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Author |
Mouritsen, K.N. |
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Title |
Hitch-hiking parasite: a dark horse may be the real rider |
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Journal Article |
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Year |
2001 |
Publication |
International Journal for Parasitology |
Abbreviated Journal |
Int J Parasitol |
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Volume |
31 |
Issue |
13 |
Pages |
1417-1420 |
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Keywords |
Animals; *Behavior, Animal; Ecology; Host-Parasite Relations; Snails/*parasitology; Trematoda/growth & development/*physiology; Trematode Infections/transmission |
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Abstract |
Many parasites engaged in complex life cycles manipulate their hosts in a way that facilitates transmission between hosts. Recently, a new category of parasites (hitch-hikers) has been identified that seem to exploit the manipulating effort of other parasites with similar life cycle by preferentially infecting hosts already manipulated. Thomas et al. (Evolution 51 (1997) 1316) showed that the digenean trematodes Microphallus papillorobustus (the manipulator) and Maritrema subdolum (the hitch-hiker) were positively associated in field samples of gammarid amphipods (the intermediate host), and that the behaviour of Maritrema subdolum rendered it more likely to infect manipulated amphipods than those uninfected by M. papillorobustus. Here I provide experimental evidence demonstrating that M. subdolum is unlikely to be a hitch-hiker in the mentioned system, whereas the lucky candidate rather is the closely related but little known species, Microphallidae sp. no. 15 (Parassitologia 22 (1980) 1). As opposed to the latter species, Maritrema subdolum does not express the appropriate cercarial behaviour for hitch-hiking. |
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Address |
Department of Marine Ecology, Institute of Biological Sciences, University of Aarhus, Finlandsgade 14, DK-8200 Aarhus N, Denmark. kim.mouritsen@stonebow.otago.ac.nz |
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0020-7519 |
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PMID:11595227 |
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no |
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Equine Behaviour @ team @ |
Serial |
2645 |
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Author |
Fagot, J.; Wasserman, E.A.; Young, M.E. |
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Title |
Discriminating the relation between relations: the role of entropy in abstract conceptualization by baboons (Papio papio) and humans (Homo sapiens) |
Type |
Journal Article |
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Year |
2001 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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Volume |
27 |
Issue |
4 |
Pages |
316-328 |
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Keywords |
Animals; Behavior, Animal; Choice Behavior; Cognition/physiology; *Discrimination (Psychology); Discrimination Learning; *Entropy; Female; Humans; Judgment/*physiology; Male; Papio |
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Abstract |
Two baboons (Papio papio) successfully learned relational matching-to-sample: They picked the choice display that involved the same relation among 16 pictures (same or different) as the sample display, although the sample display shared no pictures with the choice displays. The baboons generalized relational matching behavior to sample displays created from novel pictures. Further experiments varying the number of sample pictures and the mixture of same and different sample pictures suggested that entropy plays a key role in the baboons' conceptual behavior. Two humans (Homo sapiens) were similarly trained and tested; their behavior was both similar to and different from the baboons' behavior. The results suggest that animals other than humans and chimpanzees can discriminate the relation between relations. They further suggest that entropy detection may underlie same-different conceptualization, but that additional processes may participate in human conceptualization. |
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Comparative Cognition Research Group, Center for Research in Cognitive Neurosciences, 31 Chemin Joseph Aiguier, 13402 Marseille, France. fagot@lnf.cnrs-mrs.fr |
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0097-7403 |
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PMID:11676083 |
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Equine Behaviour @ team @ |
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2772 |
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Author |
Nakamura, K. |
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Title |
Perseverative errors in object discrimination learning by aged Japanese monkeys (Macaca fuscata) |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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Volume |
27 |
Issue |
4 |
Pages |
345-353 |
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Keywords |
Age Factors; Animals; Behavior, Animal/physiology; Cognition Disorders/*diagnosis/*physiopathology; Discrimination Learning/*physiology; Frontal Lobe/*physiopathology; Macaca; Neuropsychological Tests |
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Abstract |
To examine the nature of age-dependent cognitive decline, performance in terms of concurrent object discriminations was assessed in aged and nonaged Japanese monkeys (Macaca fuscata). Aged monkeys required more sessions and committed more errors than nonaged ones in the discriminations, even in simple object discriminations. Analyses of errors suggest that aged monkeys repeated the same errors and committed more errors when they chose a negative object at the 1st trial. A hypothesis analysis of behavior suggests that their incorrect choices were mainly due to object preference. Therefore, the impairment was probably caused by a failure to inhibit inappropriate responses. Together with previous neuropsychological findings, deficits of aged monkeys in the performance of object discriminations can be explained by dysfunction of the frontal cortex. |
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Department of Behavioral and Brain Sciences, Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan. knakamur@pri.kyoto-u.ac.jp |
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0097-7403 |
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PMID:11676085 |
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no |
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Call Number |
Equine Behaviour @ team @ |
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2771 |
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Author |
Kelly, D.M.; Spetch, M.L. |
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Title |
Pigeons encode relative geometry |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Experimental Psychology. Animal Behavior Processes |
Abbreviated Journal |
J Exp Psychol Anim Behav Process |
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Volume |
27 |
Issue |
4 |
Pages |
417-422 |
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Keywords |
Animals; Behavior, Animal/physiology; Cognition/*physiology; Columbidae; Discrimination Learning/physiology; Form Perception/*physiology; Space Perception/*physiology |
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Abstract |
Pigeons were trained to search for hidden food in a rectangular environment designed to eliminate any external cues. Following training, the authors administered unreinforced test trials in which the geometric properties of the apparatus were manipulated. During tests that preserved the relative geometry but altered the absolute geometry of the environment, the pigeons continued to choose the geometrically correct corners, indicating that they encoded the relative geometry of the enclosure. When tested in a square enclosure, which distorted both the absolute and relative geometry, the pigeons randomly chose among the 4 corners, indicating that their choices were not based on cues external to the apparatus. This study provides new insight into how metric properties of an environment are encoded by pigeons. |
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Department of Psychology, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9. kelly@bio.psy.ruhr-uni-bochum.de |
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0097-7403 |
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Notes |
PMID:11676090 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2770 |
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Author |
Barros, A.T. |
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Title |
Seasonality and relative abundance of Tabanidae (Diptera) captured on horses in the Pantanal, Brazil |
Type |
Journal Article |
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Year |
2001 |
Publication |
Memorias do Instituto Oswaldo Cruz |
Abbreviated Journal |
Mem Inst Oswaldo Cruz |
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Volume |
96 |
Issue |
7 |
Pages |
917-923 |
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Keywords |
Animals; Brazil; Climate; Diptera/classification/*physiology; Ecology; Horses/*parasitology; Population Dynamics; Seasons; Species Specificity |
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Abstract |
Once a month, from June 1992 to May 1993, collections of tabanids on horse were conducted in the Nhecolandia, Pantanal State of Mato Grosso do Sul, Brazil. Tabanid catches using hand nets were conducted from sunrise to sunset at grassland and cerradao (dense savanna) habitats. A total of 3,442 tabanids from 21 species,12 genera, and 3 subfamilies were collected. Although species abundance varied seasonally depending on habitat, no habitat specificity was observed for the most abundant species. In the grassland, 1,625 (47.2%) tabanids belonging to 19 species were collected, while 1,817 (52.8%) tabanids from 17 species were caught in the cerradao. The number of tabanid species varied from 7 during winter (July/August) to 15 in the spring (October). Tabanus importunus (56%) was the most abundant species, followed by T. occidentalis (8.2%), and T. claripennis (8.1%). The tabanid peak, in October, coincided with the beginning of the rainy season. The population peak of most species, including those with higher vector potential, suggests that the rainy season can be considered as the period of potentially higher risk of mechanical transmission of pathogens by tabanids to horses in the region. |
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Embrapa Pantanal, 79320-900 Corumba, MS, Brasil. thadeu@cpap.embrapa.br |
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0074-0276 |
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PMID:11685255 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2644 |
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Author |
Andrew, R.J. |
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Title |
Changes in visual responsiveness following intercollicular lesions and their effects on avoidance and attack |
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Journal Article |
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Year |
1974 |
Publication |
Brain, Behavior and Evolution |
Abbreviated Journal |
Brain Behav Evol |
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10 |
Issue |
4-5 |
Pages |
400-424 |
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Keywords |
Animals; Chickens; Humans; Male; Mutism; Superior Colliculi/*physiology; Tectum Mesencephali; Testosterone; Visual Fields; Vocalization, Animal |
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Abstract |
In the normal chick, conspicuous visual stimuli induce targetting and pecking together, with vocalization. All three are abolished by lesion of the intercollicular area (ICo) or of connections passing through its medial margin. After such lesions, chicks also cease to treat significant visual stimuli as if they were startling and exciting, and may delay response as a result. However, they are still able to recognise, orient accurately to, and respond appropriately to, a variety of complex visual stimuli (e.g. food grains, copulation object). In addition, they are little affected by strange surroundings. Lesion evidence suggests the mammalian subcollicular area to have similar functions to the ICo and to be homologous with it. A route (present in bird), which is well-known in mammals for its association with threat, defense and escape evoked by strange and frightening objects (amygdala-diencephalic periventricular system-central mesencephalic grey, A-DPS-CMG) is stimuli via the 2 ICo (subcollicular area). Two different mechanisms may be involved caudal to the ICo. One consists of tectal afferents which might modulate the evocation of targetting, pecking and other responses via the tectum. The other is the predorsal system of tectal efferents which may mediate such responses. Classical syndromes of tameness and unresponsiveness produced by various interruptions of the A-DPS-CMG route may depend on interruption of connections to these midbrain mechanisms. Attack is depressed by ICo lesions as one aspect of reduced responsiveness to conspicuous and startling visual stimuli. Avoidance, which is apparently mediated by a separate system, much as in Anura, is facilitated. |
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0006-8977 |
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PMID:1169102 |
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Equine Behaviour @ team @ |
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4626 |
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Author |
Robert, C.; Audigie, F.; Valette, J.P.; Pourcelot, P.; Denoix, J.M. |
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Title |
Effects of treadmill speed on the mechanics of the back in the trotting saddlehorse |
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Journal Article |
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Year |
2001 |
Publication |
Equine Veterinary Journal. Supplement |
Abbreviated Journal |
Equine Vet J Suppl |
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Volume |
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Issue |
33 |
Pages |
154-159 |
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Animals; Biomechanics; Electromyography/veterinary; Exercise Test/veterinary; Horses/*physiology; Locomotion/*physiology; Muscle, Skeletal/*physiology; Range of Motion, Articular/*physiology; Spine/*physiology; Video Recording |
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Abstract |
Speed related changes in trunk mechanics have not yet been investigated, although high-speed training is currently used in the horse. To evaluate the effects of speed on back kinematics and trunk muscles activity, 4 saddle horses were recorded while trotting on a horizontal treadmill at speeds ranging from 3.5 to 6 m/s. The 3-dimensional (3-D) trajectories of skin markers on the left side of the horse and the dorsal midline of the trunk were established. Electrical activity was simultaneously obtained from the longissimus dorsi (LD) and rectus abdominis (RA) muscles using surface electrodes. Ten consecutive strides were analysed for each horse at each of the 5 velocity steps. Electromyographic and kinematic data were time-standardised to the duration of the stride cycle and compared using an analysis of variance. The back extended during the first part of each diagonal stance phase when the RA was active and the back flexed during the second part of each diagonal stance phase when the LD was active. The onset and end of muscle activity came earlier in the stride cycle and muscle activity intensity increased when speed increased. The amplitude of vertical movement of the trunk and the maximal angles of flexion decreased with increasing speed, whereas the extension angles remained unchanged. This resulted in a decreased range of back flexion-extension. This study confirms that the primary role of trunk muscles is to control the stiffness of the back rather than to induce movements. Understanding the effects of speed on the back of healthy horses is a prerequisite for the prevention and treatment of back pathology. |
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UMR INRA, Biomecanique et Pathologie Locomotrice du Cheval, UP d'Anatomie, Ecole Nationale Veterinaire d'Alfort, 7 Avenue du General de Gaulle, F-94704 Maisons-Alfort, France |
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PMID:11721558 |
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Call Number |
Equine Behaviour @ team @ |
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4050 |
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Permanent link to this record |
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Author |
Meershoek, L.S.; Schamhardt, H.C.; Roepstorff, L.; Johnston, C. |
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Title |
Forelimb tendon loading during jump landings and the influence of fence height |
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Journal Article |
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Year |
2001 |
Publication |
Equine Veterinary Journal. Supplement |
Abbreviated Journal |
Equine Vet J Suppl |
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Issue |
33 |
Pages |
6-10 |
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Animals; Biomechanics; Forelimb/injuries/physiology; Horses/injuries/*physiology; Lameness, Animal/etiology; Ligaments, Articular/*physiology; Locomotion/*physiology; Physical Conditioning, Animal; Tendon Injuries/complications/physiopathology/veterinary; Tendons/*physiology; Weight-Bearing/physiology |
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Abstract |
Lameness in athletic horses is often caused by forelimb tendon injuries, especially in the interosseus tendon (TI) and superficial digital flexor tendon (SDF), but also in the accessory ligament (AL) of the deep digital flexor tendon (DDF). In an attempt to explain the aetiology of these injuries, the present study investigated the loading of the tendons during landing after a jump. In jumping horses, the highest forces can be expected in the trailing limb during landing. Therefore, landing kinematics and ground reaction forces of the trailing forelimb were measured from 6 horses jumping single fences with low to medium heights of 0.80, 1.00 and 1.20 m. The tendon forces were calculated using inverse dynamics and an in vitro model of the lower forelimb. Calculated peak forces in the TI, SDF and DDF + AL during landing were 15.8, 13.9 and 11.7 kN respectively. The relative loading of the tendons (landing forces compared with failure forces determined in a separate study) increased from DDF to TI to SDF and was very high in SDF. This explains the low injury incidence of the DDF and the high injury incidence of the SDF. Fence height substantially influenced SDF forces, whereas it hardly influenced TI forces and did not influence AL strain. Reduction of fence height might therefore limit the risks for SDF injuries, but not for TI and AL injuries. |
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Department of Veterinary Anatomy and Physiology, Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands |
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PMID:11721571 |
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Equine Behaviour @ team @ |
Serial |
3786 |
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Permanent link to this record |
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Author |
Jansen, W.L.; van Alphen, M.; Berghout, M.; Everts, H.; Beynen, A.C. |
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Title |
An approach to assessment of the efficiency of dietary energy utilization by horses and ponies kept at riding schools |
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Journal Article |
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Year |
2001 |
Publication |
The Veterinary quarterly |
Abbreviated Journal |
Vet Q |
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Volume |
23 |
Issue |
4 |
Pages |
195-198 |
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*Animal Feed; Animal Husbandry; Animals; Body Weight; Dietary Fats; Dietary Fiber; *Energy Intake; *Energy Metabolism; Female; Horses/*physiology; Male |
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The ratio of calculated net energy intake (NEi) to calculate net energy requirement (NEr) might serve as an indicator of the efficiency of dietary energy utilization. The ratio was determined for 93 horses and ponies from 10 riding schools. For each animal with an assumed constant body weight, energy intake and energy requirements were assessed. On average, the estimated NEi was 14% greater than NEr. There was a significant, negative association between crude fibre intake and the NEi: NEr ratio. Earlier work indicated that extra fat intake may lead to over estimation of the calculated energy value of the ration due to changes in macronutrient digestibility. Dietary fat concentration was found to range from 32 to 52 g/kg dry matter (5 to 6 g/MJ net energy), but on the basis of digestibility trials this range in fat concentration is too small to significantly influence the NEi: NEr ratio. This study shows that assessment of the efficiency of dietary energy utilization under normal conditions, on the basis of the NEi: NEr ratio is fraught with uncertainty. |
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Department of Nutrition, Faculty of Veterinary, Medicine, Utrecht University, The Netherlands |
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0165-2176 |
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PMID:11765239 |
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Call Number |
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Serial |
1807 |
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Permanent link to this record |
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Author |
Wilson, A.M.; McGuigan, M.P.; Su, A.; van Den Bogert, A.J. |
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Title |
Horses damp the spring in their step |
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Journal Article |
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Year |
2001 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
414 |
Issue |
6866 |
Pages |
895-899 |
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Animals; Biomechanics; Elasticity; Forelimb; Gait; Horses/anatomy & histology/*physiology; Leg Bones/*physiology; Locomotion; Models, Biological; Muscle Fibers/physiology; Muscle, Skeletal/anatomy & histology/*physiology; Tendons/anatomy & histology/*physiology; Vibration |
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Abstract |
The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb. |
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Department of Veterinary Basic Sciences, The Royal Veterinary College, Hatfield, Herts AL9 7TA, UK. awilson@rvc.ac.uk |
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0028-0836 |
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PMID:11780059 |
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Equine Behaviour @ team @ |
Serial |
2300 |
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