The Experts below are selected from a list of 786 Experts worldwide ranked by ideXlab platform
Dariusz P Malinowski - One of the best experts on this subject based on the ideXlab platform.
-
Leaf endophyte Neotyphodium coenophialum modifies mineral uptake in tall fescue
Plant and Soil, 2000Co-Authors: Dariusz P Malinowski, Ghiath A. Alloush, D P BeleskyAbstract:Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin, a fungal endophyte found primarily in shoots of tall fescue ( Festuca arundinacea Shreb.), can modify rhizosphere activity in response to phosphorus (P) deficiency. In a controlled environment experiment, two cloned tall fescue genotypes (DN2 and DN4) free (E-) and infected (E+) with their naturally occurring endophyte strains were grown in nutrient solutions at low P (3.1 ppm) or high P (31 ppm) concentrations for 21 d. Endophyte infection increased root dry matter (DM) of DN4 by 21% but did not affect root DM of DN2. Under P deficiency, shoot and total DM were not affected by endophyte but relative growth rate was greater in E+ than E- plants. In high P nutrient solution, E+ plants produced 13% less (DN2) or 29% more (DN4) shoot DM than E- plants. Endophyte affected mineral concentrations in roots more than in shoots. Regardless of P concentration in nutrient solution, E+ DN2 accumulated more P, Ca, Zn and Cu but less K in roots than E- plants. When grown in high P nutrient solution, concentrations of Fe and B in roots of E+ DN2 plants were reduced compared with those of E- plants. Concentrations of P, Ca and Cu in roots of DN4 were less, but K was greater in E+ than E- plants. In shoots, E+ DN2 had greater concentrations of Fe and Cu than E- DN2, regardless of P concentration in nutrient solution. Genotype DN4 responded to endophyte infection by reducing B concentration in shoots. Nutrient uptake rates were affected by endophyte infection in plants grown in low P nutrient solution. A greater uptake rate of most nutrients and their transport to shoots was observed in DN2, but responses of DN4 were not consistent. Results suggest that endophyte may elicit different modes of tall fescue adaptation to P deficiency.
-
tall fescue aluminum tolerance is affected by Neotyphodium coenophialum endophyte
Journal of Plant Nutrition, 1999Co-Authors: Dariusz P Malinowski, D P BeleskyAbstract:Abstract Roots of endophyte‐infected (E+) tall fescue (Festuca arundinacea Schreb.) exude more phenolic‐like reductants than roots of endophyte‐free (E‐) plants when mineral stressed. Phenolic compounds are efficient chelators of aluminum (Al) and may influence Al tolerance in many plant species. The objective of our study was to determine if enhanced release of phenolic compounds by roots of E+ plants contributes to Al tolerance in tall fescue. Two cloned genotypes (DN2 and DN11) of tall fescue infected with their naturally occurring fungal endophyte Neotyphodium coenophialum (Morgan‐Jones and Gams) Glenn, Bacon and Hanlin and their noninfected isolines were grown in nutrient solutions at 0 μM Al (Al‐) and at 640 μM Al (Al+) under controlled environment conditions. Root and shoot dry matter (DM) of endophyte‐infected tall fescue was greater in E+ than E‐ plants by 57% and 40%, respectively, when plants were grown without Al. Endophyte infection did not affect root and shoot DM of tall fescue grown with A...
-
the endophyte Neotyphodium coenophialum affects root morphology of tall fescue grown under phosphorus deficiency
Journal of Agronomy and Crop Science, 1999Co-Authors: Dariusz P Malinowski, D K Brauer, D.p. BeleskyAbstract:Mechanisms involved in mineral stress tolerance of cool-season grasses infected by Neotyphodium spp. endophytes are not known. In a controlled-environment experiment, two genotypes (DN2 and DN4) of tall fescue (Festuca arundinacea Schreb.) infected (E +) with their naturally occurring strains of N. coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin, and their non-infected (E -) isolines were cultivated in nutrient solution at two phosphorus (P) levels of 31 mg P dm -3 (P+) and 0.31 mg P dm -3 (P -) for 3 weeks. Diameters of lateral roots, root bair length, and distance between root hairs were recorded using a digital image analysis system (Dage 72S CCD camera controlled by a Power MacIntosh 7200/120PC compatible computer equipped with an AG-5 frame grabber board and NIH-Image). Irrespective of tall fescue genotype and P level in nutrient solution, E -plants had roots with a smaller diameter (16%) than E -plants. In response to P deficiency, root diameter of E + plants declined by 11 % and root hair length increased by 17% when compared to E - plants. Altered root diameter and root hair length might be one of the mineral stress tolerance mechanisms in endophyte-infected tall fescue.
-
Neotyphodium coenophialum‐endophyte infection affects the ability of tall fescue to use sparingly available phosphorus
Journal of Plant Nutrition, 1999Co-Authors: Dariusz P Malinowski, D P BeleskyAbstract:Abstract Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when ...
-
Neotyphodium coenophialum endophyte infection affects the ability of tall fescue to use sparingly available phosphorus
Journal of Plant Nutrition, 1999Co-Authors: Dariusz P Malinowski, D P BeleskyAbstract:Abstract Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when ...
D P Belesky - One of the best experts on this subject based on the ideXlab platform.
-
Leaf endophyte Neotyphodium coenophialum modifies mineral uptake in tall fescue
Plant and Soil, 2000Co-Authors: Dariusz P Malinowski, Ghiath A. Alloush, D P BeleskyAbstract:Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin, a fungal endophyte found primarily in shoots of tall fescue ( Festuca arundinacea Shreb.), can modify rhizosphere activity in response to phosphorus (P) deficiency. In a controlled environment experiment, two cloned tall fescue genotypes (DN2 and DN4) free (E-) and infected (E+) with their naturally occurring endophyte strains were grown in nutrient solutions at low P (3.1 ppm) or high P (31 ppm) concentrations for 21 d. Endophyte infection increased root dry matter (DM) of DN4 by 21% but did not affect root DM of DN2. Under P deficiency, shoot and total DM were not affected by endophyte but relative growth rate was greater in E+ than E- plants. In high P nutrient solution, E+ plants produced 13% less (DN2) or 29% more (DN4) shoot DM than E- plants. Endophyte affected mineral concentrations in roots more than in shoots. Regardless of P concentration in nutrient solution, E+ DN2 accumulated more P, Ca, Zn and Cu but less K in roots than E- plants. When grown in high P nutrient solution, concentrations of Fe and B in roots of E+ DN2 plants were reduced compared with those of E- plants. Concentrations of P, Ca and Cu in roots of DN4 were less, but K was greater in E+ than E- plants. In shoots, E+ DN2 had greater concentrations of Fe and Cu than E- DN2, regardless of P concentration in nutrient solution. Genotype DN4 responded to endophyte infection by reducing B concentration in shoots. Nutrient uptake rates were affected by endophyte infection in plants grown in low P nutrient solution. A greater uptake rate of most nutrients and their transport to shoots was observed in DN2, but responses of DN4 were not consistent. Results suggest that endophyte may elicit different modes of tall fescue adaptation to P deficiency.
-
tall fescue aluminum tolerance is affected by Neotyphodium coenophialum endophyte
Journal of Plant Nutrition, 1999Co-Authors: Dariusz P Malinowski, D P BeleskyAbstract:Abstract Roots of endophyte‐infected (E+) tall fescue (Festuca arundinacea Schreb.) exude more phenolic‐like reductants than roots of endophyte‐free (E‐) plants when mineral stressed. Phenolic compounds are efficient chelators of aluminum (Al) and may influence Al tolerance in many plant species. The objective of our study was to determine if enhanced release of phenolic compounds by roots of E+ plants contributes to Al tolerance in tall fescue. Two cloned genotypes (DN2 and DN11) of tall fescue infected with their naturally occurring fungal endophyte Neotyphodium coenophialum (Morgan‐Jones and Gams) Glenn, Bacon and Hanlin and their noninfected isolines were grown in nutrient solutions at 0 μM Al (Al‐) and at 640 μM Al (Al+) under controlled environment conditions. Root and shoot dry matter (DM) of endophyte‐infected tall fescue was greater in E+ than E‐ plants by 57% and 40%, respectively, when plants were grown without Al. Endophyte infection did not affect root and shoot DM of tall fescue grown with A...
-
Neotyphodium coenophialum‐endophyte infection affects the ability of tall fescue to use sparingly available phosphorus
Journal of Plant Nutrition, 1999Co-Authors: Dariusz P Malinowski, D P BeleskyAbstract:Abstract Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when ...
-
Neotyphodium coenophialum endophyte infection affects the ability of tall fescue to use sparingly available phosphorus
Journal of Plant Nutrition, 1999Co-Authors: Dariusz P Malinowski, D P BeleskyAbstract:Abstract Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when ...
-
Evidence for chemical changes on the root surface of tall fescue in response to infection with the fungal endophyte Neotyphodium coenophialum
Plant and Soil, 1998Co-Authors: Dariusz P Malinowski, Ghiath A. Alloush, D P BeleskyAbstract:Endophyte-infected (E+) tall fescue (Festuca arundinacea Schreb.) plants grown in phosphorus (P) deficient soils accumulate more P in roots and shoots than noninfected isolines. In a growth chamber experiment, four tall fescue genotypes DN2, DN4, DN7, and DN11, infected with their naturally occurring strains of Neotyphodium coenophialum (Morgan-Jones & Gams) Glenn, Bacon & Hanlin, and their noninfected isolines (E-), were cultivated in nutrient solution at two P levels: 31 ppm (P+) and 0 ppm (P-) for 4 wk. The Fe^3+ reducing activity of extracellular reductants and intact root tissues, and total phenolic concentration in roots and shoots were measured. Endophyte infection significantly increased Fe^3+ reducing activity rate of extracellular reductants (9.6 × 10^-3 μmol Fe^3+ h-1 g-1 root FW) when compared to E- plants (3.9 × 10^-3) and Fe^3+ reduction rate of intact root tissues (6.16 and 4.48 μmol Fe^3+ h-1 g-1 root FW, respectively for E+ and E- plants). In response to P deficiency, Fe^3+ reduction rate of intact root tissues increased in E+ plants by 375% when compared to E- plants, whereas no significant differences were observed when P was provided. Total phenolic concentration was 20% greater in shoots of E+ plants than in E- plants. In response to P deficiency, total phenolic concentration significantly increased in roots of E+ plants by 7%, and decreased in roots of E- plants by 10%. The most active Fe^3+ reducing zones were located along branching of secondary and tertiary roots. The Fe^3+ reducing activity on the root surface and total phenolic concentration in roots and shoots increased dramatically in response to endophyte infection, especially under P limiting conditions.
D.p. Belesky - One of the best experts on this subject based on the ideXlab platform.
-
the endophyte Neotyphodium coenophialum affects root morphology of tall fescue grown under phosphorus deficiency
Journal of Agronomy and Crop Science, 1999Co-Authors: Dariusz P Malinowski, D K Brauer, D.p. BeleskyAbstract:Mechanisms involved in mineral stress tolerance of cool-season grasses infected by Neotyphodium spp. endophytes are not known. In a controlled-environment experiment, two genotypes (DN2 and DN4) of tall fescue (Festuca arundinacea Schreb.) infected (E +) with their naturally occurring strains of N. coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin, and their non-infected (E -) isolines were cultivated in nutrient solution at two phosphorus (P) levels of 31 mg P dm -3 (P+) and 0.31 mg P dm -3 (P -) for 3 weeks. Diameters of lateral roots, root bair length, and distance between root hairs were recorded using a digital image analysis system (Dage 72S CCD camera controlled by a Power MacIntosh 7200/120PC compatible computer equipped with an AG-5 frame grabber board and NIH-Image). Irrespective of tall fescue genotype and P level in nutrient solution, E -plants had roots with a smaller diameter (16%) than E -plants. In response to P deficiency, root diameter of E + plants declined by 11 % and root hair length increased by 17% when compared to E - plants. Altered root diameter and root hair length might be one of the mineral stress tolerance mechanisms in endophyte-infected tall fescue.
-
Influence of phosphorus on the growth and ergot alkaloid content of Neotyphodium coenophialum-infected tall fescue (Festuca arundinacea Schreb.)
Plant and Soil, 1998Co-Authors: D.p. Malinowski, N. S. Hill, D.p. Belesky, V.c. Baligar, J.m. FeddersAbstract:Tall fescue (Festuca arundinacea Schreb.) plants infected by the fungal endophyte Neotyphodium coenophialum (Morgan-Jones & Gams) (Glenn et al., 1996) often perform better than noninfected plants, especially in marginal resource environments. There is a lack of information about endophyte related effects on the rhizosphere of grasses. In a greenhouse experiment, four endophyte-infected (E+) tall fescue clones (DN2, DN4, DN7, DN11) and their endophyte-free (E−) forms were grown in limed (pH 6.3) Porter soil (low fertility, acidic, high aluminum and low phosphorus content, coarse-loamy mixed mesic Umbric Dystrochrept) at three soil P levels (17, 50, and 96 mg P kg^-1 soil) for five months. Excluding the genotype effect, endophyte infection significantly increased cumulative herbage DM yield by 8% at 17 mg P kg^-1 soil but reduced cumulative herbage DM yield by 12% at 96 mg P kg^-1 soil. With increased P availability in the soil, shoot and root DM, and root/shoot ratio in E+ plants were significantly less when compared to E− plants. Endophyte infection increased specific root length at 17 and 50 mg P kg^-1soil. At soil P level of 17 mg P kg^-1soil, E+ plants had significantly higher P concentrations both in roots and shoots. Similar relationships were found for Mg and Ca. E+ plants had significantly higher Zn, Fe, and Al concentration in roots, and lower Mn and Al concentration in shoots when compared to E− plants. Ergot alkaloid concentration and content in shoot of E+ plants increased with increasing P availability in the soil from 17 to 50 mg P kg^-1 but declined again at 96 mg P kg^-1 soil. Ergot alkaloid accumulation in roots increased linearly with P availability in the soil. Results suggest that endophyte infection affects uptake of phosphorus and other mineral nutrients and may benefit tall fescue grown on P-deficient soils. Phosphorus seems also to be involved in ergot alkaloid accumulation in endophyte-infected tall fescue.
-
involvement of Neotyphodium coenophialum in phosphorus uptake by tall fescue festuca arundinacea schreb
1997Co-Authors: Dariusz P Malinowski, D.p. Belesky, V.c. Baligar, J.m. FeddersAbstract:Infection of cool-season grasses by clavicipitaceous endophytes usually results in increased tolerance to herbivory and environmental stresses (Latch, 1993; Bacon, 1993). Endophyte-related responses of tall fescue have focused upon nitrogen, since this element is involved in the biosynthesis of ergot and loline alkaloids (Lyons et al., 1990; Arechavaleta et al, 1992). Recent research with endophyte-infected tall fescue suggests an involvement of N. coenophialum (Morgan-Jones & Gams) Glenn, Bacon & Hanlin on phosphorus dynamics in plants (Azevedo, 1993). Although a positive influence of endophytes on root DM was reported by numerous authors (Latch et al., 1985; De Battista et al., 1990), the effect of infection on the rhizosphere of grasses is not well understood. The objective of this experiment was to determine the influence of endophyte on tall fescue phosphorus uptake from an acid, high aluminum content soil. Results of this study should help us determine the mechanisms involved in tolerance of endophyte-infected grasses to conditions of mineral nutrient stress.
Rebecca L. Mcculley - One of the best experts on this subject based on the ideXlab platform.
-
Fungal endophyte presence and genotype affect plant diversity and soil-to-atmosphere trace gas fluxes
Plant and Soil, 2013Co-Authors: Javed Iqbal, Jim A. Nelson, Rebecca L. McculleyAbstract:Aims Novel fungal endophyte (Neotyphodium coenophialum; Latch, Christensen and Samuels; Glenn, Bacon, and Hanlin) genotypes in symbiosis with tall fescue (Lolium arundinaceum; Schreb. Darbysh.) have been recently introduced to agricultural seed markets. These novel endophytes do not produce the full suite of toxins that the ‘common toxic’ form does, and therefore, may not have the same consequences on plant and soil processes. Here, we evaluated the effects of endophyte presence and genotype on ecosystem processes of tall fescue stands.
-
Fungal endophyte presence and genotype affect plant diversity and soil-to-atmosphere trace gas fluxes
Plant and Soil, 2013Co-Authors: Javed Iqbal, Jim A. Nelson, Rebecca L. McculleyAbstract:Aims Novel fungal endophyte ( Neotyphodium coenophialum ; Latch, Christensen and Samuels; Glenn, Bacon, and Hanlin) genotypes in symbiosis with tall fescue ( Lolium arundinaceum ; Schreb. Darbysh.) have been recently introduced to agricultural seed markets. These novel endophytes do not produce the full suite of toxins that the ‘common toxic’ form does, and therefore, may not have the same consequences on plant and soil processes. Here, we evaluated the effects of endophyte presence and genotype on ecosystem processes of tall fescue stands. Methods We quantified the effects of the presence of the common toxic endophyte (CT), two novel endophyte genotypes (AR-542, AR-584), no endophyte (endophyte free, E-), and a mixture of all endophyte statuses (mix) within a single genotype of tall fescue (PDF) on various soil and plant parameters. Results Endophyte presence and genotype affected tall fescue cover and plant species diversity: cover—CT, AR-542, AR -584, mix > E- and species diversity—E- > AR-542, AR -584 > CT, mix. Most measured soil parameters had significant endophyte effects. For example, higher fluxes of soil CO_2 and N_2O were measured from stands of AR-542 than from the other endophyte treatments. Conclusions These results indicate that endophyte presence and genetic identity are important in understanding the ecosystem-scale effects of this agronomically important grass-fungal symbiosis.
-
Effects of multiple climate change factors on the tall fescue–fungal endophyte symbiosis: infection frequency and tissue chemistry
New Phytologist, 2010Co-Authors: Glade B. Brosi, Jim A. Nelson, Rebecca L. Mcculley, Lowell P. Bush, Aimée T. Classen, Richard J. NorbyAbstract:Summary •Climate change (altered CO2, warming, and precipitation) may affect plant–microbial interactions, such as the Lolium arundinaceum–Neotyphodium coenophialum symbiosis, to alter future ecosystem structure and function. •To assess this possibility, tall fescue tillers were collected from an existing climate manipulation experiment in a constructed old-field community in Tennessee (USA). Endophyte infection frequency (EIF) was determined, and infected (E+) and uninfected (E−) tillers were analysed for tissue chemistry. •The EIF of tall fescue was higher under elevated CO2 (91% infected) than with ambient CO2 (81%) but was not affected by warming or precipitation treatments. Within E+ tillers, elevated CO2 decreased alkaloid concentrations of both ergovaline and loline, by c. 30%; whereas warming increased loline concentrations 28% but had no effect on ergovaline. Independent of endophyte infection, elevated CO2 reduced concentrations of nitrogen, cellulose, hemicellulose, and lignin. •These results suggest that elevated CO2, more than changes in temperature or precipitation, may promote this grass–fungal symbiosis, leading to higher EIF in tall fescue in old-field communities. However, as all three climate factors are likely to change in the future, predicting the symbiotic response and resulting ecological consequences may be difficult and dependent on the specific atmospheric and climatic conditions encountered.
C P West - One of the best experts on this subject based on the ideXlab platform.
-
performance by spring and fall calving cows grazing with full limited or no access to toxic Neotyphodium coenophialum infected tall fescue
Journal of Animal Science, 2013Co-Authors: J.d. Caldwell, J. A. Jennings, D. Philipp, A.n. Young, J. D. Tucker, D. S. Hubbell, T. Hess, M. L. Looper, K P Coffey, C P WestAbstract:Replacing toxic, wild-type Neotyphodium coenophialum-infected tall fescue (E+) with nontoxic, N. coenophialum-infected tall fescue (NE+) has improved cow performance, but producer acceptance of NE+ has been slow. The objective was to compare performance by spring- and fall-calving cows grazing either E+ or NE+ at different percentages of the total pasture area. Gelbvieh×Angus crossbred cows (n=178) were stratified by BW and age within calving season and allocated randomly to 1 of 14 groups representing 5 treatments for a 3-yr study: i) Fall-calving on 100% E+ (F100); ii) Spring-calving on 100% E+ (S100); iii) Fall-calving on 75% E+ and 25% NE+ (F75); iv) Spring-calving on 75% E+ and 25% NE+ (S75); and v) Spring-calving on 100% NE+ (SNE100). Groups allocated to F75 and S75 grazed E+ until approximately 28 d before breeding and weaning, then were then moved to their respective NE+ pasture area for 4 to 6 wk; those allocated to F100, S100, and SNE100 grazed their pastures throughout the entire year. Samples of tall fescue were gathered from specific cells within each pasture at the time cows were moved into that particular cell (∼1 sample/mo). Blood samples were collected from the cows at the start and end of the breeding season. Stocking rate for each treatment was 1 cow/ha. Forage IVDMD, CP, and total ergot alkaloid concentrations were affected (P<0.05) by the treatment×sampling date interaction. Hay offered, cow BW, and BCS at breeding, end of breeding, and at weaning were greater (P<0.05) from fall-calving vs. spring-calving. Cow BW at weaning was greater (P<0.05) from F75 and S75 vs. F100 and S100. The calving season×NE+ % interaction affected (P<0.05) calving rates. Preweaning calf BW gain, actual and adjusted weaning BW, ADG, sale price, and calf value at weaning were greater (P<0.05) from fall-calving vs. spring-calving and from SNE100 vs. S75 except for sale price which was greater (P<0.05) from S75 vs. SNE100. Cow concentrations of serum prolactin at breeding and serum NEFA at the end of breeding were affected (P<0.05) by the calving season×NE+ % interaction. Serum Zn and Cu concentrations from cows were affected (P<0.05) by calving season. A fall-calving season may be more desirable for cows grazing E+, resulting in greater calving rates, cow performance, and calf BW at weaning, whereas limited access to NE+ may increase calving rates, serum prolactin, and NEFA concentrations during certain times in the production cycle, particularly in spring-calving cows.
-
use of a rat model to evaluate tall fescue seed infected with introduced strains of Neotyphodium coenophialum
Journal of Agricultural and Food Chemistry, 2002Co-Authors: C A Roberts, D E Spiers, A L Karr, H R Benedict, D A Sleper, P A Eichen, C P West, E L Piper, George E RottinghausAbstract:Experimental cultivars of the pasture grass tall fescue are infected with unique strains of the fungal endophyte Neotyphodium coenophialum, which produce low concentrations of ergot alkaloids. A rat model was evaluated as a tool for rapid, initial screening of experimental cultivars considered to be nontoxic. Rats were fed diets that included seed from experimental cultivars of tall fescue with introduced strains of N. coenophialum and a toxic control diet containing seed of the cultivar Kentucky 31 (KY31), with its endemic strain of N. coenophialum. Rats were preconditioned to a nontoxic diet and then fed treatment diets for 13 days with 5 days at thermoneutrality (21 °C) followed by 8 days under heat stress (31 °C). For most of the 13-day treatment period, rats fed KY31 exhibited depressed daily intake compared to those fed diets of cultivars with introduced endophytes (P < 0.05). In addition, rats fed KY31 exhibited significantly less weight than rats on other diets after heat treatment was imposed. For all initial trials and repeated trials, total intake and total gain calculated at the end of each trial were the most consistent indicators of toxicity.