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0906 PD: How can we ensure our udder prep cloth towels are truly clean and sanitized?

Roger Thomson Published on 21 September 2006

In the National Mastitis Council’s February 1997 newsletter, Washington State University researchers concluded one of the following three practices were necessary to successfully clean a dairy’s cloth prep towels. Performing two of the three would add an extra margin of safety to ensure sanitized towels:

1. hot-air drying
2. hot-water washing
3. bleach

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Field experience from 2005 shows initial towel samples consistently culture bacterial growth (both coliforms and environmental Staph and streps). Was the Washington State research wrong, or have things changed in towel laundering practices since 1997?

The greatest challenge to laundering udder cloths is the huge amount of organic material typically found on each towel. This organic load must not only be loosened and removed from the fabric matrix itself, but must be rinsed out of the machine completely without recontaminating the clean towels.

Consider the following laundering practices to assist with cleaning and sanitizing udder prep towels:

1. Type of equipment used
Top-loading washing machines are less expensive initially, but they do not handle heavy loads of organic material. Therefore, they do not clean and rinse as effectively as front-loading machines.

2. Overloading machines
Cloths get cleaned by moving and rubbing against each other during the wash cycle. Cloths packed tight do not move and are therefore not cleaned. This also prevents an effective rinse cycle to remove bacteria-carrying organic material.

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3. Not drying
Money is saved on drying costs and the need for more towels. (Towels are not tied up in a dryer.) Bacteria counts (colony forming units or CFUs) are higher on wet towels than dry towels.

Drying is an excellent way to kill bacteria. Poor washing practices leave heavy organic material and bacterial load on the towels, and drying can complete the sanitization process.

Some milkers like wet towels because they wipe “cleaner” and are easier to hold. Typically, milkers struggle to clean pre-dipped teats that have dried. A good predip with a fast kill time will still be moist when wiped off. To quote Dr. Andy Johnson, “If our goal is to attach milkers to teats that are clean, dry and well-stimulated, how can we produce dry teats with a wet towel?”

4. Wash water temperature
Many dairies struggle to have hot water for clean-in-place (CIP) cleaning, let alone for multiple laundry loads. Towels are not consistently washed in water greater than 160°F. If combined with overloading, this problem creates a very “dry” load of towels accentuated by a lack of hot water.

5. Transport baskets
Baskets must be kept clean inside and out. The parlor storage and handling system represents a potential high-risk area for contamination of clean towels. Aprons or “kangaroo pouches” are excellent at increasing parlor efficiency, but they must be kept clean. Closed-topped transport baskets prevent manure from splattering onto clean towels. Do you know where your clean towels are right now?

6. Microfiber towels
These new towels have some advantages in drying speed and life expectancy, but it is more important not to overfill machines with this type of towel. If compressed in a machine, they are difficult to sanitize.

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7. Bleach or sanitizing detergent
Too much organic material can interfere with bleach, and the bleach and detergent chemically fight with each other. Bleach during the rinse cycle is very effective but not practical.

With all of these variables, it is difficult to identify the most cost-effective and efficient way to consistently produce clean, sanitized udder cloths.

Last summer, a cooperative team of ABS Global and Ecolab technical service members in the Midwest began working with several dairies to identify bacteria-contaminated towels post-washing and implement solutions to correct the problem. To date, the following steps have been used to identify and produce consistently clean and sanitized towels:

Step 1. Culture random towels to assess initial towel cleanliness.

Typically, we find gram- positive and gram-negative organisms at levels of thousands to tens of thousands of CFUs.

Step 2. Evaluate current laundering equipment and practices.

To date we have insisted on installing a front-loading commercial washing machine, if one is not in use. We establish a protocol designed to prevent overloading the machine. This has turned out to be one of the most difficult steps to change how dirty towels are managed.

Most recently we have tried to sanitize towels from residential (top-loading) washers. If the machine is not overloaded, the water is hot and bleach is added in the bleach-dispensing port so it is dispensed during the rinse cycle, we have been able to produce towels from top-loading washers with no bacterial growth.

Step 3. Install a chemical pumping system directly to the washing machine.

The pumping system automatically dispenses the correct amount of liquid detergent and liquid sanitizer into the washer for the wash and rinse cycles, respectively. After one to two weeks with this system in use, we culture more random towels.

Step 4. Start the sanitizer dispensing rate at a low level to control costs and minimize wear to the towels.

Typically, we find gram-negative organisms are less than 100 CFUs or completely eliminated. Gram-positive organisms are typically harder to clear.

Step 5. Increase the sanitizer amount.

We culture towels until we get no growth from gram-negative and gram-positive organisms and re-culture towels every three to six months to monitor results.

The value of this program has been two-fold. The decreased waste (by elimination of powder detergents) has produced a cost savings in addition to the assurance of towel sanitation. Through working with these dairies, we have realized that visual assessment of a towel is not enough to know if the towels are properly clean and sanitized.

A lack of attention to detail in correct towel laundering has resulted in bacteria-contaminated towels being used on many dairies. We know the removal of the organic matter is the largest challenge on a dairy. Through the steps discussed above, a dairy can take measures to improve towel sanitation and ensure towels are properly cleaned. A clean towel is one of the many important steps to proper udder health management. PD

References omitted due to space but are available upon request.

—From ABS Global Breeders Journal

Roger Thomson, Team Management Concepts, PLC, Battle Creek, Michigan

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