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1708 PD: Hide and seek: Manage subclinical and clinical mastitis through proper detection and treatment

Bradley Mills Published on 26 November 2008

Out of sight, out of mind. Oftentimes this mentality costs producers great economic losses to their bottom line when it comes to controlling subclinical mastitis in their dairy herds. And although clinical mastitis is easier to detect with clear signs and symptoms present in the milk, it can cause problems if there are no milk-quality protocols in place.

As consumer demand for high milk quality increases, the importance of implementing a milk-quality program that includes identification, treatment and prevention of mastitis is essential to operating a standout, successful dairy business. In a demanding market like today’s, fundamentals such as proper mastitis and milk-quality protocols must be in place in order to reduce lost profits and gain more milk in the bulk tank.

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Identifying mastitis: Conspicuous versus clandestine symptoms
Most producers can identify clinical mastitis with its obvious symptoms of flakes, clots or clumps in a cow’s milk. A systemically affected cow with grade 3 clinical mastitis is usually not eating, running an abnormally high or low temperature and displaying lethargic behavior. Early mastitis detection and immediate action saves valuable milk from being withheld from the bulk tank for longer periods of time due to more chronic or severe infections.

It’s the hidden signs of subclinical mastitis that cause setbacks on the farm, often going unnoticed and untreated, and ultimately jeopardizing the health of the animal and the overall economic health of the dairy operation.

For every case of clinical mastitis, experts believe there are 15 to 40 cases of subclinical cases in the herd. Subclinical mastitis can overtake a herd without the producer even being aware there is a problem. Early diagnosis and treatment are the best ways to combat subclinical mastitis and must be done through testing and cultures. Fortunately, there are several on-farm mastitis protocols for identifying subclinical mastitis in order to help ensure high-quality milk.

• Individual somatic cell counts
Evaluating individual cow somatic cell count (SCC) is an ideal method for identifying and detecting “hidden mastitis.” Work with your veterinarian regarding acceptable SCC measurements, but most producers identify a problem if the count is greater than 200,000 cells per milliliter. Cows above this point could potentially have subclinical mastitis. Producers can work with the National Dairy Herd Information Association (NDHIA), a great resource for individual cow testing as well.

• Bulk tank milk cultures and SCC
If producers don’t have an individual test protocol in place, they can look to the bulk tank milk cultures to see if there is a problem in the herd. Sampling intervals differ from operation to operation, but the more the better. One practice that works for many producers is to integrate bulk tank sampling into weekly, semimonthly or monthly herd health checks. It is important to obtain several samples over a long period of time when culturing – and not just a single sample – to ensure there is indeed a milk-quality problem.

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Reviewing additional elements such as the milking systems and individual cow SCC also help pinpoint deficiencies that are disrupting the milk quality. If individual and bulk tank SCC samples are high, they should be sent to a veterinarian for further examination and culturing to determine specific mastitis pathogens present within the herd.

• California Mastitis Test (CMT)
Producers can evaluate high-SCC cows with a cow-side test known as the California Mastitis Test (CMT). By taking a milk sample from each quarter, producers can determine if subclinical mastitis is present in each or any of the quarters. By reading and recording results on cows known to have high SCC levels, producers can perfect their test-administering abilities and become more accurate and consistent when it comes to identifying infected cows.

Interpreting results and matching the treatment to the bug
Subclinical treatment serves as an investment in a cow’s future milk production, but proper treatment must follow the interpretation of the culture results. Bulk tank testing can supply data such as presence or absence of a certain bacterial organism and also identifies the predominant bacterial group. The most contagious mastitis pathogens, Streptococcus agalactiae and Staphylococcus aureus, if found in the bulk tank milk, almost always indicate infected quarters in the herd. Streptococcus agalactiae in the bulk tank milk indicates that the cows have infected udders due to the shedding of bacteria in the milk from the infected quarters. Bacterial counts are usually greater when this pathogen is present because cows shed this organism in very high numbers. If the organism S. aureus is detected, it seldom causes high bacterial counts but does correlate with a higher SCC level.

Environmental streptococci and coliforms, such as E. coli, originate from poor sanitation in the milking routine and the cow’s environment. Contaminated milk lines, bedding, water and other common sources, including soil, manure, milking wet udders and inadequate cooling of milk, can produce positive milk samples. Isolating these pathogens and determining the predominant organism within the milk culture is important for pinpointing tactics regarding treatment methods.

Once the organism is determined, following up with treatment options such as intramammary infusions and teat sealants (if the cow is being dried off) are necessary, but only part of the solution. Regular evaluation of milking routines and procedures is vital to contributing to a safe and healthy milk supply. Making sure milking equipment is adequately and properly cleaned on a consistent basis is key to preventing high bulk tank bacteria levels in the future.

Lower SCC in your bulk tank with prevention methods
Finally, prevention methods must be explored on the dairy to help eliminate future mastitis problems. The following are tips that can accompany your daily milking routine to ensure you’re taking every precaution necessary to avoid mastitis problems:

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• Decrease exposure of teat ends to environmental pathogens by making sure bedding materials, milking equipment and water troughs are well-maintained and clean.
• Practice proper milking procedures, including teat dipping.
• Always milk treated cows after untreated herdmates. Incorporating standardized identification protocols for treated versus untreated cows will help eliminate problems in the milking routine.
• Work with a veterinarian to best determine specific milk-quality protocols for your farm.
• Develop a program for improving and monitoring udder health in dry cows (that are more susceptible to infection) by implementing dry cow mastitis protocols.
• Increase vitamin and mineral intake in feed with selenium, vitamin E and vitamin A, which help ward off infection.

By incorporating a milk-quality program that focuses on identification, treatment and prevention into an everyday routine, producers can have peace of mind when it comes to mastitis control and management. Working to eradicate mastitis through measures such as these will pay dividends in improved milk quality and better bottom lines. PD

Bradley Mills
Veterinarian
for Pfizer Animal Health

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