Milk quality and mastitis

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Editor’s note: Eighth in a mastitis series

Milk quality means different things to different veterinarians. To some it’s simply low somatic cell count milk. To others it’s a complex subject involving SCCs, bacteria counts, management programs, premiums, cow health and welfare and more.

“My clients are extremely focused on producing quality milk for two reasons,” says Andy Johnson, DVM, Seymour, Wis., “The main reason is consumer confidence and the second reason is economics. They fully understand that they will get more milk per cow with a lower SCC and they get a premium from their milk plants which is very significant.”

“Milk quality monitoring is all about prevention,” says Ken Mitchell, DVM, Valley Veterinarians, Inc., Tulare, Calif. “Since large herds have more animals at risk, they are more receptive to investing in such preventive services. We are much more involved in milk quality programs on dairies when we also provide lab diagnostic services. When we report lab findings to clients, we are offering them advice on how to deal with the results. No one is better suited to this role than the herd veterinarian.”

Mitchell adds that when clients know you offer these services, they know you are interested in their mastitis problems and can provide information on how to improve their milk quality. “This interaction leads to records analysis to investigate problems, discussions on mastitis prevention programs, vaccination protocols, treatment protocols and products, not to mention barn analysis, milking procedures, teat dip programs and milker training.”

Johnson also offers complete quality milk consultation services. “I do complete milking machine evaluations, complete milking time evaluations, cow comfort evaluations and offer culturing and milker schools.”

Milk quality services

Ken Mitchell’s California practice has had a milk quality lab since the mid 1970s. “Our practice serves mostly large and expanding dairy herds, and such herds are more likely to be interested in biosecurity issues such as pre-purchase sampling and regular monitoring of the milking herd for infectious mastitis,” says Mitchell. “The growth of our lab has been a direct result of client demand and cow numbers.”

The milk quality services Mitchell’s practice offer are routine mastitis bacteriology and Mycoplasma diagnosis. “Most of our sampling is focused on identification and control of infectious mastitis in dairy herds,” he says. “Bulk tank, pen and individual cow samples are plated on BBA and Mycoplasma agar for evaluation. BBA results are backed up by esculin and coagulase tests to definitively diagnose Strep. ag and Staph aureus.” Also, Mycoplasma enrichment techniques are used on tanks, pen samples and other pooled samples to increase sensitivity in detecting herd problems.

Laurie Day, DVM, Dairy Health Services/MPS, Jerome, Idaho, has been offering milk quality laboratory services for the last 10 years. The practice, run by she and husband John Day, DVM, does individual cow cultures for general bacteria, Mycoplasma cultures, and some bulk tank work, including bacteria and Mycoplasma screening and a health department series where she performs standard plate counts, LPC’s, PIs and coliform counts.

“I think there’s additional information we can glean by doing these extra steps beyond just somatic cell counts,” Day says. “For instance, with LPCs and PIs we can start focusing a little more on things that may be a clean up problem or may be related to pre-milking hygiene. Even on the bacteria screens if we’re ending up with high numbers of Streptococcus and coliforms, it may indicate that the milkers need to get the teat ends cleaner.”

Johnson says SCCs and bacteria counts are a must. “The reason SPC and SCCs are so important is because these are the two numbers our government uses to regulate farms,” he says. “When available, I like to have individual SCCs on the cows in the herd, and would like all of my herds to have an SCC in their bulk tanks under 150,000, with bacteria counts less than 10,000.”

Mitchell’s milk quality lab lends itself well to providing additional milk quality programs. “We work a lot on records programs to help record mastitis events, track herd problems and manage the hospital pen,” he says. “We work heavily with Dairy Comp 305 records to do this.”

Putting results to use

Mitchell says his practice has a zero tolerance for the presence of infectious organisms in the bulk tank. “Any identification of Mycoplasma, Staph. aureus or Strep. ag in our clients’ bulk tank is cause for investigation,” he says. “The most important task we have is evaluating our lab results and characterizing the mastitis as either an infectious or an environmental problem.”

He adds that infectious problems are followed up by sampling to identify source cows, as well as modification of milking procedures and hospital pen hygiene to prevent further spread. Environmental problems are dealt with by correcting problem areas in the environment, or in milking procedures and management.

All the great data in the world won’t solve the problem if the right people don’t see it and understand it. Johnson says if the people who do the work are not included in the program, the program usually fails. “Posting the SCC and other milk quality information on a bulletin board is a great tool so that everyone working knows what is going on,” he says. “I’ve been to dairies where the SCC is so high the farm may be shut down, yet the milkers don’t have a clue why I am there. It’s easy to convince the owner to make changes, but often the workers feel like they are being punished. The most important thing is to make sure the workers understand why changes are being made and what the benefit to them will be.”

Turn-around time on culture results, says Mitchell, is an advantage for veterinarians with their own labs. “Because we are involved in the dairy, we know if we are doing routine monitoring or are in the midst of an infectious outbreak. To respond to this, we often will plate on ‘off’ days in situations where quick results are critical, and we’ll also do ‘early reads’ on Mycoplasma to identify and remove positive cows quickly. Traditionally Mycoplasma is read at three and seven days, but most all heavy growth cows are identified by three days and I have found that if cautious, we can identify many of these cows at two days of growth.”

Day agrees and says she’s able to let her husband/partner John know immediately when one of his clients has some problems with their cultures. Almost all of the dairies they do culture work for have fax machines, and they can get results out to them right away. “We get preliminary results within 24 hours and can get that information to them quickly to help them in their segregating and culling decisions,” says Day. Like Mitchell, she likes to identify Mycoplasma in a herd early by sampling the commingled hospital milk as well as the bulk tank.

Monitoring results

Day also provides clients with a weekly results sheet. Using her technician to enter the data into a spread sheet, the lab prints out a report that is a summary of all of the cows a dairy has sent samples in for that week or month, organized by culture results. “We can look at this list and see right away who the Staph.-positive cows are, etc.,” says Day. “It organizes our data better for the client.”

For those dairies who are not clients, Day says she sends this report to the dairy’s veterinarian as well. “The other veterinarians really appreciate having this information and I think it’s one of the main reasons they recommend that their herds send samples to us instead of the other lab in town.”

Johnson says veterinarians should monitor milk quality information at least monthly or the dairyman may not pay attention to the information. “Veterinarians do not have to offer all services, but do need to monitor the information that is already there,” he says. “The veterinarian can then direct his/her client as to what services they still need and where they can get those services. Give your clients direction or else they may spend money in the wrong places.”

Mitchell says many of his clients will record all cases of mastitis and all mastitis treatments, and his practice has developed systems which allow clients to easily record disease events and drug treatments to generate a daily hospital management list. “We have a daily printout showing the number of times each cow has had mastitis, what her last mastitis date was, how many days she has been in the hospital, and when she is free of residue.”

He said a recent example of this system was Mycoplasma outbreak where he was able to list all cows who had been in the hospital pen when the exposure occurred. “We then could sample them as probable causes of our bulk tank Mycoplasma positive rather than sampling the whole pen or herd. It only took a few seconds at the keyboard with Dairy Comp 305.”

In addition to milk quality services for clients, Day does some phone consultation and a little more interpretation for dairies that are not their regular clients. “We may then give them some general recommendations and refer them to their own veterinarian to get some dialogue going,” she says.

“If the veterinarian doesn’t care about quality milk, I can assure you the farm owner also doesn’t care,” says Johnson. “If every visit consists of looking at milking procedures, milking equipment and environment, factors in the ‘mastitis triangle,’ you’ll find the problem. When you do not do a complete job, you can overlook multiple factors and not a get a permanent fix to the problem. It is the veterinarian’s responsibility to monitor milk quality and properly motivate the dairy to produce quality milk.”

Setting up a lab

Both Mitchell and Day agree that a milk quality lab can provide valuable services to clients as well as be a profit center for the practice. “I would encourage everyone to set up their own lab,” says Mitchell. “The benefits to the practice can be substantial as far as building other services and increasing your involvement with producers. As it grows, a milk quality lab can also be a good money maker for the practice.”

Day says at the minimum veterinarians should have a good relationship with a laboratory in their area. The other milk quality lab in Jerome, she says, does a lot of samples, and bulk tank work, including all the lab work for one of the cooperatives in the area. “Sometimes we send them cultures that we can’t identify by our standard means.  I don’t have to keep a lot of specialized and expensive media on hand,’ says Day.

But if there isn’t one available or you don’t feel comfortable with an area lab, it’s not that difficult to get started. “You don’t have to have a lot of fancy equipment,” Day says. “In our lab we have a very old incubator cast off from a university that works well, in addition to a converted refrigerator we use for an incubator. Your biggest investment might be the incubator, but often you can find a used one.”

She adds that it’s important to find a good supplier of media and get some good reference material. “Some that we have used and recommended are the laboratory procedure materials from the National Mastitis Council, and Current Concepts of Bovine Mastitis.”

The American Association of Bovine Practitioners quality milk seminars are also a great place to gather information and learn techniques, says Day. She says the three day seminar covers laboratory techniques, general information on organisms, equipment checks, records analysis and more, and is worth the investment.

“My experience is that if you don’t do the lab work yourself, soon you are out of the loop,” says Mitchell, “and someone else is advising your client on milk quality issues.”

Make sampling count

Laurie Day, DVM, says producers often are excited about regular bulk tank sampling, but she adds that if you leave the sampling up to the client, often in two to three months it can be forgotten.

“We’ve found that it’s easier for them and it’s better for us if we go out and get the samples ourselves,” Day says. “We have some herds where the milk truck driver will take an extra sample and put it in the freezer for us, and sometimes that can work out okay.” However, she says, when she took samples herself, she found a lot of variability in sampling by other people.

“For instance, they might take the last of the milk that went into the tank and hadn’t been agitated long enough with the rest of the milk, or that last batch of milk came from the Staph. string and that’s what they are scooping out. I’ve also seen people falsify agitation records. I feel more comfortable if we take the samples ourselves, then we know when we read the samples in the lab that our techniques are consistent and if we have high counts, they’re real.”

Day says transportation of samples is also key. Samples that may come in from producers or milk truck drivers may have warmed during transport, so she likes to keep them on ice until it gets to the lab.

Dairy Health Services/MPS also utilizes a veterinary technician, Jannell Kral to drive to dairies and take the samples herself.  “Once a month, Jannell collects and transports bulk tank samples from six to ten producers so we know the quality of samples we’re getting.”



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