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Heinrich, B., & Bugnyar, T. (2007). Just how smart are ravens? Sci Am, 296(4), 64–71.
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Heird, J. C., Lennon, A. M., & Bell, R. W. (1981). Effects of early experience on the learning ability of yearling horses. J. Anim Sci., 53(5), 1204–1209.
Abstract: Twenty-four yearling Quarter Horse fillies were divided into three groups (I) very limited handling, (II) intermediate handling and (III) extensive handling. At about 14 months of age, each horse was preconditioned for 2 weeks and then run in a simple place-learning T-maze test in which it had to locate its feed. Thirty trials were run daily for 20 days, with the location of the feed changed each day. To retire from the maze, a horse had to meet the criterion: 11 correct responses in 12 tries, with the last eight being consecutive. Horses in Group II required the fewest trials to reach criterion. These horses also learned more and had the highest percentage of correct responses (P less than .05). Mean trainability tended to predict learning ability; however, trainability and trials to criterion were not significantly correlated. Mean emotionality scores indicated a tendency for horses in the intermediately handled group to be less emotional than those in Group I or III. Results indicated that horses with an intermediate amount of handling scored higher on an intermediate test of learning. All handled horses scored higher on learning tests than those not handled.
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Heistermann, M., Palme, R., & Ganswindt, A. (2006). Comparison of different enzyme-immunoassays for assessment of adrenocortical activity in primates based on fecal analysis. Am. J. Primatol., 68(3), 257–273.
Abstract: Most studies published to date that used fecal glucocorticoid measurements to assess adrenocortical activity in primate (and many nonprimate) species applied a specific cortisol or corticosterone assay. However, since these native glucocorticoids are virtually absent in the feces of most vertebrates, including primates, the validity of this approach has recently been questioned. Therefore, the overall aim of the present study was to assess the validity of four enzyme-immunoassays (EIAs) using antibodies raised against cortisol, corticosterone, and reduced cortisol metabolites (two group-specific antibodies) for assessing adrenocortical activity using fecal glucocorticoid metabolite (GCM) measurements in selected primate species (marmoset, long-tailed macaque, Barbary macaque, chimpanzee, and gorilla). Using physiological stimulation of the hypothalamo-pituitary-adrenocortical (HPA) axis by administering exogenous ACTH or anesthesia, we demonstrated that at least two assays detected the predicted increase in fecal GCM levels in response to treatment in each species. However, the magnitude of response varied between assays and species, and no one assay was applicable to all species. While the corticosterone assay generally was of only limited suitability for assessing glucocorticoid output, the specific cortisol assay was valuable for those species that (according to high-performance liquid chromatography (HPLC) analysis data) excreted clearly detectable amounts of authentic cortisol into the feces. In contrast, in species in which cortisol was virtually absent in the feces, group-specific assays provided a much stronger signal, and these assays also performed well in the other primate species tested (except the marmoset). Collectively, the data suggest that the reliability of a given fecal glucocorticoid assay in reflecting activity of the HPA axis in primates clearly depends on the species in question. Although to date there is no single assay system that can be used successfully across species, our data suggest that group-specific assays have a high potential for cross-species application. Nevertheless, regardless of which GC antibody is chosen, our study clearly reinforces the necessity of appropriately validating the respective assay system before it is used.
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Hemelrijk, C. K., & Wantia, J. (2005). Individual variation by self-organisation. Neurosci Biobehav Rev, 29(1), 125–136.
Abstract: In this paper, we show that differences in dominance and spatial centrality of individuals in a group may arise through self-organisation. Our instrument is a model, called DomWorld, that represents two traits that are often found in animals, namely grouping and competing. In this model individual differences grow under the following conditions: (1) when the intensity of aggression increases and grouping becomes denser, (2) when the degree of sexual dimorphism in fighting power increases. In this case the differences among females compared to males grow too, (3) when, upon encountering another individual, the tendency to attack is 'obligate' and not conditional, namely 'sensitive to risks'. Results resemble phenomena described for societies of primates, mice, birds and pigs.
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Hendricks, J. C., & Morrison, A. R. (1981). Normal and abnormal sleep in mammals. J Am Vet Med Assoc, 178(2), 121–126.
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Henneke, D. R., Potter, G. D., Kreider, J. L., & Yeates, B. F. (1983). Relationship between condition score, physical measurements and body fat percentage in mares. Equine Vet J, 15(4), 371–372.
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Herholz, C., Straub, R., Braendlin, C., Imhof, A., Luthi, S., & Busato, A. (2003). Measurement of tidal breathing flow-volume loop indices in horses used for different sporting purposes with and without recurrent airway obstruction. Vet. Rec., 152(10), 288–292.
Abstract: Tidal breathing flow-volume loop (TBFVL) indices in healthy horses and in horses suffering from mild and moderate to severe recurrent airway obstruction (RAO) were measured. In addition, the ability of these indices to differentiate healthy controls from horses with mild RAO by separating the horses according to their usage was investigated. The horses were assigned to three sporting categories: 1 Leisure horses; 2 Horses competing at events with a duration of more than five minutes (eventing, coaching and endurance); and 3 Horses competing at events with a duration of less than five minutes (dressage and show jumping). Flow-volume curves were recorded with an ultrasonic spirometer and TBFVL indices were calculated with specially dedicated software. The sporting usage of the horses had a significant effect on the differentiating ability of TBFVL indices in diagnosing different degrees of RAO. The index TIF50 differentiated control horses from horses with minor RAO in all sporting categories.
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Hernandez, J., & Hawkins, D. L. (2001). Training failure among yearling horses. Am J Vet Res, 62(9), 1418–1422.
Abstract: OBJECTIVE: To compare financial returns between pinhooked yearling horses (ie, bought and trained for approximately 5 months with the goal of selling the horse at “2-year-olds in training” sales) that had mild or severe training failure and horses that had planned versus nonplanned training failure. ANIMALS: 40 Thoroughbred pinhooked yearling horses. PROCEDURE: During the period from September 1998 through and April 1999, 20 horses had mild training failure (1 to 11 days lost), and 20 horses had severe training failure (13 to 108 days lost). Horses were assigned to these 2 groups on the basis of frequency distribution (median) of days lost during training. Horses were also categorized on the basis of type of training failure (planned vs nonplanned training failure). The outcome of primary interest was financial return. Median financial returns were compared among groups by use of the Mann-Whitney U test. RESULTS: Median financial returns for horses that had severe training failure ($1,000) were significantly different, compared with horses that had mild training failure ($24,000). Analysis of results also indicated that median returns were significantly different among horses that had planned training failure (-$2,000; eg, horses with radiographic abnormalities detected during routine prepurchase examinations that required surgical treatment, resulting in days lost during training), compared with horses that did not ($10,000). CONCLUSIONS AND CLINICAL RELEVANCE: Training failure has an economic impact on revenues in pinhooked yearling horses. Lameness, planned training failure, respiratory disease, and ringworm were common and important causes of training failure.
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Hertel, J., Altmann, H. J., & Drepper, K. (1970). [Nutritional physiology studies of the horse. II. Raw nutrient studies of the gastrointestinal tract of slaughtered horses]. Z Tierphysiol Tierernahr Futtermittelkd, 26(3), 169–174.
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Heschl, A., & Burkart, J. (2006). A new mark test for mirror self-recognition in non-human primates. Primates, 47(3), 187–198.
Abstract: For 30 years Gallup's (Science 167:86-87, 1970) mark test, which consists of confronting a mirror-experienced test animal with its own previously altered mirror image, usually a color mark on forehead, eyebrow or ear, has delivered valuable results about the distribution of visual self-recognition in non-human primates. Chimpanzees, bonobos, orangutans and, less frequently, gorillas can learn to correctly understand the reflection of their body in a mirror. However, the standard version of the mark test is good only for positively proving the existence of self-recognition. Conclusive statements about the lack of self-recognition are more difficult because of the methodological constraints of the test. This situation has led to a persistent controversy about the power of Gallup's original technique. We devised a new variant of the test which permits more unequivocal decisions about both the presence and absence of self-recognition. This new procedure was tested with marmoset monkeys (Callithrix jacchus), following extensive training with mirror-related tasks to facilitate performance in the standard mark test. The results show that a slightly altered mark test with a new marking substance (chocolate cream) can help to reliably discriminate between true negative results, indicating a real lack of ability to recognize oneself in a mirror, from false negative results that are due to methodological particularities of the standard test. Finally, an evolutionary hypothesis is put forward as to why many primates can use a mirror instrumentally – i.e. know how to use it for grasping at hidden objects – while failing in the decisive mark test.
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