The upper limit of group size is dictated practically by parlor size and time spent in the holding pen. Cows should spend no longer than 45 min to 1 h waiting to be milked with 2 or 3 times per day milking. A good generalization for maximum group size in herds with herringbone and parallel parlors is 4.5× the parlor size (Smith et al., 2000). For example, groups for a double-10 parlor should contain 90 cows or
fewer. Realistically, management of feeding and housing facilities will determine how large a group can be within the constraint imposed by parlor size. Limited time in the holding area enhances cow comfort and well-being because it minimizes crowding, time away from feed, water, and resting areas.