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0907 PD: What to consider when choosing an effective teat dip

Joe Morelli Published on 31 August 2007

Mastitis is the No. 1 disease with economic impacts to dairy producers. In fact, there are more than 30 microorganisms known to cause mastitis and seemingly just as many teat dip products. So how do you choose the best product for your dairy operation? The best approach is to choose a teat dip that:

• works in your specific housing and management system
• consistently and effectively kills mastitis-causing organisms
• maintains healthy teat skin
• has been proven effective and is backed by committed service

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Management
What teat dip is best for your operation can depend on your management and the environment. Generally, non-barrier teat dips are suited for cooler, drier climates, but hot, humid weather calls for a barrier teat dip. Some dairies switch teat dips with the seasons for a customized approach. For example, an Idaho dairy might use a barrier dip only during rainy seasons. Walk through your barns. If you need boots, your cows are likely fighting environmental mastitis pathogens, so a barrier would be a smart choice. If you can wear “church shoes” into the barns, cows are more likely to face contagious mastitis spread during milking, so a non-barrier teat dip would suffice. True barrier teat dips provide excellent protection; however, be sure to train milkers to properly remove the barriers when prepping cows for their next milking.

Kill power
Generally, the stronger the germicide - the killing agent in teat dips - the better chance of reducing bacterial levels on skin and the lower the risk of mastitis. Consider the germicide’s speed of kill and how many organisms it affects. Methods for assessing germicidal performance of teat dips include variations to the AOAC Germicidal and Detergent Sanitizer Test, excised teat test and on-cow clinical studies such as the NMC’s experimental challenge and natural exposure protocols. As with all scientific endeavors, there is the balance between the speed, precision and repeatability of laboratory testing versus the more costly, complicated, but more real-world measures of clinical testing.

The most common laboratory method is a variation of the AOAC method where an interfering agent (i.e., milk) and a bacterial challenge are added to a teat dip sample. After a designated period of time, the mixture is neutralized to stop the germicidal action, and the remaining viable bacteria are counted. In parallel, a non-germicidal treatment is also run. Results are often reported in terms of Log10 reduction which indicate how much more the test product inactivated bacteria versus the non-germicidal control at the given exposure time. The Log-based numbers are used to more easily describe large numbers. The Log value shows how many zeros follow (i.e., Log 4 = 10,000, Log 5 = 100,000, etc.).

Choose teat dips that demonstrate broad spectrum kill and that have been tested with an interfering agent like milk. Many germicidal technologies do not share the same breadth of killing power, and weaknesses in germicidal systems are often found when testing with real-world interfering agents. An example standard that I use is to demonstrate at least 5 Log reduction in 15 to 30 seconds with a 10 percent milk challenge against the eight most common mastitis-relevant bacteria. Log 5 equates to about 99.999 percent kill.

It can be difficult for producers to judge accurately the germicidal performance of a teat dip because mastitis is complex in both the range of microorganisms and the array of environments on dairies. While germicidal information can be useful, only make product comparisons if germicidal testing was conducted within the same study.

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Teat condition
Teat dips should contain a skin conditioning component, such as humectants, emollients, and exfoliants, to help maintain healthy skin in many environmental conditions. Rapid changes in weather, improper milking equipment operation, harsh chemicals and infections can all irritate teats.

Teat Club International, a group within the NMC, has developed an excellent diagnostic method to identify if a skin issue exists and the possible causes to investigate. However, it offers limited discriminating power when comparing two good conditioning teat dips. Researchers also have used a visual grading scale of teat skin and teat ends known as the Goldberg method. This subjective visual grading method still has limited discriminating power.

It is difficult to design quality research studies to identify true teat dip effects. The best studies are performed using split udder designs where half the udder is treated with one product and the other half with another. They offer the lowest risk of bias, but unexplained variation in scoring is still observed, and the limits in discrimination power are apparent. Good skin conditioning is a very important factor when selecting a teat dip.

Product quality
It’s important to be confident in a consistent quality teat dip with every container. Teat dips must be manufactured under good manufacturing practices (GMPs), which are federally mandated procedures to help ensure the quality, safety and efficacy of drug products. GMP programs will include a range of testing to approve all incoming raw materials and outgoing finished goods. It will entail careful manufacturing process research and manufacturing site validation. GMP quality systems impart a significant cost, and not all teat dip manufacturers apply the same quality standards. Unfortunately, there is no way to look at a product label and discern the level of quality.

High-quality products are supported by clinical studies. The NMC provides guidelines for the clinical testing of teat dips that include “experimental challenge” and “natural exposure” protocols. The experimental challenge models the contagious path to infection by challenging a cow’s teats after milking with a concentrated solution of Staph. aureus and Strep. agalactiae, followed by dipping two of the four teats with a test product. The rate of new infections is measured over time, and the NMC recommends a minimum performance standard of at least 50 percent reductions in new infections versus the no-treatment control. These costly studies often are run in partnership with academic research herds and can be completed in just 2 to 3 months. In comparison, the natural exposure protocol monitors the natural events of new mastitis infections. This is the most real-world measure and allows assessment against both contagious and environmental mastitis cases that arise within the study herds. The studies are extremely expensive and often can take a year or more to complete. Many manufacturers primarily rely on experimental challenge studies to clinically support their products.

Kill power, skin conditioning traits and quality of a teat dip are all important factors when choosing a teat dip. But don’t just look at the label. Consider your herd’s management factors, and use the most thoroughly tested and proven teat dips from providers that offer reliable service and adhere to high-quality standards. PD

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References omitted but are available upon request.

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