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Extension > Agriculture > Dairy Extension > Milk quality and mastitis > Low BTSCC year around? Oh yes you can!

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Low BTSCC year around? Oh yes you can!

Dr. Jeff Reneau & Dr. Russ Bey

Published in Dairy Star June 11, 2005

Are you a control freak or are you of the mind to live and let live? Well, when it comes to holding bulk tank somatic cell counts (BTSCC) in check this summer we hope you are a mastitis control freak!

Everybody knows that BTSCC increases during the summer. The average BTSCC increase on Minnesota herds during the summer months is approximately 75,000 to 100,000 higher than the cooler months of the year. In fact, we have come to accept it as an unalterable fact. But, does it have to be this way? Could you do a better job to keep BTSCC at a low level this summer?

Study of BTSCC records in Minnesota dairies well known for their ability to maintain low BTSCC year around demonstrate it is possible. One striking feature that distinguishes these dairies is a very low day-to-day BTSCC variation, ranging from only 10-20,000 BTSCC. This is outstanding! These dairies can be characterized by a single word... consistency. Equipment is always clean and functioning properly, personnel follow established procedures carefully, and the cows are clean (especially teat surfaces) year around. We are not surprised by this observation. Several University studies in the U.S. and Europe have verified that this is true.

There has been a lot of recent talk about the changing mastitis pathogen profile these days. Some are saying, "things are not what they used to be and maybe that is the problem." It is true that things have changed. Today environmental mastitis pathogens (Coliforms and environmental streps) account for most clinical and subclinical mastitis on dairies. Based on University of Minnesota Udder Health Lab data, 80% of all mastitis cultures during 2000-2003 indicated an environmental pathogen origin (see chart). Several years ago, Ohio State researchers found that 82% of all clinical cases in 9 modern freestall dairies were caused by environmental bacteria. This is especially true during the summer months where they found exposure to environmental pathogens very high in bedding.

During the summer, bacteria grow at rates 300-500 times faster than during the cold winter months (40° F or less). During the summer wherever the cow lies down, bedding or pasture surfaces can be teaming with bacteria. Unless we take aggressive management steps to minimize exposure, teat surfaces will be contaminated with lots of environmental bacteria, many of which are mastitis pathogens. Both the cow's hygiene and cleanliness of the cow's environment are much more important during summer than during winter.

It is worth reminding ourselves that whatever is on teat surfaces needs to be removed prior to milking or the risk of creating a new mastitis infection increases dramatically. A routine (monthly) bulk tank bacteria culture is an excellent means of gauging how well you are doing. High levels of the environmental bacteria in the bulk tank milk indicate that you need to be doing a better job at pre-milking cow prep or bedding management. In fact you need to do A LOT BETTER during the summer to have the same effect as during winter.

With the warm summer months now upon us, are you ratcheting up your mastitis control or are you letting the bacteria take charge? What exactly do you need to do? We suggest the following:

Milking procedure

Bedding management


Cow hygiene

Cow health factors

Keeping BTSCC lower than 200,000 is possible year around. It will take at little more consistent effort during the warm months of the year but it is well worth it. For more detailed information, visit the dairy extension web site ( and click on "Quality Counts."

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