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Schnerr, C. U. (2011). Feldstudie zur Epidemiologie und Bekämpfung von Strongyliden in Pferdebeständen im Raum Baden- Württemberg. Ph.D. thesis, , .
Abstract: In der Zeit von April 2005 bis März 2006 wurden bei 105 Pferden monatlich
koprologische Untersuchungen durchgeführt. Die Pferde waren zu zwei Drittel
Jungtiere (≤ 4 Jahre) und ein Drittel > 4 Jahre. Die zur Verfügung stehenden vier
Betriebe befanden sich alle im Raum Baden-Württemberg.
Die Kotproben wurden mit Hilfe der Flotation auf Magen-Darmnematoden untersucht
und anschließend einer quantitativen Eizahlbestimmung nach Mc Master unterzogen.
Ab einem Eigehalt von 250 Eiern pro Gramm Kot (EpG) wurden die Pferde
entsprechend der Gruppenzugehörigkeit entweder mit Pyrantel oder Ivermectin
behandelt.
Es wurden bei 73 Pferden ausschließlich Strongylideneier nachgewiesen; bei vier
Pferden waren in der Flotation zusätzlich Eier von Parascaris equorum zu finden.
Bei 28 (26,7%) der untersuchten Pferde wurden in keiner der 12 untersuchten
Proben Eier von Magen-Darmnematoden nachgewiesen. Insgesamt mussten
57 (54,3%) der Pferde über den gesamten Untersuchungszeitraum hinweg nicht
behandelt werden. 48 (45,7%) Pferde mussten mindestens einmal anthelminthisch
behandelt werden. Kein Pferd musste häufiger als dreimal behandelt werden.
In den Monaten August bis November war der Anteil an positiven Proben der
Jungtiere signifikant höher als bei den Pferden > 4 Jahre. Innerhalb der
Jungtiergruppe nahm die Höhe der Strongyliden-Eiausscheidung mit zunehmendem
Alter signifikant ab.
Ebenso nahm die Anzahl der positiven Proben im Laufe des
Untersuchungszeitraums signifikant ab.
Die beiden zur Entwurmung eingesetzten Substanzen (Pyrantel und Ivermectin)
waren voll wirksam. In 98,8% der untersuchten Proben war ein Rückgang der
Ei-Ausscheidung noch vier Wochen nach der Behandlung auf 0 EpG nachweisbar,
d. h. es gab keinerlei Anzeichen für das Vorliegen von Resistenzen gegen die
eingesetzten Substanzen.
Die vorliegenden Untersuchungen sind ein weiterer Beweis dafür, dass mit Hilfe der
selektiven anthelminthischen Behandlung die Anzahl der Entwurmungen –
insbesondere auch bei Jungtieren – deutlich gesenkt werden kann.
Die Eiausscheidung und damit die Weidekontamination werden mit Hilfe dieses
Verfahrens deutlich reduziert.
[Between April 2005 and March 2006 monthly koprological examinations where
carried out on 105 horses.
Two third of the horses were young animals (≤ 4 years) and a third were > 4 years
old.
The four farms on hand were all located in the Baden- Württemberg area.
Faecal samples were examined for gastro-intestinal nematodes by means of flotation
and subsequently subjected to an egg-quantity counting according to Mc Master.
Starting from an egg content of 250 eggs per gram faeces (EpG), the horses were
treated with either Pyrantel or Ivermectin according to their group affiliation.
In 73 horses solely Strongyle eggs were detected; the flotation of four horses
additionaly showed eggs of Parascaris equorum.
In 28 (26,7%) of the examined horses none of the 12 examined samples showed
eggs of gastro-intestinal nematodes.
Overall 57 (54,3%) horses didn´t need any treatment during the total examination
cycle. 48 (45,7%) of the horses needed at least one anthelminthic treatment.
None of the horses needed to be treated more than three times.
From August to November the rate of positive samples within the group of young
animals was significantly higher than in the horses > 4 years.
Whithin the group of young animals the level of Strongyle egg excretions dropped
significantly with advancing age.
Likewise, the number of positive samples also dropped significantly in the course of
the examination cycle.
Both substances (Pyrantel and Ivermectin) applied for deworming were fully effective.
Even a further 4 weeks after treatment the examined sample showed a drop of egg
excretion to 0 EpG in 98,8% of the samples, in other words there were no signs of
prevailing resistance appearances towards the applied substance.
The present studies are further proof that the number of dewormings-especially in
young animals can be distinctly reduced by means of selective anthelminthic
treatments.
Egg excretion and therewith pasture land contamination can be clearly reduced by
means of this procedure.]
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Flauger, B. (2011). The introduction of horses into new social groups with special regard to their stress level. Ph.D. thesis, , .
Abstract: Horses are a highly social species living in complex social systems which should require them to memorise and generalise social experiences and distinguish between familiar and unfamiliar conspecifics. In the main part of my thesis I concentrated on the specific conflict situation of a horse being introduced into a new social group, and investigated its behaviour and stress level. Horses were either introduced (1) immediately, (2) after an observation period, or (3) together with an integration horse after an observation period. Additionally, in the second part of my thesis I arranged several experiments to elaborate additional aspects which could affect the behaviour of horses during introductions. In this study I could describe a simplified method for measuring stress through the analysis of faecal GCMs in horses. An enzyme immunoassay (EIA) for 11-oxoaetiocholanolone using 11-oxoaetiocholanolone-17-CMO: BSA (3?,11-oxo-A EIA) as antigen showed high amounts of immunoreactive substances. The new assay increases the accuracy of the test and lowers the expenses per sample; also storing of samples at room temperature after collection is less critical. This is a big advantage both in the field of wildlife management of equids and in the field of equestrian sports (chapter 1). Comparing the different introduction techniques, the introduction with an integration horse led to significantly less total interactions and lower levels of aggression than the introduction of single horses, both immediately and after several days of observing the new group. Additionally, by observing the behaviour of the horses during everyday sociality I could develop a formula describing the interrelationship between expected aggression level and enclosure size per horse. The curve takes an exponential shape. Starting from a space allowance of 300 m2 and more per horse, the amount of aggressions per hour approaches zero. For the reduction of aggression levels and injury risks in socially kept horses I recommend an enclosure size of at least 300 m2 per horse (chapter 2). I further investigated the stress level of the introduced animals. Horses which were immediately introduced did not show elevated faecal GCMs. In contrast, horses which were introduced after an observation period had slightly elevated values 2 and 3 days after the introduction. For horses introduced together with an integration horse faecal GCMs were significantly above the baseline value on the day of introduction and 1 day after it. These differences between introduction techniques indicate that the introduction event itself is not as stressful as previously assumed. Rather standing together with an integration horse and not being able to integrate immediately into the complete group elicits stress in horses (chapter 3). In the commentary of chapter 4 several studies are discussed which failed to demonstrate social learning in horses. It is argued that they did not consider important aspects which could have an influence, such as the dominance status or the social background of the horses (chapter 4). In chapter 5 a social feeding situation was investigated. The social rank as well as the position of conspecifics affected the feeding strategy of horses. Domestic horses used social cognition and strategic decision making in order to decide where to feed. When possible they tended to return to the same, continuously supplied feeding site and switched to an ?avoidance tendency? in the presence of dominant horses or when another horse was already feeding there (chapter 5). One possibility to recognize group members is through olfactory recognition. In chapter 6 it is shown that horses are able to distinguish their own from their conspecifics? faeces. In addition, they paid most attention to the faeces of those group members from which they received the highest amount of aggressive behaviour (chapter 6). Horses show cognitive abilities because they are able to use humans as local enhancement cues when searching for food, independently of their body posture or gaze consistency when the persons face them. Moreover, they seem to orientate on the attention of familiar persons more than of unfamiliar persons (chapter 7). Altogether, the results of this thesis provide further support for the view that horses show good conflict resolution strategies. They are perfectly able to deal with the conflict situation of being introduced to new group members, and the introduction event itself is not as stressful as previously assumed. It is rather suggested that standing together with an integration horse and not being able to integrate immediately into the complete group elicits stress in horses. All additional experimental set-ups could demonstrate that horses are well capable of social cognition.
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Bartoš, L., Bartošová, J., Pluhácek, J., & Šindelárová, J. (2011). Promiscuous behaviour disrupts pregnancy block in domestic horse mares. Behavioral Ecology and Sociobiology, 65(8), 1567–1572.
Abstract: Based on questionnaires from horse breeders, we found that bringing a pregnant mare which had been mated away from home into a vicinity of a familiar male who was not the father of her foetus increased probability of pregnancy disruption. These mares aborted in 31% of cases, while none of those mated within the home stable aborted. Repeated sexual activity either by a stallion or dominant gelding from the normal home group was observed shortly after the mare came from away-mating. Pregnant mares isolated from home males by a fence were even seen soliciting them over the fence. We speculate that, once returned to the home “herd”, and introduced to familiar males, mares were more likely to terminate their pregnancy to save energy and avoid likely future infanticidal loss of their progeny by dominant male(s) of the home social group. This is a newly discovered phenomenon where a mare manipulates the male’s paternity assessment by promiscuous mating. It may explain a common increased incidence of foetal loss in domestic horses occurring in nearly 40% of pregnancies. We conclude that the common practice of transporting the mare for mating and then bringing her back to an environment with males, stallions or geldings, which did not sire the foetus, is the main cause of high percentages of pregnancy disruption in domestic horses.
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Core Development Team, R. (2011). R: a language and environment for statistical computing. Vienna, Austria: R foundation for statistical computing.
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