Managing the fatty acid composition of grazing ruminant diets could lead to meat and milk products that have higher conjugated linoleic acid (CLA) concentrations, but forage fatty acid dynamics must be more fully understood for a range of forages before grazing systems can be specified. The fatty acid profiles of 13 different forages, including grasses, legumes, and forbs, grown under greenhouse conditions, were determined. Three separate harvests, at 3-week intervals, were made of each plant material. alpha-Linolenic [C18:3, 7.0-38.4 mg g(-1) of dry matter (DM)], linoleic (C18:2, 2.0-10.3 mg g(-1) of DM), and palmitic (C16:0, 2.6-7.5 mg g(-1) of DM) acids were the most abundant fatty acids in all species at each harvest, together representing approximately 93% of the fatty acids present. Concentrations of fatty acids declined as plants developed, but the fractional contribution of each fatty acid to total fatty acids remained relatively stable over time. Grasses had a uniform composition across species with a mean of 66% of total fatty acids provided by C18:3, 13% by C18:2, and 14% by C16:0. The fractional contribution of C18:3 to total fatty acids was lower and more variable in forbs than in grasses. Intake of fatty acid by grazing ruminants would be affected by the forage species consumed.

Pure stands of 'Grasslands Puna' chicory (Cichorium intybus L.) are productive and responsive to N fertilization in the eastern USA.We conducted a field experiment for 3 yr to investigate productivity and nutritive value of swards including chicory, orchard grass (Dactylis g/omerata L.), and birdsfoot trefoil (Lotus comicu/atus L.) as a func· tion of clipping frequency (3-and 6-wk intervals). Each treatment was replicated three times on an upland site of Dekalb series soil (loamy-skeletal, mixed, subactive, mesic Typic Dystrochrept). Modest rates of N, P, and K were applied annually. Herbage mass, botanical composition, in vitro organic matter disappearance (IVOMD), and crude protein (CP) were determined. Cumulative herbage yield was not influenced by initial sward composition with chicory, chicoryorchardgrass, and chicory-orchardgrass-trefoil averaging 6.8 Mg ha-• during a growing season. Clipping frequency influenced yield with canopies clipped at 6-wk intervals producing 26% more herbage than those clipped at 3-wk intervals. Growth rates of canopies clipped at 6-wk intervals averaged 51 kg ha-• d-1 early in the growing season, suggesting that swards including chicory would be responsive to nutrient inputs and where rapid herbage regrowth and nutrient use by the growing crop are needed. Chicory declined in swards with time, regardless of initial sward composition or clipping frequency. Fluctuations in IVOMD and CP were related to changes in sward composition arising from the interaction of time and clipping frequency. Including orchardgrass and trefoil retarded invasion of less desirable species and so provided a means to control overall sward productivity and herbage composition.

value of chicory herbage and to identify nutrient inputs that sustain production, especially when high rates of Chicory (Cichorium intybus L.), a highly productive forage under N are applied. Crush and Evans (1990) and Reid et al. midsummer conditions in the eastern USA, often has higher concentrations of minerals relative to grasses and legumes. Low concentra- (1993) reported that the mineral composition of forage tions of minerals in herbage could reduce production efficiency or chicory was comparable to or exceeded that of white create metabolic disorders in livestock. Information on the mineral and red clover (Trifolium repens and T. pratense, respeccomposition of chicory is limited, but it is needed to improve our tively) and perennial ryegrass (Lolium perenne L.). Minunderstanding of nutritive value and inputs required to sustain chicory eral concentrations in chicory met or exceeded recomproduction, especially where high rates of N are applied. We conmended dietary mineral requirements of lactating dairy ducted field experiments for 3 yr on a Ramsey soil (Loamy, siliceous, cows (Jung et al., 1996), and because chicory had a subactive, mesic Lithic Dystrudept) in southern West Virginia to derelatively high B concentration, fertilization with B termine (i) response to increasing fertilizer N and (ii) production of might be warranted. Herbage may contain mineral conchicory as a component of swards, including grass and legume as a centrations that theoretically meet livestock requirefunction of clipping frequency. Mineral concentrations and uptake in available herbage generally increased as N rate increased and were

Knowledge of seasonal distribution of herbage growth is essential for design of pasture management schemes that optimize season-long herbage productivity and nutrients for grazing livestock. Current knowledge of cool-season grass growth is derived largely from either ha:r production or high-input systems. A 3-yr field study was conducted to determine the productivity and growth rates of cool-season grasses defoliated according to sward height criteria in a marginalsoil environment. Defoliation regimes included hay harvest, lenient (50%) removal of short (10 em) canopies, and both lenient and intensive (75%) removal of tall (20 em) canopies. Species included orchard· grass (Dactylis glomeraJa L.), tall fescue x perennial ryegrass hybrid (Festuca arundinacea Schreb. x Lolium perenne L.), and prairie grass (Bromus willdenowii Kunth). Cumulative yield curves were fit to the Gompertz growth equation and growth rates were derived from the fitted data. All species had low yields relative to other defoliations and growth rates when managed for removal of 50% of canopy height regardless of height. Managing pastures on the premise of take half, leat•e luzif may not always contribute to plant persistence and sustained productivity. Frequent defoliation beginning in spring resulted in a greater portion of annual yield occurring in late than in early season, resulting in more stable distribution but less herbage within a season, compared with canopies managed as hay. High growth rates of prairie grass early in the study were followed by stand degradation, regardless of defoliation treatment, and may indicate unsuitability for use in low-input or marginal environments. Autumn recovery of herbage production did not occur under any defoliation regime.