Turn pasture acres and forage dry-matter into a stocking-rate planning estimate. Utilization and intake drive the answer — defaults are starting points, not prescriptions.
Use this when you are drafting a grazing plan: how many animal-units (or head) a pasture can carry for a season, or how many grazing days N head can stay given yield and utilization.
Rotational systems often allow higher utilization than continuous grazing. Drought, residual targets, and wildlife browse all change the real number.
Available forage = acres x yield x (utilization / 100). Animal-unit-days = available / daily intake. Animal-units for fixed days = AUD / days. Days for fixed head = AUD / head.
available_lb = acres x yield_lb_ac x (util% / 100)
AUD = available_lb / intake_lb_day
AU (for D days) = AUD / D
days (for N head) = AUD / N
One animal-unit (AU) here is simply one animal eating the intake you entered. Adjust intake for cow-calf pairs, yearlings, sheep (often ~0.2 AU), etc. This is not an NRC diet balance.
40 acres x 3,000 lb DM/ac x 35% utilization = 42,000 lb available. At 26 lb/AU/day → 1,615 AUD. Over 150 days → ≈ 10.8 AU.
Same pasture with 12 head: days ≈ 1,615 / 12 ≈ 135 days of forage at that utilization.
Assumptions: yield is usable dry matter for the period; utilization is a planning fraction; intake is constant.
Limits: regrowth, supplementation, trampling, and water distribution are not modeled.
Responsibility: planning estimate only — not a nutritionist stamp. Confirm with Extension and on-pasture residual checks.
Leaving residual protects roots and future yield. Continuous grazing often needs lower take; well-managed rotations can take more of the grown forage.
Supplemented days reduce demand on standing forage — lower effective intake from pasture or shorten the grazing-days claim.
Use a lower daily intake (or AU fraction) that matches your class; many plans use ~0.2 AU for a ewe, but verify locally.
Cut yield aggressively or raise residual (lower utilization). Recalculate mid-season.
No — it is a period estimate from the yield and days you entered.