The following is from Grazing Bites and is used with permission.
by Victor Shelton, NRCS State Agronomist/Grazing Specialist
The rains are finally replenishing reserves in most areas. Though a bit late for some things, it is still a boost for forages that have been stockpiled and they have leaped in compensatory growth! Ideally, this stockpile is best used after it goes dormant in order to not slow next spring’s growth. Dormancy often requires several nights in a row at 25 degrees or lower. That type of weather isn’t far away. Once dormant, the forage can be grazed with less harm to the plant’s energy reserves. When it is grazed, it can be taken down a bit closer than normal but leaving good residual. That good stop grazing height will slow runoff over winter, reduce any erosion and help springboard growth next season. If you open up the sod too much in early winter, you also possibly open the site up for more weeds too.
It is always a good idea to evaluate and balance grazing livestock with available feed. It is better to know now than later. First, take different grazing animal classes (cows, heifers, stockers, ewes, etc.) and figure an average weight per class and then multiply that number times the number in each class. Now you have a total live weight. Multiply the live weight by .03 to get an average daily intake. For example, 20 cows averaging a weight of 1,100 pounds is 22,000 pounds live weight. Multiply that by .03 (three percent dry matter intake) and it equals 660 pounds of dry matter needed per day.
Now what are you going to feed those animals? It could be hay, stockpiled forage, crop residue, supplements or most likely a combination of these. Stockpiled forage is usually going to be tall fescue with some other grasses and legumes mixed in. You can lay a clipboard on top of the standing sward and measure the height of the compressed forages to estimate it. If the stand is dense, there is usually about 300 pounds per acre inch of dry matter. So, if you happen to have 10 inches, that is 3,000 pounds of dry matter per acre. You do not want to remove it all, so let’s say you remove six inches. That is 1,800 pounds available for grazing times the number of acres of this stockpiled forage. Fields do vary. Adjust as needed. The efficiency of grazing will depend on how you allocate it out. If you let stock have the whole field, then expect 60-75% utilization. At best you’ll have 1,800 pounds available. If you allocate it out like you are feeding hay with temporary fence providing one- or two-days’ worth at a time, you’ll find the efficiency to be up near 90%. In areas with plenty of moisture, the stockpiled fescue is good quality and quantity and will provide a lot of good grazing. There is always some waste, it just can’t be avoided. That waste will help feed the next year’s growth.
Inventory any hay you have on hand. You should have an idea on how much bales weigh and how many you have of each. For example, if you have fifty 1,500-pound bales (about 1,300 pounds dry matter) on hand, you essentially have 65,000 pounds available. The efficiency of this hay is also dependent on how you feed it, in addition to how it is stored. The worst-case scenario is feeding hay free-choice without any feeder structure and storing hay outside on the ground, which sadly wastes about 45% of the offered hay. Feeding enough hay for only 2-3 days at a time creates some competition between cows. In ring or cone type feeders and storing bales inside is efficient with an average of about 15% waste assuming that the hay is good quality. Small bales are probably the most efficient, but are certainly a little more labor intensive and not used as often as in the past. If you have silage or balage on hand to feed, figure it into the plan and generally expect 90% efficiency adjusted to dry weight.
The nutritional value of corn stalks can certainly vary from year to year. Stalks will start out in the 8% crude protein range with approximately 70% total digestible nutrients (TDN) and over a period of about 60 days drop to 5% crude protein and 40% TDN. Spring calving cows will meet most of their energy needs during mid gestation. Growing animals such as calves and fall calving lactating cows may be lacking in energy and protein and most likely will need to be supplemented if run on stalks.
About one acre of typical corn residue will be needed per animal unit per grazing month. Weekly allocations seem to work very well so you need to figure how many acres of stalks will be needed for one week of grazing for your herd. Higher yielding corn certainly produces more residue and more potential grazing. You can usually bank on about 12-15 pounds of desired residue to graze per bushel of corn. Stalk grazing should be avoided under wet conditions.
Compare the amount of dry matter you will need for the livestock with how much you have. Now you know about how much dry matter you are going to need to get them through the winter and an idea of how much you have available to feed them. If you are a little short on forages, you can add some supplements such as corn gluten, soybean hulls, etc. into your feeding plan. In fact, you may want to anyway if hay quality is lacking, or if more energy is needed. We used 3% for the intake estimate which is actually a little high, but if we have a wet, cold winter, energy needed to keep warm will increase and any growing animals will also have higher needs. It’s better to overestimate than to be short. Cold, wet and especially muddy conditions will increase energy requirements. If you are still short on feed, then you may want to purchase some hay or consider reducing numbers.
Summer annual warm-season grasses — such as sudangrass or sorghum-sudangrass hybrids and johnsongrass produce a cyanide compound when frosted and quickly start shutting down, causing the production of the prussic acid. To be safe, livestock should be removed from these forages for at least two weeks to allow for the forages to “dry down” and the prussic acid to dissipate before grazing again. These forages can be harvested for balage right after being frosted and later fed as long as they are allowed their normal fermentation process time period of three or four weeks. Dry hay containing these is generally fine. Johnsongrass tends to be a bit more toxic than sorghums. Frosted areas could be only “pockets” in a field to start with. Any regrowth from the base of the plant after a frost can also be very high in prussic acid. If in doubt, wait.
Lastly today, if you haven’t checked your winter-feeding pads, it would be better to do that now and add more lime topping or aggregate as needed. Also, it’s not a bad idea to take the time to double check winter watering tanks while the weather is still good. I like the fall weather, but it never seems to last long enough.
Remember, it’s not about maximizing a grazing event, but maximizing a grazing season! Keep on grazing!
Reminders & Opportunities
Southern Indiana Grazing Conference – March 10, 2021 – In-person conference has been canceled. Other options are being considered.
Northern Indiana Grazing Conference – Feb. 5-6, 2021
Heart of America Grazing Conference – March 2, 2021. Details to be announced once decisions are made.
More pasture information and past issues of Grazing Bites are available at:
https://www.nrcs.usda.gov/wps/portal/nrcs/in/technical/landuse/pasture/