Poisonous Grasses: New Study Provides Reassurance


Stories of mass poisoning incidents of livestock due to toxic grasses made headlines especially overseas. 

Stories of mass poisoning incidents of livestock due to toxic grasses made headlines especially overseas. Animal ecologists from Würzburg have studied whether this hazard is also lurking on German pastures.

"Dangerous Pastures: Deadly Grass Puts Horses at Risk" – Such dire warnings on the websites of horse owners and horse lovers may cause people to see their environment in a whole new light. Because what they once considered the epitome of pristine nature, green meadows of grass gently swaying in the wind, is actually home to numerous toxic substances that can be lethal for horses, cattle and sheep.

Scientists from the Department of Animal Ecology and Tropical Biology of the University of Würzburg have teamed up with US researchers to find out whether this is also true for Germany. To accomplish this, PhD student Veronika Vikuk and Professor Jochen Krauß, her mentor, analysed the toxicity of 13 grass species in three German regions. Their results published in the journal Applied and Environmental Microbiology reveal that toxic substances are also found in German grasses. However, there is little risk of mass poisoning of grazing animals. And the risk can be further reduced by taking some simple measures.

A fungus produces the toxins

Strictly speaking, it is not the grass itself that endangers the lives of horses and other grazing animals: "Grass species can form a symbiosis with fungal endophytes of the genus Epichloë. These fungi are capable of producing so-called alkaloids that can be poisonous to grazing livestock," Veronika Vikuk describes the problem. Endophytes are fungi that live within a plant and are usually not visible from the outside. Both partners benefit from the symbiotic relationship: The grass host provides nutrients for the endophyte and the endophyte helps protect the plant from drought stress and pests. When danger is imminent, the forage grass can encourage the fungus to step up toxin production to prevent animals from eating the plant.

Read more at University of Würzburg