There are several grazing management tactics that can help stretch pasture. One such technique is called limit grazing. Limit grazing (also known as timed grazing) is when a herd is only allowed to graze for a short amount of time during the day. This is usually less than four hours per day. For the remainder of the day, the herd would be penned up in another area (e.g., a sacrifice paddock, heavy-use area, barn lot, etc.), where they would have access to another source of forage or feed (Figure 1).
It takes grass to grow grass
One way to think about limit grazing is to compare it to a savings account. Imagine one has a savings account that has a nice compounding interest rate – you know, like they had back in the old days. There are three primary factors that are of concern: the principal, the interest rate and the rate at which savings are removed from the account. If nothing is removed from the savings account, the principal quickly increases because of compounding interest. If the rate at which savings are removed from the account exceeds the interest rate, then the principal in the account will quickly decrease. This is the worst-case scenario, since the old axiom “it takes money to make money” is a fundamental truth.
When times are tough and the savings account must be drawn upon, one could minimize the damage by drawing on the savings at a rate equal to the interest rate. In this scenario, at least the principal stays the same. This is the fundamental principle of limit grazing. Just as “it takes money to make money” in financial terms, it takes grass to grow grass in grazing terms.
In times of drought or cooler weather, the amount of grazing being removed is often greater than the growth rate of the pasture. Such can reduce the grass base (principal) and make the subsequent amount of growth suffer. When done right, limit grazing allows the producer to get the use of the growth (using the interest) without decreasing the base amount of forage (dipping into the principal).
Timing is everything
Like everything else, timeliness is crucial to making limit grazing work right. Failure to remove the herd from the paddock at the desired time can result in overgrazing and irreparable damage to the paddock. Failure to understand the grazing behavior of the herd can also cause problems.
For example, cattle consume about 30 to 40 percent of their total intake just before and within two hours of daybreak, 15 to 20 percent during midmorning, 20 to 30 percent in late afternoon or early evening, and 10 to 20 percent during a midnight snack. So, the manager can choose how much grazing pressure is put on the pasture by choosing the appropriate time of day for the limit grazing to occur. Thus, choosing the wrong time of day to allow the limit grazing to occur can cause one to miss the target.
New technology makes it easier
Limit grazing has historically required someone to open the gate to let the herd have access to the pasture and someone to run them back out of the pasture at the right time. Some handy new tools help to cut down on that labor requirement. Automatic gate release timers (Figure 2) can be programmed to drop the fence at the designated time, cutting out at least one of the trips.
The black strap of the device pictured in Figure 2 wraps around one of the posts at the gate, while the end of the slinky-spring attaches to the electric fence on the other side. At the programmed time, the timer releases the red-handled end, the line springs back out of the way and the animals have access to the pasture. After a day or two of using it, the cattle learn to gather and wait at the gate at the appointed time for the gate to be released.
Overgrazing or excessive hoof traffic during a drought or cool, wet weather can leave the grazing manager dealing with their lingering effects long after the weather has changed. Limit grazing can really help stretch one’s available pasture and minimize damage. So, the next time you need to make your pasture last, stretch it to the limit. FG
- Associate Professor and Forage Extension Specialist
- University of Georgia
- Email Dennis Hancock
FIGURE 1: A hypothetical example of limit grazing, where cows are penned in a sacrifice area with access to hay and water for 20 to 22 hours (A) and allowed to graze one paddock for two to four hours each day for a few days (B) before allowing the limited grazing to occur on the next paddock with the greatest amount of available forage (C). Limit grazing can be done without subdividing the pasture, but this will result in patchy areas of overgrazing.
FIGURE 2: Technology that automatically releases a gap in the electric fence can be a great labor-saving device when using timed grazing. Images provided by Dennis Hancock.