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81.
Two female calves of the breed German Holsteins showing bilateral anophthalmia and deformations of the jaws such as brachygnathia superior and bilateral cleft of lips and noses, respectively, were born on two different farms. Similar congenital defects could be found neither in the relatives of the affected calves nor in other animals of the same herds. A monogenic autosomal recessive inheritance may have caused bilateral anophthalmia. Chromosomal aberrations could not be detected in the affected calves. The possible environmental causes such as infection by the BVD-virus or oversupply or deficiency of vitamin A are very unlikely. 相似文献
82.
In this case report about white muscle disease (WMD) in a Belgian Blue herd, the disease is described both as an individual and as a herd problem. Aetiology, diagnosis, and therapy of WMD are discussed. WMD is a disease of animals with muscle damage due to the presence of free radicals. Unsaturated fatty acids in the cell membrane are transformed into a radical form in a chain reaction: a fatty acid next to the fatty acid radical can be transformed into another free radical. In healthy animal the chain reaction is stopped by anti-oxidants such as vitamin E and glutathione peroxidase. WMD can occur when more free radicals are produced than the available anti-oxidants can deal with. The disease occurs in calves, lambs, and foals. 相似文献
83.
Van Winden SC Müller KE Kuiper R Noordhuizen JP 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2002,49(3):157-160
The pH value of the abomasal contents in adult cattle is normally constant and has a value of 2. Abomasal contents with pH values of 5.5 and higher could give rise to bacterial fermentation with subsequent gas production. The accumulation of gas is thought to form a key event in the pathogenesis of abomasal displacement. The aim of the present study was to determine the pH values of abomasal contents of dairy cows in the first 3 weeks after calving. The pH of the abomasal contents was, over several days. higher than the pH value of the abomasal juice in mid-lactation cows. The highest pH values were measured on day 14 after calving, thereafter the pH declined. Possible explanations for the rise in the pH value of the abomasal contents are discussed. 相似文献
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85.
Effects of experimental duodenal occlusion on electrical activity of the proximal duodenum in cattle 总被引:1,自引:0,他引:1
An electromyographic study of the proximal duodenum in cattle is presented. Changes of motility patterns were studied after induced mechanical obstruction of the descending duodenum in five healthy cows. Special attention was paid to the ratio of antegrade and retrograde motility. Induced duodenal obstruction of which the duration was at most 48 hours, resulted in abrupt disorganisation of the migrating myoelectric complexes; the phases of regular spiking activity disappeared completely or reappeared in a disorganised pattern, and the phases of irregular spiking activity consisted of repetitive groups of spike bursts with prolonged duration and increased propagation velocity. Retrograde peristaltic contractions in the proximal duodenum were observed. Relief of obstruction resulted in a rapid reorganisation of the cyclic pattern of the migrating myoelectric complexes, which indicates normalisation of intestinal activity. 相似文献
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87.
We have argued that planning for a search for extraterrestrial intelligence should involve a minimum number of assumptions. In view of the feasibility (at our present level of understanding) of using nuclear fusion to effect interstellar travel at a speed of 0.1c, it appears unwarranted (at this time) to assume that it would not occur for at least some technologically advanced civilizations. One cannot even conclude that humans would not attempt this within the next few centuries. On the contrary, the most likely future situation, given the maintenance of technological growth and the absence of extraterrestrial interference, is that our civilization will explore and colonize our galactic neighborhood. A comparison of the time scales of galactic evolution and interstellar travel leads to the conclusion that the galaxy is either essentially empty with respect to technological civilizations or extensively colonized. In the former instance, a SETI would be unproductive. In the latter, a SETI could be fruitful if a signal has been deliberately directed at the earth or at an alien outpost, probe, or communication relay station in our solar system. In the former case, an existing antenna would probably be sufficient to detect the signal. In the latter case, success would depend on the way in which the communications were coded. Failure to detect a signal could permit any of the following conclusions: (i) the galaxy is devoid of technological civilizations, advanced beyond our own, (ii) such civilizations exist, but cannot (for some reason which is presently beyond our ken) engage in interstellar colonization, or (iii) such civilizations are not attempting overt contact with terrestrial civilizations and their intercommunications, if present, are not coded in a simple way. To plan at this time for a high-cost, large-array SETI based on the last two possibilities appears to be rather premature. 相似文献
88.