EN
The purpose of the research was to assess the effectiveness of Biomast manufactured by Abiotest. The preparation was given in the right and left supramammary lymph nodes subcutaneously to cows with staphylococcal latent infections of the udders; the drug was also ad- ministred to 30 cows with subclinical forms of mastitis. It was found that in a period of 6 weeks Biomast was effective in the subclinical forms of mastitis caused by Staphylococcus spp. (IER = 80%) and yeasts in mixed infections. However, it was of little efficacy (IER = 50%) in nonspecific subclinical mastitis and in the staphylococcal latent infections of mammary glands. The parameters used in the experiment were useful in the analysis and estimation of the dynamics rates of mammary glands infections.