TRENDING TOPIC ARTICLE: HERD HEALTH Published: September 22, 2010 print issue In this article, University of Kentucky’s Jeffrey Bewley outlines several ways producers can achieve and maintain low somatic cell count milk, including adjusting milking protocols and culturing high-SCC cows. or scroll down to jump to the article. Because this article was so popular, we asked Bewley, “Of the best management practices you outlined, which practice do you think producers and employees most struggle with?” Bewley says, “Of those management practices listed, I think using bacteriological cultures is the most underutilized. So much information can be obtained from culturing milk samples. On-farm culturing systems make this practice even more useful.

"I think the main reason people don’t do this is because of negative experiences or unrealistic expectations. Many people think that a culture will tell them exactly how to treat a particular animal.

"Given how long it takes to get cultures back from distant labs and the relatively poor relationship between antibiotic sensitivity on a plate and in a cow, this is not a realistic goal. Cultures provide valuable information to focus prevention efforts toward controlling mastitis including identification of potential cull animals..”

By now, in one form or another, you have likely heard about upcoming changes to somatic cell count (SCC) limits for the dairy industry. Although there is some uncertainty about what the final requirements will be, it is clear that changes are occurring and most everyone will be affected. At this stage, the official regulatory SCC limit remains at 750,000 cells per milliliter. This limit has been in effect since 1993.

EU changes
Interestingly, the market has driven the current demand for lower SCC milk. Much of the rest of the world has had a lower SCC limit for many years. As we move toward a more global dairy market, what we do in the United States is increasingly affected by forces outside of our borders.


The European Union (EU) has indicated that, beginning October 1, 2010, any processor who ships milk products to the EU must ensure that the milk is obtained from farms with SCC less than 400,000. Actually, this regulation has been in place for awhile, but the 400,000 limit could be achieved by mixing milk from multiple farms. Now, the EU has indicated that each farm must meet this requirement.

Although a large percentage of the milk in the Southeast is used for domestic fluid consumption, the rest of the product is used for manufactured products or milk byproducts. This is where processors may export some product to the EU at times. Because of the changes in milk utilization, some processors may find it necessary to require all of their milk meets this requirement.

Across the country, some processors and cooperatives have already made decisions about how they will handle this situation and have distributed letters to producers. Other processors are still deciding how they will handle the new limits.Exactly how this limit will be calculated remains to be seen also. The EU standard states that the three-month rolling “geometric” average cannot exceed 400,000.

Essentially, this means that a few tanks over 400,000 would not be a problem as long as they were balanced out with more tanks less than 400,000.Regardless of this new development, all milk processors would like to acquire milk with lower SCC. Milk with a lower SCC results in higher cheese yields and longer fluid milk shelf life. An important distinction to make is that milk with a higher SCC does not represent any risks or threats to human health.

Over the next few months, we will learn more about how this limit will be enforced. For some producers, these changes may lead to some painful decisions and challenging hurdles to reduce bulk tank SCC. However, looking at the glass half-full, we should view this as an opportunity. Maybe we can use this opportunity to produce a higher- quality product for dairy product consumers. Maybe this will have a positive effect on consumer demand.

At minimum, it can have a positive effect on consumer perception of production of a safe, wholesome product. Perhaps, most importantly, reducing somatic cell counts at the farm level will help improve production and profitability. With a bulk tank SCC of 500,000, it is estimated that 16 percent of the quarters in the herd are infected and milk production is 6 percent less than it would be if the bulk tank SCC were 200,000.

Back to the basics
In dealing with SCC problems and maintaining a low somatic cell count, it is important to remember that there is no single- most important component. When we ask dairy producers who maintain a low SCC how they do it, they tend to answer, “attention to detail.” Don’t try to make the milking process more complicated than it is.

Resist the temptation to find magic bullets to fix underlying management problems. There are numerous products designed to help keep a low SCC in your herd, from milking equipment to teat dip to feed additives. However, none of these products can overcome cows in a dirty environment or poor milking procedures.

Seizing the opportunity
If you are dealing with a SCC problem, here are a few things to consider in thinking about how to deal with the problem. Even if your SCC is low, take a few minutes to review these points yourself and also with your milking staff to keep producing low SCC milk.

• Keep cows clean.
You should strive to keep cows as clean as possible before they ever enter the milking area. Clean cows are not only exposed to fewer environmental mastitis bacteria, but they are also easier to clean prior to milking.

• Milk clean, dry teats.
Communicate with your milkers to make sure they understand it is critical to milk clean, dry teats at all times, paying particular attention to ensure that the teat ends are clean.

• Wear gloves
Because bacteria are less likely to adhere to gloves than rough, calloused skin, nitrile or latex gloves should be worn during milking. Contagious mastitis-causing bacteria, like Staph. aureus, may live on your hands and be transmitted between cows during milking. Gloves minimize the spread of contagious mastitis between cows during milking and help protect the milker’s skin. Gloves are also easier to disinfect than bare hands.

• Pre-dip
Teats should be pre-dipped with a sanitizing solution. Pre-dipping eliminates bacteria on teat ends prior to milking and helps to control mastitis caused by environmental mastitis pathogens. When pre-dipping, at least three-quarters of the teat should be covered, with a goal of covering the entire teat. The pre-dip should remain on the teats for at least 30 seconds before drying.

• Dry cows with individual towels.
Teats should be thoroughly dried with a single-service, absorbent cloth or paper towel. Never use the same towel on two cows. Using the same towel on multiple cows increases the chances of spreading mastitis from cow to cow during milking.

• Post-dip
As soon as possible after the milking units are removed, teats should be dipped with a post-dip, demonstrated to be an effective germicide through independent research. An effective post-dip kills bacteria on teats and reduces the rate of new infections from contagious mastitis pathogens.

• Revise prep-lag time.
Prep-lag time is the time between when teat surfaces are first massaged or forestripped until the milking machine is applied. Oxytocin, which causes milk letdown, reaches peak levels at 60 seconds after stimulation. Therefore, milkers should be attached within 1 to 1.5 minutes after teat stimulation. Coordinating milker attachment with milk letdown helps ensure that the milkers are attached during the time frame when milk flow is highest. Attaching milkers too soon or too late can result in excessive milking time or reduced milk yield.

• Culture high-SCC cows.
To get a handle on the situation, you need to collect milk samples from high-SCC cows to determine the causative bacteria. High-SCC cows can be identified through DHI or with a CMT (California Mastitis Test). This information can be used to alter mastitis control, prevention, and treatment options to fit your herd’s conditions.

Extra care and precaution are necessary during the collection process. By using strict, clean, aseptic procedures, bacteria from milk originating in the cow’s udder and not the cow’s teat end or hair, the sampler’s hands or the barn environment are collected. If samples are not collected and transported correctly, culture results will not be of any diagnostic value. Work closely with your veterinarian to submit milk samples to be cultured and to interpret the results.

• Cull chronically high-SCC cows.
Particularly in small herds, one or two cows can contribute a higher percentage of cells within a bulk tank. Often, removing a few cows can make a big difference in bulk tank SCC. If you have cows with consistently high SCC (even high producers), it may be more economical to cull them than keep them in the herd.

• Equipment check
Although it may be expensive, it would be worthwhile to have a thorough equipment evaluation performed to make sure your equipment is not contributing to your SCC issues.

• Treat dry cows.
All quarters of all cows should be treated with an antibiotic at dry-off. The cow is most highly susceptible to mastitis immediately after dry-off. Thus, we want to give cows as much ammunition to fight off new infections during this period as possible. Without dry cow treatment, 8 to 12 percent of quarters will develop a new infection during the dry period. Dry cow treatment helps cure existing infections and prevents new infections from developing. An internal teat sealant (i.e Orbeseal) will provide additional effective protection.

• Consider using a coliform mastitis vaccine.
A coliform mastitis vaccine will reduce the number and severity of clinical coliform mastitis cases, which are generally picked up from the cow’s environment. Check with your veterinarian for recommended protocols for commercially available vaccines. PD

—Excerpts from Kentucky Dairy Notes, July 2010

Jeffrey Bewley