The starting pasture and animal figures are examples. The result can be a fraction of an animal. The grazing plan and current pasture conditions determine the number of animals to turn out.
Calculated results
Measure
Result
Usable forage
25,000 lb DM
Animal unit months
31.6 AUM
Head for the grazing periodAt the weight and days you entered
5.3 head
Acres per head
7.5 ac / head
Forage budget in a pasture visit note
You are discussing how long a pasture’s forage needs to last. You enter acres, dry matter per acre, harvest efficiency, animal weight and days here. The calculation holds the forage supply fixed for that period.
Your visit note can hold the result beside the date and how you estimated forage. You can also describe uneven use or changing pasture conditions in the photos and words you record.
Once the note uploads, we prepare the report you review with your own interpretation. Later growth and supplemental feed sit outside this calculation, and the grazing decision stays with the person making the plan.
Forage budget: what you said and what the report says
The voice note
“Forage-budget example: 40 acres, 2,500 pounds of dry matter per acre and 25 percent harvest efficiency. For 1,200-pound animals over 150 days, the calculation gives about 5.34 head. That is the arithmetic for these assumptions.”
Forage budget - Pasture visit
At a glance
1
The example has 25,000 pounds of usable forage after applying 25% harvest efficiency to 40 acres at 2,500 pounds of dry matter per acre.
2
For 1,200-pound animals over 150 days, the fixed-supply calculation gives about 5.34 head. It includes no later growth or supplemental feed.
Observations
The example has 25,000 pounds of usable forage after applying 25% harvest efficiency to 40 acres at 2,500 pounds of dry matter per acre.
For 1,200-pound animals over 150 days, the fixed-supply calculation gives about 5.34 head. It includes no later growth or supplemental feed.
After your review
Stocking rate from usable forage
Multiply acres by forage dry matter per acre and harvest efficiency to get usable forage. This tool uses 26 pounds of dry forage per animal unit per day and approximates animal units as body weight divided by 1,000 (SDSU forage budget). Livestock-class equivalents can differ.
SDSU describes 25% harvest efficiency for moderate continuous season-long grazing (SDSU forage budget). The site’s grazing plan supplies that value. Our AUM display uses 30.4 days, or 790.4 pounds; SDSU’s 30-day AUM uses 780 pounds (SDSU forage budget).
The supply stays fixed. Later growth, supplementation and changing intake sit outside this calculation.
animal units per head = animal weight (lb) ÷ 1,000
AUMs = usable forage ÷ (26 × 30.4)
head = usable forage ÷ (26 × animal units per head × grazing days)
The example works out to 5.34 head over 150 days
Forty acres at 2,500 pounds of dry matter per acre contain 100,000 pounds. At 25% harvest efficiency, 25,000 pounds are available. Dividing by the estimated demand of 1,200-pound animals over 150 days gives about 5.34 head.
How far to trust it
The weight approximation is not a species-specific feeding standard.
Later growth, drought and uneven use can change the field balance.
