Farmers should take grazing precautions

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Since we might have a frost this week it is a good time to remind farmers about the risks of grazing Johnsongrass at this time of year. Even though it is categorized as a weed and doesn’t belong here because of its invasive nature, Johnsongrass is actually very nutritious and cattle sheep and goats love it. It is often the first thing they will graze when turned into a new field.
Johnsongrass is a native of Africa and was brought into the U.S. as a plant for cattle to graze. Those who introduced it, however, did not realize how prolific it was and it has become a nuisance, growing just about everywhere. Since it is a warm season plant it has a different growth mechanism than our cool season grasses like fescue and orchard grass and can overwhelm and crowd out these plants in the late summer and fall.
The problem with Johnsongrass is it can form cyanide gas in its plant cells when stressed by drought or frost. Stress causes the pores that allow air and moisture in and out of the leaf to close up and trap the cyanide gas in the leaf. When ruminant animals eat the stressed grass the cyanide is converted to prussic acid in the rumen which can then be absorbed in the bloodstream and kill the animal. Since we have had plenty of rain, drought is not an issue so our biggest risk is from frost.
A heavy frost that kills the plant will cause the Johnsongrass to be unsafe to eat for three to four days or until the leaf turns brown. During this period, as the plant dies the pores begin to open and the cyanide gas is dissipated. What is more dangerous is when there is a light frost that doesn’t kill the plant. After a light frost the leaf pores can stay closed and trap the gas inside for an extended period of time. It is recommended that you wait two weeks after a light frost before grazing. If there is another frost during this time that does not kill the plant the period of waiting starts over. If there is a killing frost after a light frost it is OK to graze four days after the killing frost or when the leaves are brown.
If hay is made from frost damaged Johnsongrass the action of cutting, crimping and drying the leaves will cause the cyanide to dissipate. A four-day wait before feeding is sufficient. If baled as haylage or ensiled the material stays green and can trap the gas when tightly packed so it is best to wait six to eight weeks before feeding.
Other summer annuals like sorghum, Sudan grass or sorghum-Sudan hybrids are from the same family as Johnsongrass and can cause prussic acid poisoning after a frost. Treat these grasses the same as Johnsongrass. Wild Cherry trees also cause prussic acid poisoning but the biggest risk is from trees that are uprooted in a storm which gives cattle an opportunity to eat the wilted but not dead leaves. Usually frost kills the leaf but it stays on the tree until it is dead and dried up so risk from cattle eating among the dead leaves under cherry trees is not significant.
For more information on grazing precautions with these plants, call the extension office.
There will be a Beef Quality Assurance Certification class at 5 p.m., Thursday, Oct. 19, at the Marion County Extension Office. This is required for farmers making cattle related investments with CAIP Cost Share Funds. This is the only time the class will be offered prior to the Nov. 15 deadline for the program.
The Marion County Cattlemen will meet at 7 p.m., Thursday, Oct. 19, at the extension office. Please call the office at 270-692-2421 if you plan to attend.
The first of our Woods and Wildlife Webinars will be at 7 p.m., Thursday, Oct. 26. The topic will be “Identifying Kentucky’s Trees.” This hands-on webinar will help you learn how to identify the many trees found in Kentucky’s forests. Participants will learn how to use a handy dichotomous leaf key to help them identify the trees around us. The seminar will be presented by Extension Forester Laurie Thomas. The webinar will meet the education requirement of the CAIP Cost Share Program.
The Kentucky Beef Conference will be held Thursday, Oct. 26 at the Fayette County Extension Office. Registration begins at 9 a.m. Cost is $10 per person to be paid at registration. Lunch is included. One of the highlights of this conference is the outlook for cattle prices for the upcoming year. This program will qualify for the educational requirement for the CAIP Cost Share Program.
The second in the series of Woods and Wildlife Webinars will be at 7 p.m., Thursday, Nov. 2, entitled “Mushrooms and More from Your Woodlands” and presented by Forest Pathologist Dr. Ellen Crocker. Non-timber forest products can add enjoyment and value to your woodlands. This webinar will provide an introduction to wild and cultivated mushrooms and connect you to resources to get you started in the right direction. The webinar will meet the education requirement of the CAIP Cost Share Program.
There will be a class on the topic of “Hay Sampling and Analysis and Feeding Cattle through the Winter” at 1 p.m., Thursday, Nov. 9, at the extension office. This program will qualify for the educational requirement for the CAIP Cost Share Program. Call the office for more information.
Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin.