The term weed can be broadly applied to any plant that is undesired or out of place based on certain criteria.
It is important to understand that the word weed has become a general term with no universal definition, and many native plants are considered to be weeds depending on location. This becomes problematic in pasture management because producers can be misled regarding what a weed is or is not and what their responsibilities for control may be.
Some producers perceive that cattle eat primarily grass species, leading to a conclusion that if a plant is not a grass, it is a weed and has no value to livestock production.
This simplified approach can result in a broad-scale application of chemicals to control broadleaf plants in pastures. Producers should consult a variety of resources in order to assess whether a plant is truly a weed or whether it has some intrinsic value to the system or to livestock diets.
Managing Weeds With Livestock
Researcher and author Kathy Voth is a leading expert in the emerging science of managing weeds with livestock. In “Cows Eat Weeds”, Voth’s book, she outlines simple methods that any producer can implement to train cattle to eat a variety of weedy species, including many of the exotic species found on the South Dakota noxious weed list.
She describes how one can train cattle to forage a variety of weeds previously thought to be non-palatable. This type of innovation can provide alternatives to producers struggling with the expense, scale, or timing of traditional weed control on rangeland and pasture.
By utilizing grazing as a means of cultural control, producers have the potential to decrease input expenses while reaping the benefits of inexpensive weed control through animal nutrition.
Information on the palatability of individual species can be difficult to find and can oftentimes be contradictory. Location, time of year and time of day can influence a plant’s relative nutritional (or toxic) value. The relationship between toxins and nutrients in ruminant animals is complex, and in many cases livestock can successfully mix their own diets as long as enough variety is available.