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Sol, D. (2003). Behavioural flexibility: a neglected issue in the ecological and evolutionary literature. In S. M. Reader and K. N. Laland (Ed.), Animal innovation. (pp. 63–82). Oxford: Oxford University Press.
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Lee, P. C. (2003). Innovation as a behavioural response to environmental challenges. In S. M. Reader and K. N. Laland (Ed.), Animal Innovation (pp. 261–279). Oxford: Oxford University Press.
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Laland, K. N., & van Bergen, Y. (2003). Experimental studies of innovation in the guppy. Animal Innovation, , 155–174.
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Greenberg, R. (2003). The role of neophobia and neophilia in the development of innovative behavour in birds. In S. M. Reader and K. N. Laland (Ed.), Animal Innovation. Oxford: Oxford University Press.
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Reader, S. M., & MacDonald, K. (2003). Environmental variability and primate behavioural flexibiity. In S. M. Reader, & K. L. Laland (Eds.), Animal Innovation (pp. 83–116). Oxford: Oxford University Press.
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Young, R. J. (2003). Environmental Enrichment for Captive Animals.
Abstract: Environmental enrichment is a simple and effective means of improving animal welfare in any species – companion, farm, laboratory and zoo. For many years, it has been a popular area of research, and has attracted the attention and concerns of animal keepers and carers, animal industry professionals, academics, students and pet owners all over the world.
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Haidn, B., & Berger, N. (2003). Arbeitszeitbedarf für die Pensionspferdehaltung in landwirt-schaftlichen Betrieben. Tagungsband 6, Vechta 25.-27. März 2003, Tagung: Bau, Technik und Umwelt in der landwirtsch, 386–391.
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Spadavecchia, C., Arendt-Nielsen, L., Andersen, O. K., Spadavecchia, L., Doherr, M., & Schatzmann, U. (2003). Comparison of nociceptive withdrawal reflexes and recruitment curves between the forelimbs and hind limbs in conscious horses. Am J Vet Res, 64(6), 700–707.
Abstract: OBJECTIVE: To compare nociceptive withdrawal reflexes (NWRs) evoked from the distal aspect of the left forelimb and hind limb in conscious standing horses and to investigate NWR recruitment for graded electrical stimulation intensities. ANIMALS: 20 adult horses. PROCEDURE: Surface electromyographic (EMG) activity evoked by transcutaneous electrical stimulation of the digital palmar (or plantar) nerve was recorded from the common digital extensor and cranial tibial muscles. Stimuli consisted of 25-millisecond train-of-5 constant current pulses. Current intensity was gradually increased until NWR threshold intensity was reached. The EMG signal was analyzed for quantification of the NWR. Behavioral responses accompanying the reflex were scored (scale, 0 to 5). The NWR recruitment curves were determined at 0.9, 1.1, 1.2, and 1.3 times the NWR threshold intensity. RESULTS: The NWR threshold was significantly higher for the hind limb (median value, 6.6 mA; range, 3 to 10 mA) than the forelimb (median, 3 mA; range, 1.7 to 5.5 mA). The NWR of the hind limb had a significantly longer latency (median, 122.8 milliseconds; range, 106 to 172 milliseconds), compared with the forelimb (median, 98 milliseconds; range, 86 to 137 milliseconds), and it was associated with significantly stronger behavioral reactions. Gradual increase of NWR amplitude was evident at increasing stimulation intensities and supported by the behavioral observations. CONCLUSIONS AND CLINICAL RELEVANCE: We documented NWRs evoked from the forelimb and hind limb and their recruitment with stimuli of increasing intensity in horses. These results provide a basis for use of NWRs in studies on nociceptive modulation in horses.
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Herholz, C. P., Gerber, V., Tschudi, P., Straub, R., Imhof, A., & Busato, A. (2003). Use of volumetric capnography to identify pulmonary dysfunction in horses with and without clinically apparent recurrent airway obstruction. Am J Vet Res, 64(3), 338–345.
Abstract: OBJECTIVE: To investigate whether volumetric capnography indices could be used to differentiate between horses without recurrent airway obstruction (RAO) and horses with RAO that were in clinical remission or that had clinically apparent RAO. ANIMALS: 70 adult Swiss Warmblood horses (20 used for pleasure riding and 50 used for dressage or show jumping). PROCEDURE: Horses were allocated to 4 groups on the basis of history, clinical signs, results of endoscopy, and cytologic findings (group 1, 21 healthy horses; group 2, 22 horses with RAO that were in remission; group 3, 16 horses with mild RAO; group 4, 11 horses with exacerbated RAO). Expiratory volume and CO2 curves were recorded by use of a computerized ultrasonic spirometer. Volumetric capnograms were plotted, and derived indices were calculated. RESULTS: Dead-space volume (VD) was calculated by use of the Bohr equation (VD(Bohr)) and for physiologic VD (VD(phys)). Ratios for VD(Bohr) to expiratory tidal volume (VT) and VD(phys) to V(T) as well as an index of effective CO2 elimination were significantly different among groups of horses. Age and use of the horses also significantly affected volumetric capnography indices. CONCLUSIONS AND CLINICAL RELEVANCE: Ratios of VD(Bohr) to VT and VD(phys) to VT as well as an index of effective CO2 elimination were sufficiently sensitive measures to distinguish between healthy horses and horses with RAO in remission. To optimize the ability of volumetric capnography indices to differentiate among horses in heterogeneous populations, it is important to account for effects of age and specific use of the horses.
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Dubois, F., & Giraldeau, L. - A. (2003). The forager's dilemma: food sharing and food defense as risk-sensitive foraging options. Am Nat, 162(6), 768–779.
Abstract: Although many variants of the hawk-dove game predict the frequency at which group foraging animals should compete aggressively, none of them can explain why a large number of group foraging animals share food clumps without any overt aggression. One reason for this shortcoming is that hawk-dove games typically consider only a single contest, while most group foraging situations involve opponents that interact repeatedly over discovered food clumps. The present iterated hawk-dove game predicts that in situations that are analogous to a prisoner's dilemma, animals should share the resources without aggression, provided that the number of simultaneously available food clumps is sufficiently large and the number of competitors is relatively small. However, given that the expected gain of an aggressive animal is more variable than the gain expected by nonaggressive individuals, the predicted effect of the number of food items in a clump-clump richness-depends on whether only the mean or both the mean and variability associated with payoffs are considered. More precisely, the deterministic game predicts that aggression should increase with clump richness, whereas the stochastic risk-sensitive game predicts that the frequency of encounters resulting in aggression should peak at intermediate clump richnesses or decrease with increasing clump richness if animals show sensitivity to the variance or coefficient of variation, respectively.
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