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Author |
Lucas, Z.; Raeside, J.I.; Betteridge, K.J. |
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Title |
Non-invasive assessment of the incidences of pregnancy and pregnancy loss in the feral horses of Sable Island |
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Journal Article |
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Year |
1991 |
Publication  |
Journal of Reproduction and Fertility. Supplement |
Abbreviated Journal |
J Reprod Fertil Suppl |
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Volume |
44 |
Issue |
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Pages |
479-488 |
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Keywords |
Abortion, Veterinary/*epidemiology; Animals; Animals, Wild/*physiology; Atlantic Islands; Estrogens/analysis; Feces/chemistry; Female; Fertilization; Gestational Age; Horse Diseases/*epidemiology; Horses; Incidence; Pregnancy; *Pregnancy, Animal |
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Field observations of 400 totally unmanaged feral horses on Sable Island, Nova Scotia, were complemented by oestrogen determinations in faecal samples from 154 identified females over a 4-year period (454 mare-years). Of mares that were sampled throughout the year and subsequently produced foals, 92.1% exhibited elevated faecal oestrogens between 15 October and 30 March. The results confirm that faecal oestrogens are a useful indicator of pregnancy after approximately 120 days gestation. Distribution of foaling resembled that seen in other feral populations, with 95% of births occurring from April through July. The foaling rate for mares aged 3 years or older was 62.0%, with 50.7% of mares foaling in 3 or 4 years. Foaling rates were low (4.1%) in mares bred as yearlings and rose with age to 70.8% in those bred as 4-year-olds. Fetal loss after Day 120 was deduced from faecal oestrogens to be 26.0% overall, with marked variation from year to year (9.6-37.3%) and with age (70.0% in those bred as yearlings, decreasing to 5.6% in those bred as 4-year-olds). Of 58 mares aged 2 years or older that were sampled every year, about half (49.6%) the barren years were attributable to fetal loss after 120 days gestation. All mares conceived in at least 2 of the 4 years, suggesting that pregnancy loss, even after Day 120, is as important as failure to conceive in causing barren years. |
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Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada |
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0449-3087 |
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PMID:1795292 |
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Equine Behaviour @ team @ |
Serial |
2247 |
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Author |
Houpt, K.A. |
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Title |
Animal behavior and animal welfare |
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Journal Article |
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Year |
1991 |
Publication |
Journal of the American Veterinary Medical Association |
Abbreviated Journal |
J Am Vet Med Assoc |
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Volume |
198 |
Issue |
8 |
Pages |
1355-1360 |
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Keywords |
*Animal Welfare; Animals; *Behavior, Animal; Cats/*psychology; Hoof and Claw/surgery; Horses/*psychology; Housing, Animal |
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Abstract |
The value of behavioral techniques in assessing animal welfare, and in particular assessing the psychological well being of animals, is reviewed. Using cats and horses as examples, 3 behavioral methods are presented: (1) comparison of behavior patterns and time budgets; (2) choice tests; and (3) operant conditioning. The behaviors of intact and declawed cats were compared in order to determine if declawing led to behavioral problems or to a change in personality. Apparently it did not. The behavior of free ranging horses was compared with that of stabled horses. Using two-choice preference tests, the preference of horses for visual contact with other horses and the preference for bedding were determined. Horses show no significant preference for locations from which they can make visual contact with other horses, but they do prefer bedding, especially when lying down. Horses will perform an operant response in order to obtain light in a darkened barn or heat in an outside shed. These same techniques can be used to answer a variety of questions about an animal's motivation for a particular attribute of its environment. |
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New York State College of Veterinary Medicine, Cornell University, Ithaca 14853 |
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0003-1488 |
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PMID:2061151 |
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refbase @ user @ |
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40 |
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Author |
Dougherty, D.M.; Lewis, P. |
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Title |
Stimulus generalization, discrimination learning, and peak shift in horses |
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Journal Article |
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Year |
1991 |
Publication |
Journal of the experimental analysis of behavior |
Abbreviated Journal |
J Exp Anal Behav |
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Volume |
56 |
Issue |
1 |
Pages |
97-104 |
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Keywords |
Animals; *Appetitive Behavior; Attention; *Conditioning, Operant; *Discrimination Learning; Female; *Generalization, Stimulus; Horses/*psychology; Male; *Pattern Recognition, Visual; Size Perception |
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Abstract |
Using horses, we investigated three aspects of the stimulus control of lever-pressing behavior: stimulus generalization, discrimination learning, and peak shift. Nine solid black circles, ranging in size from 0.5 in. to 4.5 in. (1.3 cm to 11.4 cm) served as stimuli. Each horse was shaped, using successive approximations, to press a rat lever with its lip in the presence of a positive stimulus, the 2.5-in. (6.4-cm) circle. Shaping proceeded quickly and was comparable to that of other laboratory organisms. After responding was maintained on a variable-interval 30-s schedule, stimulus generalization gradients were collected from 2 horses prior to discrimination training. During discrimination training, grain followed lever presses in the presence of a positive stimulus (a 2.5-in circle) and never followed lever presses in the presence of a negative stimulus (a 1.5-in. [3.8-cm] circle). Three horses met a criterion of zero responses to the negative stimulus in fewer than 15 sessions. Horses given stimulus generalization testing prior to discrimination training produced symmetrical gradients; horses given discrimination training prior to generalization testing produced asymmetrical gradients. The peak of these gradients shifted away from the negative stimulus. These results are consistent with discrimination, stimulus generalization, and peak-shift phenomena observed in other organisms. |
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Department of Psychology, Ohio University, Athens 45701 |
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0022-5002 |
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PMID:1940765 |
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1764 |
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Author |
Huizinga, H.A.; van der Werf, J.H.J.; Korver, S.; van der Meij, G.J.W. |
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Title |
Stationary performance testing of stallions from the Dutch Warmblood riding horse population. 1. Estimated genetic parameters of scored traits and the genetic relation with dressage and jumping competition from offspring of breeding stallions |
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Journal Article |
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Year |
1991 |
Publication |
Livestock Production Science |
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27 |
Issue |
2-3 |
Pages |
231-244 |
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Keywords |
dressage; genetic parameters; horse; jumping; performance; stallion |
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Abstract |
The stationary performance testing (SPT) of stallions as breeding candidates in the Dutch Warmblood riding horse population is evaluated. Genetic and phenotypic parameters of traits scored during SPT and the genetic correlation of these traits with performances in dressage and jumping competition from offspring of breeding stallions are estimated. Data from 1978-1988 are used, covering scores from 337 3-year-old stallions. Eight subjectively scored traits are considered. These traits are: walk; trot; canter; riding ability; show jumping; free jumping; cross country; character. SPT lasts for a period of 100 days. Data from SPT are analysed using an animal model. The relations between SPT of stallions and performances in jumping and dressage competition are analysed with an animal model for SPT data and a sire model for competition data. Variance and covariance components are estimated by restricted maximum likelihood (REML) procedures. Estimates of heritability are high (0.64) for gaits and riding ability, intermediate (0.41) for cross country and medium-high (0.31) for jumping. Estimated genetic correlation between show jumping scored during SPT and jumping in competition from offspring of breeding stallions is 0.84; for dressage this relation is 0.83. Some possible bias due to selection and the subjectivity of scoring is discussed. It is indicated that selection on SPT of stallions before entering breeding service is an effective tool to breed for ability of performance in competition. |
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refbase @ user @ |
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3962 |
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Author |
Huizinga, H.A.; Korver, S.; van der Meij, G.J.W. |
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Title |
Stationary performance testing of stallions from the Dutch Warmblood riding horse population. 2. Estimated heritabilities of and correlations between successive judgements of performance traits |
Type |
Journal Article |
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Year |
1991 |
Publication |
Livestock Production Science |
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27 |
Issue |
2-3 |
Pages |
245-254 |
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Keywords |
dressage; genetic parameters; horse; jumping; performance; stallion |
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The length of test period of stationary performance testing (SPT) of stallions of the Dutch Warmblood riding horse population is evaluated. Heritability of successive judgements of traits and the phenotypic and genetic relations between successive judgements are estimated. Data from 1983-1988 are used, covering scores from 206 mostly 3-year-old stallions. Ten subjectively scored traits are considered: walk, trot, canter, riding ability, jumping ability, free jumping, cross country, character, stable behaviour, training report. Traits are successively scored at about 25, 50, 80 and 100 days in SPT. Missing scores are predicted on basis of the available scores using multiple partial regression coefficients. Validity of this method is checked in an independent data set for walk, trot and canter. The correlations between predicted and realized scores average 0.74, 0.77 and 0.79 when first, first and second, and first, second and third judgements are available, respectively. Variance and covariance components are estimated by restricted maximum likelihood (REML) procedures. Data from SPT are analysed using an animal model. Estimates of heritability are high and constant for gaits during the successive judgements. Except for stable behaviour estimates of heritability, the traits decrease slightly during the successive judgements. Estimates of the phenotypic and genetic correlations between successive judgements are high. It is concluded that length of SPT can be shortened and selection during SPT can be intensified. |
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refbase @ user @ |
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3963 |
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Author |
Marean, C.W.; Gifford-Gonzalez, D. |
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Title |
Late Quaternary extinct ungulates of East Africa and palaeoenvironmental implications |
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Journal Article |
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Year |
1991 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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350 |
Issue |
6317 |
Pages |
418-420 |
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Abstract |
UNGULATE communities of two East African savannas, the Serengeti and Athi-Kapiti Plains, are dominated by wildebeest (Connochaetes taurinus) supplemented by zebra (Equus burchelli), topi (Damaliscus lunatus), hartebeest (Alcelaphus buselaphus), buffalo (Syncerus caffer) eland (Taurotragus oryx) and gazelles (Gazella grand and G. thomsoni)1-3. Before this research, little was known of East African large mammal communities in the Late Pleistocene and early to middle Holocene. We document an extinct impala-sized alcelaphine antelope that is numerically dominant in Late Pleistocene archaeofaunal assemblages from the Athi-Kapiti Plains. The extinct giant buffalo Pelorovis antiquus is present, and a number of arid-adapted regionally extinct species are common. The small alcelaphine is rare in northern Tanzania, but regionally extinct arid-adapted species are present in Late Pleistocene deposits. These data indicate that as recently as 12,000 years ago, the large mammal community structure of East African savannas was very different and dry grasslands and arid-adapted ungulates expanded at least as far south as northern Tanzania during the Last Glacial Maximum. |
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10.1038/350418a0 |
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Equine Behaviour @ team @ |
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2345 |
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Potts, W.K.; Manning, C.J.; Wakeland, E.K. |
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Mating patterns in seminatural populations of mice influenced by MHC genotype |
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Journal Article |
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1991 |
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Nature |
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Nature |
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352 |
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6336 |
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619-621 |
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10.1038/352619a0 |
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Equine Behaviour @ team @ |
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5424 |
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Author |
Lee, P. |
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Title |
Adaptation to environmental change:an evolutionary perspective |
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Book Chapter |
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Year |
1991 |
Publication |
Primate responses to environmental changes |
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39-56 |
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Chapmann & Hall |
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London |
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H. O. Box |
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Equine Behaviour @ team @ |
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6523 |
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Author |
Denoix, J.M. |
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Title |
Approche mecanique des allures et du saut chez le cheval |
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Journal Article |
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1991 |
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Science & Sports |
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6 |
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2 |
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117-124 |
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cheval; locomotion; biomecanique; horse; locomotion; biomechanics |
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Resume La locomotion du cheval implique des contraintes mecaniques elevees sur les os, les articulations, les muscles et les tendons. Son etude permet de mieux connaitre les interventions actives ou passives de ces organes au cours des allures et du saut. Ces elements sont utiles pour la mise en oeuvre rationnelle d'exercices d'entrainement chez le cheval de sport ou de courses, en fonction des exigences de la discipline et des eventuels problemes locomoteurs du sujet. L'etude mecanique de la locomotion du cheval est par ailleurs indispensable pour l'amelioration de la connaissance des boiteries. Elle permet de preciser la genese des lesions osteoarticulaires et musculo-tendineuses et contribue a ameliorer leur traitement.Summary Locomotion of the horse is correlated with a great variety of mechanical stresses on bones, joints, muscles and tendons. Research on locomotion increases the knowledge of passive and active interventions of these structures during gaits and jump. These data are useful to manage the training of sport and jump horses, especially to fit with the particularities of the sport speciality and individual locomotor problems of horses. Beside, studies of locomotion in the horse are of importance to improve the knowledge of lamenesses. They contribute to precise the pathogenesis of osteoarticular and musculotendinous injuries and improve their treatment. |
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refbase @ user @ |
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3976 |
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Author |
Real, L.A. |
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Animal choice behavior and the evolution of cognitive architecture |
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1991 |
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Science (New York, N.Y.) |
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Science |
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253 |
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5023 |
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980-986 |
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Animals; Bees/genetics/*physiology; Biomechanics; *Choice Behavior; *Cognition; *Evolution; Mathematics; Models, Genetic; Probability |
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Animals process sensory information according to specific computational rules and, subsequently, form representations of their environments that form the basis for decisions and choices. The specific computational rules used by organisms will often be evolutionarily adaptive by generating higher probabilities of survival, reproduction, and resource acquisition. Experiments with enclosed colonies of bumblebees constrained to foraging on artificial flowers suggest that the bumblebee's cognitive architecture is designed to efficiently exploit floral resources from spatially structured environments given limits on memory and the neuronal processing of information. A non-linear relationship between the biomechanics of nectar extraction and rates of net energetic gain by individual bees may account for sensitivities to both the arithmetic mean and variance in reward distributions in flowers. Heuristic rules that lead to efficient resource exploitation may also lead to subjective misperception of likelihoods. Subjective probability formation may then be viewed as a problem in pattern recognition subject to specific sampling schemes and memory constraints. |
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Department of Biology, University of North Carolina, Chapel Hill 27599-3280 |
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0036-8075 |
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PMID:1887231 |
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Equine Behaviour @ team @ |
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2846 |
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