| Home | << 1 2 3 4 5 6 7 8 9 10 >> |
|
Romero L. M. (2011). Using the reactive scope model to understand why stress physiology predicts survival during starvation in Galápagos marine iguanas. Gen Comp Endocrinol, .
Abstract: Even though the term “stress” is widely used, a precise definition is notoriously difficult. Notwithstanding this difficulty, stress continues to be an important concept in biology because it attempts to describe how animals cope with environmental change under emergency conditions. Without a precise definition, however, it becomes nearly impossible to make testable a priori predictions about how physiological and hormonal systems will respond to emergency conditions and what the ultimate impact on the animal will be. The reactive scope model is a recent attempt to formulate testable predictions. This model provides a physiological basis to explain why corticosterone negative feedback, but not baseline corticosterone concentrations, corticosterone responses to acute stress, or the interrenal capacity to secrete corticosterone, is correlated with survival during famine conditions in Galápagos marine iguanas. Reactive scope thus provides a foundation for interpreting and predicting physiological stress responses.
Keywords: Reactive scope; Allostasis; Glucocorticoids; Stress; Survival
|
|
Steidele, N. (2011). Beobachtungen einer Przewalski-Junggesellenherde im Jahresverlauf unter besonderer Berücksichtigung von Ruheverhalten und Rangordnung.
|
|
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.] |
|
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.
Keywords: Pferd; Equiden; Eingliederungstechnik; Integrationspferd; Stress; Cortisol; Endokrine Reaktion; Gruppenhaltung; Verletzungsgefahr; Aggression; Futterplatzwahl; Kot; Geruchssinn; Mensch-Pferd Interaktion; horse; equids; introduction technique; integration horse; stress; cortisol; endocrine response; group housing; injury risk; aggression; feeding decision; faecal sample; olfaction; human-horse interaction
|
|
Baragli, P., Vitale, V., Paoletti, E., Mengoli, M., & Sighieri, C. (2011). Encoding the Object Position for Assessment of Short Term Spatial Memory in Horses (Equus caballus). International Journal of Comparative Psychology, 24(3).
Abstract: In this study, the detour problem was combined with the classic delayed-response task to investigate equine short-term spatial memory. Test subjects were eight female horses, divided into two groups (A and B) of four subjects each. The motivating object was made to move and disappear behind one oftwo identical obstacles in a two-point-choice apparatus. After a 10 s (Group A) or 30 s (Group B) delay the animal was released to seek the object. Both groups made more correct (14.8 ± 1.3 forGroup A and 13.5 ± 3.1 for Group B, mean ± SD) than incorrect choices (5.3 ± 1.3 for Group A and6.5 ± 3.1 for Group B, mean ± SD) and the performance of each group was significantly above chance level (z = 4.14, p = 0.000, for Group A and z = 3.02, p = 0.002, for Group B). Therefore, tested animals were able to recover the object by approaching the correct obstacle after 10 s or 30 s delays, showing that they had encoded and recovered from memory the existence of the target object and its location.
|
|
Van Schaik, C. P., & Burkart, J. M. (2011). Social learning and evolution: the cultural intelligence hypothesis. Philos Trans R Soc B, 366.
|
|
Van Horik, J., & Emery, N. (2011). Evolution of cognition. Wiley Interdiscip Rev Cogn Sci, 2.
|
|
van de Waal, E., & Bshary, R. (2011). Social-learning abilities of wild vervet monkeys in a two-step task artificial fruit experiment. Anim Behav, 81.
|
|
Morand-Ferron, J., Cole, E. F., Rawles, J. E. C., & Quinn, J. L. (2011). Who are the innovators? A field experiment with 2 passerine species. Behav Ecol, 22.
|
|
Zeder, M. A. (2011). Pathways to animal domestication. In A. Damania, & P. Gepts (Eds.), Harlan II: Biodiversity in Agriculture: Domestication, Evolution, and Sustainability. Davis: University of California.
|