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Producers learn benefits of on-farm mastitis culturing at Central Plains Dairy Expo

ST. JOSEPH, Mo. (May. 14, 2015) — During the Central Plains Dairy Expo in Sioux Falls, South Dakota, producers and veterinarians gathered to hear Dr. Sandra Godden of the University of Minnesota College of Veterinary Medicine discuss the practical applications of on-farm mastitis culturing in a seminar sponsored by Boehringer Ingelheim Vetmedica, Inc. Dr. Godden spoke on the value on-farm culturing (OFC) can bring to a dairy and how to use the system

Culturing shows many benefits

"Though substantial progress has been made, we know that mastitis is still a big challenge on dairies, and it's the cause of most of the antibiotic use in dairy cattle," says Dr. Godden. "We need to be able to use antibiotics, but to use them more judiciously where possible."

One of the ways to use antibiotics responsibly is through culturing mastitis cases to determine what type of mastitis you're dealing with, and if it will respond to antibiotic treatment. Mastitis is classified into three types:

  1. No growth. Typically in cases of no bacteria growth, the cow's immune system has already cleared the infection, making antibiotic use unnecessary.
  2. Gram-positive. Cases with Gram-positive bacteria generally respond well to antibiotic treatment, with the potential exception of chronic Staphylococcus aureus cases.
  3. Gram-negative. Most cases of Gram-negative bacteria growth will self-cure, as with no-growth cases – making antibiotic treatment unnecessary.

"If we can culture so we're not treating no-growth and Gram-negative mastitis cases, that leaves only about 40 percent of mastitis cases that we have to treat," explains Godden. "This results in cost and labor savings by being able to target treatments where they are most effective. Additionally, we can carefully consider our treatment options for Gram-positive. One study showed two tubes of cephapirin sodium had no difference in bacteriological cure rate than five tubes of ceftiofur hydrochloride, so using two tubes versus five can result in further reduction in antibiotic use."

On-farm culturing

While reference labs are the gold standard for mastitis culturing, the two- to four-day delay in getting results can inhibit the effectiveness of sending every mastitis case to a lab. However, OFC systems are relatively easily to set up, and provide fast culturing results with relatively good accuracy so producers can quickly make mastitis treatment and management decisions.

Dr. Godden outlined the following requirements for setting up an OFC system:

  • Fresh culturing media – either the Petrifilm™ system or the Minnesota Easy Culture System
  • An incubator for the media with accurate temperature
  • An engaged employee trained on the culturing process

"An employee who is well-trained in the process and engaged overall is key to a successful program. It often works best if the vet can train the employee and then check in periodically," says Godden.

Farm OFC trial

To evaluate the benefits of OFC systems, Dr. Godden's team conducted a multi-herd, multistate study comparing short-term and long-term mastitis treatment objectives of the OFC system and the blanket treatment approach.

Farms were set up with an OFC system and then randomly assigned to either a positive-control group or a culture-positive group. Cows with mastitis in the positive-control group all received cephapirin sodium as a treatment. With the culture-positive group, cows were treated only if the culturing results were Gram-positive.

Antibiotic use was cut in half with the culture-positive group in comparison to the positive-control group — with 44 percent being treated versus 100 percent. Despite the reduction in treatment, overall mastitis outcomes were similar for both groups.

"Using on-farm culturing systems to direct treatment decisions provides the option to select antibiotic protocols that allow for reduced antibiotic use, costs and treatment duration," says Dr. Godden. "If we can successfully treat mastitis using fewer antibiotics, that's a good thing for everyone involved. From an industry standpoint, it's powerful to be able to say that we are using the tools available to make more prudent mastitis decisions and reduce antibiotic use while still caring for the health of the cow."