Total Ergot Alkaloid Concentration Research Articles

164 Effect of Processing Method of Hybrid rye on Growth Performance, Efficiency of Dietary net Energy Utilization, and Carcass Characteristics of Yearling Steers fed a Finishing Diet

Abstract Predominantly Angus steers were used in a 147-day randomized complete block design experiment (RCBD) to evaluate the effects of rye processing method on growth performance, feed efficiency, and carcass characteristics. Steers [n = 192, initial body weight (BW) = 410 ± 20.9 kg] were individually weighed and allotted to 1 of 24 pens (n = 8 steers/pen; 6 pens/treatment). Four treatments were used where hybrid rye grain (total ergot alkaloid concentration = 1,007 ppb, DM basis) was processed using three different methods [unprocessed (UP); dry-rolled (DR); or hammer-milled (HM)] fed at 17% of diet DM along with 43% dry-rolled corn (DRC) compared with a control diet containing 60% DRC on a DM basis (CON). Data were analyzed as an RCBD using the GLIMMIX procedure of SAS with treatment as the fixed effect and block (Pen location) as the random effect; pen was the experimental unit. No differences (P ≥ 0.44) were observed among treatments for live final BW or average daily gain (ADG). Dry matter intake (DMI) was greater for HM (12.27 kg) compared with CON and DR (11.84 and 11.48 kg, respectively) with DR having 4.9% less DMI compared with UP (P = 0.01; SEM = 0.200). UP and HM treatments tended to have 4.8% poorer G:F compared with CON and DR (P = 0.07). Dietary treatments did not affect carcass traits, percent empty body fatness (EBF), or final BW at 28% EBF (P ≥ 0.23). Distributions of USDA Quality or Yield grades were unaffected by treatment (P ≥ 0.23), nor was the incidence or severity of liver abscesses (P = 0.25). Estimated NEm and NEg values of the diet for UP (1.90 and 1.26 Mcal/kg, respectively) were reduced compared with CON and DR (1.98 and 1.32 Mcal/kg, respectively), with HM intermediate (P = 0.05, SEM = 0.033 and 0.029 for NEm and NEg, respectively). Net energy values for UP and HM rye were within 7% of current feeding standards when calculated using the substitution method. Rolling increased apparent ingredient NEg for rye by 30.1% compared with UP or HM rye. Processing rye grain by dry-rolling increased dietary net energy values and tended to improve gain efficiency compared with not processing or using a hammer mill. Rye grain can be partially substituted for DRC with negligible impact on growth performance or carcass measures.

Determining the Rate of Ergot-alkaloid Degradation in Toxic Endophyte-infected Tall Fescue Hay and Haylage During Long Term Storage

Abstract The objectives of this experiment were to determine changes in the nutritive value and ergot alkaloid concentrations of endophyte-infected tall fescue hay and haylage during a 180-d storage period. Forage from a single field of Kentucky-31 tall fescue was cut for hay in late June and allowed to dry in the field. The dry matter (DM) of the windrow of cut forage was measured every 2 h after clipping. Forage was sampled from the windrow in 6 location blocks once forage DM reached target levels for haylage and hay treatments. Haylage and hay samples were taken when the DM of the windrow reached 50% and 80%, respectively. Seven subsamples of each treatment within block were chopped to 1.91 cm in length with a lettuce chopper and vacuum sealed in oxygen-excluding bags. Sample bags were stored indoors and opened at 30 d intervals over the 180-d storage period. Samples were analyzed for pH, nutritive value, and individual ergot alkaloid concentrations using high-performance liquid chromatography. Within each storage day, treatment within block was considered the experimental unit. Data were analyzed in SAS using the MIXED procedure with fixed effects of treatment, day, and the treatment by day interaction. Location block was considered a random effect. As expected, pH was decreased for haylage compared to hay at all time points (P < 0.01) and DM was greater (P < 0.01) for hay compared to haylage. Neutral detergent fiber values were greater (P < 0.01) for hay compared to haylage and declined during storage (P < 0.01). Total ergot alkaloid concentrations did not differ by treatment (P = 0.61), but ergovaline concentrations declined (P < 0.01) during storage. Collectively, these results indicate minimal differences in nutritive value and ergot alkaloid concentrations between hay and haylage during storage, and that ergovaline concentrations decline during storage.

61 Effects of fescue cultivar on performance of beef cow/calf pairs grazed on summer stockpiled tall fescue pastures

Abstract This 2-year experiment evaluated productivity of wild-type endophyte-infected tall fescue (KY-31) and novel endophyte-infected tall fescue (MaxQ) summer stockpiled (SS) pastures and the performance of fall-calving beef cow/calf pairs grazed on each cultivar. Pregnant Simmental x Angus cows (128 total, 64 each year) were stratified by BW, BCS, and expected calving date, then allotted to 1 of 10 groups. Forage growth was stockpiled from April to initiation of strip-grazing on 31 August of 2017 and 2018. Cows grazed treatment pastures for 52 d from 23 ± 14 d prepartum to 29 ± 14 d postpartum, and calved on treatment pastures. Forage quadrats were clipped from the grazed and ungrazed portions of each pasture to determine weekly forage mass (FM). Total ergot alkaloid (TEA) concentrations were analyzed for all pastures at the beginning of the experiment and every subsequent 2 weeks for KY-31. Cow BW was recorded on 2 consecutive d and BCS determined at the start and end of the experiment. In year 2, ultrasound 12th rib fat thickness (BF) was measured at the beginning and end of the treatment period Milk production was estimated using the weigh-suckle-weigh technique at 29 ± 14 postpartum. In year 1, TEA concentrations for KY-31 pastures did not differ (P < 0.48) over time. Fescue cultivars were not different (P ≥ 0.15) in forage CP, TDN, and grazed or ungrazed FM. Cow BW, BCS, and BF at the beginning and end of grazing were not different (P ≥ 0.41) by treatment. Milk production was higher (P < 0.01) for KY-31 grazed cows. Calving date, calf BW, calf ADG were not different (P ≥ 0.65) by treatment. Neither AI nor overall conception rates differed (P ≥ 0.23) between cultivars. Performance of fall-calving cows pre-exposed to KY-31 was not improved when grazed on MaxQ in a SS system.

PSVII-7 Effects of alkali treatment on nutrient content and ergot alkaloid concentration in tall fescue silage

Abstract Addition of alkaline compounds at harvest may affect in vitro digestion and ergot alkaloid concentrations in endophyte-infected tall fescue silage. Silage (n = 60; 10 replications/treatment) was produced by filling vacuum-sealing plastic bags (35.5 cm by 27.9 cm) with 150 g of K31 tall fescue (DM basis; forage DM=76.9%; 96% endophyte infection rate) harvested in June. Alkalizing agents (CaO and NaOH) were solubilized in water (20% inclusion; wt/wt basis) and added to the forage at inclusion rates of 0%, 1%, 2%, 3%, 4%, and 5% on a dry matter basis. After ensiling for 42 d, forage samples were lyophilized and subsampled for proximate analysis and analysis of ergot alkaloids. A separate subsample was taken for in vitro total disappearance determination, and each sample was replicated in triplicate. Forage quality and digestibility values were calculated on an organic matter basis because organic matter linearly decreased (P < 0.01) as alkali increased. Alkali increased pH linearly (P < 0.01). Forage NDF decreased linearly (P < 0.01) as greater amounts of alkali treatment were included. Crude protein did not differ (P = 0.41) among treatments. In vitro total disappearance (OM basis) increased linearly (P < 0.01) as inclusion of alkali increased. Total ergot alkaloid concentration did not differ (P = 0.62) across treatments. Ergovaline concentration increased linearly (P < 0.01) with increasing alkali inclusion, but remained below established threshold for toxicity in ruminants. Lactic acid concentration responded quadratically (P < 0.01) with the lowest value corresponding to 3% alkali treatment. Acetic acid concentration increased quadratically (P < 0.01) with the highest value occurring during the 1% alkali inclusion. Propionic acid concentration increased linearly (P = 0.02) as alkali inclusion increased. A quadratic effect (P < 0.01) was observed for butyric acid concentration, with a decrease in butyrate above 1% alkali inclusion. Under conditions of this experiment, addition of alkalizing agents increased digestibility of baled tall fescue silage.

Variability of Ergovaline and Total Ergot Alkaloid Expression among Endophytic Tall Fescue Cultivars

ABSTRACTTall fescue (Lolium arundinaceum [Schreb.] Darbysh.) is one of the most widely grown grasses in the United States. Most plants are infected with an endophyte, Epichloë coenophiala Bacon and Schardl. This endophyte produces high concentrations of ergot alkaloids, which cause fescue toxicosis in livestock. The economic losses to the US livestock industry are estimated to be approximately $1 billion annually. The objectives were to evaluate the variability in total ergot alkaloid concentrations ([TEA]) and ergovaline concentrations ([E]) in leaf blades and sheaths, and whole tillers from cultivars containing different wild‐type and novel endophytes across two seasons and environments. This study was conducted in 2012 and 2014 at two sites: Watkinsville, GA and Lexington, KY. There was no location effect for [TEA] or [E] in whole tillers. Measurements in 2012 showed no ergovaline‐producing tillers for cultivars infected with MaxQ or MaxQ II. Cultivars BarOptima Plus E34 and IS‐FTF 31‐UArk9 produced tillers expressing ergovaline but at lesser levels than endophyte‐infected KY 31. In leaf blades, [TEA] and [E] were greater in 2012 than 2014 at both sites for KY 31 (1861 and 402 vs. 1473 and 135 µg kg–1, respectively). Large variability can occur in KY 31, BarOptima Plus E34, and IS‐FTF 31‐UArk9 for ergot alkaloid content over years, within seasons, and between cultivars. This research indicates the importance of testing fields for ergot alkaloid content to determine risk from grazing and hay feeding.

Proportions of predominant Ergot alkaloids (Claviceps purpurea) detected in Western Canadian grains from 2014 to 2016

Ergot alkaloids, produced by the fungusClaviceps purpurea, are contaminants of cereal crops. Depending on various factors, the relative composition of individual ergot alkaloids can differ among samples. The objective was to determine if the percentage of individual ergot alkaloids were similar across different cereal grains (barley n=39, rye n=7, triticale n=9, wheat n=94) collected in Western Canada over different years. Ergocristine was the predominant alkaloid accounting for half of the total alkaloids in all grain types. This study documented that barley, rye, triticale and wheat collected across Western Canada had similar percentages of ergocornine (6±1%,P=0.201), ergocristine (48±2%,P=0.939), ergocryptine (17±2%,P=0.302) and ergosine (5±0.5%,P=0.239). There were differences between grain types for ergometrine (P=0.027) and ergotamine (P=0.011), which ranged between 6 to 13% and 11 to 24%, respectively, of the total alkaloid content in different cereals. Both barley and wheat alkaloid percentages were similar between 2015 and 2016; ergocornine (7±1%,P=0.969), ergocristine (47±2%,P=0.680), ergocryptine (18±2%,P=0.572), ergometrine (8±1%,P=0.080), ergosine (15±1%,P=0.119) and ergotamine (P=0.189). The ergocornine percentage was higher in wheat (P=0.017) as compared to barley for 2015/2016 samples. Ergometrine was higher in barley (P=0.002) as compared to wheat for 2015/2016 samples. While two of the alkaloid proportions varied statistically, overall proportions of the six ergot alkaloids were comparable among the four grain types collected across Western Canada. If proportions of ergot alkaloids are similar across a region, then it may be deemed acceptable to recommend a maximum total ergot alkaloid concentration for that region. However, areas that exhibit variation among the ergot alkaloid proportions, individual ergot alkaloid guidelines based on a toxic equivalence factor, may be more appropriate. In contrast, since major differences were not seen between years or grain type, from a producer perspective there may be limited biological/toxicological significance for individual alkaloid guidelines.

Meta-analysis of endophyte-infected tall fescue effects on cattle growth rates.

The objective of this study was to quantitatively summarize literature reporting endophyte-infected (Neotyphodium coenophialum) tall fescue (Festuca arundinacea) effects on cattle ADG. This meta-analysis evaluated endophyte infection level, climate, and forage yield using a literature dataset of 138 treatments from 20 articles. Three infection level measurements were tested: endophyte infection as a percentage of infected tillers (E%); ergovaline concentration in ppb ([E]); and total ergot alkaloid concentration ([TEA]). Three types of climate variables were used: base values (temperature, humidity, and relative humidity), climate indices (heat index and temperature-heat index [THI]), and novel climate variables accounting for duration of climate effects. Mixed effect models, weighted by 1/SEM, including a random effect of study were built for each factorial combination of measurement method and climate variable group. Because many studies were missing SEM, two datasets were used: one containing only data with SEM reported and one that also included missing-SEM data. For the complete-SEM dataset (CSD), models were weighted by 1/SEM. In the missing-SEM dataset (MSD) the mean reported 1/SEM was assigned as the weight for all missing SEM treatments. Although 18 initial models were created (2 × 3 × 3 factorial approach), the backward stepwise derivation resulted in models that included only endophyte infection level, suggesting a negative relationship between infection level and ADG. The CSD models predicted ADG to decrease 39 and 33 g/d with each increase of 100 ppb of [TEA] and [E], and by 39 g/d for each increase of 10% E%. In the MSD dataset, predicted ADG decreased by 39 and 33 g/d with each increase of 100 ppb of [TEA] and [E], and by 47 g/d for each increase of 10% E%. All relationships reported had P < 0.05. After visual inspection of the data, piecewise regression was used to identify an infection threshold (IT) of 60 ppb [E] and 11 E%, where the effect of infection level was constant on either side of the IT. The ADG was 40% and 49% greater for infection levels below the IT for [E] and E%, respectively. Across THI values in the analysis, ADG decreases ranged from 11.2% to 45.0% for cattle grazing endophyte-infected tall fescue compared to non-ergot alkaloid endophyte infected tall fescue. Pasture E%, [E], and [TEA] have a negative relationship with ADG in growing cattle, and increasing temperature decreases ADG when infection level is greater than the IT.

Links Between Genetic Groups, Host Specificity, and Ergot-Alkaloid Profiles within Claviceps purpurea (Fr.) Tul. on Slovenian Grasses.

In the present study, the genetic relationships and ergot-alkaloid production of the fungus Claviceps purpurea on grasses were investigated, to determine any associations between grass host specificity, ergot-alkaloid production, and geographic origin. C. purpurea sclerotia were obtained from wild and cultivated grasses along a 300-km climatic gradient, from sub-Mediterranean to continental climates. Twenty-one infected grass samples provided 39 sclerotia for analysis of the ergot alkaloids ergometrine, ergosine, ergotamine, ergocornine, ergocryptine, and ergocristine, and their "-inine" epimers, using liquid chromatography-tandem mass spectrometry. C. purpurea ribosomal DNA underwent molecular classification to determine any grass host or geographic specificity of ergot-alkaloid composition for the different operational taxonomic units. Molecular analysis of sclerotia ribosomal DNA showed three genetic groups, with some associations with specific grass host taxonomic groups. The ergot-alkaloid composition data were in agreement with the data obtained by molecular methods. The most frequent ergot-alkaloid epimers were ergocristine, and ergosine. The total ergot-alkaloid concentrations in sclerotia varied from 59 to 4,200 mg kg-1, which corresponds to 0.059 to 4.2 mg kg-1 in animal feed (assuming ergot alkaloids at 1,000 mg kg-1 sclerotia). Therefore, grasses can be associated with significant levels of ergot alkaloids. In addition, the ergot-alkaloid compositions of C. purpurea sclerotia can be different for infections with different C. purpurea genetic groups, because these show different ergot-alkaloid compositions.

Ergot and ergot alkaloids in French cereals: occurrence, pattern and agronomic practices for managing the risk

Ergot is a disease of cereals and grasses caused by the ascomycete fungusClaviceps purpurea (Fr.) Tul. This fungus infects young, usually unfertilised ovaries, replacing the seeds with dark mycelial masses known as sclerotia. The amount of sclerotia in marketable grain is strictly regulated in many countries. We found that ergot and its alkaloids were common in French farm fields during the 2012, 2013 and 2014 harvests. Before cleaning, ergot was present in harvest samples from 23 to 30% of wheat fields, 15 to 30% of durum wheat fields, 27 to 39% of barley fields, 45 to 66% of triticale fields, 12 to 29% of oat fields and 67 to 81% of rye fields. Triticale and rye were thus the cereals most prone to infection. The proportion of total ergot alkaloid in sclerotia varied, but the relationship between ergot sclerotium content and total ergot alkaloid concentration in the grain was strongly positive and independent of harvest year and cereal species. Ergot sclerotia content explained 75% of the variance for alkaloid content. We found that the main alkaloid and corresponding epimer, per gram of sclerotia, were ergotamine (29.2% of total ergot alkaloids), followed by ergosine (26.3%), ergocristine (18.5%), ergometrine (9.8%), ergocryptine (8.2%) and ergocornine (7.9%). The -ine isomers accounted for 70.5%, with the -inine isomers accounting for the remaining 29.5%. The mean total alkaloid content ofC. purpurea sclerotia was 3,103 µg/g. This survey identified and ranked agronomic practices for limiting the risk of ergot contamination in crops. Host plant, previous crop, grassweed presence and tillage system all had a significant influence on alkaloid content. We identified and ranked agronomic practices for limiting and managing the risks of ergot and ergot alkaloids in the field. However, the main factor driving ergot infection is weather conditions.

Correlation and variability between weighing, counting and analytical methods to determine ergot (Claviceps purpurea) contamination of grain

Ergot alkaloid mycotoxins produced by the fungusClaviceps purpurea, are contaminants of cereal crops and grasses. The objectives of this study were to determine the correlation between number of ergot sclerotia and weight compared to the total ergot alkaloid concentration, to evaluate the effect of grinding process (i.e. particle size (PS)) on ergot alkaloid analysis using high performance liquid chromatography – tandem mass spectrometry, and to determine the impact of sample volume on analytical variability. This study demonstrated that correlations exist between both ergot sclerotia count (R2=0.7242,P&lt;0.001) and ergot sclerotia weight (R2=0.9618,P&lt;0.001) compared to the total alkaloid concentration of 6 ergot alkaloids. However, at alkaloid ergot concentrations below 350 µg/kg grain, ergot sclerotia count (R2=0.0002,P=0.956) and ergot sclerotia weight (R2=0.0064,P=0.769) were not correlated to the total alkaloid concentration. A lower variability (P=0.041), defined by coefficient of variation (CV), was observed using a commercial UDY cyclone sample mill (PS=192 µm, CV=9 µg/kg) as compared to a household coffee grinder (PS=516 µm, CV=66 µg/kg). Total amount and concentration of individual ergot alkaloids varied (P&lt;0.05) among sclerotia of similar weight. For the analytical method, CV was numerically reduced as sample volume increased (97% CV for 75 ml to 64% CV for 1000 ml; mean of all concentrations) but increased as sample concentration declined (17% CV for 81,678 µg/kg to 284% for 35 µg/kg; mean of all sample volumes). This implies that analysis of small sample volumes at low ergot alkaloid concentrations may result in highly variable and potentially misleading results. In conclusion, number of ergot sclerotia and weight are unreliable indicators of alkaloid content at ergot concentrations below 350 µg/kg and particle size influences the variability. An analytical approach with fine grinding (mean PS&lt;200 µm, 85% particles &lt;400 µm) of a large sample should be used to assess low-level ergot contamination.

Occurrence of ergot alkaloids in wheat from Albania

ABSTRACTThe occurrence of ergot alkaloids in wheat harvested in Albania was investigated. A total of 71 samples of winter wheat collected in 2014 and 2015 were analysed for the 12 most important ergot alkaloids using liquid chromatography-tandem mass spectrometry. In the harvesting year 2014, 48.6% of samples were contaminated with ergot alkaloids, whereas in 2015 only 19.4% of samples were contaminated. In 2014, the concentrations of total ergot alkaloids ranged from 17.3 to 975.4 μg kg−1, and in 2015 they ranged from 10.3 to 390.5 μg kg−1. The samples contained from one to nine ergot alkaloids. The most frequent were ergometrine, ergosine and ergocristine, and the least frequent were ergocryptine, ergocryptinine and ergocorninine.

The effects of selected factors on measured ergot alkaloid content inClaviceps purpurea-infected hexaploid and durum wheat

Four wheat genotypes, including the ergot-susceptible durum ‘AC Avonlea’ and hard red spring wheat ‘AC Cadillac’, as well as the resistant durum wheat line 9260B-173A and the hard red spring wheat line ‘Kenya Farmer’ wereinoculated with differentClaviceps purpurea isolates. Honeydew and sclerotia were collected and analysed for 10 ergot alkaloids. Total concentrations of the 10 ergot alkaloids ranged from 16 µg/kg in honeydew to 1,798 mg/kg insclerotia. Ergonovine and ergosine were the predominant alkaloids in honeydew obtained from plants inoculated with various isolates, whereas ergocristine and ergocryptine were the main alkaloids observed in sclerotia. Bothhost plant andC. purpurea isolate were significant factors affecting total ergot alkaloid concentrations in sclerotia. Irrespective of host plant line, all mean total ergot alkaloid concentrations were higher in sclerotia produced from the EI-2 isolate (695-1,010 mg/kg), as compared to EI-4 (255-594 mg/kg). The mass of total ergot alkaloids was alsopositively correlated with the mass of individual sclerotia produced from these twoC. purpurea isolates, with the slope of the regression higher for the EI-2 isolate. The total ergot alkaloid concentrations in sclerotia from various plants inoculated with the sameC. purpurea isolate differed; however, the resistance of host plant line did notappear to be consistent with ergot alkaloid content in sclerotia. Concentrations of total ergot alkaloids were highestand lowest in sclerotia from the two lines that are both classified as ‘resistant’, suggesting that the mechanism ofresistance for these lines is not restriction on the production of ergot alkaloids in sclerotia.

Occurrence of Ergot and Ergot Alkaloids in Western Canadian Wheat and Other Cereals.

A new method was developed to analyze 10 ergot alkaloids in cereal grains. Analytes included both "ine" and "inine" type ergot alkaloids. Validation of the method showed it performed with good accuracy and precision and that minor enhancement due to matrix effects was present during LC-MS/MS analysis, but was mitigated by use of an internal standard. The method was used to survey durum and wheat harvested in 2011, a year in which ergot infection was particularly widespread in western Canada. A strong linear relationship between the concentration of ergot alkaloids and the presence of ergot sclerotia was observed. In addition, shipments of cereals from 2010-2012 were also monitored for ergot alkaloids. Concentrations of total ergot alkaloids in shipments were lower than observed in harvest samples, and averaged from 0.065 mg/kg in barley to 1.14 mg/kg in rye. In shipments, the concentration of ergot alkaloids was significantly lower in wheat of higher grades.

Ergot Alkaloid Concentrations in High‐ and Low‐Moisture Tall Fescue Silage

ABSTRACTErgot alkaloids are mycotoxins found in foods and forage crops, including common tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort.], which hosts a fungal endophyte. The objective of this study was to determine changes in ergovaline and total ergot alkaloid concentrations in tall fescue silage produced at high moisture (650 to 680 g H2O kg−1) and low moisture (340 to 400 g H2O kg−1). The study was conducted on endophyte‐infected pastures of tall fescue in northern and southern Missouri. Tall fescue was clipped after seedhead emergence but before anthesis, wilted to high or low moisture, baled, and wrapped. After &gt;100 d of ensiling, bales were cored and samples analyzed for ergovaline and total ergot alkaloid concentrations. Ergovaline concentration decreased (P &lt; 0.05) during ensiling at both locations and moisture levels, and the decrease ranged from 24 to 58%. In contrast, total ergot alkaloid concentrations increased during ensiling in high moisture silage in northern (P &lt; 0.10) and southern (P &lt; 0.05) Missouri but did not change in low moisture silage. The opposing responses of ergovaline and total ergot alkaloids offer partial explanations for differences reported in studies involving tall fescue silage. These responses also caution against recommendations to ensile tall fescue to reduce toxins because one analyte indicates detoxification is possible, while the other analyte does not.

Performance by spring and fall-calving cows grazing with full, limited, or no access to toxic Neotyphodium coenophialum-infected tall fescue1

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.

Seasonal Fluctuation of Ergovaline and Total Ergot Alkaloid Concentrations in Tall Fescue Regrowth

ABSTRACTCommon cultivars of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort = Lolium arundinaceum (Schreb.) Darbysh.] host a fungal endophyte that produces ergot alkaloids. These alkaloids are linked to fescue toxicosis, a serious livestock disorder in the United States. This study was conducted to determine how ergot alkaloid concentrations fluctuate throughout the growing season in tall fescue regrowth. In 2005, plots were established in pastures of endophyte‐infected tall fescue growing in Missouri, Georgia, and South Carolina. Each month of the growing season, plots were clipped and forage allowed to regrow; regrowth was sampled from April through October 2006 and analyzed for ergovaline and total ergot alkaloid concentrations. At all three sites, ergovaline concentration was lowest during the spring, increasing slightly through the summer months and then sharply in the early autumn. This pattern of ergovaline fluctuation did not mimic data published from experiments in which tall fescue was grazed or was allowed to grow without defoliation. Total ergot alkaloid concentration followed a bimodal curve, with highest concentration in the spring and fall and lowest concentration in the summer. We conclude that common cultivars of endophyte‐infected tall fescue should be regarded as highly toxic in the autumn and less toxic in the summer, even if pastures are clipped. We also conclude that the toxicity potential of tall fescue regrowth in the spring depends on which ergot alkaloids prove most responsible for fescue toxicosis.

Ruminal Metabolism and Transport of Tall Fescue Ergot Alkaloids

ABSTRACTCircumstantial evidence suggests ergovaline is the putative toxin causing fescue toxicosis. However, several investigators suggest lysergic acid may be involved as well. Therefore, the purpose of this study was to (i) determine the metabolic fate of ergot alkaloids in ruminants, (ii) investigate gastric transport, and (iii) validate these findings in vivo. Ruminal metabolism of the alkaloids was determined by inoculating endophyte‐infected and endophyte‐free tall fescue [Lolium arundinaceum(Schreb.) Darbysh.] with viable and nonviable ruminal fluid using in vitro techniques. Total ergot alkaloid concentration increased with time due to microbial metabolism. The alkaloids were extracted, and ruminal and omasal transport investigated in vitro. Only lysergic acid crossed gastric barriers. To validate the findings, fistulated steers were allowed to graze endophyte‐infected or endophyte‐free tall fescue paddocks in a crossover study, and ruminal fluid and urine were analyzed for ergot alkaloids over time. Ergovaline was not found in ruminal fluid or urine. Urine was immunopurified from a steer grazing endophyte‐infected tall fescue and analyzed by high‐performance liquid chromatography. A peak with a signal consistent with lysergic acid was found. These results imply that lysergic acid may be involved in the fescue toxicosis syndrome.

Ergot Alkaloid Concentrations in Tall Fescue Hay during Production and Storage

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 μg 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.

Endophyte infection level of tall fescue stockpiled for winter grazing does not alter the gain of calves nursing lactating beef cows1

We examined the effect of endophyte infection level of tall fescue (Festuca arundinacea Schreb.) used for stockpiled forage on the performance of lactating, fallscalving 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.

Influence of dietary endophyte (Neotyphodium coenophialum)-infected tall fescue (Festuca arundinacea) seed on fecal shedding of antibiotic resistance-selected Escherichia coli O157:H7 in ewes1,2

The objectives were to determine the effects of short-term feeding of a toxic endophyte (Neotyphodium coenophialum)-infected tall fescue seed (Festuca arundinacea, cultivar 'Kentucky 31') on fecal shedding and intestinal concentrations of Escherichia coli O157:H7 and the concentrations of prolactin, cortisol, and NEFA in experimentally inoculated ewes. Twelve ewes (mean BW = 46 +/- 2 kg) were fed a diet containing either high endophyte-infected (HI-E) or low endophyte-infected (LO-E) tall fescue seed for 7 d. Each diet consisted of 50% (as-fed basis) tall fescue seed. Ewes were experimentally inoculated with antibiotic resistance-selected E. coli O157:H7 on d 1 of the feeding treatment, and fecal shedding of inoculated pathogens was monitored daily on d 2 to 6. On d 7, ewes were weighed and euthanized, and tissues and contents were sampled from the ileum, cecum, and rectum for quantitative enumeration of E. coli O157:H7. Urine was collected at euthanization to determine total ergot alkaloid concentrations. Ewes fed HI-E had lower (P < 0.001) DMI than did ewes fed LO-E (0.8 and 1.6 +/- 0.1 kg/d of DMI for HI-E and LO-E ewes, respectively); consequently, there was a tendency (P = 0.06) for HI-E ewes to lose 0.3 +/- 0.4 kg of BW/d and LO-E ewes to gain 0.2 +/- 0.4 kg of BW/d during the 7 d. Urinary ergot alkaloids were increased (P < 0.001) in ewes fed HI-E (47.8 +/- 9.4 ng/mg of creatinine) compared with those fed LO-E (6.2 +/- 9.4 ng/mg of creatinine). Prolactin tended (P = 0.06) to be decreased in ewes fed HI-E (7.2 +/- 7.0 ng/mL) compared with those fed LO-E (27.7 +/- 7.0 ng/mL). Fecal shedding of E. coli O157:H7 tended (P = 0.06) to be increased in HI-E ewes [5.4 cfu (log10)/g of feces] compared with LO-E ewes [4.5 cfu (log10)/g of feces]. The population of E. coli O157:H7 in luminal contents from the ileum, cecum, and rectum did not differ (P > 0.36) between treatments. Treatment did not influence (P = 0.30) the occurrence of E. coli O157:H7 in cecal or rectal tissues; however, ileal tissues from HI-E ewes tended (P = 0.12) to have an increased incidence of E. coli O157:H7. Concentrations of NEFA tended (P = 0.12) to be greater in HI-E ewes than in LO-E ewes, whereas cortisol was similar (P = 0.49) for HI-E and LO-E ewes. We conclude that short-term feeding of HI-E tall fescue seed may alter the concentrations of prolactin and NEFA, and may increase fecal shedding of E. coli O157:H7 in experimentally inoculated ewes.