Canopy structure and neutral detergent fiber differences among temperate perennial grasses

Intake of animals grazing grass pasture is in part influenced by canopy density. Our objective was to determine the vertical distribution of dry matter and neutral detergent fiber (NDF) within temperate perennial grass' swards. The study was; conducted in 2004 and 2005 on a Plano silt loam (fine-silty, mixed, superactive, mesic Typic Argiudolls). When leaf height of each grass reached 25 cm in spring, summer, and fall, canopy layers were harvested from 20 to 25, 15 to 20, and 10 to 15 cm. Differences in canopy density were usually not significant when precipitation was below normal. With abundant spring precipitation, quackgrass [Elymus repens (L.) Gould] had greater upper canopy density (1.9 mg dry matter [DM] cm(-3)) than any of the other grasses studied. Grasses typically grazed at shorter heights such as bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.) had greater density in the lower canopy layer (1.0-1.3 g DM kg(-1)). While soft-leaf tall fescue (Festuca arundinacea Schreb.), reed canarygrass (Phalaris arundinacea L.), and meadow fescue (Festuca pratensis Huds.) had lower density in the upper canopy than timothy (Phleum pratense L.) and quackgrass in the spring, the reverse was true in the summer. Herbage NDF of grasses generally increased from the upper to lower canopy layer (mean difference of 50, g kg-1); perennial ryegrass and meadow fescue often had the lowest NDF throughout the canopy (range of 392-452 and 418-469 g kg(-1), respectively). Pasture intake may benefit from a diverse species composition because animals can graze a mixture having optimum density and NDF throughout the canopy.