EN
This research paper addresses the hypothesis that the incidence of various bovine mastitis pathogens is subject to change over time and across regions. The aim of the research was to determine the pathogen species that are currently the etiological agents of mastitis in Polish dairy herds. This comprehensive study was conducted in the period 2009-2017 and included all the Polish provinces, distinguishing between those with high and low numbers of dairy cattle. Over eight years 38,852 quarter milk samples were obtained from 22,587 cows with clinical and subclinical mastitis from herds located in all 16 provinces in Poland. Milk samples were cultured using standard microbiological methods. Most of them were positive for microorganisms but there was also part of bacteriologically negative and contaminated samples. Gram-positive catalase-negative cocci and staphylococci were the most prevalent pathogens. The growth of other microorganisms such as Gram-negative and Gram-positive bacilli, yeasts and algae was observed at lower frequencies. There were differences in the prevalence of microorganisms depending on the region. In the eastern part of the country a higher number of Streptococcus agalactiae infections than in other regions was observed. This paper provides the latest data on microbial species, frequency of their occurrence and regional location within Poland. The knowledge of mastitis pathogens enables appropriate treatment and to make prevention recommendations for the herds.