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1.
During the first half of the century, the majority of anthrax outbreaks in Canada occurred in the southern portions of Ontario and Quebec and were often associated with pastures contaminated by effluent from textile industries dealing with imported animal materials. In 1952, introduction of Federal regulations requiring disinfection of these materials greatly reduced the incidence of anthrax in eastern Canada. Since 1962, domestic outbreaks of the disease have been reported almost exclusively in cattle in the western prairie provinces. Between 1962 & 1993, nine anthrax epizootics have been recorded in the bison herds of the Northwest Territories and northern Alberta resulting in the deaths of at least 1309 animals. During the northern epizootics there has been a strong sex bias in mortalities with the majority of carcasses being sexually mature bulls. The northern epizootics occur during drought conditions in the late summer, preceded by a wet spring, and end with the arrival of coolers weather. It has been hypothesized that stress factors associated with these meteorological conditions coupled with breeding stress during the late summer rut may predispose the bulls to infection. Alternatively, the meteorological conditions may work to concentrate anthrax spores in the environment into low lying wallows preferentially utilized by the bulls. Recent genetic analyses of Bacillus anthracis isolates from Canada and the United States have identified that, while closely related to isolates from domestic outbreaks, isolates from northern bison epizootics form their own distinct strain. This suggests that the establishment of anthrax in northern Canada was a singular event that occurred prior to the first recognized epizootic in 1962. A review of the agricultural history of northern Canada has identified several situations in the first half of the century which may have provided the opportunity for the transfer of anthrax from cattle to the indigenous bison.  相似文献   

2.
1. Experiments are described which measure the sensitivity of animals exposed to continued illumination to which they have become adapted. It is shown that the amount of outside light energy necessary to stimulate an adapted animal increases with the intensity of the adapting illumination. 2. The data are analyzed quantitatively in terms of the reversible reaction S ⇌ P + A shown previously to account for the photic sensitivity of these animals. This analysis demonstrates that, though the amount of incident energy necessary for a minimal response varies with the adapting intensity, the actual amount of photochemical decomposition required to set off the sensory mechanism is a constant quantity. 3. The ability of these animals to come into sensory equilibrium with any sustained illumination is accounted for quantitatively by the presence of a stationary state in the reversible photochemical reaction S ⇌ P + A during which the concentrations of the three components are constant. 4. It is shown that the concentrations of these substances at the stationary state are automatically controlled by the outside intensity. Therefore, given the sensory mechanism as a basis, the adaptation of the animals to light and the consequent changes in sensitivity, are determined entirely by the light to which the animals are exposed. 5. Because of the properties of the stationary state, and of the constancy of photochemical decomposition for a minimal effect, it is suggested that the sensory system is not only the traditional receptor system, but is also a protecting layer which stabilizes and buffers the relation between the nervous system and the environment.  相似文献   

3.
Robustness in farm animals was defined by Knap as 'the ability to combine a high production potential with resilience to stressors, allowing for unproblematic expression of a high production potential in a wide variety of environmental conditions'. The importance of robustness-related traits in breeding objectives is progressively increasing towards the production of animals with a high production level in a wide range of climatic conditions and production systems, together with a high level of animal welfare. Current strategies to increase robustness include selection for 'functional traits', such as skeletal and cardiovascular integrity, disease resistance and mortality in various stages. It is also possible to use global evaluation of sensitivity to the environment (e.g. reaction norm analysis or canalization), but these techniques are difficult to implement in practice. The hypothalamic-pituitary-adrenocortical (HPA) axis is the most important stress-responsive neuroendocrine system. Cortisol (or corticosterone) released by the adrenal cortices exerts a large range of effects on metabolism, the immune system, inflammatory processes and brain function, for example. Large individual variations have been described in the HPA axis activity with important physiopathological consequences. In terms of animal production, higher cortisol levels have negative effects on growth rate and feed efficiency and increase the fat/lean ratio of carcasses. On the contrary, cortisol has positive effects on traits related to robustness and adaptation. For instance, newborn survival was shown to be directly related to plasma cortisol levels at birth, resistance to bacteria and parasites are increased in animals selected for a higher HPA axis response to stress, and tolerance to heat stress is better in those animals that are able to mount a strong stress response. Intense selection for lean tissue growth during the last decades has concomitantly reduced cortisol production, which may be responsible for the negative effects of selection on piglet survival. One strategy to improve robustness is to select animals with higher HPA axis activity. Several sources of genetic polymorphism have been described in the HPA axis. Hormone production by the adrenal cortices under stimulation by adrenocorticotropin hormone is a major source of individual differences. Several candidate genes have been identified by genomic studies and are currently under investigation. Bioavailability of hormones as well as receptor and post-receptor mechanisms are also subject to individual variation. Integration of these different sources of genetic variability will allow the development of a model for marker-assisted selection to improve animal robustness without negative side effects on production traits.  相似文献   

4.
2012年巫山蓝家寨遗址考古发掘中,出土了春秋时期的马(Equus caballus)、黄牛(Bos taurus)、山羊(Capra hircus)、鸡(Gallus gallus domesticus)、狗(Canis familiaris)、猪(Sus domestica)6种家畜的骨骼。这是三峡地区唯一一个在先秦时期六畜兼备的古文化遗址。遗址中的马、牛,是三峡地区同类家畜中时代最早的发现资料。三峡地区早期历史时期,人类肉食资源以野生动物为主,家畜动物骨骼发现材料较少。蓝家寨遗址出现种类较多的家畜动物种类,为全面分析和认识三峡地区经济形态发展过程、古居民行为模式和区域文化等,提供了重要资料。遗址中在春秋时期出现的家畜马和黄牛,与该时期各种区域文化在三峡地区的碰撞、交流、融合有关。  相似文献   

5.
Quantifying energy dissipation by grazing animals in harsh environments   总被引:1,自引:0,他引:1  
Grazing systems in harsh environments are common throughout the world, and animal production is the mainstay of the livelihoods of many resource-poor farmers. The energy cost of the various activities involved in the process of harvesting the pasture to transform it into animal product can be estimated through an energy balance. This cost would be the difference between the metabolizable energy intake (MEI) and the energy expenditures for maintenance (MEm), temperature regulation (MEtr), and the energy for production (MEp). Each of the ME has its own net energy (NE) and its associated efficiency (K). When MEI>MEm+MEtr+MEp, the difference is attributable to the energy dissipated during grazing. The efficiency of converting the energy consumed into animal products depends on the magnitude of the dissipation. The inefficiency is associated with the energy spent in locomotion and the stress produced when there is low availability of energy in the pasture. This paper presents a method to quantify the dissipation of energy by grazing animals by considering it as a function of available energy. Such an understanding is required in order to develop management strategies to increase conversion efficiency.  相似文献   

6.
Biotelemetry: a mechanistic approach to ecology   总被引:1,自引:0,他引:1  
Remote measurement of the physiology, behaviour and energetic status of free-living animals is made possible by a variety of techniques that we refer to collectively as 'biotelemetry'. This set of tools ranges from transmitters that send their signals to receivers up to a few kilometers away to those that send data to orbiting satellites and, more frequently, to devices that log data. They enable researchers to document, for long uninterrupted periods, how undisturbed organisms interact with each other and their environment in real time. In spite of advances enabling the monitoring of many physiological and behavioural variables across a range of taxa of various sizes, these devices have yet to be embraced widely by the ecological community. Our review suggests that this technology has immense potential for research in basic and applied animal ecology. Efforts to incorporate biotelemetry into broader ecological research programs should yield novel information that has been challenging to collect historically from free-ranging animals in their natural environments. Examples of research that would benefit from biotelemetry include the assessment of animal responses to different anthropogenic perturbations and the development of life-time energy budgets.  相似文献   

7.
The structures of animal skeletons converge repeatedly on a limited number of architectural designs that can be constructed by growing organisms and that are functionally viable, although often not optimal. Properties of materials, construction rules that determine patterns of development, and physical constraints exerted by the requirements of function suggest that organic structure must necessarily approach these recurrent elements of design. A set of potential designs for the elements of animal skeletons is derived in terms of geometric and construction rules and the properties of materials. Skeletons of actual living and extinct organisms are matched with the possibilities defined within this theoretical morphospace. This provides a metric of skeletal complexity and of the extent to which various groups of animals have been able to exploit the range of possibilities of organic structure. These analyses show that the most evolutionarily advanced animals within a given phylum do not have the most complex skeletons; that arthropods are less morphologically diverse than vertebrates and molluscs; that the physical constraints of life on land and in the air substantially limit the variety of skeletal structures suitable for life in these environments; and that overall the range of possible skeletal designs has been very fully exploited by living and extinct organisms. These results strongly support the hypothesis that the essential elements of organic design are inherent in the material properties of the universe. The organizational properties of animal skeletons suggest that their design elements are fixed point attractors, structures that we characterize as topological attractors that evolution cannot avoid.  相似文献   

8.
Brazil has various species of domestic animals, which developed from breeds brought by the Portuguese settlers soon after their discovery. For five centuries, these breeds have been subjected to natural selection in specific environments. Today, they present characteristics adapted to the specific Brazilian environmental conditions. These breeds developed in Brazil are known as "Crioulo," "local," or naturalized. From the beginning of the 20th century, some exotic breeds, selected in temperate regions, have begun to be imported. Although more productive, these breeds do not have adaptive traits, such as resistance to disease and parasites found in breeds considered to be "native." Even so, little by little, they replaced the native breeds, to such an extent that the latter are in danger of extinction. In 1983, to avoid the loss of this important genetic material, the National Research Center for Genetic Resources and Biotechnology (Cenargen) of the Brazilian Agricultural Research Corporation (Embrapa) decided to include conservation of animal genetic resources in its research program Conservation and Utilization of Genetic Resources. Until this time, they were only concerned with conservation of native plants. Conservation has been carried out by various research centers of Embrapa, universities, state research corporations, and private farmers, with a single coordinator at the national level, Cenargen. Specifically, conservation is being carried out by conservation nuclei, which are specific herds in which the animals are being conserved, situated in the habitats where the animals have been subjected to natural selection. This involves storage of semen and embryos from cattle, horses, buffaloes, donkeys, goats, sheep, and pigs. The Brazilian Animal Germplasm Bank is kept at Cenargen, which is responsible for the storage of semen and embryos of various breeds of domestic animals threatened with extinction, where almost 45,000 doses of semen and more than 200 embryos exist presently. An important challenge for this program is to make the different segments of society realize the importance of the conservation of animal genetic resources.  相似文献   

9.
10.
Selenium (Se) is required at a fundamental physiological level in all animals. Adequate levels of Se are necessary for proper bone metabolism, iodine metabolism, immune function, reproductive success, and recruitment. Selenium is a component of enzymes which scavenge oxidative free radicals that would otherwise degrade cell membranes. Severe deficiency results in obvious symptoms such as white muscle disease in ungulates. However, more frequently, deficiency may be chronic and subclinical. Individuals then display no obvious signs of malady, yet performance suffers until their populations decline without apparent cause or through proximate factors which obscure underlying primary factors. Although well known in domestic stock, the link between population performance and Se deficiency in wild populations has been difficult to firmly establish. Confounding factors include the role of vitamin E, which also acts as an antioxidant to mitigate the need for Se under some circumstances; changing Se requirements at changing times in animal life history; changing Se requirements in relation to pollution levels and other factors causing oxidative stress; and the non-uniform distribution of Se in its various chemical forms in the environment. The latter point is especially important to wild populations that have been reduced to remnant portions of their previous range. Here, we have reviewed the literature of Se in wildlife as well as provided an introduction to Se in physiology and Se behavior in the environment for the wildlife researcher and manager. We conclude that unrecognized Se deficiency may often impede optimal population performance, and we provide recommendations for habitat analysis with regard to Se which can be used in future research. Finally, evidence that the amount of available Se in the environment is decreasing from anthropogenic causes is shown.  相似文献   

11.
The skills that mountain gorillas use to deal with the stings, tiny hooks, and spines protecting common plant leaves in their diet were examined for variation within and between animals. Many elements of uni- and bimanual performance were identified, often involving delicate precision and coordination, and varying idiosyncratically, erch individual having a different set of preferred elements. Many of these elements are functionally equivalent, and all but one weaned animals showed full processing capability; the history of the one exception suggests that early experience with the task may be important. Gorillas' idiosyncrasy in manual skill elements is entirely consistent with trial-and-error learning at this level. By contrast, each individual uses very few techniques (structured sequences of elements) for most processing, and these techniques are the same across the population. Where animals deviate from this generalization, they largely employ the simpler technique normally used for undefended leaves. Lateralization increases from start to finish, consistent with a logical structure in which each stage has a laterality bias and each stage is sequentially dependent on the last. Variations from their commonest, techniques occur in all animals (on average, about nine variant techniques were recorded from each animal). The repertoire of techniques increases significantly with age, whereas the repertoire of elements does not. This points to an initial reliance on a single logical structuring that is well established by weaning (about 3.5 years), with subsequent development of the ability to vary the technique used so as to take advantage of variations in the environment. Standardization of logical organization, despite variability between different animals in individual elements and behavioral laterality, suggests that the logical ordering of elements and the interrelationships of processing stages is copied by program-level imitation. © 1993 Wiley-Liss, Inc.  相似文献   

12.
The Taï region in Western Côte d`Ivoire is characterized by extensive overlap of human and animal habitats. This could influence patterns of adenovirus transmission between humans and domestic animals. Fecal samples from humans and various domestic animals were tested for the presence of adenoviruses by PCR. Phylogenetic and species delineation analyses were performed to further characterize the adenoviruses circulating in the region and to identify potential cross-species transmission events. Among domestic animals, adenovirus shedding was frequent (21.6% of domestic mammals and 41.5% of chickens) and the detected strains were highly diverse, several of them representing novel types. Although no evidence for zoonotic transmission of animal adenovirus was obtained, the present study provides concordant evidence in favor of common cross-species transmission of adenoviruses between different animal species and first indications for adenovirus transmission from humans to animals. These findings underline the thus far underestimated importance of reverse zoonotic transmission of viruses and of the role of domestic animals as pathogen reservoirs, “bridge species,” or intermediate hosts.  相似文献   

13.
This article provides details to consider when preparing to use animals in biomedical research. The stress of transport and receipt of animals into a new environment mandate the need for a period of stabilization and acclimation. This allotment of time often occurs in conjunction with the quarantine period and permits a stress "recovery" period. Discussions in the article include specific effects of the environment on the animal, such as housing and environmental enrichment. Suggestions are offered regarding how to minimize the effects of procedures and equipment through the use of preconditioning techniques. Guidelines for these techniques and for acclimation should be instituted by the institutional animal care and use committee. Stress and distress are placed in perspective as they relate to the preparation of laboratory animals for research.  相似文献   

14.
Metabolic and hormonal acclimation to heat stress in domesticated ruminants   总被引:4,自引:0,他引:4  
Environmentally induced periods of heat stress decrease productivity with devastating economic consequences to global animal agriculture. Heat stress can be defined as a physiological condition when the core body temperature of a given species exceeds its range specified for normal activity, which results from a total heat load (internal production and environment) exceeding the capacity for heat dissipation and this prompts physiological and behavioral responses to reduce the strain. The ability of ruminants to regulate body temperature is species- and breed-dependent. Dairy breeds are typically more sensitive to heat stress than meat breeds, and higher-producing animals are more susceptible to heat stress because they generate more metabolic heat. During heat stress, ruminants, like other homeothermic animals, increase avenues of heat loss and reduce heat production in an attempt to maintain euthermia. The immediate responses to heat load are increased respiration rates, decreased feed intake and increased water intake. Acclimatization is a process by which animals adapt to environmental conditions and engage behavioral, hormonal and metabolic changes that are characteristics of either acclimatory homeostasis or homeorhetic mechanisms used by the animals to survive in a new 'physiological state'. For example, alterations in the hormonal profile are mainly characterized by a decline and increase in anabolic and catabolic hormones, respectively. The response to heat load and the heat-induced change in homeorhetic modifiers alters post-absorptive energy, lipid and protein metabolism, impairs liver function, causes oxidative stress, jeopardizes the immune response and decreases reproductive performance. These physiological modifications alter nutrient partitioning and may prevent heat-stressed lactating cows from recruiting glucose-sparing mechanisms (despite the reduced nutrient intake). This might explain, in large part, why decreased feed intake only accounts for a minor portion of the reduced milk yield from environmentally induced hyperthermic cows. How these metabolic changes are initiated and regulated is not known. It also remains unclear how these changes differ between short-term v. long-term heat acclimation to impact animal productivity and well-being. A better understanding of the adaptations enlisted by ruminants during heat stress is necessary to enhance the likelihood of developing strategies to simultaneously improve heat tolerance and increase productivity.  相似文献   

15.
植物根源逆境信使及其产生和传输   总被引:4,自引:0,他引:4  
植物不仅仅是恶劣环境的被动受害者 ,而且它也具有对环境变化快速感知和主动适应的能力 ,逆境信息传递就是其适应不良环境的重要策略。本文主要介绍了环境胁迫下 ,调控植物地上部的根源信使、信使的产生和传输以及气孔运动对根源信使的响应机制等方面的研究进展。  相似文献   

16.
植物不仅仅是恶劣环境的被动受害者,而且它也具有对环境变化快速感知和主动适应的能力,逆境信息传递就是其适应不良环境的重要策略。本文主要介绍了环境胁迫下,调控植物地上部的根源信使、信使的产生和传输以及气孔运动对根源信使的响应机制等方面的研究进展。  相似文献   

17.
The paleontological as well as the archeological record in China is unique in that there is adequate evidence of hominid association with most of the animals that we know today as domesticates beginning at very early dates. During the last few years advances have been made with studies of the dog, horse, camel,water buffalo, cattle,yak,sheep, goat, pig, and chicken in China. One drawback is that by the time most domestic animals can be dated by recorded history they are quite advanced as domesticates and are quite similar osteologicaly to their modern counterparts.  相似文献   

18.
The scientific and practical importance of trace elements   总被引:2,自引:0,他引:2  
E. J. Underwood's discovery of the essentially of cobalt for ruminant animals is the classic example of the vast benefits to agricultural production of research into the nutritional significance of trace elements. The extension of this discovery, culminating in the identification of vitamin B12, resulted in similar benefits for human health, notably the conquest of pernicious anaemia. Since then, additional essential trace elements have been discovered. Deficiency or imbalance, whether occurring naturally or from human activities, has been shown to present significant problems for the health of man and animals. Essentiality has been proved for a rapidly growing range of 'new' trace elements, whose biochemical mechanisms of action and implications for human health are unknown. In spite of an increasing knowledge of significant changes in the exposure of man and animals to trace elements from diet and environment, the concern of nutrition policy planners for inorganic micro-nutrients remains overshadowed by that for the bulk components of the diet. The application of existing knowledge of trace element nutrition to problems of human and animal health will depend on a clear understanding of events that link molecular, biochemical mechanisms to the clinical manifestation of deficiencies.  相似文献   

19.
《Anthrozo?s》2013,26(1):45-59
ABSTRACT

Attitudes toward animals are influenced by both animal traits (e.g., similarity to humans, aesthetic quality, size) and individual human attributes (e.g., gender, age, educational level, cultural factors). Although the examination of children's interest in animals, and their preference for different species, may evidence specific trends and help explain the development of attitudes, the vast majority of research has not considered children younger than 6 years. The present study was aimed at assessing preferences for a variety of animal species in a sample of 3–6 year-old Italian children, using a forced-choice task and visual aids (images of the animals). Pictures of 48 animal species, ranging from mammals to invertebrates, were presented to the children. Two photographic stimuli were simultaneously displayed and participants were asked to indicate their preference. Results show that the children preferred higher-order species, and domestic over wild animals. Apart from a few exceptions, invertebrates were the most disliked group of species among the children. Girls showed more negative and fear-related attitudes than the boys. Results are discussed taking into account different factors that may affect children's preferences for various animal species, that is, similarity to humans and aesthetical appeal. Greater knowledge on early attitudes toward animals has implications for promoting interest in animals and for building educational interventions for kindergarten children. This is particularly important in light of the growing use of different animals in educational and therapeutic contexts, as well as from an animal welfare perspective.  相似文献   

20.
Western attitudes toward animals have undergone a gradual evolution during recent centuries, driven by the scientific recognition that humans and many other species share a common anatomical template, a common phylogenetic ancestry, and certain similarities in their social and emotional lives. This evolving view has been accompanied by a heightened popular respect for animals, which has caused increasing opposition to the relatively utilitarian treatment of animals in modern farming. Western culture also tends to venerate the pastoralist image of humans caring diligently for animals, and North Americans tend to venerate the agrarian life-style of farm families living in harmony with domestic animals and the land. These positive images, which have traditionally lent legitimacy to animal agriculture, have been diminished by changes in production methods during recent decades. The resulting debate between critics and defenders of modern animal production has led to widespread confusion and concern about how animal agriculture affects animal welfare, human health, the environment, and world food security. To resolve this situation will require research to create an accurate understanding of the diverse effects of modern animal agriculture, together with measures to harmonize agricultural practices with changing public values.  相似文献   

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