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Gao, X., & Gu, J. (1989). The distribution and status of the Equidae in China. Acta Theriol. Sin., 9(4), 269–274.
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Ginsberg, J. R.,. (1989). The ecology of female behaviour and male mating success in the Grevy's zebra. Symp zool Soc Lond, 61, 89–110.
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Hunter, L., & Houpt, K. A. (1989). Bedding material preferences of ponies. J Anim Sci, 67(8), 1986–1991.
Abstract: The bedding preferences of ponies were determined using video recordings of nighttime (1900 to 0700) behavior of individually housed ponies. The ponies' behavior each minute was recorded to determine time budgets. In Exp. I, preference for bedding was determined using three mares, three stallions and two geldings given access to bedded and unbedded areas in a box stall. The ponies spent more time (66%) on the bedded area and were never observed lying on the unbedded areas. In Exp. II, three mares and six stallions were given access to a box stall, one side of which was bedded with wood shavings and the other with straw. Although some individual animals preferred one bedding over the other, neither form of bedding was preferred consistently. Time budgets in Exp. II were similar on both bedding materials. The ponies spent 12% of their nighttime lying, 2% walking, 35% eating and 50% standing inactively. Some ponies had a relatively strong preference for bedding, but the type of bedding preferred varied with the individual animal. Some individual ponies had no clear preference, but instead had a side or position preference
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Izraely, H., Choshniak, I., Shkolnik, A., Stevens, C. E., & Demment, M. W. (1989). Factors determining the digestive efficiency of the domesticated donkey.(Equus Asinus Asinus ). Q J Exp Physiol, 74(1), 1–6.
Abstract: Factors determining the digestive efficiency of donkeys were studied in animals fed either a low quality roughage (wheat straw: 77{middle dot}1% neutral detergent fibre, 2{middle dot}8% crude protein) or a high quality forage (alfalfa hay: 47{middle dot}5% neutral detergent fibre, 22{middle dot}7% crude protein). The neutral detergent fibre (NDF) intake when fed wheat straw was 1693 {+/-} 268 g animal-1 day-1, 10% higher than when fed alfalfa hay. Digestive coefficient of NDF and acid detergent fibre (ADF) when fed wheat straw amounted to 50{middle dot}9 {+/-} 4{middle dot}9 and 42{middle dot}0 {+/-} 4{middle dot}1% respectively. NDF and ADF apparent digestibilities and mean retention times (37{middle dot}7 {+/-} 1{middle dot}7 and 36{middle dot}4 {+/-} 3{middle dot}2 h respectively) were not significantly different (P [rang] 0{middle dot}05) between the two diets. The donkey appears to digest cell wall constituents as efficiently as the Bedouin goat when on low quality roughage, but less efficiently when fed alfalfa hay. Its energy digestibility is, however, as high as that reported for the Bedouin goat. The donkey's high energy digestibility is related to its capacity to digest soluble food components more efficiently than the ruminant. The mean retention time in the donkey is shorter than in the Bedouin goat and is consistent with its capacity to compensate for a lower quality diet by increasing its intake rate. Recycling of urea in donkeys maintained on wheat straw amounted to 75{middle dot}5 {+/-} 13{middle dot}0% of the entry rate. A decrease in the rate of renal urea filtration, coupled with an increase in the fraction reabsorbed, increased the retention of nitrogenous waste and permitted recycling of nitrogen into the gut. N1 -
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Klingel, H. (1989). Odd-toed Ungulates, Horses. In B. Grzimek (Ed.), Grzimek's Encyclopedia of Mammals (Vol. 4, 550+pp. 557–594). McGraw Hill.
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Rau, R. E.,. (1989). The museum's Quagga project.
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Rubenstein, D. I. (1989). Life history and social organization in arid adapted ungulates. J. Arid. Environ., 17, 145–156.
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Daniels, T. J., & Bekoff, M. (1989). Feralization: The making of wild domestic animals. Behav. Process., 19(1-3), 79–94.
Abstract: The widely accepted viewpoint that feralization is the reverse of domestication requires that the feralization process be restricted to populations of animals and, therefore, cannot occur in individuals. An alternative, ontogenetic approach is presented in which feralization is defined as the process by which individual domestic animals either become desocialized from humans, or never become socialized, and thus behave as untamed, non-domestic animals. Feralization will vary among species and, intraspecifically, will depend upon an individual's age and history of socialization to humans. Because feralization is not equated with morphological change resulting from evolutionary processes, species formation is not an accurate indicator of feral condition.
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Crowell-Davis, S. L., & Caudle, A. B. (1989). Coprophagy by foals: recognition of maternal feces. Appl. Anim. Behav. Sci., 24(3), 267–272.
Abstract: Six foals were each observed for 4 h per week during the first 6 weeks of life in an experimental situation in which they had access to feces taken from their mother and from another mare which was not pregnant or lactating. The foals sniffed at the feces equally. Two foals engaged in a total of seven bouts of coprophagy. All bouts of coprophagy involved maternal feces (χ2; P<0.01).
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Rubenstein, D. I., & Hohmann, M. E. (1989). Parasites and Social Behavior of Island Feral Horses. Oikos, 3, 312–320.
Abstract: The horses of Shackelford Banks, North Carolina, USA, are heavily parasitized by intestinal worms and harassed by dipterans, and although both types influence behavior only internal parasites affect bodily condition and the structuring of horse society. Thirteen species of internal parasites were identified, but only 4 of 13 groups contain them all and even within groups differences among individuals are large. Among individuals ova emissions vary ranging from 50 to 76,875 eggs per gram. The most important environmental factors influencing egg production are season and a group's location on the island, presumably because of salinity and soil differences and their effects on ova survival. Of the social and life history factors, age, and group size, but neither reproductive state nor dominance status are important. The fitness consequences of internal parasitism may be large since the number emitted is negatively correlated with next year's bodily condition. Biting fly burdens are also affected by a variety of environmental factors. In general, horses are covered with more flies on sunny days, when winds are moderately brisk, when occupying dunes, and around mid-day. In contrast to endoparasites, fly burden is affected by reproductive condition and dominance status and tends to decrease as groups increase in size. Since groups do not grow very large, nor do females attempt to bring groups together, the negative effects of endoparasites appear to overide those associated with ectoparasites. Consequently, endoparasites appear to exert a stronger influence on social structure, even though ectoparasites seem to play a stronger role in shaping details of behavior.
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