Fig. 1. Two perspectives are illustrated that describe the decline in forage mass during a 7-d grazing period on a rotationally stocked pasture. In 1-A, forage mass is assumed to decline daily by the product of one over the number of days in the grazing period (7 in this example) and pregraze forage mass. This is generally an erroneous assumption that is made in some calculations of forage allowance. In 1-B, forage mass declines at a rate that may more nearly represent that observed in practice as forage intake and digestibility decrease during a grazing period.