Mineral Composition and Nutritive Value of Some Common Pasture Weeds

Organic dairy farmers often introduce alternative pasture species, such as chicory (Cichorium intybus) and narrow-leaved plantain (Plantago lanceolata), to their swards because of their higher mineral contents, yet they are concerned about the presence of weed species such as docks (Rumex spp.) and dandelion (Taraxacum officinale). The mineral content and nutritive value of both desired and less desired pasture components from an organic dairy farm were analysed and compared. Minerals such as magnesium, manganese, copper, zinc, boron, cobalt and selenium were often significantly higher in species such as chicory, narrow-leaved plantain, dandelion, broad-leaved dock (Rumex obtusifolius), Californian thistle (Cirsium arvense) and hairy buttercup (Ranunculus sardous) than the perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) components of the sward. Likewise the crude protein levels of these species plus Yorkshire fog (Holcus lanatus) were significantly higher than for perennial ryegrass. Implications of these findings are discussed in terms of animal nutrition and health.