Have you ever treated a case of clinical mastitis but weren’t sure what type of bacteria was in the quarter? Have you asked yourself, “Was that treatment I just infused really effective at treating clinical mastitis?” What if the cow’s immune system had already cleared the infection? On-farm culture is a tool that is gaining more appreciation across Pennsylvania and can help answer questions like these.
Mastitis is defined as an inflammation of the mammary gland and is prevalent in dairy herds around the world. Mastitis can be caused by a wide range of bacterial pathogens or from a physical injury to the mammary gland and/or teat end. Clinical mastitis is one of the most costly diseases affecting the dairy industry, with recent estimates suggesting each case is associated with a $231 to $289 loss (Hogeveen et al., 2010).
Producers suffer economic loss through reduced production, discarded milk, veterinary services, culling cows, and treatment use. Mastitis is associated with the most frequent antibiotic use in dairy cows (Mitchell et al., 1998). One study found that milk discarded due to antibiotic treatment could exceed $100 per cow per year (Bartlett et al., 1991). Antibiotics are frequently used to treat clinical mastitis; however, oftentimes antibiotics are either ineffective or not needed to treat the disease.
Producers that use unnecessary antibiotics lose profit due to discarded milk and can contribute to antibiotic resistance. Results in one study found 10 to 40% of cultures from clinical mastitis showed no growth following culturing (Roberson, 2003). Cultures that show no bacterial growth will typically require no treatment.
Identifying the species of bacteria that are responsible for causing a mastitis infection can be beneficial in determining treatment options and reducing unnecessary antibiotic use. Traditionally, producers will send milk samples to local laboratories for culture results. One downfall of laboratory testing is the time lag from milk submission until results are in producers’ hands, which can take several days.
If a producer wants to treat based on the results of a culture they will have to wait several days. This time lag associated with laboratory results contributes to producers making uneducated treatment decisions. Adoption of an on-farm culture program could help producers make proactive treatment decisions and make them in a timely manner. Additionally, submitting a sample for bacteriological culture can be costly for a producer as they are charged a submission fee and shipping costs. On-farm culture will not only save the costs of discarded milk and treatments, but will also eliminate submission and shipping fees.