Helping dairy producers reduce mastitis losses can improve everyone’s bottom line

The most common and costly disease facing dairy cattle is generally considered to be mastitis. Helping producers avoid mastitis-related production losses and treatment costs is an ever-present concern for veterinarians and distributor sales representatives.

Not only are the immediate costs concerning, but every case of clinical mastitis reduces the cow’s production potential for the rest of her lactation, says Linda Tikofsky, DVM, professional services veterinarian (dairy), with Boehringer Ingelheim Vetmedica, Inc.

Clinical vs. subclinical

Mastitis is typically caused by a bacterial infection of the cow’s mammary gland. The bacteria can enter through the cow’s teat end. Bacteria may be found in the cow’s environment, such as bedding. In addition, contagious bacteria can be spread via milking equipment or vectors such as flies.

Generally, mastitis is classified as either “clinical” or “subclinical.” Signs of clinical mastitis can include abnormal milk, abnormal quarters, swelling or redness. In severe cases, the cow can stop eating and drinking normally. There is also a subclinical form of mastitis. The difference is lack of visual signs with subclinical, she says.

“Clinical means you actually see something, that you can visually identify it as abnormal,” Tikofsky explains. “Subclinical infection means there is a disease process going on. If we were to take a sample of milk, we would find the bacteria if we cultured it.”

Subclinical infections are often identified by regular cultures on the farms. While it’s impossible to tell from visual signs which bacteria are present, cultures can determine the exact cause. Typically, the culprits can include gram-positive streps and staphs – like Staphylococcus aureus and Streptococcus uberis – or gram-negatives, such as E. coli or Klebsiella, among others.

“Once we see clinical signs, that’s actually a sign the immune system is working to eliminate the infection,” Tikofsky says. “About 30 to 40 percent of the time, the cow’s immune system is effective at eliminating the infection on its own.”

After a comprehensive culture profile is developed on a farm, routine bulk tank testing should be conducted to monitor the udder health, notes David Lee, professor at Rutgers University Department of Agricultural and Resource Management Agents, who has worked with PortaCheck, Inc. on diagnostic and training and development of on-farm diagnostic tests.

However, producers should be aware that introducing new animals to the farm can introduce new bacteria.

“If you buy an animal at a show, or milk her at a show, there are ways you can get the contagious organisms in your herd,” Lee says. “Staph aureus or mycoplasma can get embedded in a herd and will be a chronic problem. Contagious organisms tend to produce clinical cases of mastitis.”

Vulnerable cows

Cows can develop mastitis at any point in lactation, but fresh cows – or cows in their first 60 days of lactation – are most vulnerable.

“Their immune system may not be quite as strong,” Tikofsky says. “They are producing a lot of milk and may not be able to respond to fight off bacteria quite as easily.”

Cows are again susceptible to developing the disease during dry off, typically about two months before they are due to calve again. Once an animal has stopped milking, the milk accumulates in her udder, which creates the opportunity for infection.

Most herds practice blanket dry cow mastitis treatment to help prevent infection during this time, Tikofsky notes. Now, some progressive herds are adding selective dry cow treatments to their arsenal to help reduce treatment cost and retain milk production.

“Only maybe 25 percent of quarters on those cows are affected at dry off,” she says. “Now, if we can identify only those infected quarters, we may be able to practice selective dry cow therapy, rather than blanket dry cow treatment, which reduces antibiotic use on the dairy and promotes judicious use.”

Cleaning up

One of the best ways to prevent mastitis is by providing a clean, hygienic environment. This helps limit the cow’s exposure to bacteria. This includes clean bedding, clean alleys and reducing mud or manure.

“The best mastitis prevention is a good shovel,” Tikofsky says. “Next, we want to make sure those cows have adequate energy and protein and also pay attention to vitamins, and trace minerals.”

Animals with ketosis are more likely to develop mastitis as they don’t mount as strong of an immune response to infection. As with so many diseases, employee education and training are critical steps to avoiding mastitis infections and catching cases early, Tikofsky notes.

“Make sure equipment is working and have a well-trained staff that actually follows your milking procedures – including cleaning teats and post dipping, which is a key to mastitis prevention,” she recommends. “A skilled milking crew can do a lot of mastitis detection.”

Milking crews can help prevent infections by forestripping before attaching milking units, visually identifying abnormal milk or abnormal quarters and promptly moving cows to holding pens so a herdsman can further evaluate each case, Tikofsky says.

Some types of mastitis respond to vaccination, and producers can work with their practitioner to develop a core antigen program that includes protection against coliform mastitis.

“What we really want to do is get them set up before the susceptible period – early in lactation, within the first 100 days of milk,” she says. “Following the vaccine manufacturer recommendations, you’ll typically vaccinate them before the dry period to protect during their most susceptible period.”

Identification

The gold standard in identifying mastitis is based on somatic cell counts (SCC) followed up by a milk culture like that done through Dairy Herd Improvement Association (DHIA), Lee says. However, testing options are now available that measure infection using other markers.

“Cell counts are one of the parameters producers are paid on if they sell milk to a creamery or co-op,” he says. “Now, there are various enzymes we can measure that respond to either infection or trauma.”

For example, some tests use lactate dehydrogenase (LDH), an enzyme released into milk when cells are damaged during an udder infection. LDH is correlated to SCC, but LDH levels often rise earlier than somatic cell counts. These tests can be less expensive and provide more rapid results. In addition, many can be performed on the farm, Lee says.

LDH and/or SCC tests can be used to test individual quarters at dry off and reduce use of antibiotics. In addition, these tests can be used to keep a closer eye on cows with chronically high SCC, yet no evidence of abnormal milk.

“It’s going to take at least three to four days for the white blood cells to exit the udder even if there’s no infection,” Lee says. “That’s really not going to give you very reliable information.”

Mastitis testing gives producers a window into the overall health of a cow, he says. There are always going to be some white blood cells in the udder – 60,000 to 80,000 is a normal range for a healthy animal. This helps producers keep an eye on animal welfare.

In addition, milk production and premium opportunities can be identified, he notes.

“Companies are looking at low cell counts as marketing tools,” Lee says. “The shelf life of the milk is longer, proteins and fats are altered by high counts and premiums can be based on cell counts depending on the part of the country you’re in.”

There is also an unseen loss in production for infected animals – from 60 to 80 pounds of milk, Lee warns.

On-farm testing can complement DHIA work, he notes. On-farm testing can help closely monitor cows on a mastitis “hot list,” especially in terms of reproduction and conception concerns.

“There’s some excellent research to show that if a cow has mastitis, it’s going to affect reproduction, chances for early embryonic death and extended dry days open prior to breeding,” Lee says.

Treatment

The right treatment can save producers money when confronting mastitis too, Lee says.

“We’re not only reducing treatment costs, but we’re using a drug that targets that bacteria,” he says. “Several bacteria respond differently to different treatments. It’s wasting money and developing potential resistance because we’re using the wrong antibiotic.”

Some bacteria may not even respond to antibiotics, which is another reason it pays to identify the exact cause of mastitis in a herd.

Producers can expect that 30 to 40 percent of mastitis cultures in the milking parlor will actually be negative for mastitis. In these cases, the cow’s immune system already identified the bacterial infection and eliminated it before inflammation or abnormal milk is even seen, Tikofsky notes.

“E. coli-infected cows are very good at eliminating those infections by themselves,” she says. “Streps or staphs are more adapted at living in the quarter and may need antibiotic therapy to respond.”

Next, Tikofsky recommends choosing a tube that will be most effective against the particular organisms present and follow manufacturer directions on the length of treatment and milk withholding times.

Working together

Distributor sales representatives can be an active part of the team that helps reduce mastitis incidence on a dairy, Tikofsky says. First, DSRs should have a basic understanding of product labels. Next, asking questions about the specific bacteria found on their farm through cultures can help provide the most effective treatment options.

“The more you can inform yourself about the products and general principles of mastitis, the more you can be an asset your clients,” she notes.

Key Points:

The cost of subclinical mastitis to the U.S. dairy industry exceeds $1 billion annually.

The overall production loss for the average U.S. dairy farm due to mastitis is estimated to be $110 per cow annually.

Persistent long-term infections with contagious pathogens damage milk secretory cells and result in reduced milk production.

The somatic cell count (SCC) of cows infected with subclinical mastitis rises as the cow’s immune system sends white blood cells to the udder to fight off mastitis pathogens.

Mastitis losses include lost premium opportunities, decreased milk production, discarded milk, death loss, culling, decreased genetic gain and reductions in reproductive efficiency.

¹ Ruegg, P. Premiums, production, and pails of discarded milk how much money does mastitis cost you? 2011.

Checking On Udder Health