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1. Contagious Mastitis

Dr. Susan Keller is having a typical day in her active dairy veterinary practice.  Her cell phone rings, and she speaks with Mr. Oliver McCormick who owns and operates a dairy farm of about 150 milking cows.  

“I’m having some mastitis problems. You know we’ve talked before about my trying to lower my herd’s somatic cell count (SCC) to get a bonus from the creamery?   Well, my last two counts have been over 300,000 cells per milliliter!   So it’s getting worse instead of better.  I think I’d like to treat all the infected cows with antibiotics so that my SCC comes back down."

“It sounds like you may have a mastitis problem going on there.  I will be coming to your place for your routine herd check  next Tuesday.  Let’s plan on spending some time developing a plan to lower your herd’s SCC. ”


The following Tuesday at Oliver’s dairy farm:

After Dr. Keller finishes the routine pregnancy checks, she talks to Oliver about the possible mastitis problem in the herd.  She checks both the latest farm DHIA report and the bulk milk tank SCC (bSCC) report from the milk processor.   

Looking at the DHIA report, Dr. Keller reminds Oliver that the SCC for each individual cow is a measure of the degree of subclinical mastitis in that cow.  It is estimated that each doubling of the somatic cell count by an individual cow results in the loss of about 1.5 pounds of milk production each day by that cow (6).  A farm DHIA report includes reports for each cow and a summary report for the entire herd. Also included are statistics relating to milk production and SCC and a linear SCC score that is a logarithmic transformation of the SCC score.  The SCC linear score is linearly related to lost milk production and is useful in making management decisions since it reflects how much milk is being lost due to udder infection.


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