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Miller, J. A. (1985). Telling a quagga by its stripes. (extinct South African animal). Sci. News, 128, 70.
Abstract: If, in a mix-up at a costume shop, a couple were issued the front half of a zebra suit and the back half of a horse, it could be considered a quagga disguise. But if the masqueraders were pressed as to whether they were more horse or more zebra, the latest biochemical research advises them to insist on zebra.
The quagga, a South African animal extinct for more than 100 years, has been a source of confusion among taxonomists. Some contend, on the basis of the quagga skins preserved in museums, that this front-striped animal is a zebra, either a fourth zebra species or a variant of the Plains zebra, whose hindquarter stripes are dim. But others have argued that the quagga's teeth and skeleton indicate that its nearest relative is the true horse.
Biochemists joined the fray last year when muscle tissue was obtained from a salt-preserved quagga pelt in a West German museum. The tissue yielded both proteins and genes that could be analyzed (SN:6/9/84, p. 356).
Now the analysis has yielded some results. According to “remarkably concordant” findings on the proteins and on the genes, the quagga was a subspecies of the Plains zebra, says Jerold M. Lowenstein of the University of California at San Francisco. He looked at the binding between a sample of quagga proteins and mixtures of antibodies that bind to blood-serum proteins of each of the extant Equus species. The quagga sample bound more of the antibodies against Plains zebra serum than against the other species. Lowenstein calculates that the quagga relationship with the Plains zebra is six times closer than its relationship with the two other zebra species.
“We had to use special techniques to show the difference,” Lowenstein told SCIENCE NEWS. “There is 99 percent identity on the protein level. All the [Equus] species diverged within the past 5 million years, which is only yesterday in evolutionary terms.”
The quagga-Plains zebra relationship is further supported by the analysis of quagga mitochondrial genes performed by Russell Higuchi and Allan Wilson at the University of California at Berkeley. They find seven times as great a difference between quagga and Mountain zebra DNA as they do between quagga and Plains zebra DNA.
“Stripes, the molecules tell us, do make a zebra,” Lowenstein concludes in the July 18 NEW SCIENTIST, “and the half-striped quagga was a Plains zebra.”
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Suagee-Bedore, J. K., Linden, D. R., & Bennett-Wimbush, K. (2021). Effect of Pen Size on Stress Responses of Stall-Housed Horses Receiving One Hour of Daily Turnout. J. Equine Vet. Sci., 98, 103366.
Abstract: Group turnout provides important socializing opportunities for horses, particularly those that are primarily stalled. A high percentage of equine injuries occur during group turnout, which could partly be due to the physical constraints of fencing. To investigate appropriate paddock sizes for group turnouts, horses (n = 12) from a single herd were divided into groups of 4, stalled for 24 hours, and then turned out for 1 hour into one of three differently sized pens: 342, 263, and 184 m2 per horse. Groups rotated through pens across 3 days, receiving one treatment per day. Blood was sampled for cortisol concentrations at 08:00 hours each morning, and then at 15 and 60 minutes into the turn out sessions, and 60 minutes after return to individual stalls. Groups rotated through three turnout times: 09:00, 12:00, 14:00 hours. Counts of agonistic behaviors (chasing, contact biting, and kicking) and low-level threats (pinned ears, tail swishing, bite and kick threats) were recorded. When turned out in pens that provided 342 m2 per horse, horses exhibited reduced plasma cortisol concentrations by 15 minutes after turnout and at 1 hour after return to their stalls (P < .05). Horses in pens providing 184 m2 per horse exhibited greater agonistic (P < .001) and low-level threat (P < .01) behaviors than horses in larger pens. These data provide insight into appropriate pen sizes for horses from established herds. Providing at least 342 m2 per horse may reduce the chance of injury in horses accustomed to group turnout.
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Hartmann, E., Christensen, J. W., & McGreevy, P. D. (2017). Dominance and Leadership: Useful Concepts in Human-Horse Interactions? Proceedings of the 2017 Equine Science Symposium, 52, 1–9.
Abstract: Dominance hierarchies in horses primarily influence priority access to limited resources of any kind, resulting in predictable contest outcomes that potentially minimize aggressive encounters and associated risk of injury. Levels of aggression in group-kept horses under domestic conditions have been reported to be higher than in their feral counterparts but can often be attributed to suboptimal management. Horse owners often express concerns about the risk of injuries occurring in group-kept horses, but these concerns have not been substantiated by empirical investigations. What has not yet been sufficiently addressed are human safety aspects related to approaching and handling group-kept horses. Given horse's natural tendency to synchronize activity to promote group cohesion, questions remain about how group dynamics influence human-horse interactions. Group dynamics influence a variety of management scenarios, ranging from taking a horse out of its social group to the prospect of humans mimicking the horse's social system by taking a putative leadership role and seeking after an alpha position in the dominance hierarchy to achieve compliance. Yet, there is considerable debate about whether the roles horses attain in their social group are of any relevance in their reactions to humans. This article reviews the empirical data on social dynamics in horses, focusing on dominance and leadership theories and the merits of incorporating those concepts into the human-horse context. This will provide a constructive framework for informed debate and valuable guidance for owners managing group-kept horses and for optimizing human-horse interactions.
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Stachurska, A., Janczarek, I., Wilk, I., & Kedzierski, W. (2015). Does Music Influence Emotional State in Race Horses? Journal of Equine Veterinary Science, 35(8), 650–656.
Abstract: The aim of the study was to determine the effect of music featured in the barn, on the emotional state of race horses. Seventy 3-year-old Purebred Arabian horses in their first race season were divided into experimental group (EXP) of 40 horses and control group (CNT) of 30 horses and placed in separate barns. The EXP was subject to specifically composed music featured in the barn for 5 hours in the afternoon during the whole study. The emotional state in the horses was assessed at rest, saddling, and warm-up walk under rider. Measurements were taken six times, every 30 to 35 days, starting from the beginning of featuring the music. The horse's emotional state was assessed by cardiac activity variables. The music effect on the emotional state was also considered with regard to the horse's performance estimated by race records. The cardiac activity variables were compared with repeated measures design, whereas race records were analyzed with analysis of variance generalized linear model. The music positively affected the emotional state in race horses. The influence was noticeable already after the first month of featuring the music and increased in the second and third months. Despite the fact that later the variables began to return to initial levels, a positive effect of the music on prizes won by the horses in the EXP compared to the CNT was found (P < .05). The results suggest that the music may be featured in the barn, preferably for 2 to 3 months as a means of improving the welfare of race horses.
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Piro, M., Benjouad, A., Karom, A., Nabich, A., Benbihi, N., El Allali, K., et al. (2011). Genetic Structure of Severe Combined Immunodeficiency Carrier Horses in Morocco Inferred by Microsatellite Data. J. Equine Vet. Sci., 31(11), 618–624.
Abstract: A total of 17 microsatellite deoxyribonucleic acid loci used routinely for horse parentage control were used to evaluate genetic diversity among normal Arabian horses and severe combined immunodeficiency (SCID) carrier Arabian horses (ArS) and normal Arab-Barb horses and SCID carrier Arab-Barb horses (ArbeS). On the basis of the genotype of 186 horses, mean allelic diversity was estimated as 6.82, 5.53, and 6.7059 in normal Arabian horses, ArS, and for both groups of Arab-Barb horses, respectively. Five specific alleles were observed in ArS and ArbeS, with one common with ArS at HMS6, whereas five alleles common between ArS and ArbeS had a high frequency. Expected and observed heterozygosity showed great heterogeneity in the population studied and were similar or higher when compared with other studies on Arabian horses. Coefficient of gene differentiation Gst of Nei associated with Nei's genetic distance and multivariate correspondence analysis indicated a possible differentiation between the studied populations when analyzed separately according to breed. Probability of assignment of a horse to a specific group was assessed using a full and partial Bayesian approach. In all, 80.6% of Arab horses and 78.2% of Arab-Barb horses were assigned properly with a partial Bayesian test, which provided better results than the full one. These findings will be useful for identification of SCID carrier horses by using the microsatellite deoxyribonucleic acid loci used routinely for horse parentage control in our laboratory.
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Houpt, K., Marrow, M., & Seeliger, M. (2000). A preliminary study of the effect of music on equine behavior. Journal of Equine Veterinary Science, 20(11), 691–737.
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Goursot, C., Düpjan, S., Puppe, B., & Leliveld, L. M. C. (2021). Affective styles and emotional lateralization: A promising framework for animal welfare research. Appl. Anim. Behav. Sci., 237, 105279.
Abstract: The growing recognition of animals as individuals has broader implications for farm animal welfare research. Even under highly standardized on-farm conditions, farm animals show heterogeneous but individually consistent behavioural patterns towards various stimuli, based on how they appraise these stimuli. As a result, animal welfare is likely to be highly individual as well, and studying the proximate mechanisms underlying distinct individual behaviour patterns and appraisal will improve animal welfare research. We propose to extend the framework of affective styles to bridge the gap between existing research fields on animal personality and affective states. Affective styles refer to consistent individual differences in emotional reactivity and regulation and can be predicted by baseline cerebral lateralization. Likewise, animals with consistent left or right motor biases--a proxy measure of individual patterns in cerebral lateralization--have been shown to differ in their personality, emotional reactivity, motivational tendencies or coping styles. In this paper, we present the current knowledge of the links between laterality and stable individual traits in behaviour and affect in light of hypotheses on emotional lateralization. Within our suggested framework, we make recommendations on how to investigate affective styles in non-human animals and give practical examples. This approach has the potential to promote a science of affective styles in nonhuman animals and significantly advance research on animal welfare.
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Stomp, M., d'Ingeo, S., Henry, S., Cousillas, H., & Hausberger, M. (2021). Brain activity reflects (chronic) welfare state: Evidence from individual electroencephalography profiles in an animal model. Appl. Anim. Behav. Sci., 236, 105271.
Abstract: Assessing the animal welfare state is a challenge given the subjective individual cognitive and emotional processing involved. Electroencephalography (EEG) spectrum analysis has proved an ecologically valid recording situation to assess the link between brain processes and affective or cognitive states in humans: a higher slow wave/fast wave ratio has been associated with a positive internal state. In particular, a high production of theta power (3-8 Hz) has been related to positive emotions. On the other hand, it has been hypothesized that a left hemisphere (LH) dominance may be associated with a better welfare state. Here, we test the hypothesis that individual differences in the resting-state quantitative EEG power spectrum of adult horses (N = 18) and its lateralization pattern may reflect individual subjective perception of their conditions of life and welfare state. The results show clear individual differences in the proportions of the different waves and their inter-hemispheric distribution. Three different EEG power spectrum profiles were highlighted, from a bilateral predominance of theta waves in horses in a more positive welfare state to a bilateral predominance of beta waves in horses with clear expressions of compromised welfare. Interestingly, particular correlations were found between wave power activity and welfare parameters. We found a negative correlation between the number of stereotypic behaviours per hour and the median proportion of theta waves in the left hemisphere. and between the overall state (total chronic stress score) of welfare and gamma production in the right hemisphere (RH). These findings go along the hypothesis of a particular involvement of the left hemisphere for positive processing and of the right hemisphere for negative processing. However, the pattern of laterality did not appear as the most important feature here as both extreme clusters in terms of welfare showed bilateral predominance of one wave type. It is possible that hemispheric specialization makes more sense during acute emotion-inducing conditions rather than in this resting-state context (i.e. in absence of any high emotion-inducing stimulation), although the opposition gamma versus theta waves between both hemispheres in the horses with an intermediate welfare state is noticeable and intriguing. It seems that bilateral but also LH theta activity is a promising neurophysiological marker of good welfare in horses, while a bilateral or RH high production of gamma waves should alert about potential welfare alterations. Quantitative resting-state EEG power spectrum appears as a highly promising tool for exploring the brain processes involved in the subjective perception of chronic welfare, as a useful complementary tool for welfare assessment.
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Stomp, M., d'Ingeo, S., Henry, S., Cousillas, H., & Hausberger, M. (2021). Brain activity reflects (chronic) welfare state: Evidence from individual electroencephalography profiles in an animal model. Applied Animal Behaviour Science, 236, 105271.
Abstract: Assessing the animal welfare state is a challenge given the subjective individual cognitive and emotional processing involved. Electroencephalography (EEG) spectrum analysis has proved an ecologically valid recording situation to assess the link between brain processes and affective or cognitive states in humans: a higher slow wave/fast wave ratio has been associated with a positive internal state. In particular, a high production of theta power (3-8 Hz) has been related to positive emotions. On the other hand, it has been hypothesized that a left hemisphere (LH) dominance may be associated with a better welfare state. Here, we test the hypothesis that individual differences in the resting-state quantitative EEG power spectrum of adult horses (N = 18) and its lateralization pattern may reflect individual subjective perception of their conditions of life and welfare state. The results show clear individual differences in the proportions of the different waves and their inter-hemispheric distribution. Three different EEG power spectrum profiles were highlighted, from a bilateral predominance of theta waves in horses in a more positive welfare state to a bilateral predominance of beta waves in horses with clear expressions of compromised welfare. Interestingly, particular correlations were found between wave power activity and welfare parameters. We found a negative correlation between the number of stereotypic behaviours per hour and the median proportion of theta waves in the left hemisphere. and between the overall state (total chronic stress score) of welfare and gamma production in the right hemisphere (RH). These findings go along the hypothesis of a particular involvement of the left hemisphere for positive processing and of the right hemisphere for negative processing. However, the pattern of laterality did not appear as the most important feature here as both extreme clusters in terms of welfare showed bilateral predominance of one wave type. It is possible that hemispheric specialization makes more sense during acute emotion-inducing conditions rather than in this resting-state context (i.e. in absence of any high emotion-inducing stimulation), although the opposition gamma versus theta waves between both hemispheres in the horses with an intermediate welfare state is noticeable and intriguing. It seems that bilateral but also LH theta activity is a promising neurophysiological marker of good welfare in horses, while a bilateral or RH high production of gamma waves should alert about potential welfare alterations. Quantitative resting-state EEG power spectrum appears as a highly promising tool for exploring the brain processes involved in the subjective perception of chronic welfare, as a useful complementary tool for welfare assessment.
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Christensen, J. W., Munk, R., Hawson, L., Palme, R., Larsen, T., Egenvall, A., et al. (2021). Rider effects on horses' conflict behaviour, rein tension, physiological measures and rideability scores. Appl. Anim. Behav. Sci., 234, 105184.
Abstract: Many breeding organisations include a subjective scoring of rideability by a professional rider into their evaluation of sports horses, but the consistency and reliability of the scoring system is debateable. The aim of this study was to investigate (i) whether professional riders agree in their scoring of rideability, and (ii) whether rideability scores are affected by rein tension, horse conflict behaviour, heart rate, and salivary cortisol, and (iii) whether riders induce different levels of conflict behaviour and physiological responses in the horses. Ten professional, female riders each rode 10 dressage horses (level M German scale; n = 100 combinations) through a standardised dressage test (10 min warm-up followed by a 4-min test) and subsequently scored the horses for rideability on the official 1-10 scale (1 = poor to 10 = excellent) from the Danish Riding Federation. Rein tension, horse heart rate, saliva cortisol and conflict behaviour were measured for each rider-horse pair. The riders were inconsistent in their scoring of rideability to the individual horses, e.g. scores for one of the horses ranged from 1 to 8. There was a significant effect of rider (P = 0.003) and the frequency of conflict behaviour (undesired head movements: P < 0.001, breaking the gait: P = 0.013, and other evasive behaviour: P = 0.032) on rideability scores, i.e. the more conflict behaviour the lower the score. There was no significant effect of rein tension and the physiological measures on rideability scores. However, there was a significant effect of rider on rein tension, horses' heart rate and increases in saliva cortisol concentrations and a tendency for some types of conflict behaviour, suggesting that some riders induced more discomfort in the horses. Future studies could help shed light on which elements of riding style are particularly important for sports horse welfare. In conclusion, this study found a large variation in rideability scores assigned to ten sports horses by ten professional riders. Rideability scores were dependent on the level of horse conflict behaviour, but not rein tension and physiological measures. Further studies are needed to improve the objectivity, consistency and reliability of rideability assessment of sports horses.
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