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Kruska, D. (1988). Mammalian domestication and its effect on brain structure and behavior. In H. J. Jerison, & I. Jerison (Eds.), Intelligence and Evolutionary Biology. New York: Springer-Verlag.
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Griebenow, K., & Klibanov, A. M. (1995). Lyophilization-induced reversible changes in the secondary structure of proteins. Proc Natl Acad Sci USA, 92(24), 10969–10976.
Abstract: Changes in the secondary structure of some dozen different proteins upon lyophilization of their aqueous solutions have been investigated by means of Fourier-transform infrared spectroscopy in the amide III band region. Dehydration markedly (but reversibly) alters the secondary structure of all the proteins studied, as revealed by both the quantitative analysis of the second derivative spectra and the Gaussian curve fitting of the original infrared spectra. Lyophilization substantially increases the beta-sheet content and lowers the alpha-helix content of all proteins. In all but one case, proteins become more ordered upon lyophilization.
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Pawluski, J., Jego, P., Henry, S., Bruchet, A., Palme, R., Coste, C., et al. (2017). Low plasma cortisol and fecal cortisol metabolite measures as indicators of compromised welfare in domestic horses (Equus caballus). Plos One, 12(9), e0182257.
Abstract: The hypothalamic-pituitary-adrenal (HPA) axis response to chronic stress is far from straight forward, particularly with regards to animal welfare. There are reports of no effect as well as both decreases and increases in cortisol after chronic stressors. Therefore, the first aim of the present study was to determine how measures of compromised welfare, such as chronic pain and haematological anomalies, related to cortisol levels in domestic horses (Equus caballus). Domestic horses are an informative model to investigate the impact of chronic stress (due to environment, pain, work, housing conditions...) on the HPA axis. The second aim was to determine whether levels of fecal cortisol metabolites (FCM) may be used as an indicator of welfare measures. The present study used fifty-nine horses (44 geldings and 15 mares), from three riding centres in Brittany, France. The primary findings show that horses whose welfare was clearly compromised (as indicated by an unusual ears backward position, presence of vertebral problems or haematological anomalies, e.g. anaemia) also had lower levels of both FCM and plasma cortisol. This work extends our previous findings showing that withdrawn postures, indicators of depressive-like behavior in horses, are associated with lower plasma cortisol levels. We also found that evening plasma cortisol levels positively correlated with FCM levels in horses. Future research aims to determine the extent to which factors of influence on welfare, such as living conditions (e.g. single stalls versus group housing in pasture or paddocks), early life factors, and human interaction, act as mediators of cortisol levels in horses.
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Harlow, H. F. (1950). Learning and satiation of response in intrinsically motivated complex puzzle performance by monkeys. J Comp Physiol Psychol, 43(4), 289–294.
Abstract: Two rhesus monkeys, given 60 two-hour sessions with a six-device mechanical puzzle showed clear evidence of learning, the curve showing ratio of incorrect to correct responses appearing quite comparable to similar curves obtained during externally rewarded situations. When, on the thirteenth day of tests, the subjects were presented with the puzzle 100 times at 6-minute intervals, the number of devices manipulated decreased regularly throughout the day, although there was no significant change in the number of times the problem assembly was attacked.
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Thorpe, W. H. (1963). Learning and Instinct in Animals. London: Methuen.
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Camerlink, I., Menneson, S., Turner, S. P., Farish, M., & Arnott, G. (2018). Lateralization influences contest behaviour in domestic pigs. Scientific Reports, 8(1), 12116.
Abstract: Cerebral lateralization, i.e. hemispheric asymmetries in structure and function, relates in many species to a preference to attack from their left. Lateralization increases cognitive capacity, enabling the simultaneous processing of multiple sources of information. Therefore, lateralization may constitute a component of fighting ability (Resource Holding Potential), and/or influence the efficiency of information-gathering during a contest. We hypothesized that lateralization will affect contest outcome and duration, with an advantage for more strongly lateralized individuals. In 52 dyadic contests between weight-matched pigs (Sus scrofa; n = 104; 10 wk age), the direction of orientation towards the opponent was scan sampled every 10 s. Laterality indexes (LI) were calculated for the direction and strength of lateralization. Up to 12.5% of the individuals showed significant lateralization towards either the right or left but lateralization was absent at the population level. In line with our hypothesis, animals showing strong lateralization (irrespective of direction) had a shorter contest duration than animals showing weak lateralization. Winners did not differ from losers in their strength or direction of lateralization. Overall the results suggest that cerebral lateralization may aid in conflict resolution, but does not directly contribute to fighting ability, and will be of value in the study of animal contests.
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Marr, I., Stefanski, V., & Krueger, K. (2022). Lateralität – ein Indikator für das Tierwohl?[Laterality – an animal welfare indicator?]. Der Praktische Tierarzt, 103(12/2022), 1246–12757.
Abstract: Ein gutes Tierwohl definiert sich nicht nur durch die Abwesenheit von Stressindikatoren, sondern auch durch das Vorhandensein von Indikatoren, die auf ein gutes Wohlergehen hinweisen. So können stressbedingte Erkrankungen vermieden werden. Zur Bestimmung des Tierwohls bei Pferden wurde daher untersucht, inwieweit sich die sensorische Lateralität (einseitiger Gebrauch von Sinnesorganen) und die motorische Lateralität (einseitiger Gebrauch von Gliedmaßen) als einfach, schnell und kostengünstig zu erhebende Parameter eignen. Hierzu werden neben aktueller Literatur auch die eigenen Untersuchungsergebnisse zusammenfassend dargestellt. Die nach außen sichtbar werdende sensorische und motorische Lateralität sind das Resultat der cerebralen Lateralisierung. Dies beinhaltet nicht nur die Aufgabenteilung beider Gehirnhälften für ein effizienteres Aufnehmen und Speichern von Informationen, sondern sie steht auch in Verbindung mit der Entstehung und Verarbeitung von Emotionen, die maßgeblich am Wohlergehen eines Lebewesens beteiligt sind. Kurzzeitige Stressoren führen zu einer Erregung, die je nach Erfahrungen mit positiven oder negativen Emotionen in Verbindung steht. Emotionen helfen dem Organismus dabei, zu überleben. Andauernde negative Emotionen durch regelmäßige oder anhaltende negative Ereignisse führen zu Stress und reduzieren die Erwartung positiver Ereignisse (negativer cognitive Bias). Das Tier ist im Wohlergehen beeinträchtigt. Jüngst zeigte insbesondere die Messung der motorischen Lateralität Potenzial als Indikator für lang anhaltenden und chronischen Stress, denn gestresste Pferde, deren Stresshormonlevel stark ansteigt, zeigen einen zunehmenden Gebrauch der linken Gliedmaßen über einen längeren Zeitraum. Weiterhin zeigen erste Messungen einen Zusammenhang zwischen einer linksseitigen motorischen Lateralität und einer reduzierten Erwartung positiver Ereignisse (negativer cognitive Bias). Zusammen mit der sensorischen Lateralität, die in einer akuten Stressphase ebenso eine Linksverschiebung zeigt und somit als Indikator für Kurzzeitstress gilt, kann eine generelle, vermehrte Linksseitigkeit auch einen Hinweis auf erhöhte Emotionalität und Stressanfälligkeit sein. Eine sich steigernde Linksseitigkeit bedeutet eine präferierte Informationsverarbeitung durch die rechte Gehirnhälfte, die beispielsweise reaktives Verhalten, starke Emotionen und Stressantworten steuert. Es stellte sich jedoch heraus, dass wie bei allen Stressindikatoren auch in der Lateralitätsmessung ein Vergleichswert aus einer vorangegangenen Messung notwendig ist, denn nur Veränderungen zum häufiger werdenden Gebrauch der linken Seite können auf Stress bei Pferden hindeuten und die parallele Erhebung weiterer Parameter, wie zum Beispiel das Verhalten oder Stresshormone, können die Aussage der Lateralität bekräftigen.
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Krueger, K., Schwarz, S., Marr, I., & Farmer, K. (2022). Laterality in Horse Training: Psychological and Physical Balance and Coordination and Strength Rather Than Straightness. Animals, 12(8), 1042.
Abstract: For centuries, a goal of training in many equestrian disciplines has been to straighten the horse, which is considered a key element in achieving its responsiveness and suppleness. However, laterality is a naturally occurring phenomenon in horses and encompasses body asymmetry, motor laterality and sensory laterality. Furthermore, forcibly counterbalancing motor laterality has been considered a cause of psychological imbalance in humans. Perhaps asymmetry and laterality should rather be accepted, with a focus on training psychological and physical balance, coordination and equal strength on both sides instead of enforcing “straightness”. To explore this, we conducted a review of the literature on the function and causes of motor and sensory laterality in horses, especially in horses when trained on the ground or under a rider. The literature reveals that body asymmetry is innate but does not prevent the horse from performing at a high level under a rider. Motor laterality is equally distributed in feral horses, while in domestic horses, age, breed, training and carrying a rider may cause left leg preferences. Most horses initially observe novel persons and potentially threatening objects or situations with their left sensory organs. Pronounced preferences for the use of left sensory organs or limbs indicate that the horse is experiencing increased emotionality or stress, and long-term insufficiencies in welfare, housing or training may result in left shifts in motor and sensory laterality and pessimistic mentalities. Therefore, increasing laterality can be regarded as an indicator for insufficiencies in housing, handling and training. We propose that laterality be recognized as a welfare indicator and that straightening the horse should be achieved by conducting training focused on balance, coordination and equal strength on both sides.
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Murphy, J., & Arkins, S. (2006). Laterality and visuo-spatial ability in the equine: Functional measures of sport horse selection? BSAP Occasional Publication, 35, 159–170.
Abstract: Laterality in any organism or species can be manifest as morphological, sensory and functional degrees of asymmetry such as hemispheric dominance, handedness or sidedness and other motor functional behaviours and as such is equally important in equitation. The influence of the horses' sex on both the direction and the degree of the laterality was explored within and between 4 experimental procedures in the 1st study. The findings showed that the direction, but not the degree of idiosyncratic motor preference in the horses was strongly sex-related. Male horses exhibited significantly more left lateralized responses and female horses exhibited significantly more right lateralized responses. Visuo-spatial ability is also likely to be important in the performance horse. In many species, moderate to large differences in visuo-spatial ability have been reported between the sexes, with superior visuo-spatial ability being reported in males of all species investigated to date. As no known studies had addressed visuo-spatial ability in the equine, the objective of the 2nd study, was to determine if visuo-spatial ability differed between male and female horses. The results produced the first behavioural demonstration of superior visuo-spatial ability in male horses, similar to that reported in other species. There is evidence to suggest that visuospatial ability and motor laterality are associated with cerebral hemispheric asymmetry and may be intrinsically linked. Brain development and laterality have also been associated with hair patterning, and, in a 3rd study we attempted to identify predictors of lateral bias in motor behaviour in horses. We investigated the relationship between the direction of facial hair whorl rotation and the incidence/direction of laterality in the horse. The findings suggest that direction of facial hair whorl rotation may be a useful indicator of lateralised motor behavioural preferences in the horse. We then attempted to establish if laterality was evident at birth in a 4th study, where we explored if neonatal foals exhibited lateralised patterns during and immediately post the birthing process that were correlated with their facial hair whorl patterns. The results showed a significant association between the sex of the foal and the choice of foreleg presented initially during 2nd stage parturition. Significantly more colt foals led with the left foreleg and significantly more filly foals led with the right foreleg than expected purely by random and the behaviour was correlated with facial hair whorl patterns. The findings also suggest that lateralisation in the horse is determined in utero as has also been shown in humans. Comparisons of wholly intact male and female horses are warranted as they might elucidate additional linkages between motor behaviour, visuo-spatial ability and brain organisation and development in the horse. Further research in this area could lead to more appropriate competition conditions (better fence design/construction on cross-country tracks) and so eliminate unnecessary levels of risk associated with many equestrian sports.
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Morand-Ferron, J., & Quinn, J. L. (2011). Larger groups of passerines are more efficient problem solvers in the wild. Proc Natl Acad Sci USA, 108(38), 15898–15903.
Abstract: Group living commonly helps organisms face challenging environmental conditions. Although a known phenomenon in humans, recent findings suggest that a benefit of group living in animals generally might be increased innovative problem-solving efficiency. This benefit has never been demonstrated in a natural context, however, and the mechanisms underlying improved efficiency are largely unknown. We examined the problem-solving performance of great and blue tits at automated devices and found that efficiency increased with flock size. This relationship held when restricting the analysis to naive individuals, demonstrating that larger groups increased innovation efficiency. In addition to this effect of naive flock size, the presence of at least one experienced bird increased the frequency of solving, and larger flocks were more likely to contain experienced birds. These findings provide empirical evidence for the “pool of competence” hypothesis in nonhuman animals. The probability of success also differed consistently between individuals, a necessary condition for the pool of competence hypothesis. Solvers had a higher probability of success when foraging with a larger number of companions and when using devices located near rather than further from protective tree cover, suggesting a role for reduced predation risk on problem-solving efficiency. In contrast to traditional group living theory, individuals joining larger flocks benefited from a higher seed intake, suggesting that group living facilitated exploitation of a novel food source through improved problem-solving efficiency. Together our results suggest that both ecological and social factors, through reduced predation risk and increased pool of competence, mediate innovation in natural populations.
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