Environmental temperature changes have little effect on the CMT as long as the milk has been refrigerated and is not over two days old. Herd mastitis levels can be estimated from tank CMTs. A CMT of 2 or 3 on tank milk indicates a probable high percent of infected cows. Disadvantages of the CMT Scoring the test may vary between individual testers. It is necessary to be as consistent as possible to insure uniform results.
Scores represent a range of leucocyte content rather than an exact count.
False positive reactions occur frequently on cows that have been fresh less than ten days, or on cows that are nearly dry. These animals should be tested closer to the middle of the lactation. Conducting the CMT Testing individual quarter samples requires the use of a plastic paddle having four shallow cups marked A, B, C and D for easy identification of the individual quarter from which the milk was obtained. An equal amount of the CMT reagent is added to the milk. The paddle is then rotated in a circular motion to thoroughly mix the contents.