Published online by Cambridge University Press: 01 June 2009
The adoption of the methylene blue test as an official method of grading milk in England makes this subject one of considerable importance. The predominating factor in this, as in other tests, is the condition of storage (time and temperature) of the sample. If mastitis affects the methylene blue reduction time of milk the factors responsible may be any or all of the following:
(1) The mastitis organisms themselves.
(2) Other organisms present (secondary invaders).
(3) Body cells, e.g. the so-called leucocytes of milk and also blood cells.
(4) Chemical changes in the milk as the result of the mastitis.
A related aspect is the value of the methylene blue test on single cow or quarter samples as a test for mastitis.