by Victor Shelton, Retired NRCS Agronomist/Grazing Specialist
This article reprinted with permission from Victor’s monthly newsletter, Grazing Bites (see more information below).
Grazing Bites - April 2024
As I write this, the sun is trying to shine and provide more growing degree days for plant growth. Forage growth might seem a bit early this year, and it is, but not much earlier than last year at this time. Southern Indiana is about a week to ten days earlier than last year. Some northern sites are about two weeks ahead of last year, but certainly still behind southern portions.
Do not get me wrong, I am glad to see new green growth on perennial forages, but I haven’t forgotten last year yet. Last April we had a couple fairly hard freezes in late April. Nice, new, tender forage growth does not appreciate freezing temperatures. Last year’s cold spell set forages back, stressed plants and initiated early seedhead production which reduced yields. If it wasn’t grazed or clipped quickly to get it back in a more vegetative stage, production was really impacted. I tried both ways and wish now that I had gone ahead and clipped everything. I’m not going to borrow trouble, just hope that it doesn’t do that again especially with a bit of early start.
All this new green growth does make me eager to get livestock back on pasture again although I’m not going to get in a rush. That initial growth is important to restore the solar panel/photosynthesis and restore roots. You certainly don’t want the forage to get ahead of you, but initiating grazing too quickly does hurt productivity.
Fields that have some dry matter left from the previous season are usually the best fields in which to start the season. This leftover dry matter not only is good material to help balance out the washy early spring forage, but it also has a bit more built-in armor and is better suited to be grazed under slightly wetter conditions if present.
Mud also doesn’t appear to be an issue this spring or at least not so far. Fields with a little leftover forage from the previous season with new forage growing in it is a great place to calve, kid, foal, or lamb.
It is a good idea to move to a high magnesium type mineral supplement (usually 10-20% instead of 12%) a week or so before grazing new grass and continue with it until we are past the early flush of new forage. Grass tetany is a risk any time cows are grazing lush spring forages that are high in protein, moisture and potassium, and low in magnesium, calcium and sodium. Supplementing dry forage can help to both slow the rate of passage through the digestive system and dilute the grass with dry forage. The issue with insufficient magnesium is more of a problem where nitrogen and/or potassium has been recently applied or are already in excessive amounts.
Grasses, including annuals and cover crops, are good at scavenging nitrogen from the soil. Spring growing annuals/cover crops that are heavily fertilized or manured may accumulate nitrates, which can be toxic. If questionable, test before grazing. For more detailed information about grass tetany or nitrates, contact your local extension service or large animal veterinarian.
I have already heard the question multiple times, “When can we start grazing?” With slightly earlier forage growth, similar to last year, I’m not surprised with this question. I’ve seen a lot of livestock already out grazing fields. That is OK if they are still grazing stockpiled forages left from last year’s growth, but if they are consuming only new growth and keeping every new blade of grass nibbled off, then you’re usually doing more harm than good.
Fields that were grazed hard last fall, especially prior to dormancy, and fields that were grazed early this year because the cows needed someplace to go, could absolutely use a longer recovery period prior to grazing again this spring. Those fields will need to first try to grow or regrow their new solar panel off the reserves that are left, and then spend valuable time rebuilding roots and root reserves before allocating energy and resources on growing forage. The plant is going to try and preserve itself and yield is the last thing on its mind. It’s thinking about survival.
Fields that were not grazed hard, were grazed after going dormant, and have some dry matter left behind will typically have a little earlier growth and will be a bit more tolerant of early grazing. If the pasture is plentiful and you know fields will have sufficient recovery prior to being grazed again, then that also helps the possibility of earlier grazing. Fields grazed early usually need a longer recovery period than fields grazed slightly later.
It’s not too complicated, really. Forages will do the best if grazing is initiated when tall cool season forages are about eight to ten inches tall or a bit more. I like taking the top third of the plant which just happens to be close to the ideal stop grazing height. Keep them moving on a regular basis, ideally no more than three days on any one allocation. When the first paddocks that you grazed are completely recovered and back to that ten to twelve inch height, go back and graze those again. This keeps those fields under control and vegetative. The paddocks or fields that didn’t get grazed that first round can be harvested, clipped and then put back in the rotation later or possibly stockpiled. I’m not a big fan of early stockpile unless it is clipped to keep it more vegetative.
If you think, “I can’t wait that long,” then you better keep the animals moving while rotating them pretty quickly and absolutely not allow any grazing of regrowth. Grazing tight early in the season not only is hard on total production for the season, but it can have major negative impacts if the season decides to turn dry.
Nothing is more important than rest and recovery for forage plants. Multiple removal and multiple bites off the same plant, especially of regrowth, will hamper growth for the season and that forage plant will never fully express itself.
The biggest challenge is staging out the paddocks where they don’t get ahead of you too much or are not ready for grazing again quick enough. If you start grazing too early, you will end up grazing regrowth prior to sufficient recovery. If you wait too long, you’ll have too much grass trying to mature. Each season is slightly different depending on rainfall, temperature, and sunlight. Keep an eye on what is ahead growth wise. Faster rotations work well in the spring as long as you keep them moving. Slower rotations work well later with more growth letting them remove more yet keeping the grazing period short. This normally allows for longer recovery prior to grazing again.
Management of spring regrowth will impact overall production. The cows or other ruminants are the tools to help manage the forage! Remember, it is not about maximizing a grazing event, but maximizing a grazing season! Keep on grazing!
Victor Shelton is a retired Agronomist/Grazing Specialist with the Natural Resources Conservation Service (NRCS). He continues to write Grazing Bites in his spare time from his property in southwest Indiana. - Issue 195