鸡传染性鼻炎流行病学调查（Ⅱ）

利用鸡传染性鼻炎PCR试剂盒和阻断ELISA试剂盒，对29份菌株、136份临床样品和1019份血清进行了检验和分析，结果PCR阳性率为36.4%，A型阳性率为10.3%，C型阳性率为6.4%。     

Observer variation in field data describing foot shape in dairy cattle

A qualitative scoring method was devised to describe foot shape in dairy cattle, which relied solely on visual observations. Four independent trained observers used the method to assess the foot shape of 248 cows located on three farms on two different occasions, and the percentages of agreement and near-agreement for intra-observer and interobserver variation on scores for foot shape were calculated. Score assessment methods were suitable for describing features with a broad variation within one score value; reducing the number of observers did not improve best agreement between separate observations by more than 80 per cent.     

Comparison of External and Internal Pelvic Measurements of Belgian Blue Cattle from Sample Herds in Belgium and the United Kingdom

Measurements describing pelvic conformation of pedigree Belgian Blue cows were obtained from a sample of nine herds in Flanders, Belgium, comprising 111 adult breeding cows, and from 11 herds in the United Kingdom comprising 108 similar cows. All herds in the Belgian sample (111 cows) managed parturition by elective caesarian section as did seven herds (56 cows) in the UK sample; the remainder of UK herds (52 cows) allowed cows the opportunity to calve naturally per vagina before resorting to caesarian section. The data described the external and internal measurements, and pelvic area characteristic of this breed, irrespective of the different selection pressures applied over a number of years to this breed through variation in farm management and market forces present in either country. From these data, generalized linear models were constructed to predict pelvic area; they correctly identified cows with either small or large pelvic areas. There were no significant differences in pelvic conformation between cattle bred either in Belgium or the UK, although those cows bred in herds where natural calving was allowed to take place had significantly larger internal pelvic height (p < 0.05) and area (p < 0.05) than other Belgian Blue cows. The correlation coefficients between internal pelvic height and width and external pelvic measurements were significant (p < 0.001). These results might facilitate the selection of breeding cows with larger pelvic area so that a higher proportion of cows can calve naturally than currently occurs. However, selection for other traits such as relatively low birth weight combined with higher weaning weight should be carried out at the same time.     

Clavibacter michiganensis ssp. insidiosus in lucerne seeds

Bacterial wilt is a serious disease of Iucerne. Although there are several ways to transmit the pathogen, seed transmission is practically the only way to introduce the bacteria to previously free areas. In this work, naturally infected seed material and commercial seed lots have been screened by a combination of immunofluorescence (IF) staining and dilution plating. Isolates were confirmed by biochemical characterization and finally by artificial infection of lucerne seedlings. For seed lots free from the pathogen, a diagnosis can mostly be achieved within 2 days. The culture step is necessary only if IF staining is not unequivocally negative, and the full procedure has to be run only for a small portion of the samples. The proposed seed assay provides a reliable alternative to the visual inspection of lucerne fields to fulfil the phytosanitary requirements for Clavibacter michiganensis ssp. insidiosus.     

动物疫苗及其合理使用（一）

疫苗接种是预防动物传染病发生的重要举措。依据免疫学理论,疫苗作为抗原,通过激发动物机体免疫系统,产生特异的体液免疫和细胞免疫,从而获得针对某种疾病的特异性免疫。疫苗一般分为细菌疫苗、病毒疫苗和类毒素疫苗等。用于防病治病的各种疫苗、菌苗又是特殊的生物药品,与普通化学药品具有完全不同的成分、功能和特性,疫苗中含有多种蛋白质（除细菌或病毒外,有的还含有保护剂、鸡胚尿囊液或细胞培养液）,它们均适合许多病原体的生长,有些制品还是活的微生物,一旦污染后果不堪设想。疫苗在保存、运输和使用时有其特别要求。如果方法不当,不但会使活性物质失活,起不到免疫防病作用;而且还可能适得其反,引发动物新的疾病,造成重大损失。     

乙型脑炎的发病机理及毒力致病机理的研究进展

主要介绍了乙型脑炎的病毒基因组成、发病机理和毒力致病机理的研究,从乙脑病毒的基因组结构及其所编码的蛋白质的功能上分析乙脑病毒的毒力致病机理与基因结构的关系及其研究进展,为进一步掌握乙脑病毒强弱毒株基因结构的差异及研究其基因工程疫苗提供了理论基础。     

Some relationships between spirochaete infections and digital dermatitis in four UK dairy herds

Digital dermatitis, presenting as a focal necrotic dermatitis on the skin of cows' feet adjacent to the interdigital space, has been associated with dermal infection by spirochaetes. Lesions cause severe, transient lameness. An enzyme-linked immunoassay (ELISA) was used to measure IgG(2) antibody titres against three different spirochaetes: USA bovine Treponema isolates 1-9185MED and 2-1498, and a UK strain of Borrelia burgdorferi B31. Logistic models were used to describe lesion prevalence in terms of the antibody titres, herd and milking status, year, lactation number, and yield. The antibody titres and milking status (P<0.001) dominated the logistic fits, with the other variables adding little. Generalised linear models were used to describe the antibody titres in terms of the presence or absence of lesions, herd, year, lactation number, and yield. The presence or absence of lesions had the most significant effect for all three antibodies (P<0.001). Neither the herd effects nor the effects due to lactation number or yield showed consistent patterns.     

Delayed physeal closure associated with castration in cats

Radiographs of 152 cats under four years of age were examined for evidence of physeal closure. Radiographic closure was compared between entire male, castrated male, and female (neutered and entire] cats. Physeal closure in castrated males was delayed when compared to that of entire males.