Like most producers, Joe and Jon Miley want to know what mastitis pathogens lurk on their dairy. So, when clinical cases of mastitis pop up from time to time on their 180-cow dairy in West Salem, Ohio, they do something about it.

“If we see a similarity (in clinical cases), we culture to pinpoint where it’s coming from,” says Jon Miley.

Culturing — bulk tank or individual cow sampling — determines the presence and type of mastitis-causing bacteria, such as Staph. aureus or coliforms such as E. coli, on your dairy. Furthermore, it pinpoints the predominant mastitis bugs in the herd.

Culturing to determine what pathogens infect your cows is just the first step. Once you have the results, you need to use them to find the source of the problem and make management changes to reduce the incidence of mastitis. Experts say two main courses of action exist. Here’s how to use them on your dairy.

1. Use it to find the source of mastitis

Jim Brett, veterinarian in Montezuma, Ga., uses culturing to investigate the cause of mastitis. Brett routinely runs bulk tank cultures on all herds which purchase animals and, therefore, run the risk of importing mastitis pathogens, such as Mycoplasma bovis. Brett uses routine bulk tank testing to alert him if a pathogen has made it through the preventative screening process used when buying the cattle. If he finds this bacterium in one of his clients’ bulk tanks, “we go look for it,” he says.

In fact, Brett wants to know exactly where the bug is hiding. So, on a large dairy with multiple bulk tanks, he instructs his client to milk groups of cows in a particular order so that they can identify which group is harboring the pathogen. For example, if a bulk tank culture reveals the presence of Mycoplasma bovis in “Tank A,” Brett knows what groups of cows contributed milk to this tank. Then, he takes individual milk samples from 30 to 50 cows in each of those groups to pinpoint which group is causing the problem. After he’s identified the suspect group, he and his client take steps to get Mycoplasma mastitis under control.

“By doing this, we’ve been able to keep Mycoplasma down to a bare minimum,” he adds.

2. Use it to improve mastitis management

Once you’ve found the source of mastitis on your dairy, you can use culturing to tweak your mastitis management program in these three areas:

• Treatment
  You can’t manage mastitis effectively until you realize that mastitis pathogens behave differently. In fact, the type of pathogen identified in a culture determines how you should treat it.
  
  Joe and Jon Miley, the producers from northeast Ohio, use their culturing results to make treatment decisions. Specifically, they use the culture’s sensitivity — a measure of its accuracy — to determine “what (antibiotics) will work and what won’t,” says Jon Miley. “If we can catch them right away and clear it up, the sooner we can get them back in the tank,” he adds.
  
  However, it’s well-known that gram-negative pathogens such as E. coli don’t respond to antibiotic treatment as well as gram-positive bugs, such as Staph. aureus, do. Thus, if the results of a culture point to gram-negative pathogens, you need to discuss the use of antibiotics versus supportive therapy with your veterinarian.
  
  
• Control
  While you can use culturing to make treatment decisions, it’s more useful as a management tool.
  
  But, don’t make management decisions based on the results of one bulk tank culturing sample, says Bhushan Jayarao, veterinarian at Penn State University. Instead, collect several bulk tank samples about one week to 15 days apart and use them to
  monitor pathogens and make management changes to
  control them.
  
  For instance, if the results of a bulk tank culture point to a huge growth of E. coli, an organism found in your cows’ environment, you may want to step up your management of the free-stalls and scrape alleys more frequently. Again, the type of pathogen identified in a culture often will dictate what management practices you need to take. (For a list of common mastitis pathogens and management practices to control them, please see, the table below.)
  
  Furthermore, culturing results can indicate if a breakdown occurred in your mastitis control program, says Karen Jacobsen, veterinarian in Athens, Ga. The organism Corynebacterium bovis is a good example of this, she says. This bug lives in the streak canal, not the udder, so its presence can tell you if something is amiss in your post-dipping program. For example, elevated levels of C. bovis may point to improper teat dip coverage or a change to an ineffective teat dip.
  
  
• Prevention
  Knowing which mastitis bugs exist in the herd can help you design preventative strategies to keep the problem from spread-ing and limit the incidence of clinical cases.
  
  For example, culturing will identify chronic mastitis offenders in your herd, thus giving you the information you need to make appropriate culling decisions. Or, it can help you identify contagious bugs like Staph. aureus or Mycoplasma bovis in a herd from which you plan to purchase animals. This can help you make a sound buying decision.
  
  Milk quality hinges on proper mastitis treatment, control and prevention. Use culturing as a well-oiled hinge which opens the door to good mastitis management on your dairy.