Have you ever wanted to predict the future? Now you can and, best of all, the tool to do so is free on the Noble Foundation website. Before you get too excited, the future I'm talking about only applies to your pasture and hay situation this fall and winter. If you are a cattleman, though, accurately prognosticating this future is valuable and may end restless nights wondering if the cows will have enough to eat this winter.
To begin, go to noble.org/tools. There you will find several calculators that can be used for various agriculture-related applications. The calculators to look for are the "Reserve Herd Days" and "Hay Days Available" calculators. First, go to the "Reserve Herd Days" calculator and click on the "launch calculator" button. The calculator will appear as seen in Figure 1.
Complete the sections in blue and the red sections will be calculated automatically. Note that "Forage Type" has a drop-down box with multiple categories from which to select. As an example, let us assume we have a 40-acre bermudagrass pasture that was fertilized in late August and stockpiled through fall. The bermudagrass is 15 inches tall (the 235 pounds-per-acre-inch on the screen applies). It will be grazed to a 4-inch stubble height with 50 dry cows weighing 1,200 pounds each with consumption being 2.6 percent of body weight. Plug those numbers into the calculator and click "calculate." The number of reserve herd days (RHD) is estimated to be 66.28 days at 100 percent efficiency. However, cattle will not graze all of the available forage so we have to assign utilization, which varies depending on pasture conditions. (Note: This next step is not available on the calculator.) If strip-grazed, we could assume about 90 percent utilization, but let's assume 75 percent on a continuous grazing scenario. That gives us about 50 (66.28 x 75 percent) RHDs grazing in this pasture. With good fall grazing conditions, it might last a few days longer. With an abnormally wet fall, the pasture may not last the entire 50 days. Regardless, this gives you a way to plan.
Let's do another example. This time the bermudagrass pasture was not stockpiled, however, it has been deferred from grazing since August. It is 12 inches tall and only fertilized in the spring. It was heavily grazed early in the summer, so the pounds-per-acre-inch (estimated pounds per acre of production divided by the average height in pasture) is about 160 pounds instead of 235. Since the stand is more mature, we will only graze down to a 6-inch residual height, and intake will be less at 2.4 percent of body weight. The calculator computes 26.7 RHDs, but we need to assign utilization. Being lower in quality, let's use 60 percent. Sixty percent of 26.7 days is 16 RHDs.
Turning our attention to predicting hay days, pull up the "Hay Days Available" (HDA) calculator. Your screen should show a calculator resembling Figure 2.
If we use the same cow herd as above as an example, 50 head of 1,200- pound cows consuming about 2.5 percent of body weight daily, and we have 140 1,200-pound bales of fair quality hay and assume 20 percent wastage, our HDA calculates to 89.6 days. The calculator also has the option to limit-feed the hay. If we limit hay allocation to 25 pounds per head per day, we have hay to feed for 107.5 days.
Looking at these examples as one scenario, we would have one pasture that has 50 RHDs, one pasture with 16 RHDs and hay for 90 days, if full-fed. That equals about 156 days worth of forage. If today is Oct. 15 and we have 156 days of hay, the forage supply would last until about April 10. So, will spring begin by then?
Use these calculators to test your prediction skills. Give us a call if you have questions. If you master this, you can try your hand at predicting the long-term weather forecast - but we don't have a calculator for that.