Forage Quality of Selected Cool-Season Weed Species

Abstract

Forage quality was determined at vegetative, flowering, and fruiting stages for nine cool-season weed species and four cultivated forages. When compared at the vegetative stage of maturity, Carolina geranium (Geranium carolinianumL. # GERCA), Virginia pepperweed (Lepidium virginicumL. # LEPVI), Virginia wildrye (Elymus virginicusL. # ELYVI), wild oats (Avena fatuaL. # AVEFA), cheat (Bromus secalinusL. # BROSE), and little barley (Hordeum pusillumNutt. # HORPU) had high nutritive quality as indicated by in vitro dry-matter digestibility (IVDMD) values equal or superior to rye (Secale cerealeL.), tall fescue (Festuca arundinaceaSchreb.), and ladino clover (Trifolium repensL.). Cutleaf evening primrose (Oenothera laciniataHill # OEOLA) and curly dock (Rumex crispusL. # RUMCR) had lower IVDMD values than the cultivated forages and all weed species except wild oats. However, the rate of decline in IVDMD as plants matured was generally greater for the weed species compared to cultivated forage plants. All weed and cultivated forage species had adequate levels of Ca and K for livestock. Nearly all weed and cultivated forage species had suboptimum levels of P for high-producing ruminant animals; Carolina geranium and cutleaf evening primrose had high Ca:P ratios, which can cause metabolic disorders. Carolina geranium, Virginia wildrye, wild oats, cheat, little barley, and all the cultivated forage species had inadequate levels of Mg and could be considered “tetany prone”. Most of the forbs had high Mg concentrations.