An animal unit month (AUM) is the amount of forage used to feed a 1,000-pound cow and her calf (or their equivalent) for one month. The AUMs can be different values depending on the circumstances and perspectives of their use. For livestock owners, it can be valued as the cost of the next best replacement feed source (i.e., how much it costs to buy hay) or what they have to pay for leasing that feed. The value of an AUM is also used in the sale of ranches, especially those with public land grazing. While the ranch does not own the public land allotment, it does add to the overall capacity of the ranch. Such ranches are often sold with a value per AUM for the public land permit. It is up to the public land agency to allow the transfer of the permit with the base property. However, inheritance may be charged on the permit value.