Fall Good Time to Review Mastitis Basics

By Ron Johnson Dairy Editor
Thursday, October 9, 2008 7:26 AM CDT

It won’t be long before those cold, autumn rains arrive. And with those wet conditions come better conditions for mastitis organisms.

But there are steps dairy farmers can take to reduce the impact of mastitis, reminds Patrick Gorden, a senior clinician and veterinarian at Iowa State University. Gorden points out that mastitis and other udder problems account for nearly 27 percent of dairy cow cullings, according to figures from 2002. That’s virtually tied with lameness or some other injury as the top culling reason.

Even when a cow with mastitis is not culled, she still brings additional expenses. Her lowered milk production costs an estimated average of $116.10 per year, Gorden notes. The value of the milk that has to be thrown out averages $24.44.

Pencil in $13.60 for having to replace that cow earlier than expected; add in $9.94 for her lower sales value; factor in $9.68 for drugs to treat her; plug in $4.84 for veterinary costs; and include $2.42 for the extra labor she incurred. The final tally comes to $181.

But the costs don’t always end there. Gorden notes that mastitis can hurt a cow’s reproduction, too.

A cow might take longer to get to the point where she can be bred back. Or she might fail to conceive. An abortion is another possible outcome. All tallied, says the veterinarian, mastitis is estimated to cost anywhere from $32 to $107 per case just in reproductive losses.

Gorden says a dairy farm needs a milk “quality team” to battle mastitis. Team members are the dairy manager or herdsman, veterinarian, nutritionist, dairy plant fieldman, and certain farm employees.

He notes that keeping mastitis to a minimum involves five factors. First is giving the cows a clean environment. Also on the list are getting to and maintaining a low somatic cell count (scc) and using correct milking procedures.

It’s also important to keep the milking equipment in tip-top shape. And, good cow nutrition plays a role, too.

Mastitis can be thought of as a triangle, according to Gorden. The three corners are the cow and her environment, the equipment used to milk her, and the people who care for her.

Mastitis can further be broken down into four components. These are the cow herself, the milking equipment, the milking management, and the overall herd and farm management.

Gorden places 20 percent of the cause of mastitis on the cows, and another 20 percent on the milking equipment. Milking management and overall herd and farm management each account for 30 percent.

Mastitis results from the disease-causing bacteria getting into teat ends. So, as simple as it might sound, minimize the number of mastitis-causing bacteria and you lower the cases of mastitis.

Milking machines, the weather, flies spreading bacteria, and anything that stresses a cow can contribute to a mastitis flare-up, Gorden reminded.

A key to lowering the “bacterial load” that cows are exposed to is to “minimize moisture,” says the veterinarian. This means keeping stalls “clean, dry and comfortable.”

Stall temperature

Remove old bedding often and replace it with clean dry material. One benchmark, Gorden says, is to keep stall temperatures 10 degrees below cows’ body temperatures.

Milking helps cause mastitis through poor teat sanitation, liner slippage and overmilking. If a teat is dirty, a milking machine can “flush manure and bacteria into the milk,” Gorden notes.

Dipping teats with an antibacterial solution after milking is very important, the vet emphasizes. While it sounds simple, postdipping does need to be done properly if it’s going to be as effective as it can be.

“Proper teat dipping must cover the portion of the teat that the inflation covered n at least the bottom 75 percent of the teat,” Gorden says.

Some farmers prefer to spray teats after milking instead of dipping them. Gorden has some cautions about spraying instead of dipping.

He says, “Teat sprayers are often not used at the proper angle to cover the teat. Even when held directly below the teat, the barrel of the teat is not adequately covered.”

At milking time, it’s a good idea to get into the habit of looking carefully at each cow and her teats and udder. Note her cleanliness and any swelling to a quarter.

Then, forestrip each quarter and examine the milk for any telltale flakes that could signal mastitis. After that predip and clean the teat.

Adjust the milking unit, if necessary, after it has been attached. Watch for the point at which a cow is finished milking, remove the milker right away, and postdip, remembering to cover at least the bottom three-quarters of each teat.

Dry cows

Anyone who is serious about controlling mastitis needs to use a dry-cow treatment. Gorden notes that 50 percent of mastitis infections take root when cows are dry. These are mostly “environmental” cases, caused by bacteria that are present in the overall cow environment.

Teats try to naturally seal on their own during the dry period. But sometime the “plug” of keratin does not extend far enough up the teat canal to offer total protection.

In a Canadian study and a New Zealand study, the percentage of open teats was found to decrease the farther cows got into their dry periods. Fifty percent of the cows in the Canadian study had open teats by day seven of their dry periods. That fell to about 25 percent by day 42.

In the New Zealand work, cows were allowed to stay dry as long as 93 days. There, more than 40 percent of the cows had open teats at day 21. That dropped to 5 percent by day 77, but climbed to about 6 percent by day 93.

Gorden says using internal teal sealants n sometimes dubbed “teat end toothpaste” n “economically, a no-brainer.” But, he adds, it has to be used properly. These internal barriers, he says, “can reduce environmental infections by 70 to 80 percent…”

Nutrition

Nutrition plays a role in helping cows deal with mastitis. Try to avoid ketosis, and make sure prefresh cows and lactating cows get enough vitamin E and selenium, the veterinarian says.

Vaccines

Finally, check with your veterinarian to make sure your vaccination program is the best it can be. There’s “some benefit” in vaccinating against Staph aureus, he says.

Ask about “core antigen vaccines,” too. These can protect cattle against gram-negative bacteria and aid in preventing other infections besides mastitis, such as those of the uterus, digestive tract and lungs.

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