As the season begins to warm and producers start looking to the grazing season ahead, a very common question asked is how many of X type of livestock can I raise on my land?
Most folks would like a quick estimate, such as one cow-calf pair per acre, or 1,500 pounds of animal to an acre, or some such similar estimate.
However, because there is variation between producers, what they are raising (not only species but different life stages of animals), and quality of pasture, using those estimates may be a good start but not a very solid foundation for long-term production goals.
Stocking rate is the calculation of how many animals are put on a unit of land for a determined length of time. In essence, you can look at this as the forage demand of the animals you currently have.
Stocking rate is typically measured in the number of animal units per acre. The Natural Resources Conservation Service sets one animal unit as a 1,000-pound cow with or without an unweaned calf at her side. It has been calculated that one animal unit will consume approximately 25 pounds of dry forage matter daily.
From this one animal unit, other species and classes of livestock have been given an animal unit equivalent — an estimated percentage of forage consumption in comparison to the base 1,000-pound cow.
For example, a 175-pound breeding ewe has an AUE of 0.20. By dividing 1 AU by this AUE of 0.20, we can determine that five breeding ewes would require the equal dry matter forage intake of the 1,000-pound cow.
Using this information, we can calculate a current stocking rate as total land area ÷ [(number of AUs) x (length of grazing season)].
To continue with our example above, we first need to determine a total number of animal units by multiplying the number of animals by the AUE.
If we have 50 ewes, the calculation would be 50 x 0.20, or 10 AU. Now let’s assume we have 20 acres that can be grazed for six months. Plugging that into our stocking rate equation above — 20 acres ÷ (10 AU x 6 months) = 0.33 acres per animal unit month. Said another way, our stocking rate is 2 acres per one animal unit (or five ewes) in a year.
Stocking rate does not guarantee adequate forage availability. For that, one must make additional calculations based on forage yield estimations. One example provided by Penn State Extension agronomy team suggests that 1.2 acres of an orchardgrass/white clover mixed pasture will provide adequate forage for 1 AU for most of the year.
In our sheep example, then, that means roughly 12 acres of pasture (10 AU x 1.2 acres) would be adequate for most of the year.
Source: lancasterfarming.com
Photo Credit: gettyimages-jacqueline-nix
Categories: Pennsylvania, Livestock, Beef Cattle