A study was performed in agricultural company “Nemunas”, Prienai district, the Departament of Non-contagious Diseases of the Lithuanian veterinary Academy and the Laboratory of Animal reproduction. The master of thesis analyses reproduction of the cowherd and mastitis prblems in the farm of agricultural “Nemunas”, Prienai district. Analysis of data shows that the yield of milk is quite low (3203 kg) despite the fact that annual introduction of first-calf heifers amounts to 21,1 % of the herd. By examination of 1227 milk samples in 2003, the general count of somatics cells was 590,550 ± 51,030 cells/ml. Only 61,2 % of the delivered milk satisfied standart milk indicators (SCCL < 400,000 cells/ml). An increase in the somatic cell count is closely related with hidden mastitis. By examination of 41 milk samples (SCCL < 400,000 cells/ml), a mixed micro-flora was isolated in 78 % of the cases and pure cultures isolated in 22 % of the cases. The mixed microorganism cultures constituted of Streptococci, Stafilococci, Enterococci and yeast-like fungi. The sensitivity of the isolated organism was determined by carrying out antibioticogram testing. Used anti-mastitis preparations were found differently effective against isolated microorganisms. The preparation “Penak Entervitol” was effective agaisnt enterobacter and Candida, the preparation “Targot mastitis Suspension” was effective against Streptococci, Stafilococci and Proteus. The preparation “Streptopen” was effective against... [to full text]