Short duration grazing
By: Heather Smith Thomas
Rotational short-duration (management-intensive) grazing is a good way to increase cattle performance and improve pasture health and productivity. The length of intervals — hours, days or weeks — before cattle are moved to the next paddock, pasture or strip will depend on constraints of the land base (size, type of pastures and forage species, whether it’s rangeland or irrigated pastures) growing conditions, and the goals of the stockman. Nutritional needs of the animals will also be a factor, whether they have high requirements for protein and total nutrients, such as lactating cows or young stocker cattle, or lower needs like mature dry cows.
Maximizing pasture production and allowing cattle to graze as much of the year as possible helps reduce feed costs. As stated by Jim Gerrish, American Grazinglands Services of May, Idaho, finding ways to allow cattle to harvest their own forage is the most cost-effective management tactic.
Types of forage plants in a pasture are not as important as when you graze them. “Some of the less-than-desirable forages can be used effectively if you use the right grazing strategy,” explains Gerrish. You should graze those plants when they are immature and at their peak nutrient quality — with optimal energy, protein level and palatability.
Forage growth can be divided into three phases. “First is when the plant comes out of dormancy in spring or starts growing again after being harvested/grazed short. It takes awhile to grow enough leaf area to capture solar energy for rapid growth,” he says. Cattle prefer to eat grass in this stage because it’s tender and nutritious. If a pasture is being grazed continually (rather than rotationally), they keep grazing the short areas, which never allows those plants time to grow much leaf area. Forage production is hindered.
Phase two is when the plant has enough leaf area to grow swiftly. Phase three is maturity, when growth rate slows. Phase three plants are more fibrous and less palatable; cattle avoid eating them if there are younger plants available.
“In managed grazing situations we try to keep as much of the pasture as possible in phase two. If you graze it too close, stripping the plants of leaves before moving the cattle, it takes longer to recover and needs a longer rest period,” explains Gerrish.
“Stockmen who try rotational grazing and run out of grass are usually grazing it too short, necessitating rest periods longer than they can afford to have,” he says. It’s better to graze an area quickly and move to the next section or strip, so the grazed portion can recover quickly.
“Thirty years ago when we were first suggested controlled grazing and shorter and shorter grazing periods — and then moving cattle every day, which is what we recommend today — I thought the primary benefits were increasing uniformity of grazing and obtaining more consistent pasture. Then I realized how much benefit we gain with animal nutrition,” he says.
Shorter grazing periods eliminate cattle’s opportunity for selective grazing. “When you put cattle in a new pasture for a week, they eat all the best forage in the first two days. By the end of the week they may be on a maintenance diet or less. If you split that pasture into more feed breaks you get better individual animal performance,” explains Gerrish.
“The greater the nutritional demand of the animal, the greater the benefit of going to shorter grazing periods, which provides a balanced diet with optimum nutrients. This concept is best illustrated with pasture-based dairies. Typically, they move the cows to new pasture after every milking; the cows are in that strip for only 12 hours. But some dairymen move their cows once or twice between milkings. No matter how full a cow thinks she is, if you open up new feed, she’ll get up and go eat some more.”
Glenn Shewmaker, State Forage Specialist, University of Idaho, says short duration, high-intensity grazing also maximizes effects of natural fertilizer. “The animals are highly concentrated on certain areas of the pasture for a short time and leave manure there — distributed more evenly than with low stock density.” This eventually fertilizes the whole pasture, as the animals leave behind the nutrients that go through them.
“Nutrient distribution for the pasture is a big benefit of rotational grazing. These are simple concepts, easy to apply, but some producers don’t take advantage of them,” says Shewmaker. It’s the lowest cost method to improve soil and pasture health, but producers must make a commitment to do it.