Galvijų virusinių ligų tyrimų analizė pietvakarių Lietuvos pienininkystės ūkyje ; Analysis of investigations of bovine viral diseases in southwestern Lithuanian diary farm

The aim of this thesis is to perform the analysis of the most important viral diseases in the dairy farm, located in the southwestern Lithuania, where bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) occur as the endemic diseases without applying specific preventive measures. The paper consists of 45 pages, including 6 tables, 13 images, and 61 references. The literature review describes the prevalence of viral diseases, detected in the farm, i.e. infectious bovine rhinotracheitis and bovine viral diarrhea, in Lithuania, the risk factors that could determine the prevalence of these diseases, and presents analysis of epidemiological data of BVD and IBR. The research was carried out during the period of 2014-2016. During the research, bovine blood serum samples were tested, using ELISA and PCR, with respect to BVD and IBR in Institute of Microbiology and Virology, Faculty of Veterinary Medicine, Lithuanian University of Health Sciences. In order to evaluate the importance of BVD and IBR to bovine wellness, the clinical and epidemiological findings were also analysed. 36 blood samples of different ages of bovines were collected for this research. All selected bovines were clinically healthy. Bovines were divided into 4 age groups: 6-12 months old, 12-24 months old, primiparous, and cows. ELISA revealed that bovines, seropositive for BVD or IBR, made 44.4% (16/36), and seropositive for both BVD and IBR – 50.0% (18/36). 5.6% (2/36) were seronegative. The research revealed that bovine viral diarrhea (94.4%) (34/36) is more widespread (P<0.05) than infectious bovine rhinotracheitis (44.4%) (16/36) in the farm under review. The level of spread of BVD seropositive animals in different groups was 90.0% (9/10) and 88.9% (8/9) (age groups of 6-12 and 12-24 months), and age groups of cows and primiparous (100%) (9/9; 8/8). The percentage of seropositive animals was not statistically different (P>0.05). IBR test results showed that cows (100%) (8/8) and primiparous (89.9%) (8/9) have antibodies, and younger animals were seronegative. BVD infection process takes place in the age groups of 6-12 months, and 12-24 months, or earlier, while IBR– in age groups of primiparous and cows. The percentage of seropositive animals was not statistically different (P >0.05). BVD susceptible bovine made 5.6% (2/36) of the total number of the tested animals. The tested serologically negative bovines were not carriers of the virus. The virus was detected in the age group of 6-24 months. IBR susceptible bovines were detected in age groups of 6-24 months and primiparous (18/36). The actual number of IBR susceptible bovines (55,6%) was statistically higher (P<0.05) than BVD in all age groups (5.6%).