ROTATIONAL GRAZING MANAGEMENT PREVENTS OVERGRAZING

by: Heather Smith Thomas

Rotational grazing systems are generally the most efficient way to get the best utilization of pastures and maximum beef production per acre, as well as being healthier for the land and forage plants, in many instances. When done properly, pasture rotation can prevent overgrazing, aid optimal regrowth of plants, and allow the same piece of ground to be grazed several times during a growing season.

Dr. John Hall, superintendent of the Nancy M. Cummings Research, Extension and Education Center (University of Idaho) near Salmon, Idaho, says that rotational grazing is always a very positive tool for the stockman, especially on irrigated ground. “This is a tool you absolutely have to use, to get maximum beef production on that expensive input,” he says. Irrigated land is generally high priced to begin with, compared to rangeland, and the cost of irrigation (in labor, or energy input to run a pump or pivot) is always a major item.

There are a lot of variables in what people think is the proper rotation, regarding number of days spent in a paddock. Some feel the best results are gained by moving cattle every day. “I think a person can often get by moving them once a week, however, rather than more frequently. This is one of the things each individual rancher must look at, regarding available labor,” says Hall. Pastures and paddock set-ups can also make a difference in what's most feasible.

“One of the things we plan to work on here at our research ranch is to create some very secure larger pastures and then be able to subdivide them with temporary electric fencing. A lot of stockmen rely entirely on temporary fencing, and that's fine if it works for them. But for us in our research environment it would be a little tough to rely only on that,” he says.

Having an understanding of the growth phases of forage, the amount of residual feed that should be left and when the animals need to be moved, is crucial, especially with cool season grasses, or they won't grow back very well. “This means we have to be willing to be flexible and do some things that maybe weren't planned. If the irrigation system breaks down and takes a few days to be fixed, or it doesn't rain, or whatever, we may have to be willing to feed hay at a time of year that we hate to feed hay, just to give those pastures enough time to recover,” explains Hall. The expense of feeding a little hay may actually be less costly than overgrazing some of the pastures to the point they won't grow back adequately, leaving you less forage over the long run.

Utilizing Growth Phases Of Forage To Advantage – Dr. Jim Gerrish (formerly in the Department of Agronomy, University of Missouri, and now involved with the Lost River Grazing Academy—sponsored by the University of Idaho's Extension Service) says grass growth encompasses 3 phases. “The first is when grass comes out of dormancy in spring or after being harvested short. It takes awhile to get enough leaf area to capture adequate solar energy for rapid growth,” says Gerrish.

Cattle really like the grass in phase 1 because it is tender, succulent and high in nutritional quality. “In a pasture being grazed continuously, without rotation, cattle keep going back and regrazing the short spots, seeking out the phase 1 grass. This is stressful for the plants because they don't have enough leaf area to support maintenance,” he says.

If the pasture is being rested and not grazed, plants start to accumulate enough leaf area that they can grow more rapidly. “This phase 2 growth will continue until the mass of the plant is requiring a lot of energy just to maintain its structure. There is also some shading of the lower leaves and some leaves dying. At that point, growth rate slows dramatically and the plant goes into phase 3, which is basically when we would cut it for hay; it's as big as it's going to get,” explains Gerrish.

In rotational grazing we try to keep as much of the pasture in phase 2 as possible, putting cattle into the pasture when grass is fairly high on the phase 2 portion of the growth curve. “Then we take the cattle off when grass is eaten down toward the lower height of phase 2. If you graze it too hard, all the way back to phase one—stripping the plant of leaves—it takes longer to recover, and it needs a longer rest period,” he says.

“Stockmen who try to do rotational grazing and find they are still running out of grass are usually grazing it too short. This makes their rest periods longer than they can afford to have,” he explains.

Overgrazing can happen whenever the animals are unrestricted and can keep coming back to the same plants, keeping them grazed down into phase 1. It's most common in pastures that are continuously grazed, without rotation, but can also happen in a rotation program if you leave cattle in any one paddock too long or if your rest period is too short.

“A common thing you'll see in a continuously grazed pasture is overgrazed areas (phase 1 grass) right next to mature clumps (phase 3) that the cattle are not eating—and no phase 2 grass. If you do a good job of irrigating and stocking, and always keep the grass at 4 to 6 inches in height (so it's always in phase 2), continuous grazing can work, especially in climates that are very stable. But the problems we generally have, especially in the western states, are temperature extremes and we can't always get the grass watered when it needs it. The growth rate is very fast for a while, then slows to nothing, so it's hard to keep everything in phase 2 in a continuously grazed pasture. The goal of rotational grazing is to try to hold the grass in phase 2 for as much of the season as possible, by letting the pastures rest periodically,” explains Gerrish.

Extending The Grazing Season - There haven't been many recent innovations in rotation systems that utilize the actual growing season, but there's still some research being done on ways to extend the grazing season. “One thing I have a lot of interest in is some of the swath grazing,” says Hall. “Ranchers in Canada and Montana are having some experience with this, and it may have some potential for us here, depending on elk pressure. Last year we had a lot of problem here on this ranch, with elk,” he says.

“One of the problems in thinking about rotational grazing is that we have a tendency to think one size fits all, and that such and such is the best way to do it. But this won't work for every operation. One thing that's nice about rotational grazing is that there are many pieces to it, and for all different times of the year. Swath grazing may work in your environment, but for someone who has a lot of wildlife pressure it may not work. The key to rotational grazing or trying to expand the grazing season is to try a little, on a small scale, before you jump in and change your whole system, which might put you in a situation you didn't want to be in,” says Hall.

“The basic techniques for rotation grazing management can be learned in workshops like the Lost River Grazing School that we have here at the research farm, but then you have to adapt those basics to your situation and your particular ranch,” says Hall. Elevation, climate, types of plants in your pastures, terrain, whether it's irrigated or dryland, etc. will all be factors.

Adjusting the rest periods to encourage maximum grass growth (and keep most of it in phase 2) is part of the juggling act. Gerrish says that learning how to adjust and flex the grazing and rest periods is an art and this is the part you can't learn from a textbook or a workshop. “Until you actually do it yourself, you can't learn grazing management.”

You run into situations each year that you haven't encountered before, and also learn from your mistakes. “I've been doing this for almost 30 years and I still make my share of mistakes, and learn something new each season,” says Gerrish.

Controlling Cattle Use Of Pastures Without Fences -- “We talk a lot about electric fence, but there's been some research recently, across the West, in controlling cattle use of certain areas of rangeland without fences,” says Hall. “Traditionally salt placement was a way to move cattle around and distribute them where we want them, but now we also use water and supplement tubs. These can be a really good management tool,” he says. On a dry year, especially, when range grasses become short on protein, cows will readily eat a protein supplement and you can move the location of their grazing with movement of the supplement tubs. This can encourage cows to go places they might not graze otherwise, and can help immensely with grazing distribution.

We are more limited on public range, in our abilities to try to graze certain areas at certain times of year, since there are constraints on when various pastures or allotments can be used. There isn't much flexibility on turnout and move dates, for instance; it's set by the calendar. In reality, however, some years the range is behind, due to lack of moisture or cold temperatures and you need to wait a few more days, whereas in other years the grass is ready well ahead of the prescribed turnout date.

On private range we have many more options to do what might be best for the land and cattle, utilizing innovations and flexibility. “We still have a lot to learn about this, and how best to use these grasses. If there's good moisture in the spring, how should that change what we do with grazing early in the season? If it turns dry, what should we do differently than if we had a better year? There is still much to learn about rotational grazing, especially on rangeland. We don't have an allotment here that we can use in conjunction with our research ranch, but we may, at some point in time, so we can mimic a little better what actually goes on in the industry,” says Hall.

Regarding rotation grazing management in general, his advice is to learn the basics and then try to customize it to the individual ranch, always keeping the need for flexibility in mind. Try something on a small scale to start with, then work your way into it as you discover what works best for you.

STOCKING RATES

How many cattle you can accommodate in your rotational system can be a challenging question. “To have a good grass-based operation, you almost have to be able to vary your stocking rate seasonally,” says Gerrish. If you are a cow-calf operation, this is the greatest challenge for keeping the forage supply and animal demand in balance.

“If you can run yearlings part of the season, or keep more heifers for breeding than what you need—selling some after they are bred, to reduce the number of animals on your place—these are some options you can use to adjust the stocking rate to try to match the grass supply,” says Gerrish.

Stocking rate should always be focused on forage demand rather than just cow numbers. A lactating cow has a much higher demand than a dry cow, for instance. And if you have superior milking cows, they will need almost twice the energy at peak lactation than they did when they were dry. So when you go from a dry cow (with just maintenance requirements) to peak lactation, you've doubled the stocking rate on the pastures, in terms of forage demand, even before you add in the calf.

“Ranchers who calve in January and February and hitting peak lactation in March and April have the highest energy demand before they have good grass. Calving later is one way to put more of the energy demand at the time of year you have the best grass.”







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