At any given time, 20 percent to 30 percent of your herd may be suffering from rumen acidosis. To find out if rumen acidosis is a problem in your herd, Alex Bach, director of ruminant production at Institute for Agrifood Research and Technology in Barcelona, Spain, recommends performing a rumenocentesis on 25 percent of the cows in your herd. “This is a practical way to measure rumen pH and find out if you are having a problem with rumen acidosis,” Bach says.

Samples should be collected at a time when rumen pH is likely to be near the lowest point of the day. If the ration is fed as separate components, a rumenocentesis should be performed between two to four hours after the cow is offered the primary concentrate meal of the day. If a TMR is fed, the samples should be collected at four to eight hours after the cows get access to the fresh ration.

After performing the rumenocentesis, use a pH meter for the measurement.

Other key indicators are reduced milkfat and a change in manure consistency.