By County Extension Director, Stephen Harris
October begins this Thursday and a frost is likely in the next few weeks. I’ve been trying to find the average date for the first frost in Coffee County. I have found dates from October 8 to October 28. Anyway, frost is a part of fall weather. It is a natural part of the seasonal change, but even a light frost can turn certain common forage plants into deadly poisons for cattle and other grazing animals.
Grain Sorghum, sudan grasses, sorghum-sudan hybrid, corn regrowth and Johnsongrass all contain compounds that produce cyanide when plant cells are ruptured by a frost. Wild cherry leaves also contain cyanide – producing compounds. This is commonly referred to as Prussic Acid.
Any stress, such as drought or frost, has the potential for producing hydrocyanic (prussic) acid. The plants reach toxic levels very quickly after a frost. The danger decreases over the next few days and is usually gone within ten days to two weeks, if there is no more frost.
Unfortunately, in Tennessee, it is often more complicated. There is often a light frost which is enough to induce prussic acid toxicity, but is not enough to completely kill the plant. Then, after a week or two, there is another frost and the toxicity is present again. This is why many producers remove cattle from areas with significant stands of prussic acid producing plants from first frost until at least ten days after the plants are completely killed.
Following are some simple pointers to avoid toxicity: Graze sorghum or sorghum-cross plants only when they are at least 15 inches tall (Interestingly, pearlmillet does not cause prussic acid poisoning). Try to graze or mow all significant stands of prussic acid producing plants, including Johnsongrass before frost. Do not graze plants during and shortly after drought period when growth is severely reduced. Do not graze wilted plants or plants with young tillers. Do not graze for two weeks after a partial frost, or non-killing frost. Do not graze for ten days to two weeks after a killing frost, or freeze, or until the plants have thoroughly dried. Do not graze prussic acid producing plants at night if frost is possible. Do not allow access to wild cherry leaves, whether they are wilted or not. Always check pastures for fallen wild cherry limbs following storms.
Estimating Winter Hay Needs for Horses
It’s time for horse owners to make plans to for the colder weather ahead. For most horses, cold weather does not mean coming in from the cold, but being provided with the necessary nutrients to ensure they are as comfortable as possible. Planning ahead for how much hay is needed for feeding all winter is essential for maintaining healthy horses. Jennie Ivey, our new University of Tennessee Extension equine specialist, says ideally, a horse should consume between 1.5 percent to 2 percent of their body weight of hay or forage per day (dry matter basis). For example, a 1000 pound horse will eat 15 to 20 pounds of hay daily. That’s the equivalent of roughly one small square bale of 40-60 pounds every few days. The exact number of bales needed for winter feeding will depend on the weight of the bale. “It is best to determine how much your horse will need to get through the winter based on their daily consumption” Ivey states, “Next, determine the total amount of hay needed,” she adds. Low temperatures, high winds and precipitation can increase the amount of energy horses need per day. “That means during extreme conditions you may need to increase the amount of hay horses consume. Supplementation with grain or concentrate is needed when a horse is having difficulty maintaining weight or body condition,” she cautions. Round bales are also a good option for horse owners, especially for those needing to maintain horses outside. On average, 7 to 10 horses can consume one round bale (800-1200 pounds) in 3-4 days. Feeding round bales out of a feeder can greatly reduce waste and ensure that horses have access to fresh hay even during inclement weather. Not all hay is created equal. Ivey recommends having your hay tested for nutrient content to ensure it meets the horse’s nutritional needs. Forge analysis can be performed by the UT Soil, Plant and Pest center (ag.tennessee.edu/spp). Ivey also reminds owners to check all hay for mold and dust before feeding. “Dusty hay can lead to respiratory problems, while moldy h