Fescue Challenges — Ways to Minimize Toxic Effects
Seedheads are the biggest problem for cattle.
Fescue toxicosis is common in cattle grazing endophyte-infested tall fescue and is detrimental to growth and performance. Tall fescue is a widely used forage across much of the country — for hay and pasture — because it is so hardy. It is easy to establish, and a stand lasts a long time because it is insect- and nematode-resistant, tolerates poor soil and harsh climatic conditions, and has a long growing season. Unfortunately, most tall fescue is infested with a fungal endophyte — a small fungus that lives and grows between the cells, especially in the seedhead.
The endophyte is present in the seed at the time of planting. When the seed germinates, the endophyte begins infesting the plant. As the plant grows and the stem forms a seedhead, the endophyte moves into seed, where it becomes more toxic.
This fungus has a symbiotic relationship with the plant that makes it hardy, but the downside is toxicity for animals that consume the plant. This hardy forage became popular with farmers in the 1940s and 1950s, spreading quickly throughout the Midwestern and Southern United States. Today it accounts for more than 40 million acres of pasture and hay production in this country.
After observing problems with poor performance (low weight gain) and fertility problems in cattle, research showed that the endophyte could produce ergot-like alkaloids under certain conditions. Producers with fescue pastures (and hay) have to deal with this challenge and find ways to minimize the toxic effects.
Seedhead suppression
Travis Mulliniks, beef cattle nutritionist and range production systems specialist at the University of Nebraska–Lincoln, says the seedhead is the biggest problem. This gives producers several options and strategies to reduce toxic effects.
“One is seedhead suppression,” he says. “Before plants get to that stage of maturity, producers can spray with a broad-spectrum herbicide to suppress the seedhead and keep it from emerging. In environments that have a lot of endophyte-infested tall fescue, we can spray in late March to mid-April, depending on the year. We can decrease the amount of toxin produced just by suppressing seedheads.”
Seedhead suppression has been shown to increase daily gains on steers and improve cow pregnancy rates, he says.
Dilution is a solution
Another option is to dilute the fescue by adding other plants, especially legumes, to the pasture mix or hay field. By interseeding legumes, fescue intake will be reduced as other forages are provided. This is a common practice in the Southeast, often using various clovers or alfalfa. Red clover is the legume used the most, explains Mulliniks.
Some people dilute fescue by feeding a supplement — something to replace part of the diet, he adds. “Soybean hulls have been a traditional supplement in the Southeast to help increase nutrient intake of cattle grazing tall fescue. There are benefits in increased performance, partly due to decreased intake of fescue, but also due to increased nutrients with the supplementation.”
Graze strategically
Rotational grazing can be helpful — grazing pastures early in their growth, before seedheads form, and keeping the plants in a young, growing stage.
“Many of these environments have a lot of rainfall and potential for a lot of growth,” says Mulliniks. “More intensive rotational grazing, moving through the pastures quickly, can often ensure that the fescue never gets to that seedhead stage.”
Fall-calving option
Another option is shifting the calving season. If producers calve in March, they are breeding cows June-July with cattle on mature fescue pastures. This is also during hot weather. Adverse effects on blood circulation can lead to poor weight gain and an inability to regulate body temperature properly. Fescue toxicosis causes fertility problems, as well as heat stress and “summer slump” in growth.
Fertility issues are a problem with bulls, as well as cows, says Mulliniks. “Since the endophyte toxin changes blood flow, it alters blood flow to the testicles, as well, which can result in a decrease in semen quality. This is even more problematic if you use bulls that have never been on fescue before.”
Tennessee research has shown shifting to fall calving can increase pregnancy rates and profitability, he says. “There are still some fescue issues with fall calving, due to regrowth of fescue pastures through fall and winter. But, the amount of toxin from the endophyte fungus is much lower when weather is cool.”
Stockers vs. cows
Some people with fescue pastures have changed from cow-calf to stocker operations to avoid fertility problems; however, they still have to contend with reductions in weight gain. He says weight gain problems can be overcome by supplementing with distillers’ grains to offset some of the negative effects. He also advises producers to rotate through pastures fast enough to keep plants from maturing and developing seedheads.
Editor’s note: Heather Smith Thomas is a cattlewoman and a freelance writer from Salmon, Idaho. [Lead photo by Shauna Hermel.]
