Search

Abstract: Plant growth simulation models have a temperature response function driving development, with a base temperature and an optimum temperature defined. Such models function well when plant development rate shows a continuous change throughout the growing season. This approach becomes more complex as it is extended to cool‐season perennial grasses with a dormant period and bimodal growth curves. The objective of this study was to develop such a bimodal growth model for tall fescue (Schedonorus arundinaceus (Schreb.) Dumort) in the Midwest USA based on multiyear measurement trials. Functions for bimodal growth were incorporated into the ALMANAC model and applied to tall fescue using published tall fescue yields for a variety of sites and soils. Fields of cultivars “Kentucky 31” and “BarOptima Plus E34” were divided into paddocks and sampled weekly for dry‐matter accumulation. These biomass estimates were used to derive weekly growth values by differences between sequential weekly samplings. The measured values were compared to a single tall fescue simulation each year on one soil. Using these results, the ALMANAC model was modified and tested against mean reported tall fescue yields for 11 sites, with one to three soils per site. When we introduced midsummer dormancy into ALMANAC, we assumed dormancy began on the longest day of the year and lasted until the photoperiod was 0.68 hr shorter than the longest. ALMANAC simulated previously reported tall fescue yields well across the range of sites. Thus, ALMANAC shows great promise to simulate bimodal growth in this common cool‐season grass. [ABSTRACT FROM AUTHOR]

Breeding to improve biomass production of switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) for conversion to bioenergy began in 1992. The purpose of this study was (i) to develop a platform for uniform regional testing of cultivars and experimental populations for these species, and (ii) to estimate the gains made by breeding during 1992 to 2012. A total of 25 switchgrass populations and 16 big bluestem populations were planted in uniform regional trials at 13 locations in 2012 and 2014. The reference region was USDA Hardiness Zones 3 through 6 in the humid temperate United States. Significant progress toward increased biomass yield was made in big bluestem and within upland-ecotype populations, lowland-ecotype populations, and hybrid-derived populations of switchgrass. Four mechanisms of increasing biomass yield were documented: (i) increased biomass yield per se, (ii) later flowering to extend the growing season, (iii) combined later flowering from the lowland ecotype with survivorship of the upland ecotype in hybrid-derived populations, and (iv) increased survivorship of late-flowering lowland populations in hardiness zones that represent an expansion of their natural adaption zone. Switchgrass exhibited all four mechanisms in one or more improved populations, whereas improved populations of big bluestem were likely influenced by two of the four mechanisms. The uniform testing program was successful at documenting increases in biomass yield, identifying the mechanisms for increased yield, and determining adaptation characteristics and limitations of improved populations. [ABSTRACT FROM AUTHOR]

Context. Energetic particle enhancements that are associated with corotating interaction regions (CIRs) are typically believed to arise from the sunward propagation of particles that are accelerated by CIR-driven shocks beyond 1 AU. It is expected that these sunwardtravelling particles will lose energy and scatter, resulting in a turnover of the energy spectra below ∼0.5 MeV/nuc. However, the turnover has not been observed so far, suggesting that the CIR-associated low-energy suprathermal ions are accelerated locally close to the observer. Aims. We investigate the variability of suprathermal particle spectra from CIR to CIR as well as their evolution and variation as the observer moves away from the rear shock or wave. Methods. Helium data in the suprathermal energy range from the Solar and Heliospheric Observatory/Charge, Element, and Isotope Analysis System/Suprathermal Time-of-Flight (SOHO/CELIAS/STOF) were used for the spectral analysis and were combined with data from the Advanced Composition Explorer/ SolarWind Ion Composition Spectrometer (ACE/SWICS) in the solar wind energies. Results. We investigated sixteen events: nine clean CIR events, three CIR events with possible contamination from upstream ion events or solar energetic particles (SEPs), and four events that occurred during CIR periods that were dominated by SEPs. Six of the nine clean CIR events showed possible signs of a turnover between ∼10-40 keV/nuc in the fast solar wind that trails the compression regions. Three of them even showed this behaviour inside the compressed fast wind. The turnover part of the spectra became flatter and shifted from lower to higher energies with increasing connection distance to the reverse shock. The remaining three clean events showed continuous power-law spectra in both the compressed fast wind and fast wind regions, that is, the same behaviour as reported from previous observations. The spectra of the seven remaining events are more variable, that is, they show power law, turnover, and a superposition of these two shapes. [ABSTRACT FROM AUTHOR]

Grasslands enrolled in the Conservation Reserve Program (CRP) serve as one of the potential national herbaceous resources for use as a dedicated bioenergy feedstock. The goal of this project was to assess the yield potential and suitability of CRP grassland as a bioenergy feedstock source across the USA in regions with significant CRP land resources. In addition to that goal, one major objective of this project was to assess vegetation composition changes that also occurred on these different CRP grasslands over time with different harvest and fertilization management strategies. Three levels of nitrogen fertilization (0, 56, and 112 kg ha) and two harvest timings [peak standing crop (PSC) or end of growing season (EGS)] were evaluated for effects on biomass production and resulting species composition changes. Three sites in regions containing concentrated tracts of CRP grassland and representing variable climatic parameters were analyzed for vegetation composition trends over the course of six growing seasons (2008-2013). Specifically, a mixture of warm-season perennial grasses was evaluated in Kansas (KS), while a cool-season mixture was evaluated in Missouri (MO). North Dakota (ND) contained a mixture of both warm- and cool-season grasses. At the MO and KS sites, nitrogen fertilization significantly altered the grass and legume composition over time by lowering the legume percentage in the stand. In KS and ND, the two sites with warm-season grasses, harvesting in mid-summer at PSC, greatly reduced warm-season grass composition over time in favor of annual cool-season grass invaders or perennial cool-season grasses. Any shift to less desirable or less productive species limits the ability of these lands to provide a sustainable or reliable feedstock for bioenergy production. [ABSTRACT FROM AUTHOR]

Beef cattle consume more tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] than any other perennial cool-season grass in North America. Tall fescue forms a mutualistic relationship with the fungus Epichloë coenophiala (Morgan-Jones and W. Cams) C.W. Bacon & Schardl, comb. nov.; these plants are often referred to as endophyte-infected tall fescue. Agronomically, endophyte infection is good; endophyte- infected plants resist biotic and abiotic stresses better than do endophyte-free plants. However, tall fescue plants infected with a common toxic endophyte produce the ergot alkaloids that cause tall fescue toxicosis. Several agronomic practices can eliminate or reduce the effects of tall fescue toxicosis. Renovating tall fescue fields infected with a common toxic endophyte to new cultivars infected with a novel (or nontoxic) endophyte eliminates the problem for that field. Although the cost to renovate currently exceeds US$600/ha, most economic analyses show it to be a good long-term investment, especially on fields with high forage production potential. Less effective, but popular, methods of dealing with tall fescue toxicosis include adding clovers (Trifolium spp.) or other forage species to the pastures to dilute the effects of the toxins, avoiding the use of high rates of nitrogen fertilizers, feeding supplements, and rotating cattle to warm-season forages in summer. Also, the alkaloid concentration in forage can be reduced by making it (drying) into hay. Recent research shows that animal tolerance to tall fescue toxicosis is possible, although there is still much to learn about this topic. Tall fescue toxicosis is likely a reality in the beef industry for some time to come. We contend that renovation of the most productive fields to cultivars infected with a novel endophyte coupled with the prospect of using tolerant livestock in scenarios where renovation is not possible will give innovative producers a competitive edge. [ABSTRACT FROM AUTHOR]

The primary objective was to determine the feasibility of harvesting switchgrass (Panicum virgatum L.) for biomass and/or forage in a single season. Plots were located at Mt. Vernon, on Viraton silt loam (fine-loamy, siliceous, active, mesic Oxyaquic Fragiudalf), and Columbia, on Mexico silt loam (fine, smectitic, mesic Vertic Epiaqualf), both in Missouri. Forage/biomass yields and nutritive value of samples intended for forage use, were compared between four harvest management treatments: a single post-frost harvest for biomass (Treatment I), a forage harvest at boot stage followed by a post-frost biomass harvest (Treatment II), biomass harvest at postanthesis with late summer regrowth harvested as forage (Treatment III) and biomass harvest at preanthesis with late summer regrowth harvested as forage (Treatment IV). A complementary study was conducted to determine the effects of switchgrass maturity stage on efficiency of conversion to glucose through enzymatic hydrolysis. Both studies were conducted in 2010 and 2011. The single, post-frost harvest (Treatment I) yielded as much as or more biomass than any other treatment. At Mt. Vernon in both years, yields intended for forage use were greatest for Treatment II. At Columbia, forage yields were greatest for Treatment IV in 2010 while there was no difference between treatments in 2011. When forage harvests were compared, summer regrowth was generally more lignified than growth harvested at boot stage. Two-harvest systems can yield as much as single harvest systems; producers should weigh the economic value of forage vs. biomass before deciding which strategy fits best. [ABSTRACT FROM AUTHOR]

Pasture-based dairy operators usually aim to optimize defoliation intensity to maximize forage production and nutritive value. he objective was to determine forage accumulation, nutritive value, and tiller density of tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] and perennial ryegrass (L. perenne L.) when repeatedly mowed to a stubble height of 2.5, 5, 7.5, 10, 12.5, or 15 cm. In a 2-yr study conducted near Columbia, MO, plots were mown to their respective stubble height whenever they grew to a "trigger" height of 20 to 22 plate meter units (approximately 4000 kg ha-1 dry matter [DM] to soil surface). In Year 1, tall fescue mowed to 2.5 cm accumulated 14,440 kg ha-1 which was the most of any treatment. In Year 2, forage accumulation for tall fescue mowed to 2.5, 5, or 7.5 cm did not difer, but was approximately 15% more than perennial ryegrass mowed to the same heights. For both species, forage harvested at stubble heights ≥10 cm had greater nutritive value than at heights of ≤7.5 cm. Perennial ryegrass had 60% fewer tillers for stubble heights ≤7.5 cm compared to heights ≥10 cm. Tall fescue showed no diference in tiller density for any stubble height. Milk production ha-1, predicted via MILK2006, was greater for stubble heights ≤7.5 cm, primarily due to greater forage accumulation. his study showed that tall fescue is better suited than perennial ryegrass for pasture-based dairies in the Midwest because of its greater forage yield, estimated milk production, and stand (tiller) density. [ABSTRACT FROM AUTHOR]

Silvopasture-the integration of trees, forage, and livestock can be established by planting trees in existing pastures. Successful tree establishment and acceptable tree growth in existing tall fescue [ Lolium arundinaceum (Schreb.) Darbysh.] pastures requires a vegetation-free zone near the tree base. This study was conducted to determine how large a vegetation-free zone was necessary for the establishment of black walnut ( Juglans nigra L.) in tall fescue pastures. Half-sib black walnut seeds were planted in seven different-sized vegetation-free zones [0.0 (control), 0.3, 0.6, 0.9, 1.2, 1.5, and 1.8 m radii] that were created and maintained by applying glyphosate. The study included two consecutive planting years at two locations, one in central Missouri and another in north-central Missouri. The central Missouri site was underlain with well drained, deep soil while the other site was underlain with a poorly drained soil with a defined argillic horizon. Tree height growth was greatest in 0.9-m or larger vegetation-free zones. Diameter growth was greatest in 1.2-m vegetation-free zones and larger. The results suggest that a minimum of a 1.2-m vegetation-free zone in tall fescue pastures should be used to maximize black walnut height and diameter growth in the critical first years of tree establishment. [ABSTRACT FROM AUTHOR]

Continental tall fescue [Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh.] is the predominant forage used by cattle producers throughout much of the Midwest. However, Mediterranean tall fescue is gaining popularity in warmer, drier climates. One major difference of Mediterranean tall fescue is that it enters a semidormant period during hot dry summers but resurges during the fall and winter months. During the autumn resurgence it has exceptional growth but does not survive prolonged freezing conditions typically found in the Midwest. To determine how both Continental and Mediterranean tall fescues respond to low temperatures that are typically encountered during the fall, the leaf extension rate (LER) was measured along with proline, simple sugars, fructan, and abscisic acid (ABA). Three Mediterranean and four Continental accessions were tested, including Kentucky-31 and Flecha as "typical" Continental and Mediterranean accessions, respectively. The greatest difference observed between these types of tall fescue occurred at 4.5°C. The Mediterranean genotypes had greater LER and fructan concentrations while the Continental genotypes possessed greater proline, ABA, and simple sugar concentrations. Kentucky-31 was typically found in the middle between the Mediterranean and the remaining Continental accessions. These data indicate that Mediterranean germplasm possesses superior cold growth, but the high proline levels produced by the Continental types may be critical for survival under cold conditions. [ABSTRACT FROM AUTHOR]

Tall fescue [Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh.] is widely used for hay and pasture in the Eastern regions of the United States, with new types of Mediterranean tall fescue possessing superior growth under cool growing conditions. However, they do not survive Midwestern winters. To date, little research has examined the role of endophyte infection on the ability of tall fescue to grow under cold conditions or survive freezing conditions. This study's objectives determined the endophyte's role in tall fescue growth and production of metabolites for nonfreezing conditions. Additionally, the role of endophyte infection on the ability of plants to survive freezing temperatures was determined. This experiment used five genotypes of tall fescue. Half of the plants from each genotype were endophyte infected (E+), with the remaining genotypes being endophyte free (E-). We report for the first time the effects of endophyte status on proline, simple sugars, and fructan accumulation when plants were grown under cold, nonfreezing temperatures and the survivability at various freezing temperatures. Endophyte removal only affected fructan concentrations at 4.5°C; however, plant genotype affected leaf extension rate, proline, sugars, and fructan concentration. The freezing test found no effect of the endophyte on tiller survival, while plant genotype was significant. These data indicate that endophyte removal has little influence on the measured traits, and plant genotype is more critical for survival under cold conditions. [ABSTRACT FROM AUTHOR]

The daily BW gain of stocker steers grazing tall fescue [Lolium arundiriaceum (Schreb.) S.J. Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort.]-based pastures typically declines during summer. To avoid these declines, in part to mitigate the effects of tall fescue toxicosis, it is commonly advised to move cattle to warm-season forage during this period. A 3-yr (2006, 2007, and 2008) grazing study was conducted to evaluate the effect of replacing 25% of the area of a tall fescue/clover (81% endophyte-infected) pasture system with "Ozark" bermudagrass [Cynodon dactylon (L.) Pers.] overseeded with clover (Trifolium spp.) to provide summer grazing for stocker steers (TF+BERM). The TF+BERM treatment was compared with a grazing system in which tall fescue/clover (TF) pastures were the only type of forage available for grazing. Our objective was to determine if replacement of 25% of the land area in a fescue system with bermudagrass would increase annual beef production compared with a system based solely on tall fescue. The study was conducted at the Southwest Research and Education Center of the University of Missouri near Mt. Vernon. Each treatment was rotationally stocked with 5 steers (248 ± 19.3 kg) on 1.7 ha. Fertilizer applications were applied at rates recommended for each respective forage species. Total forage production, BW gain per hectare, and season-long ADG of steers was greater (P < 0.06) for TF+BERM than for TF in 2006, but none of these measures differed (P > 0.19) in 2007 or 2008. In vitro true digestibility of pastures was greater (P = 0.01) for TF (84.4%, SEM = 0.64%) compared with TF+BERM (80.6%, SEM = 0.79%), even in summer. The decreased in vitro true digestibility of the bermudagrass pastures likely negated any benefit that animals in TF+BERM had in avoiding the ergot-like alkaloids associated with endophyte-infected tall fescue. Renovating 25% of the pasture system to bermudagrass provided some benefit to the system in years when summertime precipitation was limited (2006) but provided no value in wetter years (2007 and 2008). Although renovating endophyte-infected tall fescue pastures to a warm-season forage is a widely used practice to mitigate tall fescue toxicosis, the benefits of this practice are limited if forage quality of the warm season component is poor. [ABSTRACT FROM AUTHOR]

Using stockpiled forage can substantially reduce livestock feed costs over the winter. However, little is known about utilizing stockpiled forage in an early-stage silvopasture system. This study was conducted to determine if silvopasture production practices utilizing stockpiled forage influence stocker steer performance. The treatments were: (1) stockpiled forage in a non-forested pasture (OPEN) and (2) stockpiled forage in a silvopasture (TREE). Grazing began early December and ended in late February in each of 2 years. Each treatment was replicated three times in a completely randomized design. Forage nutritive value, production, and steer average daily gain (ADG) for the OPEN and TREE treatments were not significantly different as long as the areas occupied by trees was excluded from analyses. When the area occupied by trees was included, the OPEN treatment produced more ( P < 0.01) forage than the TREE treatment, with the OPEN producing 3510 kg ha and the TREE producing 2812 kg ha. Average daily gain ( P = 0.21) was 0.41 kg for the steers in the OPEN treatment and 0.37 kg for steers in the TREE treatment. Gain per ha was significantly different ( P < 0.01); the OPEN treatment produced 193 kg of animal gain and the TREE treatment produced 125 kg of animal gain. Exclusion of the area under the tree row from the analysis changed the total gain per ha for the TREE treatment to 148 kg, but was still less ( P = 0.01) than the OPEN treatment. [ABSTRACT FROM AUTHOR]

A 2–yr production study was conducted to evaluate 3 systems of growing stocker calves under rotational stocking. One group of steers was stocked on pasture from early April to mid August (springstocked steers = SSS), and another group of steers was stocked from early July to late October (fall–stocked steers = FSS). Steers were stratified by BW (n = 72, BW=229±llkgforSSS;n=72,BW=248±18 kg for FSS) and randomly assigned to 1 of 3 treatments. The 3 treatments were 1) rotationally stocked only (control; CON), steers rotated to a new paddock as forage availability dropped below acceptable levels in the occupied paddock; 2) rotationally stocked with distillers grains (DIST); this was the same as CON except steers were supplemented with varying amounts of distillers dried grains with solubles (DDGS) based on forage nutritive value; and 3) rotationally stocked with round–bale silage (SIL); excess forage in spring was harvested and stored as round–bale silage and fed back as needed. Total BW gain/ha over the entire grazing season did not differ between DIST and SIL (P = 0.09) steers, but both were greater thall CON (P < 0.01). Total BW gain/ha for DIST, SIL, and CON was 459 (SEM = 11.5), 402 (SEM = 31.0), and 276 (SEM = 26.2) kg, respectively. For ADG, there was a group x year (P < 0.01) and group x treatment (P = 0.02) interaction. Steer ADG for SSS did not differ between SIL and DIST (P = 0.51), but was greater than the CON (P = 0.01). The ADG for SSS was 0.79 (SEM = 0.04), 0.81 (SEM = 0.05), and 0.62 (SEM = 0.05) kg for DIST, SIL, and CON, respectively. For the FSS, ADG for all 3 treatments was different (P = 0.02). The FSS ADG was 0.72 (SEM 0.03), 0.53 (SEM = 0.04), and 0.29 (SEM = 0.04) kg for DIST, SIL, and CON, respectively. The only treatment with equivalent (P = 0.07) ADG between early and late–stocked steers (SSS vs. FSS) was DIST. Adjusting the amount of DDGS supplemented to steers based on forage nutritive value resulted in consistent BW gains throughout the grazing study, whereas steers in the SIL and CON treatments gained less BW during the latter portion of the season. Controlling forage maturity by removal in the SIL treatment resulted in total BW gains/ha that were not different than the DIST treatment. [ABSTRACT FROM AUTHOR]

Recent research shows that the meat from beef animals finished on pasture has greater concentrations of omega-3 fatty acid (FA) and conjugated linoleic acids (CLA) compared with animals finished on high-concentrate diets. However, little is known about the FA concentrations in forage that might alter these FA in the meat of pasturefinished beef. The objective was to determine the FA variation between and within forage species commonly grown in pastures in the Midwest. A secondary objective was to identify phenotypic characteristics that may be associated with individual FA. The forages analyzed included multiple cultivars of orchardgrass (Dactylis glomerata L.), tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire Schedonorus phoenix (Scop.) Holub], perennial ryegrass (Lolium perenne L.), and alfalfa [Medicago sativa L. ssp. sativa and falcata (L.) Arcang.]. Grasses had higher amounts of a-linolenic (C18:3) acid compared with alfalfa. Conversely, alfalfa had larger amounts of linoleic acid (C18:2) than did the grasses. Correlations between phenotypic traits and specific FA were found; plant total chlorophyll had the greatest correlation to total FA concentration. Overall, there is not a large amount of within-species variation that breeders could use to make large changes in FA concentrations. [ABSTRACT FROM AUTHOR]

Common tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort.] is infected with a fungus that produces ergot alkaloids, a class of compounds associated with fescue toxicosis. The objective of this research was to monitor the change in concentrations of ergot alkaloids from time of clipping through storage of tall fescue hay. A 2-yr field study was conducted in Mt. Vernon, MO, in which tall fescue was baled at high moisture (204-219 g H2O kg-1 dry matter [DM]) and low moisture (102-112 g H2O kg-1 DM) then stored for 18 mo. Hay samples were collected over the 540-d period from clipping through storage and analyzed for ergovaline and total ergot alkaloid concentration. Data were analyzed using standard ANOVA procedures and break-point regression. In both years, ergovaline concentrations decreased sharply within the first month after harvest and gradually over the remaining 17 mo. In three of the four cases, most of the ergovaline disappearance occurred within 3 d after clipping. The final ergovaline concentration remained above 250 pg kg-1 DM, which is still considered toxic to livestock. In the first year, ergot alkaloid concentration followed a pattern similar to ergovaline concentration. In the second year, however, the decrease in total ergot alkaloid was gradual throughout the entire 18 mo. A general recommendation to producers would be to delay feeding toxic tall fescue hay until at least 1 mo after clipping. [ABSTRACT FROM AUTHOR]

In the years 2004 and 2007, the instruments onboard the Voyager 1 and 2 spacecraft delivered unprecedented data on the structure of the solar wind termination shock. This shock has been assumed to be responsible for the acceleration of the anomalous component of cosmic rays from a pick-up ion seed population derived from the interstellar neutral gas penetrating the heliosphere. In expectation of the Voyager observations near the termination shock and in the heliosheath region, detailed models have been developed on the acceleration mechanism for the anomalous cosmic rays and on the structure of the termination shock. Here, an overview on the models on injection mechanisms into first-order Fermi acceleration, stochastic acceleration in the supersonic and subsonic solar wind, shock mediation by suprathermal ions, and on shock reformation by ions reflected at the shock is given. Comparing the results of these models to the Voyager observations, we try to synthesize an updated picture on the acceleration process of the anomalous cosmic rays. [ABSTRACT FROM AUTHOR]

Pasture-based dairies in the Midwest have a difficult time providing high-quality pasture during winter. Little is known about the yield and nutritive value of festulolium when stockpiled for winter grazing compared to tall fescue. In this study, the yield and nutritive value of 'Jesup' endophyte-free tall fescue [Schedonorus phoenix (Scop.) Holub.] and 'Spring Green' festulolium [Festulolium loliaceum (Hudson) P.V. Fournier] were evaluated monthly from November to March over three years. The research was conducted near Mt. Vernon, MO, on a Gerald silt loam (fine, mixed, active, mesic Aeric Fragiaqualf). In two of the three years, stockpiled tall fescue out-yielded festulolium by as much as 930 kg ha-1. Both tall fescue and festulolium yields decreased over winter by approximately the same percentage; losses from November to March ranged from 32 to >75%. The nutritive value of stockpiled festulolium was consistently greater than stockpiled tall fescue during winter. Both stockpiled festulolium and tall fescue contain sufficient crude protein and total digestible nutrients at one times maintenance to maintain most small breed dairy cows during their dry period but would be severely lacking once lactation started. Despite the greater nutritive value of stockpiled Spring Green festulolium compared to Jesup tall fescue, the low forage yield of festulolium makes its use questionable for pasture-based dairies. [ABSTRACT FROM AUTHOR]

Although feed intake and efficiency differences in growing cattle of low and high residual feed intake (RFI) classification have been established, little is known about the difference in grazed forage intake between beef cows of known RFI classification. Two experiments were conducted using Hereford cows for which RFI had been determined as heifers using the GrowSafe 4000E feed intake system, after which heifers had been divided into thirds as low RFI, mid RFI, and high RFI. During Exp. 1, 2 replicates of low and high RFI cows (n = 7/replicate) in mid- to late-gestation were blocked to 1 of 4 non-endophyte-infected tall fescue paddocks (1.8 to 2.4 ha), which they grazed continuously for 84 d during summer. Using grazing exclosures, weekly rising plate meter readings, and forage harvests every 21 d, average forage DMI was calculated. Low and high RFI groups did not differ (P > 0.05) in BW change or BCS change over the trial (19.5 vs. 22.1 kg of BW gain and 0.11 vs. 0.10 BCS gain), but low RFI cows had a 21% numerically lower DMI than high RFI cows (12.4 vs. 15.6 kg/d; P = 0.23). The average area needed per paddock over the trial was similar for low and high RFI cows (1.71 vs. 1.82 ha; P = 0.35), and the average DM on offer over the trial was less for low RFI than for high RFI cows (4,215 vs. 4,376 kg; P = 0.06). During Exp. 2, 3 replicates of low and high RFI cows with their calves (n = 4 pair/replicate) strip-grazed stockpiled and early spring growth tall fescue paddocks (0.7 to 0.9 ha) for 60 d in late winter and early spring. Because of limiting forage availability and quality at trial initiation, cow-calf pairs were also fed 3.31 kg/pair of pelleted soyhulls daily. Pre- and post-grazed forage samples were harvested for 4 grazing periods, and forage growth was estimated using a growing degree days calculation and on-site weather station data. Performance did not differ (P > 0.05) between low and high RFI cows throughout the experiment (18.4 vs. 26.6 kg of BW gain and -0.04 vs. 0.15 BCS gain). Despite the utilization of forage offered being similar for low and high RFI cow-calf pairs (P > 0.05), low RFI cows and their calves had an 11% numerically lower DMI than high RFI pairs (12.5 vs. 14.1 kg/d; P = 0.12). We concluded that either no intake differences existed between low and high RFI cows or that current methodology and small animal numbers limited our ability to detect differences. [ABSTRACT FROM AUTHOR]

In a 2-yr study, we evaluated the effect of different forage allocations on the performance of lactating beef cows and their calves grazing stockpiled tall fescue. Allocations of stockpiled tall fescue at 2.25, 3.00, 3.75, and 4.50% of cow-calf pair BW/d were set as experimental treatments. Conventional hay-feeding was also evaluated as a comparison to grazing stock-piled tall fescue. The experiment had a randomized complete block design with 3 replications and was divided into 3 phases each year. From early December to late February (phase 1) of each year, cows and calves grazed stockpiled tall fescue or were fed hay in the treatments described above. Immediately after phase 1, cows and calves were commingled and managed as a single group until weaning in April (phase 2) so that residual effects could be documented. Residual effects on cows were measured after the calves were weaned in April until mid-July (phase 3). During phase 1 of both years, apparent DMI of cow-calf pairs allocated stockpiled tall fescue at 4.50% of BW/d was 31% greater (P < 0.01) than those allocated 2.25% of BW/d. As allocation of stockpiled tall fescue increased from 2.25 to 4.50% of cow-calf BW/d, pasture utilization fell (P < 0.01) from 84 ± 7% to 59 ± 7%. During phase 1 of both years, cow BW losses increased linearly (P < 0.02) as forage allocations decreased, although the losses in yr 1 were almost double (P < 0.01) those in yr 2. During phases 2 and 3, few differences were noted across treatment groups, such that by the end of phase 3, cow BW in all treatments did not differ either year (P > 0.40). Calf ADG in phase 1 increased linearly (P r< 0.01) with forage allocation (y = 0.063x + 0.513; R² = 0.91). How- ever, calf gain per hectare decreased linearly (P r< 0.01) as stockpiled tall fescue allocations increased (y = -26.5x + 212; R² = 0.97) such that gain per hectare for cow-calf pairs allocated stockpiled tall fescue at 4.5 0% BW/d was nearly 40% less (P r< 0.01) than for those allocated 2.25% of BW/d. Allocating cow-calf pairs stockpiled tall fescue at 2.25% of BW/d likely optimizes its use; because cow body condition is easily regained in the subsequent spring and summer months, less forage is used during winter, and calf gain per hectare is maximized. [ABSTRACT FROM AUTHOR]

Switchgrass (Panicum virgatum L.) is a warm-season native grass, used for livestock feed, bioenergy, soil and wildlife conservation, and prairie restoration in a large portion of the USA. The objective of this research was to quantify the relative importance of latitude and longitude for adaptation and agronomic performance of a diverse group of switchgrass populations. Six populations, chosen to represent remnant prairie populations on two north-south transects, were evaluated for agronomic traits at 12 locations ranging from 36 to 47°N latitude and 88 to 101°W longitude. Although the population x location interactions accounted for only 10 to 31% of the variance among population means, many significant changes in ranking and adaptive responses were observed. Ground cover was greater for northern-origin populations evaluated in hardiness zones 3 and 4 and for southern-origin populations evaluated in hardiness zones 5 and 6. There were no adaptive responses related to longitude (ecoregion). Switchgrass populations for use in biomass production, conservation, or restoration should not be moved more than one hardiness zone north or south from their origin, but some can be moved east or west of their original ecoregion, if results from field tests support broad longitudinal adaptation. [ABSTRACT FROM AUTHOR]

We examined the effect of endophyte infection level of tall fescue (Festuca arundinacea Schreb.) used for stockpiled forage on the performance of lactating, fall-calving beef cows and their calves. Treatments were endophyte infection levels of 20% (low; SEM = 3.5), 51%, (medium; SEM = 1.25), and 89% (high; SEM = 2.4; 4 replications/treatment). Five cow-calf pairs grazed in each replicate (n = 60 cow-calf pairs/ yr) for 84 d (phase 1) starting on December 2, 2004 (yr 1), and December 1, 2005 (yr 2). After 84 d of grazing each treatment, the cattle were commingled and fed as a single group (phase 2) until weaning in April of each year. Phase 2 allowed measurement of residual effects from grazing stockpiled tall fescue with varying levels of endophyte infection. Pregrazing and postgrazing forage DM yield, forage nutritive value, and total ergot alkaloid concentrations of forage were collected every 21 d during phase 1. Animal performance data included cow BW, ADG, and BCS, as well as calf BW and ADG. Animal performance was monitored during both phases. Endophyte infection did not affect (P = 0.52) apparent intake (pregrazing minus postgrazing forage DM yield) of stockpiled tall fescue, because each cow-calf pair consumed 16 ± 1.7 kg/d regardless of treatment. Cow ADG during phase 1 was -0.47 ± 0.43 kg for the low treatment, which was greater (P < 0.01) than either the medium (-0.64 ± 0.43 kg) or high (-0.74 ± 0.43 kg) treatments. However, cows that had grazed the high or medium treatments in phase 1 lost -0.43 and -0.57 (± 0.24) kg/d, respectively, which was less (P <0.01) BW loss than the cows in the low (-0.78 ± 0.24 kg/d) treatment during phase 2. By the end of phase 2, cow BW did not differ (528 ± 27 kg; P = 0.15). Body condition score for cows in the low treatment was greater (P = 0.02) than that of the medium and high treatments at the end of phase 1. Body condition scores did not change appreciably by the end of phase 2, and differences among treatments remained the same as at the end of phase 1 (P = 0.02). In contrast to cow performance, calf ADG was unaffected (P = 0.10) by endophyte level and averaged 0.73 ± 0.07 kg during phase 1 and 0.44 ± 0.04 kg during phase 2. Our data suggest that fall-calving herds can utilize highly-infected tall fescue when stockpiled for winter grazing, with little impact on cow performance and no impact on calf gain. [ABSTRACT FROM AUTHOR]

The Sun is the largest reservoir of matter in the solar system, which formed 4.6 Gyr ago from the protosolar nebula. Data from space missions and theoretical models indicate that the solar wind carries a nearly unfractionated sample of heavy isotopes at energies of about 1 keV/amu from the Sun into interplanetary space. In anticipation of results from the Genesis mission’s solar-wind implanted samples, we revisit solar wind isotopic abundance data from the high-resolution CELIAS/MTOF spectrometer on board SOHO. In particular, we evaluate the isotopic abundance ratios 15N/14N, 17O/16O, and 18O/16O in the solar wind, which are reference values for isotopic fractionation processes during the formation of terrestrial planets as well as for the Galactic chemical evolution. We also give isotopic abundance ratios for He, Ne, Ar, Mg, Si, Ca, and Fe measured in situ in the solar wind. [ABSTRACT FROM AUTHOR]

Ergot alkaloids are a class of toxic compounds, some of which are produced by a fungal endophyte in tall fescue (Festuca arundinacea Schrch.). The objective of this research was to measure total ergot alkaloid content in tall fescue by near-infrared (NIR) spectroscopy with a calibration developed from immunochemical reference data. Eighty-four tall fescue samples were collected from experiments at the University of Missouri. Samples were from plants that varied in maturity, endophyte status, genotype, growing environment, and storage and preservation treatment. Samples were scanned by NIR radiation and analyzed chemically for ergot alkaloid content using a commercial immunoassay. An empirical prediction equation was developed by regressing NIR reflectance data against absorbance data from the immunoassay. The initial calibrations achieved a 1 — variance ratio (VR) of 0.86 with a mean and standard error of cross validation (SECV) of 0.606 ± 0.12; however, this was possible only when stockplied tall fescue samples were omitted from the population. Stockpiled samples were checked for chemical accuracy and spectral similarity to the population, and another set of calibrations was developed. The final calibration, which omitted only those stockpiled samples that were infected with a toxic endophyte, had a 1 — VR of 0.89, with a mean and SECV of 0.682 ± 0.11. We concluded that total ergot alkaloid content in tall rescue can be quantified by NIR spectroscopy with a calibration developed from immunochemcial data, though it may not be possible to include samples of stockpiled tall fescue if they are infected with a toxic endophyte. Such a calibration can be robust and precise, reliably predicting an entire class of compounds in a diverse population of tall rescue samples. [ABSTRACT FROM AUTHOR]

This article proposes a short review of our present knowledge of solar system magnetospheres, with the purpose of placing the study of Saturn’s magnetosphere in the context of a comparative approach. We describe the diversity of solar system magnetospheres and the underlying causes of this diversity: nature and magnetization state of the planetary obstacle, presence or not of a dense atmosphere, rotation state of the planet, existence of a system of satellites, rings and neutral gas populations in orbit around the planet. We follow the “russian doll” hierarchy of solar system magnetospheres to briefly describe the different objects of this family: the heliosphere, which is the Sun’s magnetosphere; the “elementary” magnetospheres of the inner planets, Earth and Mercury; the “complex” magnetospheres of the giant planets, dominated by planetary rotation and the presence of interacting objects within their magnetospheric cavities, some of which, like Ganymede, Io or Titan, produce small intrinsic or induced magnetospheres inside the large one.We finally describe the main original features of Saturn’s magnetosphere as we see them after the Voyager fly-bys and before the arrival of Cassini at Saturn, and list some of the key questions which Cassini will have to address during its four-year orbital tour. [ABSTRACT FROM AUTHOR]

Presents the proceedings of the workshop, titled 'A Comparative Study of the Outer Planets Before the Exploration of Saturn by Cassini-Huygens,' which was held in Bern, Switzerland, on January 12–16, 2004. Formation and Evolution of the giant planets; Neutral atmospheres of the giant planets and their satellites; Aurorae and magnetospheres.

Volatile isotope abundances are tracers for the evolutionary processes of the solar system. At the same time they carry information on the galactic nucleosynthetic sources, from which solar matter originates. This working group report summarizes the present knowledge and addresses unresolved issues regarding fractionation of isotopes of' volatile elements in the solar system. [ABSTRACT FROM AUTHOR]

Presents the glossary for the February 2003 issue of the "Space Science Reviews". Dwarf galaxy; Molecular cloud; Solar wind; Angrites; Howardites; Primitive meteorites; Anorthosite; Pyroxene; Troilite.

Observations of cosmic rays and their related radio to gamma-ray signatures are surveyed and discussed critically, and compared to theoretical models of the cosmic-ray origin and propagation. The analogous heliospheric processes are included as a well-studied case of the principal physical processes of energetic particle acceleration and propagation. Reinforcements, or conflicts, in the interpretations of cosmic-ray spectral and compositional characteristics arise when cosmic-ray source and propagation models are confronted with astronomical information about the Galaxy as a whole and from potential source sites, i.e., supernova remnants or regions with high massive-star density. This volume represents the outcome of two workshops held at ISSI. In this chapter we summarize the introductory papers presented below, and include insights from the workshop discussions. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agronomy & Crop Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

On the basis of the observational picture established in the report of Mason, von Steiger et al. (1999) the status of theoretical models on origin, injection, and acceleration of particles associated with Corotating Interaction Regions (CIRs) is reviewed. This includes diffusive or first-order Fermi acceleration at oblique shocks, adiabatic deceleration in the solar wind, stochastic acceleration in Alfvén waves and oblique propagating magnetosonic waves, and shock surfing as possible injection mechanism to discriminate pickup ions from solar wind ions. [ABSTRACT FROM AUTHOR]

This report emphasizes new observational aspects of CIR ions revealed by advanced instruments launched on the Ulysses, WIND, SOHO, and ACE spacecraft, and by the unique vantage point of Ulysses which carried out the first survey of Corotating Interaction Region (CIR) properties over a very wide range of heliolatitudes. With this more complete observational picture established, this review is the basis to consider the status of theoretical models on origin, injection, and acceleration of CIR particles reported by Scholer, Mann et al. (1999) in this volume. [ABSTRACT FROM AUTHOR]