Producing high-quality milk is a front-and-center goal of most dairy operations. Controlling mastitis and treating it effectively are key to achieving that goal. As the general public turns up its scrutiny on food production, it’s as important as ever to make sure we as an industry are using antibiotics responsibly.
Have you ever treated a case of clinical mastitis but weren’t sure what type of bacteria you were up against? On-farm milk culturing can help answer this question, reduce the amount of antibiotics being used and increase milk quality and profitability.
Culturing milk from cows with clinical mastitis can help determine which cases will benefit from intramammary antibiotic treatment. It is important to note that studies have shown that most mild to moderate gram-negative mastitis cases, including E. coli, will spontaneously cure without antibiotic treatment.
Of course, there are many cases of mastitis that do require treatment, often combatted with an intramammary tube. Two recent studies headed up by separate university researchers showed outcomes that suggest advantages to utilizing a two-tube treatment of cephapirin sodium as opposed to a once-per-day, five-tube treatment of ceftiofur hydrochloride when treating gram-positive mastitis.
Common culture profiles for U.S. dairy farms often reveal this distribution of culture results: 25 to 30 percent gram-positive, 25 to 30 percent gram-negative and 40 to 50 percent no-growth. This means a 1,000-cow dairy with a 30 percent mastitis rate could use 900 fewer tubes of antibiotics a year if it implements a two-tube cephapirin sodium protocol.
Furthermore, a 12-hour, two-tube treatment of cephapirin sodium can reduce the time cows spend in the hospital pen by 35 percent when compared to a five-day treatment.
First-generation vs. third-generation cephalosporins
Dr. Ynte Schukken of Cornell University conducted a study to determine the effectiveness of the two-tube treatment of cephapirin sodium (a first-generation cephalosporin) as opposed to a once-per-day, five-tube treatment of ceftiofur hydrochloride (a third-generation cephalosporin).
From the results of this head-to-head trial, the authors concluded, “These results indicated that the first-generation cephalosporin was not inferior with regard to clinical cure and bacteriological cure of gram-positive bacteria.”
Another conclusion indicated that “herds that do not utilize a culture-based approach for the treatment of clinical mastitis may have an economic benefit from selecting cephapirin, with a shorter non-saleable milk duration [4.5 versus eight days] as the first treatment of choice.”
Active metabolites of mastitis treatments
Dr. Pamela Ruegg and associates at the University of Wisconsin – Madison looked at the distribution of minimum inhibitory concentration values for the parent compounds and metabolites of cephapirin sodium and ceftiofur hydrochloride , two common mastitis treatment options.
It’s important to realize that when an antibiotic is administered into a cow’s udder – in vivo – the active ingredient begins to rapidly metabolize into a new compound; cephapirin sodium metabolizes into desacetylcephapirin, and ceftiofur hydrochloride metabolizes into desfuroylceftiofur.
Both the parent (cephapirin) and the metabolite (desacetylcephapirin) are compounds that have been proven through extensive in vitro testing to be highly effective against the following gram-positive organisms: Strep uberis , CNS and Staph aureus , whereas the metabolite of ceftiofur (desfuroylceftiofur) has limited activity against these pathogens.
Ruegg encourages producers to culture milk from cows with mastitis to determine which treatment path to take. “We need to stop training ourselves to just grab a tube and treat every single case,” says Ruegg. “Extended-duration intramammary therapy should not be the routine treatment for all cases of mild and moderate clinical mastitis.”
On-farm culturing
Dairymen who do not currently utilize on-farm culturing systems can look to their own herd veterinarians and extension programs across the country to get an understanding of what it takes to make culturing a part of their mastitis treatment program. The main benefits of on-farm culturing include the following.
• Appropriate treatment decisions: Producers can determine if the pathogens causing clinical mastitis are gram-positive, gram-negative or no-growth. On-farm culture results can drive decisions to select the intramammary antibiotic to specifically target most efficiently or withhold antibiotic treatment and discard milk until the cow can naturally eliminate the infection.
• Timeliness: On-farm culturing can give a producer preliminary results within 24 hours. Fast results allow the producer to make more immediate decisions on treatment.
• Cost-effectiveness: With targeted treatment, producers will see a better response to treatment of infections caused by gram-positive pathogens like staphylococci and streptococci. A recent study looked at the cost-effectiveness of using on-farm culturing to identify and treat only gram-positive infections.
The 189 cases, after accounting for all costs, resulted in an average net income of about $3,342 per month. Evaluation of numerous research studies has shown 50 to 60 percent of clinical milk samples would earn a “no treatment” decision because they are negative for bacteria (no-growths) or caused by a gram-negative pathogen.
As university researchers continue to increase the industry’s knowledge and understanding of this common and costly disease, working with your veterinarian to implement new science and farm-specific protocols can show serious returns to your bottom line.
Setting up on-farm culture capabilities can not only help reduce your overall antibiotic use but also get saleable milk back into your bulk tank faster and keep cows out of your hospital pen. PD
References omitted due to space but are available upon request. Click here to email an editor.
Linda Tikofsky
Professional Services Veterinarian
Boehringer Ingelheim Vetmedica Inc.
