Mastitis pathogens in Bavaria, Southern Germany: apparent prevalence and herd-level risk factors

Abstract

The aim of this cross-sectional study was to determine the prevalence of mastitis pathogens in Bavaria and to identify management practices as possible risk factors for the presence and within-herd prevalence of the four most common pathogens . For this purpose, aseptic quarter milk samples of 6,188 dairy cows on 152 Bavarian dairy farms were collected and a California mastitis test was performed. Udder and leg hygiene scores as well as teat end condition scores were recorded at cow-level. Teat end hygiene score after udder preparation was evaluated for about ten cows per herd. Herd information and information on management practices were obtained using a standardized checklist. To determine herd-level risk factors, Fisher’s exact test for categorical, and Student’s t-test or Mann-Whitney-U test for continuous data were performed. The most frequently detected pathogens at quarter-level were coagulase-negative staphylococci (4.4%), Staphylococcus aureus (2.9%), Streptococcus dysgalactiae (0.9%), and Streptococcus uberis (0.9%).  Each of these four pathogens was detected in more than half of the herds (90%, 70%, 61%, and 54%, respectively). Free stall housing and larger herds were associated with detection of coagulase-negative staphylococci and Streptococcus uberis. The usage of post-milking teat disinfection was associated with a lower within-herd prevalence of Staphylococcus aureus. The use of internal teat sealants and blanket dry cow therapy reduced the odds for detection of Streptococcus dysgalactiae at the herd-level. However, the latter practices were implemented by only a minority of herds. The study shows for the first time the apparent prevalence of mastitis pathogens in Bavaria using an unbiased sample. Coagulase-negative staphylococci were found to be the most frequently isolated pathogens, further studies on the etiology and reduction of these pathogens should be considered