Application of various methods for studying the secretion of the bovine mammary gland in the diagnosis of mastitis

The study presents data on the analysis of the application of various methods for examining mammary gland secretions in cows for the diagnosis of mastitis. The studies were conducted during 2023. The object of the study was lactating cows and the secretion of their mammary gland. The prevalence of mastitis in cows during the study was 36.6%; during the repeated examination, the number of animals with latent inflammation of the mammary gland increased by 3.4%. At the time of the first examination, 63.3% of cows had milk of the highest grade in terms of somatic cell (SC) count (up to 250 thousand cells/ml). In 8.3% of cows with clinical mastitis, an increase in SC count over 750 thousand cells/ml was recorded. The minimum lactoferrin concentration in mammary gland secretions during the first examination was 0.25 mg/ml, and the maximum was 3.5 mg/ml; the mean value was 1.62 mg/ml. During the second examination, an increase in both the minimum and maximum lactoferrin concentrations was observed, reaching 0.69 mg/ml and 4.1 mg/ml, respectively. At the time of the initial study, the maximum deviation of urea concentration from reference values in the mammary gland secretion of cows was 35.15 ± 0.45 mg/100 ml, and the minimum was 14.18 ± 0.18 mg/100 ml. During the repeated examination, the proportion of cows showing deviations from reference urea values (either decreased or increased) was 38.3%, and 46.7% after 7 days. Microbiological analysis of mammary gland secretions revealed the following microorganisms: coliform bacteria (38.9%), Staphylococcus aureus (38.9%), Enterococcus faecalis (22.2%), using the cultural research method; taphylococcus spp. (55.6%), S. aureus (22.2%), and Escherichia coli (22.2%) using PCR, with repeated testing showing the presence of Pseudomonas aeruginosa in 46.2% of samples; and Streptococcus dysgalactiae (36.4%), Staphylococcus epidermidis (18.2%), Aerococcus viridans (18.2%), S. aureus (9.1%), Staphylococcus haemolyticus (9.1%) and Corynebacterium pseudotuberculosis (9.1%) using the MALDI-TOF method. Repeated examination using these methods revealed an increase in microbial species diversity and changes in the proportions of isolated bacteria. Antibiotic susceptibility testing using the disk diffusion method revealed resistance in individual isolates of C. pseudotuberculosis to benzylpenicillin, S. dysgalactiae to tetracycline, S. aureus to benzylpenicillin and amoxicillin. During the repeated study, 2.2% of the identified isolates of P.aeruginosa were found to carry the blaVIM and blaNDM genes associated with carbapenem resistance.