A prospective longitudinal observational study based on a stratified random sample of 113 Swiss dairy farms was conducted between April 1993 and July 1994 with the following objectives: (i) to ...provide statistically valid estimates of disease frequency in the Swiss dairy cow population, and (ii) to evaluate the feasibility and quality of an intensive farm-based data recording system. During the 15-month study period, farmers were asked to record every health and management event related to their cattle herd. This information was mailed back to the study centre at fortnightly intervals. Additionally, farms were visited regularly to verify received data and to discuss specific problems. During these farm visits, management data were recorded using questionnaires. A complete data set of individual animal events with a total observation time of about 1740 cow-years and 275 calf-years was collected and disease-incidence measures were calculated. The most frequent events were reproductive disorders and udder diseases, followed by lameness and metabolic disorders. Experience with the data collection technique used in this study suggests that a farm-based system is effective and reliable, as long as good contact with the farmers is maintained, and incentives to stimulate their motivation are provided.
It is poorly understood why vaccines could not be developed for the control and prevention of African swine fever (ASF) virus infection. The aim of our study was to identify genes non-essential for ...ASF virus replication because there were indications that certain viral gene products, which apparently are non-essential for viral replication, conferred protection from death due to ASF. A cosmid library representing the genome of ASF virus strain France 64 was established and characterized. Then, in order to inactivate viral genes by insertion, the beta-galactosidase (beta-gal) gene was introduced either randomly or at specific locations of selected cloned DNA fragments. These constructions were transfected into cells which had been previously infected with a cell-culture-adapted viral strain in order to allow the generation of recombinant progeny virus. Viable recombinant progeny was identified by at least one of the following means: (1) expression of beta-gal; (2) detection of beta-gal specific DNA by plaque hybridization, and (3) absence of a functional product of the inactivated gene. Presently, we are characterizing a recombinant virus with an insertionally inactivated thymidine kinase gene.
Pet skupina po deset životinja cijepljeno je različitim kombinacijama vakcina. Prva je skupina cijepljena polivalentnim cjepivom koje je sadržavalo antigene virusa slinavke i šapa, virusa bjesnoće te ...bakterija Pasteurella multocida i Clostridium chauvoei. Ostale su skupine cijepljene pojedinačnim antigenima, pa je tako druga skupina cijepljena antigenima virusa slinavke i šapa, treća antigenima virusa bjesnoće, četvrta antigenima bakterije Pasteurella multocida, a peta antigenima bakterije Clostridium chauvoei. Serološki odgovor svih životinja provjeren je 21. i 90. dana nakon cijepljenja. Na osnovi serološkoga odgovora nisu utvrđene značajne razlike među različitim načinima cijepljenja.
