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Brinkmann, L., Gerken, M., & Riek, A. (2015). Energetic adaptations of Shetland pony mares. In Proceedings of the 3. International Equine Science Meeting.
Abstract: Recent results suggest that wild Northern herbivores exhibit signs of a hypometabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. However, there are speculations that domestic animals lost the ability to reduce energy expenditure. To examine energetic and behavioural responses 10 Shetland pony mares were exposed to different environmental conditions (summer and winter). During winter ponies were allocated into two groups receiving two different food quantities (60% and 100% of maintenance energy requirement). We measured the field metabolic rate, water turn over, body temperature, locomotor activity, lying time, resting heart rate, body mass and body condition score.
In summer, the field metabolic rate of all ponies (FMR; 63.4±15.0 MJ/day) was considerably higher compared with food restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ/day, respectively). Furthermore, during summer, locomotor activity, resting heart rate and total water turnover were significantly elevated (P<0.001) compared with winter. Animals receiving a reduced amount of food (N=5) reduced their FMR by 26% compared with control animals (N=5) to compensate for the decreased energy supply. Furthermore, resting heart rate, body mass and body condition score were lower(29.2±2.7 beats/min, 140±22 kg and 3.0±1.0 points, respectively) than in control animals (36.8±41 beats/min, 165±31 kg, 4.4±0.7 points; P<0.05). While no difference could be found in the observed behaviour, nocturnal hypothermia was elevated in restrictively fed animals. Our results indicate that ponies adapt to different climatic conditions by changing their metabolic rate, behaviour and some physiological parameters. When exposed to energy shortage, ponies, like wild herbivores, exhibited hypometabolism and nocturnal hypothermia. Keywords: Body temperature, Energy expenditure, Food restriction, Hypometabolism, Locomotor activity, Shetland pony |
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Brinkmann, L., Gerken, M., Hambly, C., Speakman, J. R., & Riek, A. (2014). Saving energy during hard times: Energetic adaptations of Shetland pony mares. J. Exp. Biol., 217, 4320–4327.
Abstract: Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperatures and food shortage in order to reduce their energetic needs. It is however not known if domesticated animals are also able to reduce their energy expenditure. We exposed ten Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60 and 100% of maintenance energy requirement, respectively) during low winter temperatures to examine energetic and behavioural responses. In summer ponies showed a considerably higher field metabolic rate (FMR) (63.4±15.0 MJ d-1) compared to restrictively fed and control animals in winter (24.6±7.8 MJ d-1 and 15.0±1.1 MJ d-1, respectively). During summer conditions locomotor activity, resting heart rates and total water turnover were considerably elevated (P<0.001) compared to winter. Restrictively fed animals (N=5) compensated for the decreased energy supply by reducing their FMR by 26% compared to control animals (N=5). Furthermore, resting heart rate, body mass and body condition score were lower (29.2±2.7 beats min-1; 140±22 kg; 3.0±1.0 points) than in control animals (36.8±41 beats min-1; 165 ±31 kg; 4.4±0.7 points; P<0.05). While the observed behaviour did not change, nocturnal hypothermia was elevated. We conclude that ponies acclimatize to different climatic conditions by changing their metabolic rate, behaviour and some physiological parameters. When exposed to energy challenges, ponies, like wild herbivores, exhibited hypometabolism and nocturnal hypothermia.
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Brinkmann, L., Gerken, M., & Riek, A. (2013). Effect of long-term feed restriction on the health status and welfare of a robust horse breed, the Shetland pony (Equus ferus caballus). Res. Vet. Sci., 94(3), 826–831.
Abstract: Outdoor group housing is increasingly recognized as an appropriate housing system for domesticated horses. The objective of this study was therefore to investigate the effect of potential feed shortage in semi-natural horse keeping systems in winter on animal health and welfare. In 10 female Shetland ponies blood concentrations (NEFA, total protein (TP), total bilirubin (TB), beta-hydroxybutyrate (BHB) and thyroxine (T4)), body mass and the body condition score (BCS) were monitored for 7months including a 4months period of feed restriction in five of the 10 ponies. Restrictively fed animals lost 18.4±2.99% of their body mass and the BCS decreased by 2.2±0.8 points (BCS scale: 0=emaciated, 5=obese). Feed restriction led to a continuous increase in TB (P<0.001) and NEFA (P<0.01) concentrations compared to control ponies. The TP and BHB values only differed at the end of the trial with lower concentrations in restricted fed mares (P<0.05). Feed restriction had no effect on thyroxine concentrations. TB concentrations in the feed restricted group were out of the reference range during the entire feeding trial. The increased NEFA concentrations in feed restricted compared to control ponies suggest that fat was mobilized. The BCS, as well as plasma NEFA and TB concentrations were good indicators for a rapid detection of possible health problems caused by undernourishment in horses when kept under semi-natural conditions. In contrast, blood parameters of the control animals were within the reference ranges, suggesting that a year round outdoor housing with additional feed supply is an adequate housing system for a robust horse breed like the Shetland pony.
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Gabor, V., & Gerken, M. (2015). Shetland ponies (Equus caballus) show quantity discrimination. In , & K. Krueger (Ed.), Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: The complex housing environment and the close contact between humans and horses in equine sports place high demands on the learning capacity of horses. To date only limited information is available on the learning ability of the horse including higher order cognition. A type of higher order cognition is to perceive and discriminate quantities. Several mammals and birds have shown to be capable of discriminating objects due to their quantity (Brannon and Roitman, 2003). With regard to horses, there are only few studies available concerning their numerosity judgment (Uller and Lewis, 2009) and this ability is discussed controversially (Henselek et al, 2012). Possibly, the legacy of ‘‘Clever Hans’’ overshadowed further research on numerical capacity in horses, a horse to whom several psychologists incorrectly attributed the capacity of symbolic calculation (Pfungst, 1907; Rosenthal, 1965). In the present study we wanted to show whether Shetland ponies are able to transfer a previously learned concept of sameness to a numerosity judgment. The base of the test design was a “matching to sample” task, where the ponies had learned to relate abstract symbols to another which were presented on a LCD screen. Three Shetland ponies, which previously solved the matching to sample task, were tested in two test phases. In the first test phase different quantities of dots were presented (1 vs. 2; 2 vs. 3; 3 vs. 4; 4 vs. 5). To exclude discrimination due to the shape of the stimuli, the dots were varied in size and arrangement. The stimuli were presented in a triangular arrangement on the LCD screen; the sample stimulus was presented in the middle above and the discrimination stimuli in the two lower corners (S+ and S-). The pony received a food reward, by choosing the positive stimulus (S+). When the negative stimulus (S-) was chosen, the pony entered the next trial. Each learning session consisted of 20 decision trials. To investigate whether the numerosity judgment was transferable to mixed geometrical symbols (tri-, rectangle, rhomb, dot and cross) a second test phase was designed. All of the three Shetland ponies met the learning criterion of the first test phase (80% correct responses in two consecutive sessions) within the first eight sessions. One pony could transfer all judgments to the mixed symbols (up to 4 vs. 5), another pony up to 3 vs. 5 and the third on the level 2 vs. 3. These are the first reported findings that ponies are able to discriminate up to five objects. The numerosity judgment seemed to be easier for the ponies when homogenous objects were presented, than in the case of heterogeneous symbols. The reaction of the ponies occurred within few seconds, suggesting that the animals used subitizing for their numerosity judgment.
Keywords: Cognition, numerical capacity, numerosity judgment, Shetland ponys References: Brannon E, Roitman J (2003) Nonverbal representations of time and number in animals and human infants. In: Meck WH (ed) Functional and neural mechanisms of interval timing. CRC Press, Boca Raton, pp 143–182 Henselek Y, Fischer J, Schloegl C (2012) Does the stimulus type influence horses’ performance in a quantity discrimination task? Front Psychol 3:504 Pfungst O (1907) Der Kluge Hans. Ein Beitrag zur nicht-verbalen Kommunikation. 3rd edn. (reprint of the original 1983) Frankfurter Fachbuchhandlung für Psychologie, Frankfurt Rosenthal R (1965) Clever Hans: the horse of Mr. Von Osten. Holt, Rinehart and Winston, New York Uller C, Lewis J (2009) Horses (Equus caballus) select the greater of two quantities in small numerical sets. Anim Cogn 12:733–738 |
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Gabor, V., & Gerken, M. (2014). Shetland ponies (Equus caballus) show quantity discrimination in a matching-to-sample design. Anim. Cogn., 17(6), 1233–1243.
Abstract: Numerical competence is one of the aspects of animal cognition with a long history of research interest, but few results are available for the horse. In the present study, we investigated the ability of three Shetland ponies to discriminate between different quantities of geometric symbols presented on a computer screen in a matching-to-sample arrangement. In Experiment 1, the ponies had to relate two similar quantities to another, paired in contrasts (1 vs. 2, 3 vs. 4 and 4 vs. 5) of the same stimulus (dot). Specific pairs of quantities (all differing by one) of up to five different geometrical symbols were displayed in Experiment 2. In each session, both quantities (more and less) were used as sample in such a way that each of the two quantities presented in one test served as positive and as negative stimulus, respectively. The three Shetland ponies were able to discriminate between the given quantities of dots by showing more than 80 % correct responses in two consecutive sessions. Only one of the ponies distinguished different shapes of geometric symbols at a level of 4 versus 5 items. The results show that all ponies were capable of visual quantity discrimination in the present matching-to-sample design, but task solving seemed more difficult when quantities were composed of heterogeneous stimuli. The present results confirm our hypothesis that the ponies based their decision on the matching concept of sameness and were not biased by a spontaneous preference for higher quantities.
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Gabor, V., & Gerken, M. (2012). Cognitive testing in Shetland ponies (Equus caballus) using a computer based learning device. In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Complex housing environments such as group housing with automatic feeding or the close contact to humans in sports make high demands on the learning ability of the horse. These learning processes include not only habituation, sensitization and simpler forms of operant conditioning, but also stimulus generalization and possibly some type of concept learning. Studies concerning cognitive abilities in the horse increased in the last decades, but for optimizing housing conditions and horse training, deeper insight into the learning behaviour of this species is necessary. In the present study we used the advantages of a computer based learning device to train 7 Shetland ponies to solve a matching to sample task. With this more complex type of a discrimination task, animals are trained to recognize two out of three presented stimuli as identical. In a first step animals learned to operate the learning device and in further learning steps to recognize and assign geometric symbols (dot, cross, square, and triangle) presented on a LCD screen that were ‘equal’. Four of the 7 ponies could solve the given task by performing over 80% correct responses in two consecutive sessions (p < 0.001). In the subsequent transfer test with new symbols, we found that the ponies were able to transfer the learned rule. In further experiments it should be clarified whether the good learning performance of the ponies in the present study is indeed based on their capability to form an abstract concept of sameness. The present results indicate that ponies possibly posses higher cognitive abilities than so far known.
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Gabor, V., & Gerken, M. (2010). Horses use procedural learning rather than conceptual learning to solve matching to sample. Appl. Anim. Behav. Sci., 126(3-4), 119–124.
Abstract: Research into higher cognitive abilities of the horse may be limited by developing the adequate experimental design. In this study four pony mares between 8 and 19 years old were included. Three of them reached the criterion to be tested in a new design of matching to sample using a black circle and a cross as visual cues attached to an apparatus. The attention was directed to the question of whether the animals are able to concept formation in a given time period or if their decisions depend on other cues or strategies. After familiarization to the testing area and the test procedure, the animals were given 27 sessions of 20 trials each during 14 weeks. While there was no preference for one of the stimuli used, horses showed a significant left sidedness. None of the mares reached the learning criterion of 80% correct answers in one session. However, the ponies showed procedural learning based on correction runs that were given between incorrect decisions, by then selecting the correct stimulus on the other side of the apparatus. This learning type arose in three individuals in session four, six and eleven, respectively. It is concluded that discrimination tasks may be biased by the involvement of unexpected learning strategies, which complicates the interpretation of such tests and may even mask possible conceptualization capabilities.
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