AMES – "What is rotational grazing?" and "How can I use it on my farm?" are two questions many Iowa beef producers are asking these days.
"Rotational grazing is still a fairly new concept to Iowa beef producers," said Jim Russell, Iowa State University beef cow-calf nutritionist and a cooperator with the Iowa Beef Center. "However, nearly any producer can begin using the practice in his/her operation with a little pre-planning and a few management changes."
Rotational grazing is a technique in which grazing animals are moved between separate pastures or paddocks. By doing this, the forage in the unoccupied paddocks can "rest," allowing it to recover nutrient reserves in the roots. Additionally, grazing selectivity is greatly reduced as animals' forage choices are limited.
The number of pastures a producer partitions off is determined by the ultimate goal he/she wishes to accomplish, Russell said. "A producer who wants to reduce grazing selectivity will probably need more paddocks than a producer who wishes to allow a forage rest period," he pointed out.
If the goal is to allow a recovery period for grazed forages, Russell recommends eight to 10 paddocks. "This allows a four- to five-day grazing period then a 35-day rest period for each paddock," he said. "Depending on the stocking rate and forage growth rate, four to five days' grazing will remove the recommended 50 percent of the plant. The remaining 50 percent is enough to replenish the paddock."
If efficiency of forage use is the goal, then 20 to 24 paddocks grazed for one to three days is recommended. "Some forages do not have the palatability of others. Given a choice, the cattle won't eat the less desirable grasses," Russell said. "This selectivity will lead to overuse of some forages and under-use of others, undermining the productivity of the entire pasture." By restricting cattle to one smaller area, the pasture will be grazed uniformly, saving the higher quality forages from being completely exhausted and promoting their recovery and growth.
Rotational grazing also can be helpful for producers who plan to renovate a pasture. "Instead of attacking the entire pasture all at once, a rotational grazing system can give a producer the opportunity to strategically renovate smaller portions of the pasture one at a time," Russell said.
Starting a new rotational grazing system takes planning. Russell suggests producers sit down with an aerial map of their pasture and sketch where and how many paddocks they want. "Producers should remember that the paddocks need to be as square as possible," Russell pointed out. "Cattle prefer to graze in a circular pattern. They will graze more uniformly in a square area than one that is oblong or triangular."
After the paddocks are mapped out on the photo, Russell said producers are wise to use small flags to indicate fencing prior to purchasing the materials. "There may be a stream or a sinkhole in the pasture that wouldn't be apparent in the aerial photo," he said. "It's much better to find these things out before you're ready to put up fences."
Temporary or semi-permanent fencing is the best choice for producers trying rotational grazing for the first time. Temporary fencing gives producers the ability to change paddocks to fit their needs.
Ideally, each paddock should have its own water supply. "The reasoning behind water in every paddock is then cattle will remain within that paddock continuously, leading to uniform grazing, uniform manure distribution and a lower occurrence of lanes and erosion," Russell said. "However, that may not be feasible for every producer. We recommend that each producer carefully consider water placement with all aspects of the system in mind."
Once the paddocks are ready, Russell said producers should rotate the cattle at a rate comparable to plant growth. From late April to mid-June, cattle should move frequently (every one to three days) to keep up with the forage. "Sixty percent of grass growth occurs in May and June," Russell commented. "Often, there is excess forage available during these two months. In order to keep continual high quality forage, producers need to determine a way to remove this excess, whether it be cutting it for hay or temporarily increasing stocking numbers."
When growth begins to level out by mid-June, producers can slow the rotations and work toward 50 percent removal for the remainder of the summer.
By August, producers who stockpile graze during winter months should begin that process. "Grazing really requires year-round planning," Russell commented.
Should the summer of 2001 become as dry as 2000, Russell said there are several options available for rotational grazers. If paddocks are dry and becoming deficient, calves can be creep fed to help maintain their nutritional needs and limit stress on the pasture.
If cattle have to be supplemented with hay or grain, or if pastures become severely dry, Russell suggests producers use a "sacrifice paddock." Using this method, producers allow cattle in only one area for an extended period of time, sacrificing the quality of one paddock so the rest of the pasture can recover.
Probably the worst thing producers can do during dry spells is rotate cattle too quickly. "One of the biggest mistakes producers make is visually appraising pastures during dry weather," Russell emphasized. "They believe the forage is too stressed, so they move the cattle after only one or two days. The same thing happens at the next paddock, and every paddock after that. Soon, they are re-grazing a paddock that has had only a few days to recover. As grazing intervals become shorter and the rotation faster, the forage has no time to rest and the entire pasture is compromised. It's better to sacrifice one paddock so the rest of the forage can recover."
For more information on rotational and stockpile grazing, contact your county Extension office or your local Extension livestock field specialist.
Iowa Beef Center