As the herd average days dry deviates from 60 days, average milk production of the herd decreases. However, as the genetic potential for milk production continues to increase, it becomes a management challenge to stop milk production in high producing individuals in order to achieve the 60 day goal.s the herd average days dry deviates from 60 days, average milk production of the herd decreases. However, as the genetic potential for milk production continues to increase, it becomes a management challenge to stop milk production in high producing individuals in order to achieve the 60 day goal.