|
|
Steelman, S. M., Michael-Eller, E. M., Gibbs, P. G., & Potter, G. D. (2006). Meal size and feeding frequency influence serum leptin concentration in yearling horses. J. Anim Sci., 84(9), 2391–2398.
Abstract: Energy is an essential nutrient for all horses, and it is especially important in performance horses, pregnant and lactating mares, and young growing horses. A negative energy balance in horses such as these may result in unsatisfactory performance, decreased fertility, or slow growth. Therefore, ensuring adequate energy intake is an important aspect of the nutritional management of the equine. This study was undertaken to investigate the effects of feeding large, carbohydrate-rich, concentrate meals on the satiety-inducing hormone, leptin. Three groups of yearling horses were rotated through 3 feeding schedules in a replicated 3x3 Latin square design. Horses were fed 2, 3, or 4 times per day (2x, 3x, and 4xfeeding schedules, respectively), each for a period of 11 d, with the total amount of daily feed held constant. Horses were weighed and BCS was determined on the first day of each period. Blood samples were collected before the morning meal on d 1, 4, and 7 of each period. Additionally, blood was sampled for the last 24 h of the 2xand 4xdietary periods. Neither weight nor BCS changed during the study (P = 0.99 and P = 0.28, respectively). Both mean and peak plasma glucose were greatest in 2xhorses (P < 0.05), as were mean areas under the curve. Serum leptin concentration increased in 2xhorses (P < 0.05), but not in horses fed 3 or 4 times daily. Leptin was elevated in horses with greater BCS (P < 0.05) and increased steadily throughout the study (P < 0.05). Data from the 24-h collection indicated that 2xhorses had fluctuations in leptin production throughout the day (P < 0.05), whereas horses fed 4 times daily did not. Overall, this study indicates that feeding horses 2 large concentrate meals daily can increase mean serum leptin concentrations and may cause fluctuations in leptin production over a 24-h period. This departure from baseline leptin concentration has the potential to affect appetite, along with numerous other physiological processes.
|
|
|
|
McGreevy, P. D. (2006). The advent of equitation science. Vet J, 174(3), 492–500.
Abstract: The lengthy association of humans with horses has established traditional equestrian techniques that have served military and transport needs well. Although effective, these techniques have by-passed the research findings of modern psychologists, who developed the fundamentals of learning theory. That said, the pools of equestrian debate are far from stagnant. The latest wave of horse whisperers has offered some refinements and some novel interpretations of the motivation of horses undergoing training. Additionally, the Federation Equestre Internationale (FEI) has introduced the concept of the 'happy equine athlete' and, in the light of the hyperflexion (Rollkur) debate, recently examined the possible effects of some novel dressage modalities on equine 'happiness'. However, many still question the welfare of the ridden horse since it is largely trained using negative reinforcement, has to respond to pressure-based signals and is seldom asked to work for positive rewards. Science holds tremendous promise for removing emotiveness from the horse-riding welfare debate by establishing how much rein tension is too much; how much contact is neutral; how contact can be measured; how discomfort can be measured; how pain can be measured; and how learned helplessness manifests in horses. These are some of the topics addressed by equitation science, an emerging discipline that combines learning theory, physics and ethology to examine the salience and efficacy of horse-training techniques.
|
|
|
|
Tomasello, M., & Call, J. (2006). Do chimpanzees know what others see ? or only what they are looking at? In M. Nudds, & S. Hurley (Eds.), Rational Animals? (pp. 371–384). Oxford: Oxford University Press.
|
|
|
|
Kuntz, R., Kubalek, C., Ruf, T., Tataruch, F., & Arnold, W. (2006). Seasonal adjustment of energy budget in a large wild mammal, the Przewalski horse (Equus ferus przewalskii) I. Energy intake. J Exp Biol, 209(22), 4557–4565.
Abstract: Large ruminants respond to changing plant phenology during winter by decreasing voluntary food intake, increasing gut passage time and utilizing body fat reserves. It is uncertain, however, how other large mammals with a non-ruminant digestive physiology cope with winter forage conditions. Therefore, we investigated seasonality of energy intake in a large herbivorous wild mammal, the Przewalski horse (Equus ferus przewalskii). Throughout all seasons we used the n-alkane method to measure daily dry matter intake (DMI), diet composition and digestion, and determined an index of gut passage time in horses living under close to natural conditions. DMI correlated positively with its content of crude protein and nitrogen-free extract. Independent of these effects, DMI further varied seasonally with a peak in autumn and a nadir in late winter. Fluctuations of DMI corresponded to the annual change in body condition, which decreased during winter while energy reserves were depleted, and increased during the fattening period. Gut passage time varied in the course of the year and was longer during winter when the diet was high in crude fibre. Nevertheless, changes in gut passage time occurred rather independently of changes in forage composition and DMI, suggesting endogenous control for timely adaption of the digestive strategy to meet predictable changes in forage quality.
|
|
|
|
McElreath, R., & Strimling, P. (2006). How noisy information and individual asymmetries can make `personality' an adaptation: a simple model. Anim. Behav., 72(5), 1135–1139.
Abstract: Recent attention has been drawn to the existence of individual differences in correlated behaviour across contexts, animal `personality' (Gosling 2001, Psychological Bulletin, 127, 45-86) and behavioural syndromes (Sih et al. 2004b, Quarterly Review of Biology, 79, 241-277). The causes of these patterns of behaviour are subjects of debate. Here, we present a very simple model of how adaptively managing noisy information, combined with differences in individual state, can lead to evolutionarily stable differences in how individuals respond to environmental cues. When information is very noisy, behavioural syndromes are most likely, but as long as there is some error, some types of individuals display the same behaviour in all contexts. In extreme cases, very few individuals display flexible behaviour, and different stable behavioural types dominate the population.
|
|
|
|
Rosell, F., & Sanda, J. I. (2006). Potential risks of olfactory signaling: the effect of predators on scent marking by beavers. Behav. Ecol., 17(6), 897–904.
Abstract: Mammals scent mark their territories to advertise occupancy and ownership. However, signaling with scent for territorial defense can have a negative effect by advertising an individual's presence and location to predators. In this study, we measured responses to a simulated territorial intrusion by conspecific adult male Eurasian beavers (Castor fiber) either in the localized presence or in the absence of odor of a predator to test the hypothesis that the territorial defense of free-living beavers would be disrupted by the presence of predation risk in their natural environment. We predicted that beavers would significantly reduce their willingness to countermark intruder's scent in the presence of the scent of predators (wolf [Canis lupus] and lynx [Lynx lynx]), compared with a control (no odor), as responses are in general stronger to predator scent marks than nonpredator scent. Therefore, we also predicted that the effects of nonpredatory mammal scent (neophobic control) (eland [Taurotragus oryx] and horse [Equus cabalus]) are to be expected somewhere in between the effects of the predator odor and a control. Our results suggest that both predator and nonpredator scents reduce beavers response to a simulated intruder's scent mounds and therefore disrupt their territorial defense. However, predator scent had a stronger effect than nonpredator scent. Beavers may therefore be at great risk on territories with predators present because of the trade-off between predator avoidance and territorial defense. Our study demonstrates the potential of predation risk as a powerful agent of counterselection on olfactory signaling behavior.
|
|
|
|
Karl von, P. (2006). Irrwege der modernen Dressur. Die Suche nach der “klassischen” Alternative. Brunsbek: 978-3861274131.
Abstract: Philippe Karl, einer der mutigsten Kritiker einer Dressurwelt, deren Ausbildungsmethoden einzige darauf abzielen, ein Pferd möglichst schnell in mit hohen Preisgeldern dotierten Prüfungen an den Start zu bringen, legt mit diesem Buch den Finger in die Wunde.
Auf der Grundlage der psychischen, anatomischen und physiologischen Voraussetzungen des Pferdes analysiert der Autor die Grundsätze der modernen Dressur, wie sie in den Richtlinien der Deutschen Reiterlichen Vereinigung festgeschrieben sind.
|
|
|
|
Ligout, S., & Porter, R. - H. (2006). Social recognition in mammals: Mechanisms and sensorial bases. Prod. Anim., 19(2), 119–133.
Abstract: Social recognition plays a major role in the mediation of interactions between individuals and the organisation of societies. During the last 20 years, numerous studies have investigated the adaptive significance, underlying mechanisms and sensory basis of individual recognition of kin as well as non-kin. The results indicate that the recognition of conspecifics involves complex, flexible processes that are widespread throughout the vertebrate kingdom. Such recognition can be based upon different mechanisms and sensory modalities, and influenced by diverse factors. Learned phenotypic traits of conspecifics through familiarisation, including oneself, is the fundamental mechanism implicated in recognition. Animals become directly familiar with others with which they interact. Moreover, kin of familiar conspecifics may be discriminated because of their resemblance to the known individuals. An animal's genotype and environmental variables may both contribute to its recognisable individual signatures (e.g. distinctive olfactory, visual, or auditory characteristics). In general, the study of social recognition enhances our understanding of the cognitive world of animals.
|
|
|
|
Ferrari, M. C. O., Capitania-Kwok, T., & Chivers, D. P. (2006). The role of learning in the acquisition of threat-sensitive responses to predator odours. Behav. Ecol. Sociobiol., 60(4), 522–527.
Abstract: The supposition that prey animals respond to a predator with an intensity that matches the risk posed by the predator is known as the threat-sensitive predator avoidance hypothesis. Many studies have provided support for this hypothesis; yet, few studies have attempted to determine how such abilities are acquired by prey species. In this study, we investigated whether fathead minnows (Pimephales promelas) could learn to recognize an unknown predator (northern pike, Esox lucius) in such a way that they could match the intensity of their antipredator response with the threat posed by the predator. We exposed pike-naive minnows to conspecific alarm cues paired with either a high or low concentration of pike odor. The following day, both groups were tested for a response to either high or low concentration of pike odor alone. We found that minnows conditioned with alarm cues paired with a given concentration of pike odor subsequently responded with a higher intensity to higher concentrations of pike odor, and with a lower intensity to lower concentrations of pike odor. These results demonstrate that during a single conditioning trial, minnows learn the identity of the predator in a threat-sensitive manner. Minnows use predator odor concentrations that they experience in subsequent interactions to adjust the intensity of their antipredator behavior. © Springer-Verlag 2006.
|
|
|
|
Grinder, M. I., Krausman, P. R., & Hoffmann, R. S. (2006). Equus asinus. Mammalian Species, 794(1), 1–9.
|
|
