Impact of mastitis pathogens on blood antioxidant enzymes in transition dairy cows

Dairy cows in early postpartum experience significant metabolic stress that increases their susceptibility to mastitis. This study examined the correlation between mastitis pathogens and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in blood serum. Over a two-year study, udder health and antioxidant enzyme activity were assessed across three physiological periods, from the 21st day before calving up to the 42nd day of lactation. During the trial period, each cow in lactation was observed daily for clinical signs of mastitis. Categorisation of the observed population was done following screening for mastitis using udder clinical examination, the California Mastitis Test, and bacteriological culturing. The measurement of the SOD and GPX activity in blood serum was done with spectrophotometric assays expressed as mU/mg protein. Mastitis pathogens were isolated from 43.83% of udder quarters with milk secretion disorder, and the dominantly isolated microorganisms were grouped as contagious: Streptococcus agalactiae (19.14%) and Staphylococcus aureus (6.17%) or environmental: Enterococcus spp. (8.02%), Pseudomonas aeruginosa (7.41%), Escherichia coli (1.85%) and Aspergillus niger (1.23%). The results indicated that contagious mastitis pathogens had a statistically significant influence on the SOD and GPX activity in the blood serum of transition dairy cows. The relationship between oxidative stress, anti-oxidative enzymes, and mastitis in dairy cows underscores the importance of managing oxidative levels to enhance udder health and prevent mastitis. Keywords: dairy cows, antioxidative enzymes, mastitis