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K D Flossmann H Hauke P Heilmann J K?cher 《Archiv fuer experimentelle veterinaermedizin》1977,31(5):789-795
By means of two aerosol apparatures radioactive labelled Pasteurella-multocida-germs were given to calves via a respiratory mask. Labelling of Pasteurellae was done internal by using special nutritive media with Fe-59 or P-32. In a period of 10-25 minutes 5 X 10(9)-10(10) labelled bacteria were given to the animals for inhalation. Another animal group was injected intratrachealy with the same quantity of labelled germs. Immediately after termination of germ application the animals were killed and dissected. After solution or homogenization, respectively of the total lung tissue radioactivity was determined by liquid-scintillation-counting (Fe-59) or Cerenkov-measurement (P-32), respectively. The activities recovered from lung homogenates rendered is possible to calculate the received amount of bacteria. 40-80% of germs would be recovered in the lung after application by intratracheal injection while only 1-7% could be recovered after individual aerosol application lasting for 15-25 minutes. 相似文献
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H Pfützner H Hauke K Illing D Schimmel G Templin 《Archiv fuer experimentelle veterinaermedizin》1979,33(5):675-683
Strains of M. bovis, A. laidlawii, A. axanthum, and one unidentified strain of the family of mycoplasmataceae as well as altered secretion obtained from cows with mastitis were intracisternally applied in experiments and proved to be pathogenic to cattle udder. The results are likely to suggest the importance of mycoplasma isolated from the milk of mastitis cows to the aetiology of enzootic mastitis in three large dairy cattle stocks. Intravenous application of M. bovis and A. laidlawii caused neither mastitis nor mycoplasma secretion in the milk. 相似文献
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Di Jin Hauke Kite-Powell Porter Hoagland 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):369-387
ABSTRACT We develop a framework for risk assessment in open-ocean aquaculture. The framework consists of three components: a firm-level investment-production model simulates a specific grow-out project and estimates the project's benefit-cost values, a second model calculates the risk premium for a risk-averse investor, and a third model quantifies the option value for a risk-neutral investor. We show that under uncertainty, the traditional NPV rule for making an investment should be modified. We illustrate our models using a case study of open-ocean aquaculture of Atlantic cod (Gadus morhua) in New England. 相似文献
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Recent technological advances mean that samples from animal experiments may be analysed more cheaply, more easily and with a much greater return of data than previously. Research groups are frequently faced with a choice of continuing to use established technology in which they may have made a significant investment of time and resources, and have significant amounts of reference data, or switching to new technology where reference data may be limited. Apart from cost, the choice needs to be based on a comparison between the increase in data available from future experiments by switching and the value of comparison with reference data from historical experiments analysed with earlier technology. One approach to this problem is to ensure that sufficient quantity and variety of samples are taken from each experiment and appropriately stored to allow re-establishment of a sufficiently large reference set and to avoid the need to repeat animal experiments. The establishment of ‘biobanks' of experimental material will require funding for infrastructure, consistent storage of metadata and, importantly,horizon-scanning to ensure that samples are taken appropriately for techniques which will become accessible in future. Such biobanks are a recognised resource in human medicine, where the value of samples increases as more analysis is carried out and added to the metadata. 相似文献
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Ohne Zusammenfassung 相似文献
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The aim of this paper is to review the most relevant findings obtained over the last four years on the physiology, microbiology and immunology of the gastrointestinal tract of pigs as influenced by weaning and nutrition in the post-weaning period through the action of feed components or alternative substances to in-feed antibiotics. In recent years, some light has been shed on the physiology of the stomach, including motility, gastric emptying and acid secretion. This organ is important in the control of pathogen entry into the intestines. Recent studies on basic intestinal physiology around weaning have been scarce. Most investigations have been devoted to nutritional approaches on the effects of diet components (e.g. protein, fibre, etc.) and alternative substances (e.g. organic acids, zinc, prebiotics, probiotics, other substances of animal or plant origins) on pig performance and various aspects of gastrointestinal tract physiology, microbiology and immunology. Among these, beneficial effects of some organic acids have been confirmed. Additional data with zinc sources include possible mechanisms of protection. Overall it appears that manipulating carbohydrate (prebiotic) composition of the weaning diet may be the most promising way to improve gut health in weaned piglets. In that respect, consistent results have been obtained with lactose supplementation, and interactions with other feed constituents have been studied. Significant positive results have also been produced with probiotics (bacteria, yeasts) fed to the piglets or to the sows. The major parts of the responses appear to be mediated through changes in gastrointestinal microbiology, including enhanced numbers of favourable bacteria (lactobacilli, bifidobacteria) and/or decreased numbers of potentially pathogenic bacteria (Escherichia coli, Clostridia, etc.) together with more favourable profiles of fermentation products along the intestines. In contrast, measurable effects of these dietary factors on intestinal physiology and mucosal immunology have been limited or difficult to interpret in many cases. Finally, investigations have been conducted with varying diet composition (other than carbohydrates: protein source or level, amino acids, etc) or supplementing with different substances of animal or plant origin. However, positive effects on the gut have often been more variable and sometimes inconsistent. 相似文献
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