How the endophyte affects different animal species
Studies show that consumption of endophyte-infected tall fescue decreases the feed intake of cattle and therefore lowers their weight gains. They also produce less milk, have higher internal body temperatures and respiration rates, retain a rough hair coat, demonstrate unthrifty appearance, salivate excessively, have poor reproductive performance and maintain reduced serum prolactin levels.
Research from across the southern United States shows that the endophyte can reduce weight gain by more than 50 percent in steers fed on pasture (Table 1). It also shows that the seed head is the most toxic portion of the plant.
Agalactia — a diminished ability to produce milk — is especially severe when cows graze tall fescue during the last trimester of gestation. Agalactia leads to thickened placentas, aborted fetuses and, if the offspring should survive, a lack of colostrum and milk for the calf.
Tall fescue fertilized with high levels of nitrogen can also lead to bovine fat necrosis. As hard masses appear in the fatty tissues surrounding the intestines, this condition causes digestive problems and can also interfere with calving. High nitrogen rates also increase concentrations of toxic alkaloids such as ergovaline.
Table 1 Effect of the endophyte on weight gain in steers
Research location | Gain | Forage fed | |
---|---|---|---|
High endophyte | Low endophyte | ||
Texas | 0.99 pound per day | 2.14 pounds per day | Pasture |
Alabama | 1.41 pounds per day | 2.18 pounds per day | Pasture |
Georgia | 1.02 pounds per day | 1.31 pounds per day | Pasture |
Alabama | 1.00 pounds per day | 1.83 pounds per day | Pasture |
Missouri | 0.97 pound per day | 1.41 pounds per day | Pasture |
Alabama | 0.44 pound per day | 2.12 pounds per day | Seed |
Alabama | 0.62 pound per day | 1.46 pounds per day | Hay |
Horses, particularly mares, grazing endophyte-infected tall fescue are prone to reproductive problems such as late-term abortions and stillborn foals, prolonged gestation periods and dystocia, thickened or retained placentas, laminitis (founder), poor conception rates, decreased prolactin and progesterone levels and agalactia.
Foals that survive in utero will generally be larger than normal, have overgrown hooves, poor suckling reflexes, incoordination and lowered body temperatures. Foals may also have poor immunity due to the lack of colostrum produced by the mare. Because horses are sensitive to the toxins in endophyte-infected tall fescue, even the lowest levels of endophyte can produce equine fescue toxicosis.
Sheep appear to be less affected by the endophyte in tall fescue, possibly because they are inherently hardy. However, sheep are prone to “fescue foot,” hyperthermia, poor wool production and reproductive problems as well as lowered feed intake and the resulting poor weight gains.
The endophyte is present in the seed at the time of planting. If the seed is less than a year old, the endophyte is still alive. When the seed germinates and grows into a seedling, the endophyte begins infecting the plant at the base of the leaf. It remains there until the plant begins its reproductive cycle. At this time, the endophyte moves into the stem, growing as the stem elongates. Eventually, the stem forms a seed head, and the endophyte moves into seed.
It is important to understand how the endophyte spreads — from inside the plant (Figure 1). In its natural setting, it does not form spores and infect other plants from the air. Thus, a well-established field of endophyte-free tall fescue will not become reinfected unless the stand thins, thereby creating an opportunity for infected seed to germinate and become established.
Figure 1 The tall fescue endophyte fungus inside a leaf sheath cell. The fungus is not found in a leaf blade
What kind of grass is safe for dogs to eat?
Both cats and dogs need a little grass in their diets, especially if they do not spend a lot of time outdoors. So if you have a pet, growing pet grass is a great idea. This grass is also called intermediate wheatgrass, but it is not the wheat from which bread flour is made.
Can dogs eat tall fescue grass?
Fescue. There are a variety of different fescues available, so you’ll have to pick a good variety for your climate. However, as a group, fescues tend to be hardy grasses. They exhibit excellent moisture-absorbing properties and generally handle the indignities your dog will dole out.