Investigations on some aerobic bacterial agents isolated from heifers at the beginning of the first lactation

In this study, it was aimed to identify the predominant coagulase-negative staphylococci (CNS) species in subclinical, clinical, and persistent infections in Konya province, to determine various virulence and resistance mechanisms of CNS species within the age-lactation level. The research has been carried out in a dairy herd that is free from brucellosis and tuberculosis and uses an automated herd management system. Thirty-two heifers at the beginning of lactation with milk yields of more than 20 liters have been observed in terms of udder infections during the first 1–4 months of lactation. The prevalence of intramammary infections (IMI) and of CNS-caused IMI has been 75% and 53%, respectively. The rate of CNS was 61% among all isolates, with the rate of the major pathogen 26%, and the rate of the other pathogen 12%. S. chromogenes has been the most frequently isolated CNS species (45.5%). In conclusion, CNS may cause udder infections at the herd level in heifers during the early lactation period, which may cause persistent infections with different mechanisms, and S. chromogenes may emerge as a new contagious mastitis agent in the future. CNSs should be identified at the species level rather than the group level in order to develop effective control programs. Based on the epidemiological data, the current udder health control programs in heifers in the early lactation period were detected to be insufficient.