The right stocking rate depends on your pasture's forage production and your cows' intake. A 500 kg cow eats about 2.5% of body weight daily (12.5 kg dry matter). If your pasture produces 5,000 kg DM/ha/year, that supports about 1 cow per hectare (0.4 cows/acre). Use this as a starting point, then adjust for your specific conditions.
Stocking rate = Forage production (kg DM/ha) ÷ (Animal intake (kg DM/day) × grazing days) × utilization rate (50-60%).
The utilization rate is critical — you should never graze more than 50-60% of available forage. The rest maintains plant health, root reserves, soil cover, and future production. Overgrazing (utilization >70%) reduces pasture productivity by 30-50% within 2-3 years and leads to weed invasion and soil erosion.
Forage production is primarily driven by rainfall. General guidelines: Arid (<500 mm/year): 0.1-0.3 cows/ha. Semi-arid (500-800 mm): 0.3-0.8 cows/ha. Sub-humid (800-1200 mm): 0.8-1.5 cows/ha. Humid (>1200 mm): 1.5-3 cows/ha (with improved pasture). Irrigated pasture can support 2-5 cows/ha year-round. These are rough estimates — actual production varies with soil type, pasture species, and management.
Not all forage is equal. Native rangeland produces 1,000-3,000 kg DM/ha with 6-8% crude protein. Improved pasture (ryegrass, clover, alfalfa) produces 8,000-15,000 kg DM/ha with 15-22% protein. Legume-based pastures (alfalfa, clover) fix nitrogen and have higher protein, supporting higher stocking rates and better animal performance. Toxic plants (tansy ragwort, locoweed) reduce effective forage availability.
Continuous grazing: utilization 30-40%, lower carrying capacity, uneven utilization (some areas overgrazed, others underutilized). Rotational grazing (4-8 paddocks): utilization 50-60%, higher carrying capacity, more uniform utilization. Intensive rotational/MOB grazing (12+ paddocks, 1-3 day moves): utilization 60-70%, highest carrying capacity, best pasture health, but requires more fencing and water infrastructure. Managed grazing can increase carrying capacity by 30-50% compared to continuous grazing on the same land.
Stocking rates are often expressed in Animal Units (AU). 1 AU = 455 kg (1000 lb) cow with calf, consuming 12 kg DM/day. A 500 kg cow = 1.1 AU. A 600 kg cow = 1.3 AU. Yearlings = 0.7-0.8 AU. Sheep = 0.1-0.15 AU. Always calculate based on actual animal weight, not breed averages. Lactating cows eat 20-30% more than dry cows. Growing animals eat more per kg body weight than mature animals.
Farm: 20 hectares, 800 mm rainfall, improved ryegrass/clover pasture, rotational grazing (6 paddocks), 500 kg cows.
Step 1: Estimate forage production = 8,000 kg DM/ha/year (improved pasture, good rainfall).
Step 2: Available forage = 8,000 × 55% utilization = 4,400 kg DM/ha/year.
Step 3: Cow intake = 500 kg × 2.5% = 12.5 kg DM/day × 365 = 4,563 kg DM/year.
Step 4: Stocking rate = 4,400 ÷ 4,563 = 0.96 cows/ha (about 1 cow/ha or 0.4 cows/acre).
Step 5: Total herd = 20 ha × 0.96 = about 19 cows (with calves at foot).
Conservative approach: start at 80% of calculated rate (15 cows), monitor pasture condition, and increase gradually if pasture remains healthy.
Check pasture height weekly during growing season. Optimal grazing height: 15-25 cm pre-graze, 5-8 cm post-graze for ryegrass. If pastures are consistently below 5 cm post-graze, you are overstocked — reduce numbers or increase rest period. If pastures are consistently above 25 cm pre-graze and getting stemmy, you are understocked — increase numbers or cut hay/silage.
Keep records: monthly pasture growth rates, actual grazing days, animal weight gains, and hay/silage made. Use these to refine your stocking rate each year. The best managers treat stocking rate as a moving target, not a fixed number.
Related tools:Feed Ration Calculator for daily feed needs, Livestock Stocking Density for barn housing, Feed Conversion Ratio for efficiency tracking.