The Term disturbed ground
A plant growing in its natural habitat has to deal with a large number of biotic and non-biotic factors. Biotic factors have to do with living organisms like bacteria, fungi, animals, and other plants in the surrounding environment. Non-biotic factors are related to non-living facets of the surroundings such as the climate, weather, water quality and soil. Read more
Horse pastures and Ragwort. Prevention is easier than cure.
Common ragwort (Jacobaea vulgaris) is a common weed native to Europe, and north and western Asia. It usually grows in places where the original vegetation has been disturbed, in nutrient poor pastures, and areas that have been recently transformed into nature preserves. This species, just like all other ragworts in western Europe, contains pyrrolizidine alkaloids of the senecionine type. Upon ingestion, these chemical compounds are poisonous to most vertebrates and insects. When growing in pastures that are used for grazing or hay production, ragwort species are therefore a potential health hazard to cattle and horses. Although horses usually don’t feed on living ragworts, dried plants are not recognized as poisonous and alkaloid poisoning may therefore occur when ragwort ends up in hay that is meant for consumption. Read more
Ragwort poisoning: How does it work?
Common ragwort (Jacobaea vulgaris) and all other Ragworts and Groundsels growing in the Netherlands (Family Asteraceae; Tribe Senecioneae) contain compounds that are poisonous to most vertebrates and insects. These secondary metabolites are called pyrrolizidine alkaloids (PAs). Ragwort poisoning can take place when animals eat fresh or dry plants. Because fresh plants have a repellent smell and taste, these are usually avoided. In dried plants, however, the smell and taste is much less noticeable and animals can therefore not always recognize Ragworts and Groundsels as being toxic, especially when these plants end up in hay. Read more
Pyrrolizidine alkaloid metabolism.
In plants, pyrrolizidine alkaloids (PAs) are mostly stored in their non-toxic form (as pyrrolidizine N-oxides). Figure 1a shows an example of a PA called heliotrine. The blue ‘N’ in the heliotrine molecule is a nitrogen atom, which can be oxidized. Read more