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Christie, J. L., Hewson, C. J., Riley, C. B., McNiven, M. A., Dohoo, I. R., & Bate, L. A. (2006). Management factors affecting stereotypies and body condition score in nonracing horses in Prince Edward Island. Can Vet J, 47(2), 136–143.
Abstract: In North America, there are few representative data about the effects of management practices on equine welfare. In a randomized survey of 312 nonracing horses in Prince Edward Island (response rate 68.4%), owners completed a pretested questionnaire and a veterinarian examined each horse. Regression analyses identified factors affecting 2 welfare markers: body condition score (BCS) and stereotypic behavior. Horses' BCSs were high (mean 5.7, on a 9-point scale) and were associated with sex (males had lower BCSs than females; P < 0.001) and examination date (P = 0.052). Prevalences of crib biting, wind sucking, and weaving were 3.8%, 3.8%, and 4.8%, respectively. Age (OR = 1.07, P = 0.08) and hours worked weekly (OR = 1.12, P = 0.03) were risk factors for weaving. Straw bedding (OR = 0.3, P = 0.03), daily hours at pasture (OR = 0.94, P = 0.02), and horse type (drafts and miniatures had a lower risk than light horses; P = 0.12) reduced the risk of horses showing oral stereotypies. Some of these results contradict those of other studies perhaps because of populations concerned.
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Church, D. L., & Plowright, C. M. S. (2006). Spatial encoding by bumblebees (Bombus impatiens) of a reward within an artificial flower array. Anim. Cogn., 9(2), 131–140.
Abstract: We presented bumblebees a spatial memory task similar to that used with other species (e.g., cats, dogs, and pigeons). In some conditions we allowed for presence of scent marks in addition to placing local and global spatial cues in conflict. Bumblebees (Bombus impatiens) were presented an array of artificial flowers within a flight cage, one flower offering reward (S+), while the others were empty (S-). Bees were tested with empty flowers. In Experiment 1, flowers were either moved at the time of testing or not. Bees returned to the flower in the same absolute position of the S+ (the flower-array-independent (FAI) position), even if it was in the wrong position relative to the S- and even when new flower covers prevented the use of possible scent marks. New flower covers (i.e., without possible scent marks) had the effect of lowering the frequency of probing behavior. In Experiment 2, the colony was moved between training and testing. Again, bees chose the flower in the FAI position of the S+, and not the flower that would be chosen using strictly memory for a flight vector. Together, these experiments show that to locate the S+ bees did not rely on scent marks nor the positions of the S-, though the S- were prominent objects close to the goal. Also, bees selected environmental features to remember the position of the S+ instead of relying upon a purely egocentric point of view. Similarities with honeybees and vertebrates are discussed, as well as possible encoding mechanisms.
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Church, R. M. (1997). Quantitative models of animal learning and cognition. J Exp Psychol Anim Behav Process, 23(4), 379–389.
Abstract: This article reviews the prerequisites for quantitative models of animal learning and cognition, describes the types of models, provides a rationale for the development of such quantitative models, describes criteria for their evaluation, and makes recommendations for the next generation of quantitative models. A modular approach to the development of models is described in which a procedure is considered as a generator of stimuli and a model is considered as a generator of responses. The goal is to develop models that, in combination with many different procedures, produce sequences of times of occurrence of events (stimuli and responses) that are indistinguishable from those produced by the animal under many experimental procedures and data analysis techniques.
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Cilnis, M. J., Kang, W., & Weaver, S. C. (1996). Genetic conservation of Highlands J viruses. Virology, 218(2), 343–351.
Abstract: We studied molecular evolution of the mosquito-borne alphavirus Highlands J (HJ) virus by sequencing PCR products generated from 19 strains isolated between 1952 and 1994. Sequences of 1200 nucleotides including portions of the E1 gene and the 3' untranslated region revealed a relatively slow evolutionary rate estimated at 0.9-1.6 x 10(-4) substitutions per nucleotide per year. Phylogenetic trees indicated that all HJ viruses descended from a common ancestor and suggested the presence of one dominant lineage in North America. However, two or more minor lineages probably circulated simultaneously for periods of years to a few decades. Strains isolated from a horse suffering encephalitis, and implicated in a recent turkey outbreak, were not phylogenetically distinct from strains isolated in other locations during the same time periods. Our findings are remarkably similar to those we obtained previously for another North American alphavirus, eastern equine encephalomyelitis virus, with which Highlands J shares primary mosquito and avian hosts, geographical distribution, and ecology. These results support the hypotheses that the duration of the transmission season affects arboviral evolutionary rates and vertebrate host mobility influences genetic diversity.
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Clara, E., Regolin, L., Vallortigara, G., & Rogers, L. (2007). Perception of the stereokinetic illusion by the common marmoset (Callithrix jacchus). Anim. Cogn., 10(2), 135–140.
Abstract: Stereokinetic illusions have never been investigated in non-human primates, nor in other mammalian species. These illusions consist in the perception of a 3D solid object when certain 2D stimuli are rotated slowly in the plane perpendicular to the line of sight. The ability to perceive the stereokinetic illusion was investigated in the common marmoset (Callithrix jacchus). Four adult marmosets were trained to discriminate between a solid cylinder and a solid cone for food reward. Once learning criterion was reached, the marmosets were tested in sets of eight probe trials in which the two solid objects used at training were replaced by two rotating 2D stimuli. Only one of these stimuli produced, at least to the human observer, the stereokinetic illusion corresponding to the solid object previously reinforced. At test, the general behaviour and the total time spent by the marmosets observing each stimulus were recorded. The subjects stayed longer near the stimulus producing the stereokinetic illusion corresponding to the solid object reinforced at training than they did near the illusion corresponding to the previously non-rewarded stimulus. Hence, the common marmosets behaved as if they could perceive stereokinetic illusions.
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Clark, G. G., & Hibler, C. P. (1973). Horse flies and Elaeophora schneideri in the Gila National Forest, New Mexico. J Wildl Dis, 9(1), 21–25.
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Clark, T. B., Peterson, B. V., Whitcomb, R. F., Henegar, R. B., Hackett, K. J., & Tully, J. G. (1984). Spiroplasmas in the Tabanidae. Isr J Med Sci, 20(10), 1002–1005.
Abstract: Spiroplasmas were observed in seven species of the family Tabanidae (horse flies and deer flies). This is the fifth family of the order Diptera now known to harbor spiroplasmas. Noncultivable spiroplasmas were seen in the hemolymph of three species of the genus Tabanus, and cultivable forms were isolated from the guts of six species in three genera. Isolates from T. calens and T. sulcifrons were serologically similar and closely related to a spiroplasma in the lampyrid beetle, Ellychnia corrusca. These three isolates represent a new serogroup. Isolates from Hybomitra lasiophthalma were related to Group IV strains, while those from T. nigrovittatus and Chrysops sp. both represented new serogroups. At least some tabanids probably acquire spiroplasmas from contaminated flower surfaces. The possibility of vertebrate reservoirs for some tabanid spiroplasmas remains an open question.
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Clayton, H. M. (1997). Classification of collected trot, passage and piaffe based on temporal variables. Equine Vet J Suppl, (23), 54–57.
Abstract: The objective was to determine whether collected trot, passage and piaffe could be distinguished as separate gaits on the basis of temporal variables. Sagittal plane, 60 Hz videotapes of 10 finalists in the dressage competitions at the 1992 Olympic Games were analysed to measure the temporal variables in absolute terms and as percentages of stride duration. Classification was based on analysis of variance, a graphical method and discriminant analysis. Stride duration was sufficient to distinguish collected trot from passage and piaffe in all horses. The analysis of variance showed that the mean values of most variables differed significantly between passage and piaffe. When hindlimb stance percentage was plotted against diagonal advanced placement percentage, some overlap was found between all 3 movements indicating that individual horses could not be classified reliably in this manner. Using hindlimb stance percentage and diagonal advanced placement percentage as input in a discriminant analysis, 80% of the cases were classified correctly, but at least one horse was misclassified in each movement. When the absolute, rather than percentage, values of the 2 variables were used as input in the discriminant analysis, 90% of the cases were correctly classified and the only misclassifications were between passage and piaffe. However, the 2 horses in which piaffe was misclassified as passage were the gold and silver medallists. In general, higher placed horses tended toward longer diagonal advanced placements, especially in collected trot and passage, and shorter hindlimb stance percentages in passage and piaffe.
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Clayton, H. M. (1995). Comparison of the stride kinematics of the collected, medium, and extended walks in horses. Am J Vet Res, 56(7), 849–852.
Abstract: Six horses, highly trained for dressage competition, were used to study the stride kinematics of the walk, and to compare the kinematics of the collected, medium, and extended walks. Horses were filmed in a sagittal plane at a rate of 150 frames/s; temporal, linear, and angular data were extracted from the films. Results of ANOVA and Duncan's multiple range test indicated that the speed of the collected walk (1.37 m/s) was significantly (P < 0.01) slower than that of the medium (1.73 m/s) and extended (1.82 m/s) walks, values for which were not significantly different from each other. The increase in speed was associated with a significant increase in stride length, from 157 cm in the collected walk to 193 cm in the extended walk. This was a result of an increase in the over-tracking distance, whereas there was no significant difference in the distance between lateral placements of the limbs. Stride duration decreased (P < 0.01) from the collected walk (1,159 ms) to the extended walk (1,064 ms). Angles of the metacarpal and metatarsal segments, measured on the palmar/ plantar aspect, were higher at impact and lower at lift off in the collected than in the extended walk (P < 0.01). This indicated greater range of angular motion of this segment during the stance phase in the extended walk. Only 1 of the 6 horses had a regular 4-beat rhythm of the footfalls, with equal time elapsing between the lateral and diagonal footfalls.
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Clayton, H. M. (1994). Comparison of the stride kinematics of the collected, working, medium and extended trot in horses. Equine Vet J, 26(3), 230–234.
Abstract: Highly-trained dressage horses were studied to test the hypothesis that stride length is altered independently of stride duration in the transitions between the collected, working, medium and extended trot. Six well-trained dressage horses were filmed at a frame rate of 150 frames/s performing the collected, working, medium and extended trots in a sand arena. Temporal, linear and angular data were extracted from the films, with 4 strides being analysed for each horse and gait type. There were no significant asymmetries between the left and rights limbs or diagonals when data from the whole group were pooled, but 3 horses showed asymmetries in one or more variables (P < 0.01). Analysis of variance and post-hoc tests indicated that the speed increased significantly (P < 0.01) from the collected (3.20 m/s) to the working (3.61 m/s) to the medium (4.47 m/s) to the extended (4.93 m/s) trot. The increases in speed were associated with a significant increase in stride length from 250 cm in the collected trot, to 273 cm in the working trot, 326 cm in the medium trot and 355 cm in the extended trot (P < 0.01). The lengthening of the stride was a result of increases between each gait type in the over-reach distance, whereas the diagonal distance was significantly longer in the extended than the collected trot only (P < 0.01). The stride duration tended to decrease as speed increased, and the difference became significant between the collected and extended trots (P < 0.01).
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