Tall Fescue: High-Yielding Forage Grass or Toxic and Invasive Weed?

During his travels around the state in 1931, Dr. E.N. Fergus of University of Kentucky obser

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10 thoughts on “Tall Fescue: High-Yielding Forage Grass or Toxic and Invasive Weed?

  1. Great article! As a Virginian, fescue is definitely the king of grass where I’m from. But recently there’s been some great research about how converting some pasture to native warm-season grasses in the fescue belt can mitigate the summer slump a great deal. They had a cost of just 31 cents per pound of gain per acre, which was including the cost of establishment.


    It’s better for wildlife, water quality, and drought mitigation too.

    My ideal setup in Virginia would be 1/3 NWSG, 1/3 introduced cool season grasses (VA used to be the orchardgrass capital of the nation), and 1/3 fescue for winter stockpiling.

    1. Shayan,

      Very interesting idea. My graduate research at Michigan State University looked at a system similar to what you are describing I will try to turn that into an article in the near future. Briefly, I will say that big bluestem was far more palatable than switchgrass. Gains were not affected as long as they were not on the NWSG too long before rotating back to cool-season grasses. Establishment for switchgrass is particularly slow, which is costly. Also, grazing starts about a 4-5 weeks later in the spring and ends a month before the end of the cool-season grass grazing season. Warm-season grasses are slower to start in the spring and need to ‘refill’ their root reserves prior to the winter.

      For a producer trying to maximize profit/acre, this was not a great system for Michigan, but it might work well other places. For producers who have great concern about wildlife but are less concerned about profit/acre, it might be helpful. While it is very palatable in the summer, big bluestem goes flat during the winter, while switchgrass stands up nicely. Deer did seem to appreciate the cover that the switchgrass offered in the winter. I am not sure how beneficial the NWSG would be to nesting birds if the producer’s goal was to maximize livestock gain on that grass. The animals would need to be going into those pastures before most of the young birds have fledged. At traditional stocking densities, things probably would not go very well for the nests.

      1. Thanks for your response and sharing your study results!

        I think there’s definitely a regional component–in the UTK studies, the daily gains weren’t bad at all, with much of the ADG values approaching those of corn silage. Pretty amazing, considering the bad rap NWSG get.

        In Virginia in the summer, when the fescue’s all crispy, I regularly see the NWSG pastures boasting stands exceeding 5 or 6 feet tall, with the densest growth around 3 feet. The productivity per acre has to be huge, and Patrick Keyser of UTK has said that the traditional measures of forage nutrition did no justice to the gains they saw.


        They started grazing after giving the grass just one year to establish, and it didn’t seem to impact it much.

        All in all, I’ve been pretty impressed with the stuff coming out of UTK, and when I’m more permanently situated, I’d like to try it for myself.

        Thanks again for a great article and your comments!

  2. Dan,

    You mentioned Kentucky Bluegrass is not native to N.A. Are we sure about this. There are references that suggest KBG is native to the northern regions of NA.

    As a grassland ecologist, I have a hard time considering we didn’t have a strong Poa component in our grasslands.

    1. Hi Steve,

      Thanks for the comment. Discussions about native vs. non-native are intriguing for a number of reasons.

      I think that there are several ways to answer the ‘native’ question. The first is ‘ask the government!’ The USDA classifies Kentucky bluegrass (poa pratensis) as ‘native and introduced’: ” Native and Introduced – some infra-taxa are native and others are introduced.”

      This means that there they think that there were representatives of the poa genus here prior to European settlement. Among many other reputable sources, there seems to be little dispute that what we call ‘Kentucky bluegrass’ was brought here by Eurpoean settlers. It is worth noting that some members of the festuca (fescue) genus are native to North America.

      I agree that it is possible (even likely) that there is some genetic influence of our native poa species in Kentucky bluegrass. I would be interested to learn more about how similar KBG is to the representatives of the poa genus that may have been here prior to European settlers.

      I am not sure how useful this analogy is: Bison are native to North America, but we brought the bos tarsus and bos indicus types of cattle. They are native in the sense that there were ‘cattle’ here previously with bison can potentially reproduce. From an ecological perspective, they are different in many ways.

  3. Our farm in southeast PA is within the “fescue belt” and our pastures have been well endowed for years with Endophyte toxic Tall Fescue (E+TF). Killing it out and replanting with a less toxic cultivar or other forage is not a risk that I would take. We consulted with Jim Gerrish some years ago, and he suggested a breeding program intended to give us a breeding herd that would become adapted (tolerant, resistant) to this otherwise excellent forage. It has taken some years, but I’m pretty sure we’re there now (fingers XX’d). Our grazing program takes strategies from Greg Judy, including NO mowing to reduce seedheads, a tactic recommended by many to reduce fescue toxicity. Seed-heads of E+TF are rich in the ergot alkaloids (EA), toxins produced by the endophyte which mediate the toxic effects of this forage. Needless to say, I was very nervous at first about giving up the mowing option, but so far this has resulted only in huge savings of my time and money, albeit with continuing “summer slump” among juniors in the herd .
    We have been sending forage and urine samples to measure content of EA (Agrinostics Ltd, Watkinsville, GA) in order to get quantitative estimate of the toxic load ingested by our cattle from time to time over several years**. To make a long story short, we frequently find urinary EA titers elevated 10-100 fold in breeding females that go on to conceive and deliver normal calf. This finding was unexpected because titer of urinary EA is inversely correlated with weight gain in stockers grazing E+TF and has thus been proposed as objective marker for fescue toxicity **. The whole story is complex, and I’m still working on it (6 yrs!), but my best guess to account for the high titers of EA in good-doing breeding cows is the same as set forth in my comment posted above re Kathy’s Hemlock eaters (see June3, Poisonous Plants…)
    **N.S. Hill et al- 2000. Urinary alkaloid excretion as a diagnostic tool for fescue toxicosis in cattle. J.Vet.Diagn.Invest 12:210

  4. “Including other forage grasses will likely result in extreme selective grazing and eventual loss of the non-tall fescue grass species.”

    Stand diversity is really an issue of management. Graze tall and let the plants recover between grazings. I don’t mind that my cows avoid the fescue in the summer. They eat the wild oat, bluegrass, smooth bromegrass, rye, orchardgrass, foxtail, dandelion, chickory, narrow-leaf plantain, plantain, the full spectrum of clover, lambsquarters, horseweed, ragweed and sometimes the thistle. They trample everything uneaten to the ground. The cows get plenty to eat. The soil, thanks largely to fescue and high cattle density, gets plenty to eat. After 50 years of continuous grazing, the change of management is causing the pastures to thicken and increase in diversity.

    A fair portion of the fescue gets eaten in the summer and there is no doubt that the fescue is infected. Some cows do better than others infected fescue, just as some cows do better than others on corn. Rather than rip, spray and seed the world with “improved” varieties, the solution is to select for cows that breed back every year on your native forages and manage your pastures for diversity. If all else fails, broadcast 5# of red clover every year until the stand gets established. It worked for Greg Judy.

    Haylage? How would you pay for it?

    1. Chris,

      Thanks for the comments and questions. The recommendation to use improved varieties is primarily in the context farm managers who have already made the decision to seed down a new pasture or hay field and is making decisions about what seed mix to use. In this case, the field might be coming out of corn silage production, or it could be recently cleared land. The comments are especially directed toward producers living in areas where tall fescue has not traditionally been used and where cows have not been selected for their compatibility with endophyte-infected tall fescue. This is the situation in the Northeast.

      You are right that the botanical composition of the pasture reflects the management history of the field. Hungry cows will eat fescue. In my experience, however, they will eat everything else first, and often eat it to the ground, which reduces the chances of survival of that plant and improves the odds for the fescue. I do not encourage graziers to plant mixed stands that include tall fescue because they will not end up with the botanical composition that they might expect based on the seed tag. Under most management, tall fescue will dominate, other pasture species will be grazed into oblivion. Other species that they may or may not prefer will fill in the gaps.

      In a mob-grazing situation, the outcome might be different — I cannot say for sure. Unlike some, I think mob-grazing is best used as a tool to complement to other time-tested grazing practices — not as the centerpiece of a grazing management system. For example, when I first turn the livestock out in the spring, I want them to eat the tops off of just about everything; a very low stocking density will accomplish this goal. As I am trying to keep up with the pasture at the stage that seedheads are being produced, mob-grazing becomes a very attractive practice.

      As a livestock producer, if I had a choice for my livestock to eat non-toxic fescue or to avoid toxic fescue in the summer, I rather that they eat the non-toxic fescue. A few reasons include: more grazing days per acre, higher weight gains per acre, less grazing time, improved forage utilization — all factors that influence economic sustainability.

      That said, I agree with what you say about using the animals that work given your situation. If endophyte-infected tall fescue is endemic in your area, it will pay to have cows that tolerate it.

      Finally, regarding haylage: almost all dairy farmers in the Northeast harvest at least some of their forages as haylage. The exception would be some cheesemakers and a few ‘very traditional’ producers. One of the ways it pays for itself in this part of the world is that it allows farmers to harvest the crop earlier in the spring and get the crop into storage before it gets rained on. Intense forage managers organize their workflow to allow them to mow in the morning and start putting it into the bunker silo in the afternoon of the same day. The feed quality in this system is outstanding.

      1. That was an excellent response.

        Where I am I would have to kill the infected fescue in the ditches – even on the neighbor’s side of the road – to get ahead of it. It always comes back.

        I still can’t imagine haylage…but I don’t live in the Northeast. Interesting about morning mowing as the brix would be lower.

  5. Hi Dan–interesting article giving the history of Ky31.

    While dairy graziers in the Northeast may not want to plant novel endophyte fescue for their lactating cows many dairy graziers in Southwest Missouri [a hot bed of grazing dairies] are finding it a good alternative to ryegrass and orchardgrass, two grasses often unable to tolerate the heat and dry spells of summer. Here is a link to the Southwest Missouri Research Center Dairy, a working grass based dairy run by University personel. http://aes.missouri.edu/swcenter/grzdairy.stm

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