There are many different mating patterns used around the world. In general, Choice recommends a range of 12 to 18 hours between AI services if possible. An example of the preferred mating pattern for a gilt found in heat in the AM is 1) skip the AM service, 2) first service 12 hours later, 3) second service 12 hours after the first, 4) third service 12 hours after the second service. Take care; the third service should only happen if the gilt is still in good standing heat.