Reduce mastitis at milking

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Editor’s note: Fifth in a mastitis series.

In the last 25 years, teat dipping or spraying with a germicidal solution immediately after every milking has been an effective management tool to reduce the rate of new intramammary infections in dairy cows, says Steve Nickerson, PhD, Louisiana State University Agricultural Center. More recently, he adds, premilking teat sanitation has also been widely adopted. But many more factors surrounding the cleanliness of the udder and teats contribute to the load of bacterial pathogens which cause mastitis.

Before the parlor

Cows housed in muddy lots or pastures obviously have a more difficult time coming to the parlor clean. But cows confined to barns can be at a high risk for pathogen contact via organic bedding materials or dirty stalls. “Wood shavings, shredded newspaper, ground corn cobs and rice hulls support the growth of bacteria,” says Nickerson. “Sand, clay or crushed limestone support fewer bacteria. But if the dairyman only has access to chopped straw or wood shavings, the most important thing he can do is keep udders clean and dry during the intermilking period by changing the back one-third of the stalls at least once a day.”

Washpens are used in certain parts of the country and mostly on larger dairies. How well they work for your clients depends on how well dairy employees manage the cows when they’re in the washpen. At the Duo Dairy, Ltd., in Loveland, Colo., Greg Goodell, DVM, says, “After going through the washpen, too much water left on the udder can be a problem.”

Washpens should be fully loaded with cows whenever possible so the water is confined to the belly of the cow. Incorrect sprinkler heads will also cause problems by getting the cow wetter than she needs to be, especially if the entire body of the cow is getting wet. Additionally, washpen cycles that are incorrectly set will lead to inadequate drip-drying time for the cow, which Goodell says should be between 10 and 12 minutes minimum.

“Water is an excellent transport medium for all kinds of bacteria,” adds Nickerson. “When cows come into the parlor and are not dry, water runs down the side of the udder to the teat and gets sucked into the inflation. It can infect other teats via cross contamination or go into the bulk tank and raise the bacteria count.”

Pre-dipping and forestripping

While washpens work to remove visible dirt from udders, pre-dipping goes after bacterial pathogens. “Pre-dipping is only effective if you can place pre-dip on a relatively clean teat,” says Jeff Reneau, DVM, University of Minnesota. “Organic matter has to be removed so the sanitizer can contact the skin surface, and there must be complete coverage of the teat.” Reneau says in addition, pre-dips should have a 20 to 30 second contact time. “It’s been shown not only to reduce cell count but also numbers of clinical cases. We don’t think of pre-dipping as having much influence on contagious mastitis, but there’s overwhelming evidence to show it can reduce environmental mastitis.”

Goodell says incidents like liner slips and flooded milking claws are often associated with increased mastitis because milk is driven back up against the teat end, carrying bacteria that may have come off the teat or from within the quarter. “Even properly functioning milking systems have splash-back of milk while the unit is attached, but the cleaner we get the teats before attaching the units, the fewer problems we’ll see with mastitis.”

In the age of  “paper or plastic?,” dairies face their own choice of paper or cloth towels to wipe udders clean before attaching milking units. Experts say whichever product is used, it must thoroughly dry the teat and it’s used once and thrown away (for paper towels) or washed with a sanitizer and dried (cloth towels).

You should select a pre- or post-dip that is shown to be effective by the National Mastitis Council (NMC) protocol testing. “The most important characteristic of a dip is if the company has subjected it to controlled proven study methods to prove its efficacy,” says Reneau. “There are enough dips that have been through this process that there’s no need to pick one that hasn’t been tested.”

Forestripping is also important. It helps lower SCC by removing the high somatic cell milk from the teat cistern and is an excellent method for identifying the early stages of mastitis. In today’s dairying, however, where throughput often takes higher priority, forestripping may not be done. Nickerson says forestripping helps catch cows that are beginning to show signs of clinical mastitis. “Often you won’t notice that a quarter has clinical mastitis until you look at the foremilk,” he says. “Your clients may be milking high cell count cows right into the tank, and if the dairy has had a low SCC, it’s really going to hurt them.”

Another advantage of forestripping, says Reneau, is that it’s a powerful milk-letdown stimulus. “Applied properly and early in the prep phase, it offers excellent stimulation and a good way to screen for clinical cases,” he says.

Goodell says it is inevitable that the legal limit of somatic cells in bulk milk tanks will continue to be lowered. “Large and small herds alike will have to adopt effective methods of controlling and monitoring SCCs. Forestripping will be among them.”

Post-dipping

The National Mastitis Council says more than 50% of new udder infections can be prevented by dipping teats with an effective product immediately after every milking, but teat dipping does not affect existing infections. Post-dips are especially effective against the contagious pathogens Staphylococcus aureus and Streptococcus agalactiae.

Depending on where you live, environmental conditions can play a big part in teat dip management. “Teat dipping is extremely important when it’s hot and humid – conditions under which bacteria flourish” says Louisiana’s Nickerson. “Cows will do anything to keep themselves cool and relieve thermal stress. If they can find a mudhole to wallow in, they will. It’s important to practice post-milking teat dipping with conventional or barrier products to prevent bacteria from gaining access to teats.”

In extreme cold conditions, more care must be taken in properly applying teat dip, says Minnesota’s Reneau. After a review of human frostbite and extrapolating data, Reneau found that under any combination of temperature and windspeed that creates a windchill of minus 20-25 below zero, cows need to be protected from the wind when leaving the parlor. “If this isn’t possible, then I recommend that you don’t stop dipping, but after dipping the milker should blot the teats dry before sending cows out.”

Don’t blame mastitis on dips

If your client has rising SCCs and increased
mastitis and wants to change teat dips, first go back and look at the milking management. If the client is using an approved and tested dip, usually something else is to blame.

“Many factors can cause problems such as dirty stalls, alleys that need cleaning, teat surfaces that are dirty and others,” says Reneau. “You should never look at a single issue when investigating a mastitis problem. Dips and milking equipment are too easy to blame.”

Goodell adds that if there is a problem with the teat dip itself, it’s usually due to a recent change in how the dip is used, such as spraying vs. dipping, or due to a product change.

   “Often dairymen will let the teat dip cups get grossly contaminated and they’ll dip teats in them. They can be inoculating the teat with a slurry of milk, manure and bacteria,” says Nickerson.

There are also subtle differences in how individual milkers do their jobs. One may leave pre-dip on longer than another, will or won’t strip out a quarter or leave milking units on too long. Nickerson notes that if HACCP regulations go into effect in the future, dairies are going to need standard operating procedures for milking cows. “Not enough dairies have standard procedures for milking or monitoring systems to make sure employees are following procedures.”

Reneau suggests when investigating mastitis or higher SCCs, you watch the milking routine. “The key is having a standard protocol and every milker should be trained in that protocol. Even if they do it wrong, they’ll be doing it the same way. Build a protocol that ensures teat coverage, dips, proper contact time, adequate cow prep, teat sanitation and stimulation.”

Goodell says he likes to monitor the number of mastitis cows identified on each shift, the amount of milk produced per shift, the number of reattaches and the amount of time it takes a particular crew to milk a shift. He says it’s important to only compare night shifts to night shifts and day shifts to day shifts.

Of course how your clients handle teat dip itself can determine if it will be effective or not. Freezing or overheating of dips can cause
components to settle out. Nickerson says sometimes dairymen don’t get containers closed and the dip is contaminated by air or water which destroys the integrity of the dip. He adds that water quality or water contaminated with organisms like Pseudomonas that is used for reconstitution also can contaminate the dip.

NMC suggests that teat dip is not used after its expiration date and that it be used according to label instructions including recommended concentrations and correct dilutions.

Clean and dry cows as well as sanitized teats are critical in the fight against mastitis, but prevention strategies of mastitis still go head to head with parlor efficiency and a faster throughput. “At an NMC meeting someone said a faster milking routine is not acceptable if losses in milk yield or milk quality are higher than reduced labor costs,” sums Reneau. “There is undue pressure on throughput when you put it in context of the whole issue of milk quality, mastitis and maximizing yield. That’s something each dairy has to decide for itself as that issue continues to be pushed, but they have to decide on throughput or doing a better job.”

 

Selecting teat dips

Teat dips are numerous, but not all have been registered by the FDA, and still fewer have controlled data to support their claims, which can make it confusing for your clients, says Greg Goodell, DVM. “There are five major groups of teat dips: iodophor-based dips, chlorine-based dips, chlorhexidine-based dips, quaternary ammonium-based dips and everything else. I try to steer producers away from the ‘everything else’ category unless it has excellent data supporting it.” Goodell says the basic differences between products within each of these categories are concentration of germicide and type and amount of skin conditioners. He recommends to:

1. Use a product registered with the FDA with efficacy data to support its claim. This should be available from the distributor.

2. Pre-dip and post-dip with the same product to avoid skin irritation by chemical interactions.

3.   Herds with an active mastitis outbreak may want to consider a slightly stronger teat dip, but care should be taken to monitor teat health. If the change results in increased skin irritation it will lead to hyperkeratosis of the teat skin and may increase mastitis.

4. Use barrier dips during periods of inclement weather.

When selecting a teat dip, the National Mastitis Council recommends choosing a dip that is FDA-registered and has been tested by either of the following methods:

  • Experimental challenge evaluates ability of a teat dip to prevent infections in dairy cows under conditions of experimental exposure to mastitis pathogens. This protocol determines effectiveness under experimental conditions only.
  • Natural exposure evaluates ability of a teat dip to prevent infections in dairy cows under commercial dairy practices. This protocol determines effectiveness under natural conditions.
  • Each year, NMC publishes a list of commercially-available, FDA-registered teat dips and the type of peer-reviewed study used to test them.

 

To flame or not?

Flaming udders has become more popular, especially on larger dairies, to decrease dirty udders coming into the parlor. Karen Jacobsen, DVM, MS, University of Georgia, says in areas like the southeast where udder hair holds a lot of mud and dirt, flaming the hair off can help SCCs go down because cows come into the parlor cleaner.

“There’s a tremendous difference between trying to wash off udders with dirt and manure in the hair, and cows coming into the parlor clean,” she says. Jacobsen recommends that a dairy flame every cow that is going to freshen that week, then flame the whole herd once every three months.

She says flaming in itself is not difficult and cows don’t seem to mind. If you’re unsure about recommending it to clients, she says to do what she did – go to a client’s dairy and try it yourself.  “I always feel better recommending it now that I’ve done it, and I feel I can teach people. It only take seconds, and it’s much easier to do in the parlor than in the lockups or freestalls. Even first calf heifers that have never been in the parlor will let you do it if you’re quick,” she says. “You just need to move the wand quickly across the base of the udder.”



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