About 50 people gathered at the Weyers Cave Community Center on Nov. 20 to hear Dr. Joe Bouton ask, “What alkaloid levels are you willing to live with?”
It’s not a question commonly asked by farmers today, but Bouton hopes that in the future, testing for alkaloid levels will be as common as measuring forage for nutrients, protein and NDF.
Alkaloids are naturally occurring compounds produced by fungi, bacteria, plants and animals. Alkaloids can have medicinal properties. Morphine, caffeine and ephedrine are alkaloids. Some alkaloids are toxic to other organisms — for example, nicotine. Tobacco dust is an effective pesticide, if not used today as widely as it once was.
Many strains of tall fescue — such as the renowned cultivar Kentucky 31 — are host to an endophytic fungus which produces alkaloids toxic to livestock. This complex is what’s known as fescue toxicosis. When a grazing animal consumes fescue with alkaloid-producing endophytes, the alkaloids cause the animal’s blood vessels to constrict. Follow-on effects include elevated body temperature and possible loss of blood flow to the extremities. Fescue toxicosis leads to decreased feed intake, which lowers weight gains, and can affect reproductive performance.
“The first symptoms show at very low levels” of alkaloids, said Bouton.
Knowing that, it’s tempting to conclude that endophytes are the problem.
That’s not the whole picture, however. As it turns out, endophytes also play a positive role in the health of a fescue stand. Endophytes enhance host fitness and persistence (through a variety of pathways, including by producing a plant growth hormone and improving utilization of nitrogen fertilizer), impart pest resistance and help the plant better withstand drought. Therein lies the conundrum of endophyte-infected fescue — it weakens livestock which graze it, but strengthens the grass which is its host.
Dr. Bouton, together with scientists from New Zealand, found a way out of this conundrum by developing a type of fescue which contains non-toxic endophytes: Jesup MaxQ®.
Fescue became prominent on our nation’s landscape following the Dust Bowl era. The creation of the Soil Conservation Service in 1935 signified the country’s newborn commitment to maintaining and restoring soil and other natural resources. One of the first steps taken by the SCS was the revegetation of overused farmland. Kentucky 31 was a hardy grass perfect for the erosion control efforts of the early decades of the SCS. Today some 40 million acres of Kentucky 31 grow across our nation.
“It did what it was supposed to do,” Bouton said. “It covered land and prevented gullies.”
It also, unfortunately, provided for the nation’s livestock herds a supply trough of toxic alkaloids. Once it was realized that the toxicosis associated with fescue came from the fungus associated with the grass, efforts began to develop a fungus-free fescue. That’s when breeders realized that fungus-free fescue doesn’t have the persistence and performance farmers had come to expect from endophyte-infected fescue. Fungus free fescue has poor stand persistence as well as poor drought and grazing tolerance.
The animal health industry was also working on the problem, developing medicines, supplements and vaccines to treat animals afflicted with fescue toxicosis. Breeders tried to develop animals resistant to fescue toxicosis. Farmers also developed ways to contend with toxic fescue. Some eliminated toxic fescue from their farm, using either non-fescue varieties. Others took the necessary management steps to be able to grow a stand of the more delicate fungus-free fescue. Interplanting with other species — such as clover — is another approach, one which remains common today.
Plant breeders focused their efforts on creating a better grass. They tried to develop fungus-free fescue with more persistence, but their success was limited. The same was true of their work to reduce the amount of alkaloid toxicity produced by endophyte-infected grass. The big breakthrough was the development of fescue which hosted a non-toxic endophyte. The endophyte provided the positive, persistence-boosting traits of the toxic endophyte without releasing toxic alkaloids.
That grass, which is derived from Jesup fescue, is Jesup MaxQ®.
It took many years to test the effectiveness of the new cultivar. Bouton had to prove that the grass had the features he expected — high persistence and no toxicity. Trials proved that to be the case. Additional trials were taken to test animal safety — and MaxQ® was shown to be safe for animals. What’s more, it was shown to be productive, leading to good weight gain in grazing animals.
Bouton later created a second cultivar, Texoma MaxQIITM for more arid western environments.
Bouton recently retired from the University of Georgia after a 35-year research career, but he’s looking forward for more research into fescue. In particular, he’d like to see scientists start using alkaloids as a testing parameter. Hence, his questions, “What alkaloid levels are you willing to live with? Where is the threshold where you need to do something?”
There is no clear answer to that question yet, but one study seems to indicate that weight gain suppression begins at 400 parts per billion (of alkaloid). Another study showed blood prolactin dropping at just 200 parts per billion.
“We need better information on setting the threshold,” Bouton said. “We need more research.”
It is clear, however, that the lower the level, the better. “If you’re in the thousands,” of parts per billion, Bouton said, “it’s not good. You want to go as low as possible.”
To get there, first you need to know what your alkaloid levels are. Hence, Bouton’s expectation that in the future farmers will regularly measure for alkaloid levels. Once you get your fescue tested, try planting a small plot of either fungus-free or non-toxic endophyte fescue, and compare it to your established fescue stands. A trial like that will allow you to measure both the change in alkaloid levels as well as the change in grazing behavior. To plant a new stand of fescue, keep seedheads from emerging in the spring through clipping (to minimize the latent seed bank of toxic fescue, which remains viable for about 18 months). Spray glyphosate about six weeks before planting the new fescue and again at planting.
Once a stand of non-toxic fescue is established, keep it from being contaminated by toxic fescue by holding animals for two to three days before bringing them from a stand of toxic fescue to a stand of non-toxic fescue. Likewise, don’t feed hay with toxic fescue in stands of non-toxic fescue.