3. Methylene blue reduction test ( Redox potential)
· It reflects the anaerobic fermentative metabolism of the bacterial population.
· Mix 20 ml ofrumen fluid with 1 ml of 0.03 % methylene blue in a test tube and let to stand at room temperature.
· Measure the time needed for the color of the mixture to be changed.
· Normal rumen fluid from cattle fed on a hay and grain diet needs 3 mm. to decolorize leaving a narrow ring of blue color at the top of decolorizing mixture.
· Abnormal reduction of time up to 15 mm indicates:
o Indigestible roughage.
o Anorexia of several days.
o Rumen acidosis.
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