animals by chronobiological analysis of continuously recorded behavioural data. In Proceedings of the 3. International Equine Science Meeting.
Abstract: We developed a biorhythmical method to assess behaviour patterns and to evaluate living conditions of animals. All kinds of continuous and equidistant long-term recordings of behaviour are suitable for this method. As simple behavioural parameters, such as motor activity, can be conveniently recorded by telemetry from wild animals now, it is possible to investigate stressors by analysing its biorhythmic structure. It is the purpose of this report to describe the basic idea, and the procedure, and to give some examples of application measured on Przewalski horses in an Semireserve.
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Berger, A., & Wolfram, M. (2015). Integration of zoo-kept Przewalski horses into a herd of Przewalski horses living in a semireserve. In Krueger. K. (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: Naturally, horses live in groups in which all individuals are long-term acquainted with each other and a stable hierarchical system is established. In conservation management, introduction of horses into foreign groups is often required but will lead to fights, stress and increased health risks for the animals. We investigated the integration process of four Przewalski mares from the Zoo Leipzig into the herd of five Przewalski horses of the semireserve Liebenthal (Brandenburg, Germany). We observed changes in social hierarchy as well as a higher stress level (expressed by disturbed activity pattern and lower synchronization with environmental conditions) especially in the introduced horses (from Zoo Leipzig). We investigated the animals continuously over two years to detect what time is needed for a successful integration. Finally, we give some advice for the integration of Przewalski horses into a new herd to reduce the stress of the animals substantially.
Keywords: Przewalski horse, introduction, stress
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Bouskila, A.,, Lourie, E., de Vries, H., Hermans, Z. M.., & van Dierendonck, M. (2015). Sex, but not relatedness nor age, affect the social network of horses in a semi-natural reserve. In Proceedings of the 3. International Equine Science Meeting.
Abstract: For some time now, social network analysis provides tools to describe concisely the social structure of animals. Nevertheless, the factors that shape the social network and determine the frequency of different types of affiliations are often unclear. For example, the effects of relatedness on social networks have been only studied on relatively few species. Both among social or sub-social species the effects ranged from no effect to a substantial effect. Here we test the hypothesis that relatedness has an effect on the social network of horses (Equus caballus) that live freely in semi-natural conditions, and specifically, that individuals with high values of relatedness to their neighbors in the network will have fewer links Wolf et al, 2011). This hypothesis is based on the notion that related individuals have common interests and are likely to assist each other, and may need less links to other, unrelated individuals. In addition, individuals of similar age and sex are likely to have common needs, and thus are more likely to be associated. We thus tested a second hypothesis: homophily to individuals with similar age and sex will have a role in determining the associations within the social network. The field study was conducted on 27 horses in the Blauwe Kamer reserve in the Netherlands (1.1 sq km). We videotaped horses and their groups and used the information from 22 horses, after excluding the five foals from the analysis. Relatedness was calculated from the pedigree, which was based on parentage, determined by DNA analysis. The social network was constructed based on spatial proximity data. We assessed the influence of relatedness, age-homophily and sex-homophily on the network structure with Multiple Regression Quadratic Assignment Procedure (MRQAP) (Krackhardt 1988), with the R package sna. The results show that there was no significant effect of relatedness on the network, nor an effect of age-homophily. Nevertheless, we found a significant effect of sex-homophily, the tendency of individuals to associate with individuals of the same sex. We argue that the lack of a relatedness effect is not likely to have been caused due to the inability to detect who is kin. The structured social system in horses includes strong associations between often unrelated individuals, alongside with young individuals leaving their natal harem as part of the inherent inbreeding avoidance (Linklater & Cameron 2009; Boyd et al. in press). The significant effect of sex-homophily could stem from the protection females get from associations with other females, e.g., in the reduction of harassment from males. Previous studies on feral horses showed that mares that were better connected with other females in their harem benefited from higher survival rates to their foals (Cameron et al. 2009). The associations among bachelor males could also contribute to the strength of the sex-homophily effect.
In order to generalize from our results, one needs to examine additional populations of horses, because the conditions in the Blauwe Kamer reserve may not be representative, mainly due to the limited opportunity for dispersal in a restricted area. Keywords: Long-term affiliation; spatial proximity, kin detection Boyd, L., Scorolli, A. L., Nowzari, H., & Bouskila, A. (2016). Chapter 2: Social organization. In J. I. Ransom, & P. Kaczensky (Eds.), Wild equids. Baltimore, Maryland (in press): The Johns Hopkins University Press. Cameron, E. Z., Setsaas, T. H., & Linklater, W. L. (2009). Social bonds between unrelated females increase reproductive success in feral horses. Proceedings of the National Academy of Sciences, 106(33), 13850-13853 Krackhardt, D. (1988). Predicting with networks: Nonparametric multiple regression analysis of dyadic data. Social Networks, 10(4), 359-381. Linklater, W. L., & Cameron, E. Z. (2009). Social dispersal but with philopatry reveals incest avoidance in a polygynous ungulate. Animal Behaviour, 77(5), 1085-1093. Wolf, J. B., Traulsen, A., & James, R. (2011). Exploring the link between genetic relatedness r and social contact structure k in animal social networks. The American Naturalist, 177(1), 135-142. |
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Briefer Freymond, S., Piovesana, L., Briefer. E. F., Beuret. S., Zuberbühler, K., Bshary, R., et al. (2015). Crib-biting behaviour of horses: stress and learning capacity. In Proceedings of the 3. International Equine Science Meeting.
Abstract: Crib-biting is a stereotypy in horses that is potentially linked to both chronic stress and genetic predisposition. Chronic stress can cause neurobiological changes such as alteration of the dopaminergic modulation of the basal ganglia [1]. These neurobiological changes could alter and modify the learning profile of the horses [2,3]. We tested 19 crib-biters and 18 non-crib-biting horses (controls) in five challenging spatial tasks, in order to test if differences in dopaminergic modulation impair learning capacities. The tests were performed in two time periods, in a small arena (8 x 10 m) that was familiar to the horses. For each trials, the horses were led to the start zone in front of a four-meter-long solid fence and were then left alone in the arena. Their task was then to find a bucket containing food, which was situated in different positions around the fence, depending on the tests. The time to reach the food bucket, the trajectory taken by the horse (left or right side of the fence) and the ECG trace were recorded continuously. Additionally, salivary cortisol was collected before the tests (baseline), after the first time period, and after the second time period. We found that crib-biters and controls behaved similarly during the learning tasks. However crib-biters that did crib-bite on the solid fence during the task (group A; 10 horses) behaved differently than crib-biters that did not crib-bite (group B; 9 horses) and controls (group C; 18 horses) for some tests, in their trajectory or time to reach the bucket. These differences are more likely explained by the time taken to crib-bite, than by differences in learning capacity. We did not find any difference between groups in their heart-rate variability (RMSSD). Yet, we found a difference in salivary cortisol after the first time period between groups A, B and C. Indeed, the crib-biters that did not crib-bite had higher salivary cortisol values than all the other horses (mean±SE: A, 0.51±0.16ng/ml, B, 0.78±0.17ng/ml, C, 0.59±0.20ng/ml; Linear mixed model (LMM), p<0.05). Our results suggest that crib-biting horses that did not crib-bite during the learning tasks were more stressed than all other horses. This difference could be due to higher stress sensitivity in crib-biters, which could be reduced by the opportunity to crib-bite. These results replicate our previous findings testing differences in cortisol levels between crib-biters and control horses during an ACTH challenge test. Therefore, crib-biting behaviour might be a coping strategy helping stereotypic horses to reduce their stress during frustrating situations [4].
Keyword: stereotypy, chronic stress, learning task |