Endophytic Fungus Acremonium Coenophialum Research Articles

GC-MS Analysis of extract for Endophytic fungus Acremonium coenophialum and its Antimicrobial and Antidiabetic

The aim of the present work was to study antimicrobial and antidiabetic activities of the fungal extract of endophytic fungus Acremonium coenophialum isolated from medicinal plant Myrtus communis was evaluated. The fungal extract was carried out by Ethyl acetate solvent. Column Chromatography, Thin Layer Chromatography (TLC) and Gas chromatography-mass spectrometry (GC-MSS) were used to determine the chemical composition of fungal extract from endophytic fungus A. coenophialum. As a result, a total of nineteen compounds of Fungal extract were demonstrated for antimicrobial activity against seven Gram-Positive Bacteria named Staphylococcus aureus, S. epidermidis, Streptococcus Pneumoniae, Strep. pyogenes, Enterococcus faecalis, Bacillus cereus and B. subtilis which range between (10.0-17.0) mm against seven Gram-Negative Bacteria namely; Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Klebsiella pneumoniae, Morganella morganii, Serratia sp. and Proteus vulgaris which range between (10.0-18.0) mm and against both yeasts test was (10.0) mm. Minimum inhibitory concentrations were in the range between (25.0-100), (50-100)µg/ml and (100)µg/ml against Gram-Positive bacteria, Gram-Negative and yeasts test respectively. Minimal bactericidal concentrations ranged from (50-100)µg/ml and (100-200)µg/ ml against Gram-Positive bacteria and Gram-Negative bacteria respectively and minimal fungicidal concentrations (200)µg/ml against both yeasts test. The fungal extract also exhibited antidiabetic potential by inhibition of a-amylase activity. The activity was found to be similar to that of acarbose.

Effects of endophyte consumption on food intake, growth, and reproduction in prairie voles

Grasses infected with fungal endophytes are known to deter herbivores. Athough ingestion of infected plant tissues has detrimental effects on insects, birds, domestic livestock, and laboratory rodents, little is known about the consequences of endophyte consumption for wild rodent consumers. This multigenerational study investigated how consumption of tall fescue (Festuca arundinacea) seeds infected with the endophytic fungus Acremonium coenophialum affects prairie voles (Microtus ochrogaster). Breeding pairs were fed one of three base diets: laboratory rodent chow (C; control diet), 50% uninfected tall fescue seeds plus 50% chow (E-), or 50% endophyte-infected seeds plus 50% chow (E+). In the first generation, the E+ diet suppressed food and water intake, growth rates, and reproductive success, so no voles fed on the E+ diet could be followed in the second generation. In general, voles of the two generations performed similarly on the C and E- diets. Our findings show that prairie voles are sensitive to the presence of endophytes, or associated alkaloids, in their diets, and suggest that free-ranging voles avoid consuming endophyte-infected plant tissues if other foods are available.

Feeding Preferences and Changes in Mass of Canada Geese Grazing Endophyte-Infected Tall Fescue

In the late 1940s and 1950s southern farmers began planting a newly-discovered tall fescue cultivar (Kentucky-3 1), which was much hardier and more productive than other cultivars. Unknown at the time, this cultivar was infected with the endophytic fungus Acremonium coenophialum. By the 1910s there were over 14 million ha of tall fescue pastures in the U.S., mostly in the southern and south-central states, and most were infected with the fungus (Shelbv and Dalrvmule 1987. Stuedemann and Ho>eland 1988). The total infected area may have increased recently, because tall fescue has been the predominant grass seeded in Conservation Reserve Program plantings in the central and southern

Expression of Russian Wheat Aphid (Homoptera: Aphididae) Resistance in Genotypes of Tall Fescue Harboring Different Isolates of Acremonium Endophyte

Experiments were conducted to compare the expression of Russian wheat aphid, Diuraphis noxia (Mordvilko), resistance in 2 genotypes of tall fescue grass, Festuca arundinacea Schreb., harboring different isolates of the endophytic fungus Acremonium coenophialum Morgan-Jones & Gams. Aphids did not select endophyte-free over endophyte-infected tiller sections in laboratory tests. In a laboratory population growth test, aphid numbers declined for 2 d on all endophyte-free plants and then increased. Aphid mortality was 100% on all infected plants after 4 d. Thus, antibiosis resistance to D. noxia was not specific to tall fescue genotype or to Acremonium isolate. In a field plot, numbers of Russian wheat aphids were significantly higher on endophyte-free tall fescue. Using these results, and results of other studies involving Acremonium -enhanced resistance to D. noxia in tall fescue and other host grasses, tile potential for using D. noxia to screen grass germplasm for Acremonium fungi is discussed.

Effects of Tall Fescue Endophyte Infestation on Relative Abundance of Small Mammals

AbstractSmall mammal populations were characterized nine times during six sampling periods on six plots in five different fields of tall fescue (Festuca arundinacea Schreb.) to determine differences in their abundance and species composition associated with the presence or absence of the endophytic fungus Acremonium coenophialum Morgan‐Jones & Gams. No differences were found in species richness (n = 4 for both types) between endophyte‐free (E−) plots and endophyte‐infested (E+) plots. Capture success, number of individuals, total captures, and recapture rates were more for E− plots than for E+ plots. All four species [eastern harvest mice (Reithrodontomys humulis Giglioli), short‐tailed shrews (Blarina brevicauda Gray), pine voles (Microtus pinetorum McMurtrie), and cotton rats (Sigmodon hispidus Say & Ord)] were captured more often in E− than in E+ plots. The diminished population densities of small mammals demonstrate the potential of E+ tall fescue as a permanent ground cover for waste disposal sites, orchards, tree farms, irrigation ditch banks, golf courses, and other residential, commercial, and industrial situations where burrowing activities of mammals may create human health hazards or financial burdens.

The effects of fescue toxicosis on beef cattle productivity.

Consumption of tall fescue forage infested with the endophytic fungus Acremonium coenophialum can result in a condition termed "fescue toxicosis," which is characterized by decreased weight gains, milk production, conception, and serum prolactin and an inability to dissipate body heat by beef cattle. These decreases in productivity have been estimated to cost beef producers more than $600 million annually. The unthrifty appearance of cattle consuming endophyte-infected tall fescue (E+) is most evident during periods of environmental heat or cold stress, suggesting an interaction with environmental conditions. Without temperature stress, cows consumed similar amounts of E+ and endophyte-free tall fescue (E-). But, when temperatures exceeded 32 degrees C, cows that grazed E+ consumed less forage than cows that grazed E-. After removal of E+ from the diet of steers, compensatory growth was observed, indicating no long-term negative effects of E+. A decrease in serum prolactin but apparently little change in other hormones has been measured after consumption of E+. Under periods of heat stress, animals had reduced ability to dissipate body heat, and blood flow to peripheral (rib skin), core-body (duodenum colon), and brain (cerebellum) tissues was decreased. Due to the depressive effects of E+ on prolactin and heat dissipation, dopamine antagonist therapy has been used in an attempt to rectify these changes. Dopamine antagonists have increased serum prolactin but there is limited evidence to suggest an improvement in heat dissipation. Experiments to elucidate the effects of E+ on alpha-1 and -2 adrenergic receptors may also offer insights into developing strategies to overcome the negative effects of E+ consumption. Preliminary results suggest that injections of an alpha-1 adrenergic antagonist (prazosin) in rats fed E+ under 32 degrees C conditions increased DM intake and reduced rectal temperature.

Response of Plant-Feeding, Predatory, and Soil-Inhabiting Invertebrates to Acremonium Endophyte and Nitrogen Fertilization in Tall Fescue Turf

The endophytic fungus Acremonium coenophialum Morgan-Jones & Gams conveys resistance to herbivory in tall fescue, Festuca arundinacea Schreber. In contrast, nitrogen fertilization generally enhances plant quality for herbivores. We studied the main effects and interaction of A. coenophialum and fertilization on plant-feeding, predatory, and soil-dwelling invertebrates in tall fescue turf. Fall armyworms, Spodoptera frugiperda (J. E. Smith), developed faster when reared on foliage from plots treated with medium or high rates of urea than on unfertilized tall fescue, but development rates were not affected by A. coenophialum. Greenbugs, Schizaphis graminum Rondani, preferred fertilized, endophyte-free fescue over nonfertilized, endophyte-free grass. Similarly, bird cherry-oat aphids, Rhopalosiphum padi (L.), developed fastest on fertilized, endophyte-free tall fescue. Fertilization, however, did not override the strong, adverse effects of A. coenophialum on both aphid species. In field plots, densities of leafhoppers, flea beetles, and Staphylinidae were generally higher in fertilized than in nonfertilized turf. Flea beetles and two of the five most abundant species of leafhoppers were less numerous in endophyte-infected plots. Predatory arthropods, earthworms, oribatid mites, and Japanese beetle grubs were equally abundant in endophyte-infected and endophyte-free plots. Fertilization did not affect the densities of oribatids or P. japonica, but earthworms were more abundant in fertilized plots on some dates. Results showed variable main effects, and an absence of interactive effects of A. coenophialum and fertilization on invertebrates in tall fescue. Fertilization of tall fescue probably will not nullify the benefits of endophyte-enhanced resistance

Long‐term changes of endophyte infection in tall fescue stands

AbstractPastures of tall fescue (Festuca arundinacea) presumed to be free of the endophytic fungus (Acremonium coenophialum) had increasing levels of endophyte, averaging 4% per annum over periods of 9–12 years. Similarly, replicated plots sown at four levels of initial endophyte infection increased in infection over a 4‐year period: for example, plots with a 27% initial level increased to 84%, and those with a level of 58% increased to 92% by the fourth year. Mowing plots to prevent seed formation did not affect the rate of change in infection percentage, except that plots with 0% initial endophyte began to show detectable levels in un‐mown blocks, presumably as a result of contamination by seed from adjacent infected plots. By the fourth year of the study, fescue plant densities, measured by plant counts, as well as ground cover, were significantly higher in plots with high initial endophyte level. It is proposed that the change in infection percentage was due to enhanced survival of infected plants in mixed stands where there was intense competition for available moisture in conditions of drought.

Vasoconstriction in bovine vasculature induced by the tall fescue alkaloid lysergamide2

Treatment of bovine lateral saphenous vein (cranial branch) and dorsal metatarsal artery with lysergamide (lysergic acid amide), an alkaloid in abundance in tall fescue, resulted in vasoconstriction similar to that previously shown for the ergot alkaloids ergonovine and ergotamine. Preincubation of tissues with lysergamide resulted in partial inhibition of the contractile response induced by the selective adrenergic agents phenylephrine and BHT-920 (P < .05), indicating partial agonist or antagonist activity of lysergamide at these receptors. Bovine vessels were strongly contracted by serotonin, and the response was markedly inhibited (P < .01) when tissues were preincubated with lysergamide. Studies with selective serotonergic agents indicated that lysergamide may have predilection for serotonin-2 receptors (5-HT2). Thus, lysergamide by itself has vasoconstrictor activity and acts as a partial agonist or antagonist at adrenergic and serotonergic receptors. Further studies are needed to establish the exact receptor effects of lysergamide. However, it is evident that this important alkaloid found in tall fescue infested with the endophytic fungus Acremonium coenophialum should be given consideration in studies designed to alleviate the fescue toxicosis syndrome in cattle.

Combined analysis of tall fescue steer grazing studies in the Eastern United States

The mixed-models procedure (MMP) was used to analyze pooled data sets from 12 independent studies conducted during the last 13 yr at nine locations in seven states to provide combined estimates of daily gains by beef steers (Bos taurus) grazing tall fescue (Festuca arundinacea Schreb.) pastures free of (E-) or infested (E+) at different levels with the endophytic fungus Acremonium coenophialum. Treatments included low-infestation (< or = 5% E+), moderate-infestation (> or = 20 to < or = 35% E+), and high-infestation (> or = 50 to < or = 97% E+) tall fescue pastures, and, in tall fescue-clover (Trifolium spp.) mixtures, pastures at the same E+ levels with approximately 25 and 10% clover in spring and summer stands, respectively. Spring, summer, and combined spring+summer data were analyzed separately. The MMP permitted estimation of the fixed effects of treatments over a broad inference space of future years and different tall fescue pastures over a wide geographic range; detected relationships that had not been apparent in the individual studies, such as the interactions between clover presence and E+ infestation levels; and provided a more coherent body of information than did the results obtained from each discrete study. Logistical and financial constraints that force undesirable compromises in the conduct of future grazing and other expensive or time-consuming research may be avoided by using MMP within the context of cooperative projects.

Animal Preference of Tall Fescue during Reproductive Growth in the Spring

AbstractAnimal preference may create problems when diverse tall fescue (Festuca arundinacea Schreb.) germplasm is evaluated under grazing. The objective of this experiment was to relate differences in animal preference of tall fescue populations to maturity and genetic background. In 1988, 25 entries were established in small plots at the Black Belt Substation, Marion Junction, AL on a Eutaw clay (very‐fine, montmorillonitic, thermic, Entic Peluderts) within each of four 0.8‐ha pastures. Pastures were grazed during the spring 1990 and 1991 seasons at stocking rates of 2.5, 3.75, 5.0, and 6.25 crossbred yearling Angus steers ha±1 (Bos spp.). Animal preference was measured by visually rating the amount of forage removed at 3, 6, and 13 d after grazing was begun in 1990, and after 3 and 6 d in 1991. Population‐by‐stocking‐rate interaction was significant for all preference ratings, but accounted for only 2 to 5% of the total variation. Changes in magnitude were not important. Based on bivariate plots of preference during spring reproductive growth vs. maturity, three groups were distinguishable: (i) two very early maturing populations with a low preference score, (ii) a group of 17 medium‐maturing populations with a medium to low preference score, and (iii) six late maturing populations with a high preference score. Low preference during grazing of tall fescue during spring reproductive growth was an attribute of mediterranean germplasm and of populations selected in the southern USA. A comparison of ‘Georgia 5’ EI vs. EF tall fescue revealed that cattle preferred the endophyte free material at all rating times during reproductive growth in the spring in both years. This preference can be uniquely attributed to the absence of the endophytic fungus Acremonium coenophialum Morgan‐Jones and Gams.

Antibiotic and Deterrent Qualities of Endophyte-Infected Tall Fescue to Two Aphid Species (Homoptera: Aphididae)

Poor survival and reproduction of the aphid Rhopalosiphum padi (L.) was observed on tall fescue plants infected with the endophytic fungus Acremonium coenophialum Morgan-Jones & Gams. Reproduction was always much higher on uninfected plants, but on older infected plants, some R. padi survived long enough to molt and reproduce. In choice studies, R. padi and the greenbug, Schizaphis graminum (Rondani), preferred uninfected fescue plants. Greenbugs quickly destroyed their uninfected hosts and died. Those S. graminum that moved to infected plants also died. High numbers of R. padi on fescue plants could be a reliable indicator for the absence of endophyte-associated alkaloids that cause resistance to a number of other insect herbivores.

Effects of hydrated sodium calcium aluminosilicate on fescue toxicosis and mineral absorption.

The possibility of supplementing livestock diets with an aluminosilicate to protect them from fescue toxicosis was investigated. An in vitro study showed that hydrated sodium calcium aluminosilicate (HSCAS) removed greater than 90% of the ergotamine from aqueous solutions at pH 7.8 or lower, indicating a high affinity of ergotamine for HSCAS in vitro. Rats fed diets containing tall fescue seed infested (E+) with the endophytic fungus Acremonium coenophialum had lower (P less than .05) feed intakes and weight gains than did rats fed diets containing uninfested (E-) tall fescue seed. When feed intake by rats fed the E- seed diet was limited to that of rats fed the E+ seed diet, weight gains did not differ, but testes weights and serum prolactin (PRL) concentrations were lower (P less than .05 and .10, respectively) in rats receiving E+ seed. Supplementing E+ seed diets with HSCAS did not eliminate effects of E+ seed on intake, PRL, or testes weights. Sheep fed E+ tall fescue hay had higher (P less than .05) rectal temperatures than did sheep fed an equal amount of E- tall fescue hay, but OM and N digestion coefficients did not differ between the two hays. Supplementing E+ hay diets with HSCAS did not eliminate the effect of E+ hay on rectal temperatures. Addition of 2% HSCAS to tall fescue hay diets did not affect apparent absorption by sheep of OM, N, Ca, P, Na, K, or Cu, but it reduced (P less than .05) the apparent absorption of Mg, Mn, and Zn.(ABSTRACT TRUNCATED AT 250 WORDS)

Amount and diurnal distribution of grazing time by stocker cattle under different tall fescue management strategies

Three experiments were conducted to evaluate the effects of endophyte level, ladino clover interseeding, grazing management or supplemental antibiotics on stocker cattle performance and the amount and diurnal distribution of grazing time by stocker cattle on tall fescue ( Festuca arundinacea Schreb.) pastures. Grazing time was measured during 7-day periods by fitting 12 steers per experiment with vibracorders that recorded grazing time. In Experiment 1, 40 crossbred steers ( Bos taurus) grazed eight 2.02 ha tall fescue pastures from 9 April to 4 November. Six of the pastures were of ‘Kentucky 31’ tall fescue, two pastures simply infected (IF; 65% of the plants infected) with the endophytic fungus Acremonium coenophialum, two uninfected (NIF) and two infected and overseeded with ‘Regal’ ladino clover ( Trifolium repens L.; IFL). The other two pastures were of ‘Missouri 96’ (MO96; non-infected) tall fescue. Steers grazing NIF gained 50 and 59 kg more ( P < 0.01) and those grazing IFL gained 46 and 55 kg more ( P < 0.01), respectively, than those grazing MO96 or IF. Herbage type did not affect total grazing time, but IF cattle spent a greater ( P < 0.10) percentage of their total grazing time between 22:00 h and 06:00 h than NIF cattle. In Experiment 2, 48 stocker steers were allotted to 2.02 ha IF (70% of the plants infected) or IFL pastures and managed by either allowing them continuous access to their respective pastures or rotating them through 0.2 ha strips at 1–4 day intervals from 21 April to 4 November. Cattle allowed continuous access to IFL pastures gained more ( P < 0.05) than cattle from the other treatment combinations. Controlled-rotational management reduced ( P < 0.01) total grazing time by 164 min. In Experiment 3, consumption of 357 mg day −1 of oxytetracycline in a mineral mixture did not alter grazing time or performance by stocker heifers grazing IF (70% of the plants infected) from 18 June to 8 October. Interseeding ladino clover into high-endophyte fescue pastures or replacing them with endophyte-free fescue may be viable management options for increasing cattle gains. Total grazing time may not be related to the performance of cattle allotted to endophyte-infected tall fescue pastures, but those cattle may graze more after dark than cattle allotted to endophyte-free fescue.

Effect of ammoniation on toxicity of Acremonium coenophialum infested tall fescue

Two trials were conducted to determine if toxic compounds in tall fescue ( Festuca arundinacea Schreb.) hay, infested with the endophytic fungus Acremonium coenophialum (Morgan-Jones & Gams) might be detoxified with anhydrous ammonia. The experimental arrangement in each trial was a 2 × 2 factorial of the dietary treatments with three or four replications in a randomized complete block. Dietary treatments were: (1) endophyte infested (E+) tall fescue hay; (2) endophyte free (E−) tall fescue hay; (3) ammonia-treated E+ hay; (4) ammonia-treated E− hay. Simultaneous exposure of E+ and E− hays to NH 3 (3% of dry matter) was done under a plastic sheet for 21 days. Maximum temperature of hays during ammoniation was 42.7 °C. When hays were fed at equal intakes in the digestion trial, digestibilities of organic matter and fiber were higher ( P < 0.05) for ammoniated hays than untreated hays, but were similar for E+ and E− hays within untreated or ammoniated treatment groups. Higher ( P < 0.05) digesta passage rates were observed in sheep fed untreated E+ hay than in sheep fed the other hay treatments. During a 63 day growth study, lambs received hay ad libitum plus 180 g day −1 soyabean meal. Dry matter intakes and weight gains were lower ( P < 0.05) for lambs fed untreated E+ hay than for lambs fed untreated E− hay, but were similar among lambs fed ammoniated E+ and E− hays. In both trials, serum prolactin concentrations of sheep were lower ( P < 0.05) when fed untreated E+ hay than when fed untreated E− hay. However, serum prolactin concentrations of sheep fed ammoniated E+ hay were similar to those fed untreated or ammoniated Eþays. Rectal temperatures of sheep ingesting E+ hay were not higher than those of sheep consuming Eþay in these trials. Although endophyte infestation of tall fescue did not affect nutrient digestion, it reduced dry matter intake, weight gains and serum prolactin concentrations, and increased liquid and paniculate digesta passage rates in sheep. These effects were alleviated when E+ hay was ammoniated and were the result of factors other than increased fiber digestion.

Genetic Diversity in Tall Fescue Ecotypes from Alabama I. Maturity, Morphological Traits, and Disease Reaction

There is a large hectarage of tall fescue in Alabama. Recognition of the deleterious effects of the endophytic fungus Acremonium coenophialum has resulted in substantial acceptance of new endophyte-free cultivars. Destruction of old pastures and the concomitant loss of potentially valuable adapted germplasm could be a valid cause for concern. The objectives of this study were to evaluate genetic variation for maturity and plant morphological traits, both among and within tall fescue cv. ‘Kentucky 31’ populations from 18 to 38 year-old pastures in Alabama. Ten populations of approximately 50 plants each were collected from old Alabama tall fescue pastures. Two pastures were sampled in each of five counties, representing the five major land use areas of the state. In 1990, spaced plants of all populations were evaluated at heading time for maturity, morphological, and disease traits at two locations in central Alabama. Endophyte infection level of the populations ranged from 2 to 100 %. Maturity was highly correlated with tiller length and flag leaf width and was used as a covariate for these traits in the analysis of variance. Leaf rust and net blotch ratings were negatively correlated. Significant variation among populations was observed for maturity and flag leaf dimensions, most variation being due to differences among source counties. Significant variation was observed within all populations for maturity and morphological traits, but only in seven populations for leaf rust. No within-population variation was detected for net blotch. The average precipitation for the month of May explained 81 % of the variation among populations for maturity. Age of the pasture sampled had a significant effect on tiller diameter (r2= 0.55), and latitude of the pasture sampled was the best individual predictor of leaf width (r2= 0.42). This study reveals that considerable genetic diversity, largely influenced by climatic conditions, exists among ‘Kentucky 31’ tall fescue ecotypes from Alabama.

Nitrogen Effects on Yield and Forage Quality of Perennial Ryegrass and Tall Fescue

AbstractNegative animal effects of tall fescue (Festuca arundinacea Schreb.) infected (EI) with the endophytic fungus Acremonium coenophialum Morgan‐Jones and Gams are reduced by substituting endophyte‐ free (EF) tall fescue or other forage species. A field experiment was conducted on Maury silt loam (fine, mixed, mesic, Typic Paleudults) soil from 1986 to 1988 to compare forage yields and quality of ‘Kenhy’‐EF, Kenhy‐EI, and ‘Johnstone’ tall fescue with ‘Ensilo’ (diploid) and ‘Reveille’ (tetraploid) perennial ryegrass (Lolium perenne L.) and ‘Bison’ ryegrass (Lolium intermediate). Each cultivar received 0, 75, or 150 kg ha−1 of N annually. At 150 kg ha−1 of N, Johnstone produced the highest 1987 to 1988 average dry matter (DM) yields of 6.7 Mg ha−1 compared with 5.7 Mg ha−1 for Kenhy‐EI. Tall fescue generally produced higher yields than ryegrass. Ground cover after 3 yr for Reveille of 72% did not differ from Kenhy‐EI (79%), but Ensilo (61%) and Bison (31%) were lower. Endophyte effects on yield and quality of Kenhy were seldom significant. Two‐year weighted average in vitro dry matter disappearance (IVDMD) values were 685, 663, 626, 628, and 641 g kg−1 for Reveille, Ensilo, Kenhy‐EF, Kenhy‐EI, and Johnstone, respectively. Increasing N levels increased N concentration of tall fescue but did not consistently affect that of ryegrass. These results indicate that some cultivars of ryegrass can persist at this location, but that summer productivity is well below that of tall fescue. However, some potential may exist for germplasm improvement of perennial ryegrass based on existing cultivars. Endophyte effects on yield and quality of Kenhy tall fescue under the conditions of this study were small.

Reduced blood flow to peripheral and core body tissues in sheep and cattle induced by endophyte-infected tall fescue

Four wethers and 14 steers (environmentally heat stressed, 32 degrees C, 60% relative humidity) were evaluated for changes in blood flow induced by endophyte-infected tall fescue. Concentration of the ergopeptide ergovaline was used as an indicator of diet toxicity due to the endophytic fungus Acremonium coenophialum. Blood flow to specific tissues was measured using radiolabeled microspheres. Wethers received one of two dietary treatments for 30 d before determination of tissue blood flow: 1) a low-endophyte diet (less than .05 ppm ergovaline) or 2) a high-endophyte (1.18 ppm ergovaline) diet. Blood flows to the adrenal glands and skin covering the inner hind leg were less (P less than .10) in wethers consuming the high-endophyte diet than in those consuming the low-endophyte diet. Tissue blood flows in steers were determined on two occasions: 1) after steers had received a low- (less than .01 ppm ergovaline) or high-endophyte (.52 ppm ergovaline) fescue diet for 14 d and 2) 8 d after steers had been switched to a common, fescue-free diet. Blood flows to skin covering the ribs, cerebellum of the brain, duodenum, and colon were less (P less than .10) in steers consuming the high-endophyte diet. However, 8 d after consuming fescue-free diets, steers that had previously consumed the high-endophyte diet had greater (P = .08) blood flow to the coronary bands of the front hooves than steers that had consumed the low-endophyte diet. Blood flows to all other tissues were similar between treatments. We inferred from these experiments that the toxin(s) associated with endophyte-infected tall fescue caused decreased blood flow to peripheral and core body tissues and that this effect was abated within 8 d of removing the toxin(s).

Effects of Acremonium coenophialum Infestation, Bermudagrass, and Nitrogen or Clover on Steers Grazing Tall Fescue Pastures

Performance of cattle grazing tall fescue (Festuca arundinacea Schreb.) is depressed when the grass is infested (E+) with the endophytic fungus Acremonium coenophialum Morgan-Jones and Gams. Steer performance can be improved when clover (Trifolium spp. L.) is overseeded into tall fescue pastures, and beef production/acre can be increased when bermudagrass [Cynodon dactlyon (L.) Pers.] is grown in combination with tall fescue. The objective of this study was to compare effects on steer performance of including ladino clover (T. repens L.), ‘Midland’ bermudagrass, or a combination of both in E+ and noninfested (E−) tall fescue pastures. Three tester steers (Bos taurus L.) per pasture grazed between April and September from 1983 through 1985. Additional cattle were used in a modified put-and-take management system to maintain similar quantity and quality of forage among pastures. Forage growth and consumption were measured by cage-and-strip methodology. Pastures with bermudagrass treatments averaged 18 and 53% bermudagrass in spring and summer, respectively. Clover content of pastures overseeded with clover was variable among treatment combinations and years and ranged from 6 to 53%. Greater average daily gains (ADG), beef production per acre, and forage dry matter consumption, and lower rectal temperatures and hair coat scores, were observed when cattle grazed E− rather than E+ tall fescue. Steer ADG was higher on E+ pastures when bermudagrass was present. Clover was equally effective in increasing ADG on E+ and E − tall fescue pastures. Bermudagrass and clover were both effective in improving steer performance and/or production on both E+ and E− tall fescue. Additionally, bermudagrass reduced somewhat the detrimental effects of E+ tall fescue.

Detection of Ergot Alkaloids in tall fescue by competitive immunoassay with a monoclonal antibody

Ergonovine was coupled to human serum albumin by a modification of the carbodiimide procedure. The conjugate was used to immunize mice, one of which developed specific anti‐ergonovine antibodies as measured by a competitive indirect (CI) enzymelinked immunosorbent assay (ELISA). Lymphocytes from this mouse were used to produce a hybridoma cell line which continued to produce specific anti‐ergonovine monoclonal antibody (MAb); the MAb was then used to develop an assay for ergot alkaloids associated with fescue (Festuca arundinacea) infected with the endophytic fungus Acremonium coenophialum. In this CI‐ELISA, the 50% inhibition value of the MAb by ergonovine was approximately 0.5 ng ml−1. The MAb recognized clavine, ergopeptine and lysergic acid derivatives. In tall fescue plants, the assay identified pastures with infection percentages as low as 3% and could be used to determine infection in a single plant, using as little as 0.5 g of material. Infection in seed was similarly detectable at infection level...