Canopy and Chemistry of Pasture Weeds

Abstract

Morphological and chemical characteristics of 11 warm season pasture weed species were defined. Goldenrod (Solidago altissima L.) was significantly taller and common ragweed (Ambrosia artemisiifolia L.) had the largest canopy diameter of the 11 species studied. Species ranged from 14 to 134 cm in height with canopy diameters of 25 to 70 cm. No direct correlation was found between individual leaf size and total leaf area. Macro- and micromineral content varied widely among species but all values obtained were considered high enough to meet the requirements of ruminant animals. Redroot pigweed (Amaranthus retroflexus L.) and horsenettle (Solanum carolinense L.) contained potentially toxic levels of nitrate. Five of the 11 species contained sufficient crude protein for ruminants and six of the 11 species were more than 50% digestible. Digestible energy values averaged 1.9 Mcal/kg for the 11 weeds evaluated.

Dispersal of Small Seeds by Big Herbivores: Foliage is the Fruit

“…Foliage is of sufficiently high nutrient value to be attractive to a large herbivore. That large 'herbivores voluntarily consume many herbs is undeniable, but this point is reinforced by the observation that wild weeds may have as much or more nutrient value (in vitro digestibility trials, mineral analyses) as do standard forage plants (e.g., Carlisle et al 1980). 4. Seed maturation is synchronized such that the vegetative portion bitten off is contaminated with mostly mature seed (though the expectation of this trait is complicated by the observation that immature reproductive parts, as well as sterile foliage, may be bait for the large herbivore).…”

Evaluation of Perennial Warm‐Season Grass Mixtures Managed for Grazing or Biomass Production

“…In this experiment, some unsown weedy species had high nutritional values, such as clovers and crabgrass (Digitaria spp.). Despite concerns about toxicity, several weed species present in this study contain high CP concentrations and digestible energy levels and only low levels of antiquality compounds (Marten and Andersen, 1975;Carlisle et al, 1980). Other weeds also mature later in the season than prairie plants and may therefore have higher protein and lower fiber concentrations in midsummer.…”

“…Despite concerns about toxicity, several weed species present in this study contain high CP concentrations and digestible energy levels and only low levels of antiquality compounds (Marten and Andersen, 1975;Carlisle et al, 1980). The inclusion of weed species with higher protein concentrations and lower fiber concentrations, particularly in late summer, may help reduce NDF concentrations to values where animal intake could potentially provide sufficient energy for nonlactating cows.…”

Tolerance of Three Clovers (Trifoliumspp.) to Common Herbicides

“…White clover improves sward color by contributing N to associated grasses (Sincik and Acikgoz 2007) and is suitable for maintaining roadside slopes (Roberts and Bradshaw 1985). Yet, herbicide applications are often required to maximize yields of mixed grass-legume swards (DiTomaso 2000;Seefeldt et al 2005) and are especially important during seedling establishment (Carlisle et al 1980;Evers et al 1993;Young et al 1992).…”