Zaritskyi R. Distribution and scientific-theoretical substantiation of methods of laboratory diagnosis of contagious and environmental causative agents of bovine mastitis

Оne of the most serious problems affecting high milk yields in dairy farming has been and remains mastitis, according to foreign and domestic scientists, mastitis affects 7 to 80 % of cows of different breeds. A wide range of pathogens (bacteria, viruses, fungi) can cause mastitis. According to the literature, there are 130 to 150 different types of microorganisms that can cause mastitis in cattle. In addition, some mastitis pathogens can cause food poisoning and zoonoses. Mastitis is one of the most common diseases for which antimicrobial substances are most often used to treat dairy cows. Despite mastitis control measures such as disinfection of udders before and after milking and proper udder hygiene during milking, cows that develop mastitis often require antimicrobial treatment. Antimicrobial therapy continues to be an important component of mastitis control in dairy cattle, however, acquired bacterial resistance to antibiotics is a potential problem and has reached unprecedented levels worldwide, threatening global health and requiring urgent intervention. The results of bacteriological studies of individual samples of the mammary gland secretion of cows with mastitis are highlighted in the dissertation. The sensitivity of mastitis pathogens to various antimicrobial substances is shown in accordance with the order of the Ministry of Economy of Ukraine dated December 30, 2021 No. 1177-21 on the "Procedure for the use of antimicrobial veterinary medicinal products in veterinary medicine". Samples of collected cow's milk were studied using the ELISA method for the presence of antibodies to Leptospira interrogans serovar hardjo. It was established that the complex application of molecular genetic (PCR-RT) and bacteriological studies allows to obtain new data on the spread of infectious agents of mastitis in collected milk samples. The results of the analysis of the data from the Laboratory of Pathology and Bacteriology of the Veterinary Diagnostics Center LLC show that contagious pathogens of mastitis account for 184 (57.5 %) and enteric pathogens 136 (42.5 %) of the 320 isolates. The most common contagious pathogens of mastitis are Streptococcus agalactiae – 24,1 %, Staphylococcus aureus – 18,4 %, Corynebacterium spp. – 7,2 %, Streptococcus dysgalactiae – 5,6 %, Streptococcus uberis – 2,2 % of 184 isolates, and the most common environmental pathogens of mastitis are Staphylococcus spp. 10,3 % and E. coli 8,4 % of 136 isolates. Mastitis of cows caused by yeast was detected in 5 (1,4 %) isolates of the total number of diagnosed pathogens.