How many cow/calf pairs are needed to graze off 3,226 AUMs in 4.5 months? Easy, just divide the available forage (AUMs) by the grazing season (months):
Cow/calf pairs = AUMs ÷ Grazing season
If you don’t know the grazing season, assume it’s six months.
To compute the annual forage requirement for a given number of cow/calf pairs, just reverse the math:
AUMs = Cow/calf pairs × Grazing season
Although wild horses and cow/calf pairs are said to be equivalent in terms of their forage consumption, their AUM budgets differ because of their grazing seasons.
Western Horse Watchers Association 