Generally, cow behavior (especially when she stands to be mounted or standing heat) is the best way to determine when a cow should be inseminated (normally 12 hours after the initiation of standing heat and/or after the cow was first observed in heat or standing). Several commercial products that measure mounting activity are available (such as Heat Watch by ABS or Kamar Mounting patches) with some being able to define the actual time of initiation of standing estrus. Activity measurement devices (such as pedometers) can also be useful.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
