Pedometer.

Pedometer.
Electronic heat detection by means of a pedometer applied just above the fetlock. The amount of activity / walking is recorded by the device which is read by a scanner each time the cow enters the milking parlor. An added advantage, particularly on large farms, is that the cows are inventoried each time they come into the milking parlor. A disadvantage is the initial cost of the computerized system.

Drost M (1979)