– Victor Shelton, NRCS State Agronomist/Grazing Specialist
The fuel has been thrown on the fire. Forages are starting to really grow and may have enough available forage to start grazing depending on where you are at. One question I hear quite frequently this time of year is: “When do I start grazing?” Most grazers are eager to get the animals back out grazing and reduce feeding hay. Depending on where you are located, it would be easy to say that on a certain day you should to go open a gate and initiate grazing, but you know it is not that easy.
Remaining stockpiled fields should have more residue left behind and should also have the most “green” growth because of more reserves. These fields should be the first ones to start grazing this spring. Fields grazed later into the winter or very early spring will be shorter and will need extra rest to rebuild root reserves prior to grazing. You need a game plan on how you are going to graze the paddocks so you can know where and when to start. You need to “stage” the paddocks to keep them in the preferred condition with quality forage.
Each year is certainly different because of prevailing weather and soil conditions that set the precedence for the onset of grazing in the spring. This is somewhat dictated by how hard the pasture was last grazed and more importantly how much residue or stubble was left behind. Pastures that were grazed down real tight early last fall and prior to going dormant will tend to be very short in the spring and slower to start growing because the plants will also have to grow roots at the same time. Dependent on how they were grazed, closely grazed pastures are often a slightly darker green because of higher concentrations of nitrogen, especially if they were grazed at high density. These pastures will benefit from a longer resting period prior to being grazed the first time.
Pastures that were stockpiled and grazed after going dormant are in a little better shape and, depending on how fast regrowth comes, can be grazed fairly soon. Stockpiled pastures that had adequate residue left behind, usually a minimum of 3-4 inches, are really good places to start grazing and are actually better balanced as far as crude protein, nitrogen, carbon, and fiber is concerned. As I quite often say, “you can walk a little closer behind these cows.”
So, here is how to answer the real question of the day of “when do I start grazing?” Preferably, you will want to start grazing when the plants are about 6 to 8 inches tall (tall cool-season forages such as fescues and orchardgrass) and the ground is dry enough to support the weight of the livestock without causing damage to the forage base. On some soils, especially ones that tend to be wet, the forages may be closer to 10 inches or more before conditions allow for grazing with no damage to roots, crowns and added compaction. The more residue left from the previous year and consequently the more root base, the earlier you can normally graze without damage which is basically the same concept for grazing stockpiled forages on non-frozen ground all winter.
Especially in a rotated grazing system, there is some advantage to grazing fairly early as long as you use some control…animal control. Starting early and making sure to maintain stop grazing heights for the forages is really the critical issue, but it also helps to keep the forages from getting too far ahead of you before you graze them. Staging forages helps you to be able to keep more of the paddocks in better condition longer with less need of haying or clipping. Like mentioned at the beginning, fields with more rest and more residue will be ready earlier and tighter grazed fields will be ready later.
If you are dealing with wet conditions and less residue then you would be better off waiting until forages are at least 6 – 8 inches providing better, thicker growth to hold up the weight of the grazing animals. I would still promote grazing for short periods, keeping the animals moving and never grazing closer than 3-4 inches whenever possible. If the forages do start getting ahead of you, consider making the paddocks slightly bigger and grazing the areas for shorter periods of time letting the animals harvest the best of the best. Quality forage with good intake will ensure good growth on growing animals and milk for lactating animals. When forages are growing fast, move the animals from paddock to paddock quicker. When forage growth slows down, slow down the rotation too.
Clipping can help simulate proper grazing and will greatly improve these pastures for later grazing, but I would only do this if really necessary to maintain quality . . . not for just aesthetics. We’ll talk more about clipping in a month or two.
Keep grazing new paddocks until the first paddocks grazed have grown back to that 6-8 inch desirable height and then start back on them. You need to try and keep the paddocks as vegetative as possible for growing animals and not wait too long to re-graze them or you will quickly get frustrated in trying to play catch-up. Applying fertilizer sparingly, especially nitrogen, in the early spring will help keep this furious growth under a little more control.
If I have to skip a paddock, it is always best to be thinking ahead of time what field(s) would be advantageous to bypass. Paddocks with thin soils, low organic matter and low fertility, are south/southwest/west facing (hotter soils), and are always the first fields to consider and the ones that usually could reap the benefits of extra growth and rest.
I’ll end today with a thought on magnesium. With temperatures fluctuating quite a bit right now and new grass starting to be utilized by livestock, it is pretty easy to be short on magnesium when the animals consume lots of new “washy” green grass. It is a good idea to move to a high magnesium type mineral supplement (usually 10-20% instead of 1 or 2%) and continue with it until we are past the early flush of new forage. The issue with insufficient magnesium is more of a problem where nitrogen and/or potassium has been applied recently or in excessive amounts. Grass tetany is the name of the disease where magnesium is deficient. For more detailed information about grass tetany, contact your local extension service or large animal veterinarian.
Enjoy the spring weather and keep on grazing!