Serum antibody response to Mycoplasma hyopneumoniae measured by enzyme-linked immunosorbent assay after experimental and natural infection of pigs

Studies were conducted under experimental and field conditions to determine the effect of infection with M. hyopneumoniae on the immune response in serum as measured by ELISA. Following intratracheal challenge or contact exposure, serologically negative pigs derived from mycoplasma-free piggeries developed an immune response within 10 days. This response continued to rise for a further 50 days. In a field study in a commercial piggery, no animals (0/44) were observed to have M. hyopneumoniae antibodies at day 86 of life. However between day 86 and day 144, 97.7% (42/43) animals sero-converted. These results are discussed in terms of infection spread, particularly in the grower/finisher shed.     

Epidemiological investigation of the buller steer syndrome (riding behaviour) in a western Canadian feedlot

Objective To describe the buller steer syndrome in a Western Canadian feedlot. Design A retrospective epidemiological study. Animals 78,445 male cattle that entered a 24,000-head feedlot in western Canada from 1991 to 1993. Procedure All cattle were given a hormonal growth promotant containing 20 mg oestradiol benzoate and 200 mg progesterone within 24 h of arrival at the feedlot. A ‘buller’ was a steer that was observed at daily pen checking to be ridden persistently by pen mates or had evidence of having been persistently ridden by pen mates. At the completion of the feeding period, animal health records for bullers were collected and analysed. Results The prevalence of bullers in the total population was 2139/78,445 (2.7%, range per pen 0 to 11.2%). The prevalence of bullers increased with increasing weight and age. The relapse risk after first treatment (three days in the feedlot hospital plus treatment for concurrent disease) was 30% on average (27 to 35%). Individual records from 9734 yearling steers that entered the feedlot in 1991 and 1992 showed that bullers were significantly (P < 0.05) heavier at processing than non-bullers. Bullers occurred as a point source epidemic with the cause occurring soon after cattle arrived at the feedlot and were mingled into pen groups. This gave a ‘days on feed’ distribution. The peak incidence of bullers occurred much sooner after arrival and dropped off much quicker in older cattle. The daily incidence of bullers was temporal, but was not related to season of the year, weather conditions or any other feedlot management practice. It was related to the seasonal arrival of cattle at the feedlot, their age at entry to the feedlot and the post arrival occurrence of bullers. Reimplantation with hormonal growth promotants and castration of intact bulls did not produce an epidemic of bullers. Conclusion The findings of this study support the theory that bullers are the result of agonistic interactions, which occur concurrent with the establishment and maintenance of a social hierarchy within pens of feedlot cattle.     

Serum and mucosal antibody responses and protection in pigs vaccinated against Mycoplasma hyopneumoniae with vaccines containing a denatured membrane antigen pool and adjuvant

Objective To investigate the protective efficacy of a pool of denatured membrane protein antigens of Mycoplasma hyopneumoniae (J strain) in the molecular size range 70 to 85 kDa (F3 antigen) in combination with adjuvants for pigs challenged with M hyopneumoniae .
Design A vaccine efficacy experiment with assessment of serum and respiratory tract antibody responses.
Procedure F3 antigens were emulsified with five different adjuvants. To groups of three pigs per vaccine, four vaccines were given by intramuscular injection, and two vaccines, including one of those given intramuscularly, were given by intraperitoneal injection.
Results Compared to six unvaccinated pigs, animals vaccinated with F3 antigen displayed significantly reduced pneumonia (54% reduction in mean lung score) following experimental challenge. Analysis of post-vaccination, pre-challenge IgG and IgA ELISA antibody absorbances in serum and respiratory tract washings revealed no correlation with lung score. Six weeks after challenge, pigs previously vaccinated intramuscularly mostly demonstrated greater IgG and IgA responses in respiratory tract washings, and greater IgG serum antibody responses, than those vaccinated by intraperitoneal injection.
Conclusion Pigs vaccinated with M hyopneumoniae antigens in the molecular size range of 70 to 85 kDa showed a significant reduction in lung lesions compared with unvaccinated control animals after experimental challenge. IgG and IgA antibody concentrations in serum and respiratory tract washings after vaccination do not provide a useful prognostic indicator of protection from enzootic pneumonia.     

Eimeria meleagrimitis in young turkeys: effects on weight, blood, and organ parameters

Weight and biochemical studies were conducted on 2-week-old turkeys inoculated with 10(4) to 5 X 10(5) sporulated Eimeria meleagrimitis oocysts, on their pair-fed controls (equivalent food intake), and on control turkeys fed ad libitum. Food consumption and rate of weight gain of all inoculated and pair-fed turkeys fell sharply on day 4 postinoculation (PI), but deaths occurred primarily among the birds inoculated with 5 X 10(5) oocysts. Heart weights (expressed as percentage of body weight) were reduced in inoculated and pair-fed birds, but liver, spleen, and pancreas weights did not differ from those of either control group. Feed conversion (feed consumed/gain) was less efficient for inoculated turkeys than for ad libitum or pair-fed controls and was least efficient for turkeys inoculated with 5 X 10(5) oocysts. Plasma glutamic oxaloacetic transaminase (GOT, aspartate and aminotransferase) activity increased, and carotenoid and total protein levels decreased in inoculated turkeys but not in the pair-fed turkeys, indicating that these changes were caused by the infection and not by reduced food intake. Plasma glutamic pyruvic transaminase (GPT, alanine aminotransferase) remained stable in all groups. Plasma glucose levels of inoculated birds did not differ from those of the control groups, but liver glucose and glycogen levels decreased in both the inoculated and pair-fed birds.     

云南玛咖产业发展现状及促进对策分析（英文）

药食植物玛咖是重要的保健品原料,近年来云南省玛咖产业发展迅速,但由于起步较晚、基础薄弱,种植、加工与国外相比仍有较大的差距。从玛咖生产基地、加工企业、优势区域布局、种植与初加工技术体系、经济效益等方面阐述了云南省玛咖产业发展现状,并对制约其产业发展的主要因素进行分析,最后提出了加强组织领导,抓好宏观调控;加大财政投入,拓宽投融资渠道;加快原料生产加工基地建设;加强现代科技研发工作,建立科技支撑体系;加快培育龙头企业;构建市场营销体系;促进集聚发展,严格质量标准等促进对策。