Clinical and Subclinical Mastitis Causing Pathogens in Tennessee Dairy Cattle

Milk quality impacts the producers and consumers. Higher milk quality leads to a longer shelf life, improved cheese making ability, and improved taste. Milk quality can be severely impacted by intramammary infections which can result in mastitis. Identifying the common mastitis causing pathogens in milk samples collected from subclinical and clinical mastitis cases can assist the producer in managing mastitis. This can lead to improved milk quality, improved cow health, and reduced need for antibiotics to treat mastitis. This study investigates the prevalence of bacteria causing intramammary infection in dairy cattle of Tennessee. Milk samples were collected from 9 farms across Tennessee in February/March and in September/October 2016 resulting in 1231 subclinical and 245 clinical mastitis samples. The milk samples were cultured and colonies were biochemical tested to determine the types of organisms present. The most frequent mastitis causing pathogens for each type of mastitis, farm, and season will be evaluated. The top three subclinical pathogens isolated were coagulase-negative Staphylococci (11.86%), Staphylococcus aureus (5.61%), and Other (6.50%). The top three clinical mastitis organisms isolated were coagulase-negative Staphylococci (8.16%), Escherichia coli (7.35%), and Other (7.35%). An analysis of pathogen prevalence in late winter versus early fall also will be presented.