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981.
982.
D. J. STEWART B. L. CLARK J. E. PETERSON D. L. EMERY E. F. SMITH† D. A. GRIFFITHS† I. J. O'DONNELL‡ 《Australian veterinary journal》1985,62(5):153-159
A highly purified pilus vaccine prepared from cells of Bacteroides nodosus strain 198 provided a high level of protection against homologous challenge and small, not statistically significant, levels of protection against challenge with 4 other strains each from different serogroups. In a second experiment, a partially purified pilus vaccine from strain 198 induced significant immunity to 1 of 4 heterologous strains which were different from those used in the first experiment. In a third experiment a strain 198 whole cell vaccine produced significant immunity against 3 of 6 heterologous strains used in the first 2 experiments. There was no obvious relationship between the colony type, degree of piliation and level of cross-protection obtained against a particular strain. The results provide further evidence that immunogens associated with, but distinct from, the pilus are involved in cross-protection and that cross-protective antigens are common to some, but not all, strains. 相似文献
983.
984.
Feather follicle movement control was studied on feathers of the pectoral tract in the anaesthetized chicken. Dissection of nerves leading to the follicles showed that their origin was at least partially in the sympathetic ganglia. Reflectoric ruffling of feathers could be obtained after adequate stimulation. Intravenous injections of drugs in doses which influenced the circulation gave the following results: Adrenaline caused erection of feathers which was abolished by phentolamine. Noradrenaline caused up and down movements after injection only at high doses. Similar results were obtained by placing of skin pieces in saline containing the drugs. The reaction to drugs was typical always for a given group of feathers. Killing of birds and anaesthesia caused general erection of feathers which was not abolished by phentolamine. The findings suggest that adrenergic synapses are involved in feather follicle movement control, but at least another mechanism (CNS) regulates feather follicle movement. 相似文献
985.
1. Activities of digestive enzymes in meat-type chickens under ad libitum or alternate-day feeding were determined from 14 to 83 d of age. 2. Final body weight of intermittently fed birds attained 75% of that of the ad libitum-fed controls. 3. When compared with the ad libitum-fed counterparts, a marked increase in the relative weight of the pancreas and intestinal contents were found on repletion days. On depletion days the relative weights of the pancreas and of the intestinal contents were about half those found in ad libitum-fed birds. 4. The activity of the digestive enzymes in the pancreas, expressed as U/g pancreas or U/kg body weight, was not affected consistently by the feeding regime. In the small intestine a marked increase in relative activity (U/kg body weight) was observed on repletion days and a marked decrease on depletion days as compared with ad libitum-fed controls. The activities per g intestinal contents following food restoration did not differ significantly from those of ad libitum-fed controls except for trypsin, which was higher in the former. On depletion days the activities per g intestinal contents were lowest, lipase excepted. 相似文献
986.
A mail survey of disease occurrence in Canadian sheep flocks was conducted. The survey, which covered the period from September 1982 to August 1983, utilized flocks on the Record of Performance (ROP) sheep program and relatively complete data were available from 116 flocks. Data about lambing rates, incidence of a variety of lamb and ewe diseases and reasons for culling were obtained. At the same time a retrospective evaluation of records of diagnoses of sheep diseases recorded at diagnostic laboratories across the country was performed. Data from the years 1978 to 1982 were obtained and summarized. A lambing percentage of 153% (1.53 lambs live born per ewe lambing) was observed and an additional 0.05 lambs were stillborn. The major identified causes of mortality amongst lambs were starvation, pneumonia, scours and accidents. Pasteurella spp. were the etiological agents most commonly associated with pneumonia in lambs and Escherichia coli had the same predominant position with regards to nonparasitic scours. A large discrepancy existed between the proportional mortality rates for internal parasites and coccidiosis as determined from the farm survey data compared to diagnostic laboratory data. This suggests that clinical parasitism may not be adequately recognized at the farm level. Abortions in ewes occurred in approximately half the flocks, but generally at a low level and no severe abortion storms occurred. Pneumonia was the most commonly identified cause of mortality in ewes and although Pasteurella spp. appear to be the most important etiological agents, regional differences were apparent.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
987.
A strain of Pasteurella haemolytica biotype A serotype 1, which had been isolated from a pathologically-confirmed outbreak of bovine pneumonic pasteurellosis, was used successfully to reproduce the disease in conventional calves. The development of the various pathological features was studied at regular intervals following infection. The acute inflammatory reaction which had developed by day 2 after initial infection was characterised by flooding of the alveoli by oedema and neutrophils together with a mild degree of bronchiolar epithelial necrosis. This progressed to an acute exudative fibrinous pneumonia with extensive involvement of the interlobular septa and often with pleurisy. Subsequently, these pulmonary lesions became walled off by fibrous tissue which became infiltrated by plasma cells and lymphocytes. At this stage organisms could be demonstrated only within these nodules in the lung tissue. 相似文献
988.
989.
990.