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Pere, M. C. (1995). Maternal and fetal blood levels of glucose, lactate, fructose, and insulin in the conscious pig. J. Anim Sci., 73(10), 2994–2999.
Abstract: To study nutrition and metabolism in the fetal pig, a chronic catheterization method was developed that allows blood sampling in arteries and veins, at both the umbilical and uterine sources, in the conscious, unstressed animal. A catheter was inserted in the fetal aorta through a femoral artery, and another one was introduced in the umbilical vein. A catheter was put in a femoral artery of the sow so that its end was in the abdominal aorta. A fourth catheter was placed in a uterine vein draining the fetoplacental unit studied. This procedure was applied to 18 Large White primiparous sows at 99 d of gestation. Blood samples were drawn simultaneously using the four catheters before a meal at 103 d of pregnancy, and glucose, insulin, lactate, and fructose were determinated. Glycemia was 2.5 times higher in the sow than in the fetus. The extraction coefficient of glucose by the fetus amounted to 14% of the umbilical supply. The insulin level in the fetal pig was very low ( < 5 microU/mL). Lactate and fructose seemed to originate from the placenta. Blood lactate was 2.6 times lower in the sow than in the fetus, and its extraction coefficient by the fetus amounted to 8%. Fructose in the fetal blood was 2.3 times higher than that of glucose. Fructose was not utilized by the pig fetus. The present results obtained in the fetal pig are comparable to the conclusions drawn from studies with other species.
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Allen, C. (1998). Assessing animal cognition: ethological and philosophical perspectives. J. Anim Sci., 76(1), 42–47.
Abstract: Developments in the scientific and philosophical study of animal cognition and mentality are of great importance to animal scientists who face continued public scrutiny of the treatment of animals in research and agriculture. Because beliefs about animal minds, animal cognition, and animal consciousness underlie many people's views about the ethical treatment of nonhuman animals, it has become increasingly difficult for animal scientists to avoid these issues. Animal scientists may learn from ethologists who study animal cognition and mentality from an evolutionary and comparative perspective and who are at the forefront of the development of naturalistic and laboratory techniques of observation and experimentation that are capable of revealing the cognitive and mental properties of nonhuman animals. Despite growing acceptance of the ethological study of animal cognition, there are critics who dispute the scientific validity of the field, especially when the topic is animal consciousness. Here, a proper understanding of developments in the philosophy of mind and the philosophy of science can help to place cognitive studies on a firm methodological and philosophical foundation. Ultimately, this is an interdisciplinary task, involving scientists and philosophers. Animal scientists are well-positioned to contribute to the study of animal cognition because they typically have access to a large pool of potential research subjects whose habitats are more controlled than in most field studies while being more natural than most laboratory psychology experiments. Despite some formidable questions remaining for analysis, the prospects for progress in assessing animal cognition are bright.
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Kimura, R. (2001). Volatile substances in feces, urine and urine-marked feces of feral horses. Can. J. Anim. Sci., 81(3), 411–420.
Abstract: The identity and amount of volatile substances in the feces, urine and feces scent-marked with urine (i.e., feces mixed with urine) of feral horses was determined by acid/steam distillation and gas chromatography-mass spectrometry. The frequency of excretion and scent marking, as evaluated in the breeding and non-breeding seasons, showed clear evidence of seasonal behavioral differences. The concentration of each substance (fatty acids, alcohols, aldehydes, phenols, amines and alkanes) in the feces differed according to maturity, sex and stage in the reproductive process. They had a characteristic chemical fingerprint. Although the levels of tetradecanoic and hexadecanoic acids in the feces of estrous mares were significantly higher than the respective levels in the feces of non-estrous mares, in the case of scent-marked feces by stallions, the levels of them in the feces from estrous mares had decreased to levels similar to those in non-estrous mares. The concentration of these substances in mares were not significantly different. The presence of a high concentration of cresols in the urine of stallions in the breeding season suggests that one role of scent marking by stallions is masking the odor of the feces produced by mares.
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McCall, C. A. (1990). A Review of Learning Behavior in Horses and its Application in Horse Training. J. Anim Sci., 68(1), 75–81.
Abstract: A literature review of the equine learning research conducted in the past 20 yr revealed that the purpose of most of the studies was to determine whether horses respond to learning situations in the same way that other animals do. The results indicated that horses can discriminate many different types of stimuli, and they learn through stimulus-response- reinforcement chains. Most equine learning studies have utilized learning tasks depending on primary positive reinforcement to get the horses to work the tests. Yet, the majority of horse trainers use negative reinforcement more often than primary positive reinforcement in their training procedures. Therefore, past research often did not have a direct application to training methods commonly utilized in the horse industry. Research also demonstrated that 1) early experiences of horses can affect learning ability later, 2) equine memory is efficient and 3) concentrating learning mals in long training sessions decreases equine learning efficiency. Many factors that might affect equine learning ability and be applicable to training practices in the horse industry have not been thoroughly investigated; for example, interactions between nutrition and learning and between exercise and learning, the use of negative and secondary reinforcements in horse training, and the horse's ability to make few initial errors compared to its ability to eliminate errors as training progresses all require investigation in future equine learning studies. N1 -
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Ralston, S. L. (1984). Controls of feeding in horses. J. Anim Sci., 59(5), 1354–1361.
Abstract: Members of the genus Equus are large, nonruminant herbivores. These animals utilize the products of both enzymatic digestion in the small intestine and bacterial fermentation (volatile fatty acids) in the cecum and large colon as sources of metabolizable energy. Equine animals rely primarily upon oropharyngeal and external stimuli to control the size and duration of an isolated meal. Meal frequency, however, is regulated by stimuli generated by the presence and (or) absorption of nutrients (sugars, fatty acids, protein) in both the large and small intestine plus metabolic cues reflecting body energy stores. The control of feeding in this species reflects its evolutionary development in an environment which selected for consumption of small, frequent meals of a variety of forages.
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Krzak, W. E., Gonyou, H. W., & Lawrence, L. M. (1991). Wood chewing by stabled horses: diurnal pattern and effects of exercise. J. Anim Sci., 69(3), 1053–1058.
Abstract: Nine yearling horses, stabled in individual stalls, were used in a trial to determine the diurnal pattern of wood chewing and the effects of exercise on this behavior. The trial was a Latin square design conducted over three 2-wk periods during which each horse was exposed to each of the three following treatments: 1) no exercise (NE), 2) exercise after the morning feeding (AM), and 3) exercise in the afternoon (PM). Horses were fed a complete pelleted feed in the morning and both pelleted feed and long-stemmed hay in the afternoon. Exercise consisted of 45 min on a mechanical walker followed by 45 min in a paddock with bare soil. Each stall was equipped with two untreated spruce boards during each period for wood chewing. Wood chewing was evaluated by videotaping each horse for 22 h during each period, determining the weight and volume of the boards before and after each period, and by visual appraisal of the boards. Intake of trace mineralized salt was also measured. Wood chewing occurred primarily between 2200 and 1200. All measures of wood chewing were correlated when totals for the entire 6 wk were analyzed. When analysis was performed on 2-wk values, videotape results were not correlated with volume or weight loss of boards. Horses chewed more when on the NE treatment (511 s/d) than when on AM or PM (57 and 136 s/d, respectively; P less than .05). Salt intake tended to be greater for NE than for the other treatments (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)
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Hall, C. A., Cassaday, H. J., & Derrington, A. M. (2003). The effect of stimulus height on visual discrimination in horses. J. Anim Sci., 81(7), 1715–1720.
Abstract: This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training.
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Mader, D. R., & Price, E. O. (1980). Discrimination learning in horses: effects of breed, age and social dominance. J. Anim Sci., 50(5), 962–965.
Abstract: The discrimination learning ability of Quarter Horses and Thoroughbreds was compared by means of visual cues in a three-choice test with food as a reward. Quarter Horses learned significantly faster than Thoroughbreds, and learning progressed more rapidly for both breeds in a second discrimination task. Significant negative correlations were observed between age and rate of learning. Quarter Horses tended to be less reactive than Thoroughbreds, but individual emotional reactivity ratings and learning scores were not correlated. No correlation was found between social dominance and learning scores. Learning studies with horses may provide a better understanding of the behavioral traits that influence trainability in this species.
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Craig, J. V. (1986). Measuring social behavior: social dominance. J. Anim Sci., 62(4), 1120–1129.
Abstract: Social dominance develops more slowly when young animals are kept in intact peer groups where they need not compete for resources. Learned generalizations may cause smaller and weaker animals to accept subordinate status readily when confronted with strangers that would be formidable opponents. Sexual hormones and sensitivity to them can influence the onset of aggression and status attained. After dominance orders are established, they tend to be stable in female groups but are less so in male groups. Psychological influences can affect dominance relationships when strangers meet and social alliances within groups may affect relative status of individuals. Whether status associated with agonistic behavior is correlated with control of space and scarce resources needs to be determined for each species and each kind of resource. When such correlations exists, competitive tests and agonistic behavior associated with gaining access to scarce resources can be useful to the observer in learning about dominance relationships rapidly. Examples are given to illustrate how estimates of social dominance can be readily attained and some strengths and weaknesses of the various methods.
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Houpt, K. A. (1991). Investigating equine ingestive, maternal, and sexual behavior in the field and in the laboratory. J. Anim Sci., 69(10), 4161–4166.
Abstract: Some of the techniques that may be used to study social, reproductive, and ingestive behavior in horses are described in this paper. One of the aspects of equine social behavior is the dominance hierarchy or patterns of agonistic behavior. Paired or group feeding from a single food source may be used to determine dominance hierarchies quickly. Focal animal studies of undisturbed groups of horses may also be used; this method takes longer, but may reveal affiliative as well as agonistic relationships among the horses. Reproductive behavior includes flehmen, the functional significance of which can be determined using combinations of field observations of harem groups and laboratory studies of stallions exposed to female urine or feces in the absence of the donor mare. Ingestive behavior may include food, salt, or water intake. Direct and indirect measurements of intake can be made and used to answer questions regarding the ability of horses to control their energy intake when the diet is diluted, the effect of feral equids on the ecology of an area, and the abilities of horses to compensate for dehydration and hypovolemia.
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