Pasture Rotation Days Calculator
Calculate rotational grazing days for cattle, sheep, or goats.
Enter pasture size, livestock count, and forage availability to get optimal paddock time.
Pasture Rotation Days
Rotational grazing (also “managed intensive grazing” or “MiG”) moves livestock through small paddocks to maximize forage growth and minimize overgrazing.
The simple formula: Days per paddock = (Paddock area × Forage availability) / (Animals × Daily intake)
Animal forage demand (AUM = Animal Unit per Month, where 1 AU = 1,000 lb cow):
| Animal | AU Equivalent | Daily Dry Matter (DM) Intake |
|---|---|---|
| Cow with calf (1,000 lb) | 1.0 AU | 26 lb DM |
| Bull | 1.3-1.5 AU | 35-40 lb |
| Steer (yearling, 700 lb) | 0.7 AU | 18 lb |
| Horse (1,000 lb) | 1.25 AU | 25 lb |
| Sheep (ewe + lamb) | 0.20 AU | 5 lb |
| Goat | 0.15-0.20 AU | 4-5 lb |
| Llama | 0.30 AU | 8 lb |
Forage production by pasture quality (annual):
| Pasture Type | DM lbs/acre/year | Stocking Rate (AUM/acre) |
|---|---|---|
| Native rangeland (semi-arid) | 500-1,500 | 0.2-0.6 AUM |
| Improved cool-season (Kentucky bluegrass) | 4,000-7,000 | 1.5-3 AUM |
| Improved warm-season (Bermuda, Bahia) | 5,000-10,000 | 2-4 AUM |
| Irrigated improved (alfalfa/clover mix) | 8,000-14,000 | 3-6 AUM |
| Tropical highland (Brachiaria, Pangola) | 10,000-20,000 | 4-8 AUM |
Paddock size formula: Paddock acres needed = (Animals × Days × Daily intake) / (Available forage lb DM/acre × Take rate)
Where take rate is 40-60% for sustainable grazing (leave at least 40% of plant for regrowth).
Rest period after grazing:
| Climate | Rest Period |
|---|---|
| Cool, well-watered (Pacific NW, UK, NZ) | 21-30 days |
| Continental moderate (Midwest US) | 30-45 days |
| Semi-arid (Texas, Australia) | 45-90+ days |
| Tropical (year-round growth) | 18-25 days |
Why rotational grazing wins:
- More forage per acre: 30-100% more grass production than continuous grazing
- Soil health: Hoof action breaks crust, manure spreads evenly
- Weed suppression: Heavy competition from grasses outcompetes weeds
- Animal performance: Fresher feed = more weight gain or milk
- Drought resilience: Diverse plants and rest periods build root reserves
Key management rules:
- Move animals before grass is grazed below 4 inches (cool-season) or 6 inches (warm-season)
- Rest period > grazing period: typically 25-50 days rest, 1-3 days grazing
- Start with longer paddocks, divide as you learn forage / animal pace
- Watch for poison plants that grow when grass is overgrazed (jimsonweed, lupines)
- Provide water in every paddock — single-source water doubles labor and stresses cattle
Tools: polywire fence + step-in posts + portable energizer = subdivide a 5-acre pasture into 10 paddocks in 30 minutes.