Lesson 1. Planning a Grazing System — Appendix D
Visual Method to Estimate Stand Productivity
Determine the average vertical height of the undisturbed stand of forage species in inches and use the table below to estimate the forage available for consumption.
Estimated dry matter yield in pounds per acre per inch of height for pasture types and stand conditions
| Pasture Species | Stand Condition, (lb./acre/inch)* | ||
|---|---|---|---|
| Fair | Good | Excellent | |
| Bluegrass/Clover | 150-200 | 250-300 | 350-400 |
| Perennial Ryegrass/Clover | 150-200 | 250-300 | 350-400 |
| Orchardgrass/Legume | 150-200 | 250-300 | 300-350 |
| Timothy/Legume | 150-200 | 250-300 | 300-350 |
| Tall Fescue + Nitrogen | 100-150 | 200-250 | 350-400 |
| Mixed Pasture | 150-200 | 250-300 | 300-350 |
*Values from Pasture Stick developed by Cornell University and NRCS
Tall growing species should be grazed at different heights than low growing species. Grazing should start in a paddock when vegetation is 6 to 8 inches high for tall growing species such as timothy, orchardgrass, and bromegrass and 4 to 6 inches high for low growing species like bluegrass, redtop, fine leafed fescues, sweet vernal, and white clover. For rapid regrowth and to maintain a healthy stand, animals should be removed when the forage height is reduced to 2-3 inches for tall growing species and 1 to 2 inches for low growing species.
For example, an Orchardgrass/legume pasture in excellent condition with an average undisturbed height of 7 inches will have 4 inches of usable forage (3-inch stubble height left after grazing). The available forage dry matter would be estimated to be 300-350 pounds/acre-inch or 1,200-1,400 pounds/acre.
Use the following formulas to calculate the number of animals that can be grazed or the approximate number of days the pasture can support a specific group of animals:
| Total lbs. Forage/Ac. x #Ac. x % Grazing Efficiency | |
| Days = |
|
| Avg. Animal Wt. x Intake Rate in % Body Wt. x Animal # |
| Total lbs. Forage/Ac. x #Ac. x % Grazing Efficiency | |
| Animal Number = |
|
| Avg. Animal Wt. x Intake Rate in % Body Wt. x Days # |
| Pasture system | Grazing Efficiency (total season) |
|---|---|
| Continuous | 30% |
| 4 pastures | 35% |
| 8 pastures | 50% |
| 12 pastures | 65% |
| 24 + pastures | 75% |
For example,
| 1,300 lbs. Forage/Ac. x 1 Ac. X .75 Grazing Efficiency | ||
| 19.5 Animals = |
|
= 19 animals fed |
| 1,250 lbs. Animal wt. x 4% (ie. .04) of Body Wt. Intake x 1 Day |