Figure out how many paddocks you need, how large each one should be, and how long pasture should rest between grazings. Works for cattle, sheep, goats, horses, and mixed herds — with animal unit conversion, stocking rate, and estimated hay savings.
1 cow / steer = 1.0 Animal Unit
5 sheep = 1.0 Animal Unit
6 goats = 1.0 Animal Unit
1 horse = 1.25 Animal Units
Cattle: 1.0 AU each | Horses: 1.25 AU each | Sheep: 0.20 AU each | Goats: 0.167 AU each
Intensive: 3–7 days. Strip grazing: 1–3 days. Lenient: 7–14 days.
Growing: 30–60 days typical. Dormant: 90–120 days typical.
Rotational grazing divides your total pasture into smaller paddocks and moves livestock through them in sequence, giving each section a rest period before animals return. The core insight is that grass grows fastest in its middle growth stage — after it has fully recovered from being grazed but before it becomes mature and stemmy. Continuous grazing (leaving animals on the same land all season) allows animals to selectively re-graze the most palatable plants repeatedly, preventing those plants from ever recovering fully while less-palatable species take over. Rotational grazing interrupts this cycle.
The two variables that control everything in a rotational system are the grazing period and the rest period. The grazing period is how long your herd stays in one paddock before moving. Shorter grazing periods (3–7 days for intensive systems) prevent selective re-grazing within a paddock and keep plant root systems from being stressed by repeated defoliation. The rest period is how long each paddock sits ungrazed before the herd returns — long enough for grasses to recover fully, rebuild root carbohydrate reserves, and reach the ideal grazing height. The number of paddocks you need is simply a function of these two numbers: paddocks = (rest period ÷ grazing days) + 1. So if you rest paddocks for 40 days and graze each for 5 days, you need at least 9 paddocks.
Season changes this math dramatically. During the growing season when soil moisture and temperatures are ideal, cool-season grasses can recover in 25–35 days and warm-season grasses in 35–50 days. Move livestock too soon and you graze regrowth before it has rebuilt root reserves, progressively weakening the stand. During dormancy, grasses aren't growing at all — rest periods of 90–120+ days are needed, or you simply keep animals off entirely and feed hay. Many producers run a continuous system through winter and return to rotational management in spring.
The Animal Unit (AU) is the standard measure for comparing forage demand across different livestock. One Animal Unit is defined as a 1,000-pound cow with or without a calf, consuming approximately 26 pounds of dry forage per day. Everything else is expressed as a fraction or multiple of that baseline. A horse is heavier and has a less efficient digestive system than a ruminant, so it's rated at 1.25 AU — meaning a horse eats about 25% more forage than a beef cow. Five sheep or six goats have a combined forage intake equal to one cow, so each sheep is 0.2 AU and each goat is approximately 0.167 AU.
These are averages and your actual animals will vary. A 1,400-pound mature bull eats more than a 700-pound yearling heifer, even though both count as "one cow." A lactating ewe nursing twins eats significantly more than a dry ewe. For planning purposes, the standard AU conversions give you a close enough estimate to build a rotation plan — but in practice you'll adjust based on how quickly each paddock is being grazed down and how well the forage is recovering.
The height at which you move animals into and out of a paddock matters as much as timing. Most grazing research recommends moving cattle into a paddock when cool-season grasses (fescue, bluegrass, orchardgrass) reach 8–12 inches and moving out when grazed down to 3–4 inches. For warm-season grasses (bermudagrass, bahiagrass, native grass mixes), move in at 12–18 inches and out at 4–6 inches. The "leave height" is critical: it represents the leaf area remaining for photosynthesis. If animals graze below 3 inches, recovery takes significantly longer because the plant must rebuild from root reserves rather than existing leaf tissue.
Horses are harder to manage for height targets than cattle because they graze very close to the ground and can denude a paddock faster than cattle of equal AU. If you're running horses, err toward shorter grazing periods (3–5 days) and monitor residual height closely. Sheep and goats often complement cattle well in mixed systems — sheep prefer grasses, goats browse more forbs and brush, reducing competition and improving overall utilization of mixed-species pastures.
The minimum number of paddocks is calculated as: (rest period ÷ days grazed per paddock) + 1. If you graze each paddock for 5 days and want a 40-day rest period, you need (40 ÷ 5) + 1 = 9 paddocks. In practice, adding one or two extra paddocks gives you flexibility — you can skip a paddock if it's not recovered, stockpile extra forage in a paddock for drought insurance, or allow a paddock to go to seed to thicken the stand. Most well-designed small farm systems run 8–12 paddocks. Very intensive operations with skilled managers run 20–30 paddocks with grazing periods as short as 1–2 days, which maximizes both forage quality and utilization.
Rest period is determined almost entirely by grass growth rate, which is a function of temperature, moisture, and species. During peak growing season — cool-season grasses in spring and fall, warm-season grasses in summer — rest periods of 25–45 days are typical. As temperatures move toward extremes (either too hot or too cold for active growth), rest periods lengthen. A general guide: 30–40 days in active spring growth, 45–60 days in summer stress, 60–90 days in early fall recovery, and 90–120+ days in true dormancy. If you're unsure, let the grass tell you — move animals in when it reaches your target height, not when the calendar says it's time. An overly rigid schedule is one of the most common mistakes in rotational grazing.
An Animal Unit (AU) represents the forage consumption of a 1,000-pound beef cow consuming about 26 pounds of dry matter per day. Other livestock are expressed as AU equivalents: 1 cow = 1.0 AU, 1 horse = 1.25 AU, 1 sheep = 0.2 AU (5 sheep per AU), 1 goat = 0.167 AU (6 goats per AU). To find your total AU, multiply the count of each animal type by its AU factor and add them together. For example: 10 cattle (10.0 AU) + 3 horses (3.75 AU) + 20 sheep (4.0 AU) = 17.75 total AU. This is used to calculate stocking rate (AU per acre) and to compare your herd's forage demand against what your pasture can supply. Calves, lambs, and kids are often excluded from AU counts until they are weaned and grazing independently.
The general rule for most temperate pastures is to graze in at 8–12 inches and graze out at 3–4 inches for cattle. Horses should enter slightly taller pasture (10–14 inches) and leave at 4–6 inches because they graze more selectively and will overgraze favored spots. Sheep and goats can graze somewhat shorter due to their smaller bite depth. The critical number is the leave height, not the entry height — leaving 3–4 inches of leaf material allows the plant to photosynthesize and recover using existing leaf tissue, dramatically shortening the recovery period vs. a plant grazed to the crown. For warm-season grasses like bermudagrass, entry height can be 12–18 inches and leave height 4–6 inches. See your local Extension office for region-specific recommendations, as species composition varies widely across the country.