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Poysa, Hannu |
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Title |
Group Foraging in Patchy Environments: The Importance of Coarse-Level Local Enhancement |
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Journal Article |
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Year |
1992 |
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Ornis Scandinavica |
Abbreviated Journal |
Ornis[ Scand[ |
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Volume |
23 |
Issue  |
2 |
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159-166 |
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Local enhancement is one way individuals may realize foraging advantages from grouping. A distinction between fine-level and coarse-level local enhancement is made, the latter often being neglected in theoretical research on group foraging. In the former case, an individual has a higher feeding rate as a member of a group because individuals copy other group members' foraging, whereas in the latter, groups simply attract other individuals to patches where food is particularly abundant and copying does not occur within the group. Coarse-level local enhancement may decrease the time needed to find profitable feeding patches in spatially and temporally variable environments. A review of the empirical literature indicated that coarse-level local enhancement is typical in bird species foraging in open habitats and in large groups with relatively little competition between group members whereas the opposite attributes fit the species for which fine-level local enhancement had been documented. Furthermore, species in which coarse-level local enhancement prevails usually forage in temporary groups. However, coarse-level and fine-level local enhancement are not necessarily mutually exclusive, but which one is more important in a particular case may be habitat-dependent. |
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Equine Behaviour @ team @ |
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4272 |
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Author |
Aureli, F.; Cossolino, R.; Cordischi, C.; Scucchi, S. |
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Title |
Kin-oriented redirection among Japanese macaques: an expression of a revenge system? |
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Journal Article |
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Year |
1992 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
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Volume |
44 |
Issue |
2 |
Pages |
283-291 |
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The ability to recognize the close associates of other group members may permit the display of redirected aggression against the relatives of the former aggressor. However, the dominance structure and the kin-based alliance system of macaque society are expected not to favour the occurrence of this kin-oriented redirection. Nevertheless, within 1 h of being the victim of an attack, Japanese macaques, Macaca fuscata, were more likely to attack the former aggressor's kin than without such a conflict. The conditions under which the victim redirected against the former aggressor's kin were investigated. This kin-oriented redirection did not occur preferentially either after conflicts between individuals with unstable and/or uncertain dominance relationships or after conflicts with individuals that were unlikely to intervene in favour of their kin. Victims redirected against individuals that were younger than the former aggressor and often subordinate to the victim. They also redirected in an opportunistic way by joining polyadic interactions against the former aggressor's kin. The possibility that this kin-oriented redirection may have a long-term function in changing the aggressive attitude of the aggressor towards the victim is also discussed. In addition, the victim's kin also displayed a form of kin-oriented redirection. They were more likely to attack the kin of an individual after it had attacked their own kin. |
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10.1016/0003-3472(92)90034-7 |
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Equine Behaviour @ team @ |
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4867 |
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Author |
Dugatkin, L.A.; Godin, J.G. |
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Title |
Reversal of female mate choice by copying in the guppy (Poecilia reticulata) |
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Journal Article |
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Year |
1992 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
249 |
Issue |
1325 |
Pages |
179-184 |
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Keywords |
Acclimatization; Animals; *Choice Behavior; Female; Male; Poecilia; *Sexual Behavior, Animal |
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Ever since Fisher (1958) formalized models of sexual selection, female mate choice has been assumed to be a genetically determined trait. Females, however, may also use social cues to select mates. One such cue might be the mate choice of conspecifics. Here we report the first direct evidence that a female's preference for a particular male can in fact be reversed by social cues. In our experiments using the Trinidadian guppy (Poecilia reticulata), this reversal was mediated by mate-copying opportunities, such that a female (the 'focal' female) is given the opportunity to choose between two males, followed by a period in which she observes a second female (the 'model' female) displaying a preference for the male she herself did not prefer initially. When allowed to choose between the same males a second time, compared with control tests, a significant proportion of focal females reversed their mate choice and copied the preference of the model female. These results provide strong evidence for the role of non-genetic factors in sexual selection and underlie the need for new models of sexual selection that explicitly incorporate both genetic and cultural aspects of mate choice. |
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Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada |
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0962-8452 |
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PMID:1360679 |
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1824 |
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Author |
Timney, B.; Keil, K. |
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Title |
Visual acuity in the horse |
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Journal Article |
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Year |
1992 |
Publication |
Vision Research |
Abbreviated Journal |
Vis. Res. |
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Volume |
32 |
Issue |
12 |
Pages |
2289-2293 |
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Keywords |
Horse Visual acuity Visual discrimination |
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We assessed the ease with which horses could learn visual discriminations and measured their resolution acuity. We trained three horses to press their noses against one of two large wooden panels to receive a small food reward. Following training on a series of two-choice discrimination tasks, resolution acuity was measured. Although there was some variability between animals, the best acuity obtained was 23.3 c deg-1. Within the margin of error imposed by limited anatomical data, the obtained values are consistent with predictions based on retinal ganglion cell density estimates and posterior nodal distance/axial length ratios. They suggest that the resolution acuity of the horse is limited by ganglion cell density in the temporal portion of the narrow visual streak. |
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refbase @ user @ |
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851 |
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Author |
Romano, N.; Vitale, F.; Alesi, D.R.; Bonura, F.; La Licata, R.; Intonazzo, V.; Dardanoni, G.; Mammina, C. |
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Title |
The changing pattern of human immunodeficiency virus type 1 infection in intravenous drug users. Results of a six-year seroprevalence study in Palermo, Italy |
Type |
Journal Article |
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Year |
1992 |
Publication |
American Journal of Epidemiology |
Abbreviated Journal |
Am J Epidemiol |
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Volume |
135 |
Issue |
11 |
Pages |
1189-1196 |
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Keywords |
Acquired Immunodeficiency Syndrome/*epidemiology; Adolescent; Adult; Chi-Square Distribution; Cross-Sectional Studies; Female; HIV Antibodies/blood; HIV Infections/*epidemiology; HIV Seroprevalence/*trends; *Hiv-1; Hepatitis B Antibodies/blood; Hepatitis B Surface Antigens/blood; Heroin; Humans; Incidence; Italy/epidemiology; Logistic Models; Male; Multivariate Analysis; Odds Ratio; Prevalence; Risk Factors; Substance Abuse, Intravenous/*epidemiology; Time Factors |
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A cross-sectional seroepidemiologic study was carried out between 1985 and 1990 in 1,567 heterosexual intravenous drug users who had been seen at the AIDS Regional Reference Center in Palermo, Italy, to evaluate the rate of human immunodeficiency virus type 1 (HIV-1) seroprevalence in this group and its long-term trend. Sixty serum samples collected from drug users in 1980 and 1983, before the founding of the Center (1985), were tested as well. Some demographic and behavioral risk factors were studied in a subgroup of intravenous drug users enrolled in 1985, 1987, and 1990 for their possible association with HIV-1. These factors were also studied in relation to hepatitis B virus infection, since both viruses share the same modes of spread. These drug users had a higher prevalence of markers for hepatitis B virus than of HIV-1 antibodies, and the prevalence rates in sera collected declined over time for both infections. The presence of both antibodies to HIV-1 and markers for hepatitis B virus was independently associated with the age of the drug user, the duration of drug use, and the year of serum collection. Antibodies to HIV-1 were observed more frequently in females than in males. No relation was found between education or employment status and the presence of HIV-1 antibodies or hepatitis B virus markers. Although new HIV-1 infections still occur, the decline in seroprevalence observed at the end of the 1980s might be related to modifications in social behavior among newer drug users, partial exhaustion of the susceptible population, and increasing risk awareness in more experienced users. |
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Giuseppe D'Alessandro Department of Hygiene and Microbiology, School of Medicine, University of Palermo, Italy |
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0002-9262 |
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PMID:1626537 |
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Equine Behaviour @ team @ |
Serial |
5258 |
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Author |
Eisgruber, H.; Stolle, F.A. |
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Title |
[Clostridia in carcasses and fresh meat--a literature review] |
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Journal Article |
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Year |
1992 |
Publication |
Zentralblatt fur Veterinarmedizin. Reihe B. Journal of Veterinary Medicine. Series B |
Abbreviated Journal |
Zentralbl Veterinarmed B |
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Volume |
39 |
Issue |
10 |
Pages |
746-754 |
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Keywords |
Abattoirs; Animals; Cattle; Clostridium/*growth & development; *Food Microbiology; Horses; Meat/*microbiology; Muscles/*microbiology; Sheep; Swine |
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Clostridia are of large clinical importance as well as in the field of food hygiene, where they are responsible for spoilage but they also have a certain significance as food poisoning organisms. Information on the ecology of Clostridia in samples of deep muscle tissue of slaughtered animals is insufficient. This article is intended to increase the knowledge on the occurrence of different Clostridia species in slaughtered animals. The main emphasis is put on the significance of clostridia in meat hygiene. The theoretical basis of the so called original content of microorganisms (intrinsic bacteria), the factors and pathways of Clostridia spreading in muscles and organs are demonstrated. |
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Institut fur Hygiene und Technologie, Ludwig-Maximilians-Universitat Munchen |
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German |
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Clostridien in Schlachttierkorpern und frischem Fleisch--Eine Literaturubersicht |
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0514-7166 |
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PMID:1492516 |
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Equine Behaviour @ team @ |
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2668 |
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Author |
Lamprecht, J. |
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Title |
Variable Leadership in Bar-Headed Geese (Anser Indicus) : an Analysis of Pair and Family Departures |
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Journal Article |
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Year |
1992 |
Publication |
Behaviour |
Abbreviated Journal |
Behaviour |
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122 |
Issue |
1-2 |
Pages |
105-119 |
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This paper reports quantitative leadership differences in semi-captive bar-headed geese (Anser indicus) at different times of the year, and in different types of groups. Leading is defined here as causing the departure or determining the direction of movement of the whole group. No permanent and exclusive leader of a pair or family group was found, rather relative leading frequencies of male, female and young showed a definite shifting pattern. Females led more often than their mates prior to breeding, and on nest pauses during the incubation period, but less often in summer, autumn and early winter. In families there was no difference between the frequencies of male and female leading. Family females led relatively more often than those of pairs without offspring. This difference was related to the presence, not the number, of young. Goslings led the family about as often as the parents during the rearing period in early summer, less often in autumn, winter and next spring. Such differences and changes are to be expected where competence in particular tasks and dependence on partners vary between group members, and where different situations require different abilities. For the geese, the results can be related to the different options of group members and to the different benefits they derive from leaving (or 'staying put') or following (or waiting for the others) in different situations. |
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Equine Behaviour @ team @ |
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5128 |
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Author |
Kraus-Hansen, A.E.; Fackelman, G.E.; Becker, C.; Williams, R.M.; Pipers, F.S. |
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Title |
Preliminary studies on the vascular anatomy of the equine superficial digital flexor tendon |
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Journal Article |
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Year |
1992 |
Publication |
Equine veterinary journal |
Abbreviated Journal |
Equine Vet J |
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Volume |
24 |
Issue |
1 |
Pages |
46-51 |
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Keywords |
Angiography/veterinary; Animals; Exercise Test/veterinary; Forelimb; Horses/*anatomy & histology/surgery; Microcirculation; Microscopy, Electron, Scanning; Tendons/*blood supply/surgery/ultrastructure |
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Abstract |
The vascular and microvascular anatomy of normal equine superficial digital flexor tendons was studied by dissection of vinyl-perfused specimens and by microangiography on high detail film. The presence of an extensive intratendinous vascular latticework was confirmed, and a 'nutrient artery' described closely associated with the accessory ligament of the superficial digital flexor tendon (proximal check ligament). Circumferential stripping of the paratenon from the tendon to eliminate afferent vessels was performed bilaterally in three horses and unilaterally in a fourth, followed by a treadmill training regimen. No resulting intratendinous lesions could be documented on gross post mortem and histological examination at three, 10, or 35 days post operatively. There was mild paratendinous proliferation in all instances. In one horse, four intratendinous ligatures were placed within the medial and lateral borders of the contralateral tendon to isolate further from its blood supply a 10 cm segment. Gross lesions at 35 days post operatively included a marked paratendinous response involving the entire 10 cm segment, and a darkened, soft focus within the core of the tendon. Histopathology and electron microscopy demonstrated focal degeneration. It was concluded that the blood supply of the normal equine superficial digital flexor tendon is primarily intratendinous, rather than paratendinous as previously thought. The lesions in one horse similar to those in naturally occurring tendinitis supported a vascular aetiology of the disease, and set the groundwork for studies aimed at the development of a clinically relevant tendinitis model. |
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Department of Surgery, Tufts University School of Veterinary Medicine, North Grafton, Massachusetts 01536 |
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0425-1644 |
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PMID:1555540 |
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Call Number |
refbase @ user @ |
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151 |
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Author |
Gutierrez Rincon, J.A.; Vives Turco, J.; Muro Martinez, I.; Casas Vaque, I. |
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Title |
A comparative study of the metabolic effort expended by horse riders during a jumping competition |
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Journal Article |
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Year |
1992 |
Publication |
British Journal of Sports Medicine |
Abbreviated Journal |
Br J Sports Med |
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Volume |
26 |
Issue |
1 |
Pages |
33-35 |
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Keywords |
Adult; Animals; Energy Metabolism/*physiology; *Exertion; Heart Rate/physiology; Horses; Humans; Lactates/blood; *Sports |
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The three main Olympic horse riding disciplines are dressage, jumping, and three-day eventing (including dressage, cross country and jumping). In the jumping discipline (obstacle race), the 'team' (horse rider) is judged under the different conditions that might take place in a varied run. The horse is expected to show power and ability; the rider must show riding skill and good physical condition. However, the different conditions encountered by the rider during competition (duration of event, continuous isometric working level, especially in the inferior trunk, lead us to consider the need for a rider to develop different metabolic pathways to meet the high energy requirements of the competition. |
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Centre de Medicina de l'Esport de Barcelona, Spain |
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0306-3674 |
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PMID:1600451 |
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Equine Behaviour @ team @ |
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3754 |
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Author |
Hertsch, B. |
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Title |
[The appearance of stress on the movement apparatus in dressage, jumping and versatility horses] |
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Journal Article |
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Year |
1992 |
Publication |
DTW. Deutsche Tierarztliche Wochenschrift |
Abbreviated Journal |
Dtsch Tierarztl Wochenschr |
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Volume |
99 |
Issue |
1 |
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36-39 |
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Animals; Bone Diseases/etiology/*veterinary; Horse Diseases/*etiology; Horses/*injuries; Joint Diseases/etiology/*veterinary; *Sports; Stress, Mechanical; Tendon Injuries/etiology/veterinary |
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Jumping and military (three days events) horses are exposed, during sports activities, to a particularly high stress especially in the region of the extremities (limbs). The genesis of tendon, joint and bone diseases are traced in accordance to the centers of the load during movement sequence. A special statistics on injuries concerning the German competition horses does not exist yet. Out of the available statistics about the German competition horses it is not obvious that as a result of its use as sports horses a particular high loss occur among these horses. |
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Klinik fur Pferde, Tierarztlichen Hoschschule Hannover |
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German |
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Belastungserscheinungen am Bewegungsapparat bei Dressur-, Spring- und Vielseitigkeitspferden |
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0341-6593 |
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PMID:1555516 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3755 |
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