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2. Contagious Mastitis

Somatic cell count linear score1:

A somatic cell count linear score is a log2 transformation of the SCC score.   Each one unit increase in the linear score is associated with a doubling of the somatic cell count, and an estimated loss of 1.5 pounds of milk production per day (6).


Purpose of somatic cell counts:

  1. Identify individual cows affected with subclinical mastitis.
  2. Monitor herd improvement after management changes are instituted.
  3. Identify herd mastitis problems as soon as possible.


Interpretation of somatic cell count linear score for an individual cow:

  • 0 and 1: no evidence of subclinical mastitis
  • 2 : low suspicion of subclinical mastitis
  • 3 and 4: suspect for subclinical mastitis
  • ≥ 5: subclinical mastitis
  • 7 – 9: indicates that the cow is shedding extremely high numbers of somatic cells and is on the verge of showing signs of clinical mastitis.


A herd goal should be to have >80% of the animals with SCC linear scores ≤3.


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