Stocking rate versus grazing pressure
Stocking rate and grazing pressure are important aspects of grazing management. Stocking rate is the number of animals per unit area (for example five wethers per hectare, two steers per hectare). Grazing pressure is the balance between how much the animals are eating from a paddock each day, and how fast the pasture is growing in that paddock each day.
That is, grazing pressure (GP) = rate of removal of pasture/rate of supply of pasture.
For example, comparing the grazing pressure of a paddock in winter stocked at 20 sheep/ha to the same paddock in spring also stocked at 20 sheep/ha, it is clear that the grazing pressure in winter is higher because the pasture is growing slower, while in spring the grazing pressure is lower because the pasture is growing faster. In each case, the stocking rate is the same (20 sheep/ha) but the grazing pressure varies.
In winter, 20 sheep/ha will eat pasture faster than it is growing, so there is an overall decrease in FOO. In spring, pasture can grow faster than 20 sheep/ha can eat, so there is an overall increase in paddock feed.
Using animals to maintain a target FOO requires an understanding of grazing pressure and knowledge of the rate of pasture growth and the rate of pasture removal by grazing animals.
Grazing pressure is a better yardstick than stocking rate for grazing management because it takes into account how well a pasture is growing. FOO is the simplest indicator of grazing pressure.
- GP <1 (light grazing pressure, FOO increases)
- GP = 1 (neutral grazing pressure, FOO doesn’t change)
- GP >1 (heavy grazing pressure, FOO decreases)