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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
dry land, 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.”
PARASITE ISSUES
Whenever cattle are congregated in large numbers on small areas,
disease and parasite issues must be dealt with. On irrigated
pasture, especially, where a large group of cattle can be
utilized to quickly graze a small area and then move on,
allowing the grass to regrow, this puts an unnatural stress on
cattle and also concentrates them more than nature intended.
Unless parasite issues are taken into consideration, “mob”
grazing can lead to health problems.
Cattle normally don’t graze
forage plants next to their manure pats, and definitely don’t
like to eat plants that have been spattered with feces. This is
one way they tend to avoid heavy parasitism, since the worm
larvae that hatch from eggs passed in manure migrate onto nearby
forage plants to be eaten.
“When I was in Minnesota we did
some studies on this, with a parasitologist. In these intensive
rotation systems on irrigated pasture, we have to be a little
careful that our timing of when we come back to regraze that
pasture does not coincide exactly with the life cycle of the
parasite,” says Hall. It takes a certain amount of days for the
eggs to hatch and the larvae to mature to the infective stage,
where they can be eaten by the cattle and continue their life
cycle.
“What the parasitologist found in
our Minnesota study was that we could inadvertently very rapidly
increase the internal parasite loads in the cattle if we didn’t
watch the timing. He did find, however, that from an external
parasite standpoint, mob grazing with very lush pastures could
actually reduce the numbers of flies that breed in manure,” says
Hall. In very intense grazing on lush forage with a high water
content, cattle feces are runny and there’s not a significant
pat in which the immature stages of the fly can develop. Horn
fly larvae (from eggs laid by the fly in fresh manure) need
manure in which to pupate, but the very flat, liquid pat dries
out quickly and is not an ideal environment for maturation of
fly larvae.
Thus you may find a reduction in
the fly population, but an increase in internal parasites unless
you are careful in timing the regrazing of these paddocks. It
would be wise to work with your veterinarian for a strategic
deworming program, to knock down the parasite levels so there
won’t be mature worms laying maximum amounts of eggs to be
passed in the feces just when cattle will be grazing and
regrazing these areas.
“We did some work in Virginia,
where we didn’t have irrigated pasture, but on good years
(plenty of rainfall) the pastures were very lush, and the season
gets warmer earlier than it does here. In our spring calving
cows, we did not see a major increase in parasite load until mid
to late June. Thus we found a significant benefit to a single
strategic deworming in the middle of the summer, for calves.
This really knocked the level of parasites down, especially when
using some of the dewormers that have persistent activity,” says
Hall.
Depending on the time of year you
calve, coccidiosis may also be a concern, if young calves are
grazing pastures that are heavily contaminated with cow feces.
Young calves are very vulnerable to coccidiosis because they
have no prior exposure or resistance. Mature cows rarely develop
coccidiosis because they tend to have some immunity due to
previous exposure, but generally shed low numbers of oocysts in
their feces. This is not a problem for calves unless they ingest
a large number of oocysts when eating contaminated feed—and this
is most apt to happen when cattle are confined in small areas
and the calves are exposed to a lot of cow manure.
FENCES ON IRRIGATED PASTURES
Gerrish points out that wheel line irrigation can be compatible
with paddock division fences, if you can use portable electric
fence. “You can also put up permanent single strand high tensile
fence 2 feet tall, that you don’t have to move. The wheel lines
can cross right over them because they are not a physical
barrier, especially if you run the fence perpendicular to the
wheel line path. The pipes are tall enough to pass over the
fence, as long as you don’t have the fence where the wheels have
to go across,” he says.
Temporary electric fence can be
inexpensive and efficient (fast and easy to move), partly
because no gates are needed. Cattle can be easily moved just by
putting a couple of tall sticks or pieces of PVC pipe in the
fenceline for a few moments, to raise the electric wire enough
that cattle can go under it and into the newly created paddock.
Once cattle learn they can do this, they can be easily moved
without gates. |
