Tall Fescue Endophyte Research Articles

Determining the earliest growth stage to detect the presence of endophytes in tall fescue and perennial ryegrass seedlings using molecular markers

AbstractBackgroundTall fescue (Festuca arundinacea [Schreb.], Lolium arundinaceum [Schreb.] Darbysh) and perennial ryegrass (Lolium perenne) are important cool‐season forage and amenity grasses that have a mutualistic association with an endophytic fungus. Endophytes confer insect and drought resistance to plants but can produce mammalian toxins. Novel endophytes that do not produce mammalian toxins have been introduced to elite cultivars for commercial production. Seed companies need to maintain adequate levels of novel endophytes within the elite forage cultivars. Endophyte detection is performed using immunochemical and molecular techniques because of their speed and reliability. Early detection in seedlings is essential to evaluate the viability of the endophyte within seed lots.MethodsThis research aimed to identify the earliest growth stage in which immunochemical and molecular methods can detect viable endophyte in seedlings of tall fescue cultivars BarOptima (e34), Texoma MaxQII (584), and Jesup MaxQ (542), as well as the perennial ryegrass cultivar Remington (NEA2).ResultsImmunochemical testing detected endophytes in seedlings 14 days after germination (DAG), but the detection rate increased until 42 DAG in some cultivars tested. The molecular marker Tef1exon detected endophytes at a lower rate than the immunochemical method at 28–42 DAG. However, there was insufficient DNA to detect endophytes in 14 DAG seedlings using markers.ConclusionsWe conclude that the most accurate detection of viable endophytes in seedlings was 42 DAG, at which sufficient and consistent endophyte colonization occurred.

1 Challenges in the Pasture

Abstract Cow-calf farms are abundant across the southeastern US and there is a wide diversity of farm sizes and types of farmers. Farms include small-scale part-time farms, and large commercial-scale farms, often integrated with other farm enterprises. Many farmers have full-time employment off the farm and little if any hired labor, such that there is little time to devote to farming activities. In contrast, large farms often have access to labor, equipment and other inputs that may not be available to small farms. The diversity of farms and farmer demographics makes extension programming challenging as motivational factors vary considerably. Many pasture management practices proven by research have very low levels of adoption including active grazing management, pasture renovation, hay testing, etc. We assume that all farmers are focused on profitability, but this is clearly not the case especially with small part-time farmers. Other motivations may be enjoyment of spending time with animals, time spent with family, improving animal welfare, interest in machinery and “gadgets”, and other non-farm interests including using a cow-calf enterprise to hold land in some kind of agriculture for future development. New management practices may make sense from a profitability perspective but might require the development of new skills that the farmer does not have. Additionally, there may be other barriers including access to necessary equipment, conflicting information provided by advisers, and expertise in simple practices such as planting and spraying. As an example, novel endophyte tall fescue (NETF) has potential to eliminate the negative aspects of endophyte infected tall fescue while maintaining the desirable agronomic characteristics. While NETF technology is research proven and has been available to producers for over two decades, adoption has been very slow. The Alliance for Grassland Renewal is a multi-state private/public collaborative formed to promote the appropriate adoption of NETF. The Alliance conducts workshops to teach farmers and their advisors about how to best implement the NETF technology. The collaborative effort provides a more uniform set of recommendations than was formerly available through each member state. Through workshop evaluations we found several important factors that limit adoption including 1) the balance of cost and benefit is unclear, 2) farmers have limited financial resources, 3) the land is rented or unsuitable for renovation, and 4) farmers lack of knowledge, and 5) farm forage reserves are limiting. Many of these pasture management practices are difficult to adopt because they require many sequential steps that must be completed in a timely way. This may leave the farmer hesitant to take the first step in the process. For practices that are very different than standard management, use of on-farm demonstrations and hands-on learning have proven valuable.

Interactions between animal temperament and exposure to endophytic tall fescue: Effects on cell-mediated and humoral immunity in beef heifers

Two experiments (n=12 Angus heifers/experiment) investigated influences of animal temperament, as indicated by exit velocity (EV; determined at weaning) and consumption of toxic endophyte-infected tall fescue seed on peripheral lymphocyte production of interferon-γ. Heifers were selected from calves born on the University of Kentucky’s C. Oran Little Research Center. In experiment 1, calves were randomly selected from 50 heifers within a single calf crop. In experiment 2, calves with the 6 fastest and 6 slowest EV in the subsequent year’s calf crop were selected. In both experiments, heifers were assigned to either high or low EV treatments based on relative ranking, and endophyte treatments (toxic endophyte-infected, E+, or endophyte-free, E-, fescue seed) were balanced by body weight. Rations were restricted to 1.8 x NEm and common diet was top-dressed with fescue seed each morning. Experiment 1 had four phases (pre-endophyte treatment/thermoneutral, increased room temperature, increased room temperature/endophyte treatment, and post-endophyte/thermoneutral) and experiment 2 had two phases (increased room temperature/endophyte treatment and thermoneutral). During endophyte treatment phases, heifers were fed their respective treatment seed. During all other phases, all heifers received E- seed. In experiment 1, proportions of lymphocytes producing interferon-γ were decreased in E+ heifers during the heat/endophyte phase (P=0.03) whereas during the subsequent thermoneutral period this response was greater in high, compared with low, EV heifers on E- treatment, with no difference observed among E+ heifers (interaction P=0.08). Also during the recovery phase, average lymphocyte production of interferon-γ was higher in E+ heifers (P=0.01). Consistent with experiment 1 findings, during the recovery period of experiment 2, endophyte exposure increased the per cell production of interferon-γ (P<0.01). In this experiment, the difference was of sufficient magnitude to result in a concomitant increase (P=0.03) in total interferon-γ production during that period. These results indicate peripheral lymphocyte production of interferon-γ can be influenced by both EV and endophyte exposure following periods of increased ambient temperature humidity indices, though there was minimal indication of interactions between temperament and alkaloid exposure. This may imply that cattle with high exit velocities and those previously exposed to toxic endophyte-infected tall fescue are better poised against cell-mediated challenges.

Influence of form of selenium supplementation and tall fescue endophyte toxicity on growth performance, serum parameters, and tissue masses of grazing beef steers.

To test the hypothesis that average daily gain (ADG) and clinical parameters of steers grazing novel non-toxic (NTE) or toxic KY-31 (TE) endophyte-infected tall fescue would be improved by ad libitum intake of vitamin‐mineral mixes (V-M) that contain 27 ppm Se as a 1:1 blend of SELPLEX:sodium selenite (MIX) vs. sodium selenite (ISe), 32 fescue-naïve beef steers partially depleted of Se were randomly assigned to ad libitum consumption ISe vs. MIX for 35 days and fed enough of a NTE/alfalfa/grain diet to achieve 0.57 kg BW gain/day. Then, within Se-form treatments, two steers were randomly assigned to each of four NTE (ISe = 316 ± 31 kg BW, MIX = 315 ± 22 kg BW) or TE (ISe = 316 ± 37 kg BW, MIX = 314 ± 39 kg BW) paddocks for 84 days and had ad libitum access to their respective V-M. The MIXED procedure of SAS was used to assess effects of day, Se-form (ISe, MIX) and endophyte (NTE, TE) treatments, and their interactions. Whole blood Se decreased (P < 0.01) 31% from days 0 to 84 and was 6.2% greater (P < 0.01) for MIX steers. Serum prolactin decreased (P < 0.01) 18% for NTE and 48% for TE steers from days 0 to 84 and was 17% greater (P = 0.01) for MIX vs. ISe for TE steers. Serum alkaline phosphatase activity decreased (P < 0.02) 27% from days 0 to 84 and was 15% greater (P < 0.02) for MIX steers. Serum urea nitrogen increased (P < 0.02) 8.2% from days 0 to 84 for TE but not NTE steers. Average daily gain was less (P < 0.01) for steers grazing TE (−0.18 kg/day) compared with NTE (0.09 kg/d). Although there was increased serum alkaline phosphatase activity and increased serum prolactin for TE + MIX steers compared with TE + ISe steers, MIX supplementation was unable to increase serum prolactin concentrations or ADG to the same levels as steers grazing NTE. Longer adaptation to MIX supplementation ad libitum may be necessary for maximal Se assimilation to restore serum prolactin levels in steers grazing TE.

Transcriptome analysis of Epichloë strains in tall fescue in response to drought stress

ABSTRACT Epichloë coenophiala, a systemic fungal symbiont (endophyte) of tall fescue (Lolium arundinaceum), has been documented to confer to this grass better persistence than plants lacking the endophyte, especially under stress conditions such as drought. The response, if any, of the endophyte to imposition of stress on the host plant has not been characterized previously. Therefore, we investigated effects on gene expression by E. coenophiala and a related endophyte when plant-endophyte symbiota were subjected to acute water-deficit stress. Plants harboring different endophyte strains were grown in sand in the greenhouse, then half were deprived of water for 48 h and the other half were watered controls. RNA was isolated from different plant tissues, and mRNA sequencing (RNA-seq) was conducted to identify genes that were differentially expressed comparing stress treatment with control. We compared two different plants harboring the common toxic E. coenophiala strain (CTE) and two non–ergot-alkaloid-producing Epichloë strains in tall fescue pseudostems, and in a second experiment we compared responses of E. coenophiala CTE in plant pseudostem and crown tissues. The endophytes responded to the stress with increased expression of genes involved in oxidative stress response, oxygen radical detoxification, C-compound carbohydrate metabolism, heat shock, and cellular transport pathways. The magnitude of fungal gene responses during stress varied among plant-endophyte symbiota. Responses in pseudostems and crowns involved some common pathways as well as some tissue-specific pathways. The fungal response to water-deficit stress involved gene expression changes in similar pathways that have been documented for plant stress responses, indicating that Epichloë spp. and their host plants either coordinate stress responses or separately activate similar stress response mechanisms that work together for mutual protection.

Sub-acute feeding study of a tall fescue endophyte in a perennial ryegrass host using mice

Epichloë endophytes in grass associations express a myriad of secondary metabolites which can affect the health of grazing animals and reduce the impact of insect pests on pasture. The ideal endophyte-grass association must have a favourable chemical profile such that the impact on animal health is minimised while the beneficial, deterrent effect on insect pests is maximised. A number of endophyte-perennial ryegrass associations have been successfully commercialised but research is on-going to further improve production in farming systems. Secondary metabolites expressed by endophyte-infected tall fescue include lolines, an animal-safe class of compound which imparts a potent effect on insects. Since endophyte-infected perennial ryegrass does not express lolines, a tall fescue endophyte, AR501, was inoculated into perennial ryegrass in an attempt to improve the insect resistance of this pasture type. In addition to animal safety, it is imperative that consideration is given to the safety of humans consuming animal products derived from livestock grazing the novel pasture. Although pure loline alkaloids have previously been tested on mice it is essential that the entire AR501 endophyte-infected perennial ryegrass matrix is tested since this will result in the exposure of both known and unknown secondary metabolites to mice. Three treatment groups each containing 6 male and 6 female mice were fed diets containing AR501 endophyte-infected perennial ryegrass seed (30%), perennial ryegrass seed containing no endophyte (30%) or a diet without seed (control) for 3 weeks. Mice fed control diet ate more than either of the treatment groups fed a diet containing seed. Male mice fed diet containing Nil endophyte seed ate more than those eating AR501 endophyte-infected perennial ryegrass seed although there was no difference observed in the food intake of female mice. While a few statistically significant differences were observed in the haematology and serum biochemical data, in every instance the difference was restricted to only one gender so is considered unlikely to be of toxicological significance. Mice fed AR501 endophyte-infected perennial ryegrass seed remained healthy throughout the experimental period despite consuming 62,000 mg/kg lolines and 4600 mg/kg peramine per day as well as the wide array of other unknown secondary metabolites expressed by this endophyte. Although animal products may contain additional metabolites as a result of animal metabolism, this experiment raises no food safety concerns for AR501 endophyte-infected perennial ryegrass.

23 Performance of Pregnant Beef Heifers During Spring Rotational Grazing of Novel Endophyte Tall Fescue Following Complete Renovation

Abstract The objective of this study was to analyze animal performance following renovation of toxic-infected tall fescue (TF) to novel endophyte tall fescue (NE) in order to increase producer adoption of NE. In 2018, three renovation strategies were implemented in a randomized complete block design. Strategies included: 1) control (C), 2) renovation to NE after one season of a single-specie cover crop (1-SM), 3) renovation to NE after three seasons of a single-specie cover crop (3-SM), and 4) renovation to NE after three seasons of a multi-specie cover crop (3-CM). Forty-eight pregnant (30-90-d) Angus heifers (initial BW 383 kg ± 32) were randomly assigned to rotationally graze spring growth for 56-d, two years after NE establishment. Pre- and post-grazing forage mass was measured every 7-d. Animal measurements were collected every 14-d. Data were analyzed using procGLIMMIX of SASv9.4. Average daily gain was greatest (P &amp;lt; 0.0001) for cattle grazing 3-CM (0.74 kg/d), 1-SM (0.72 kg/d), and 3-SM (0.62 kg/d) and least for C (0.33 kg/d). Pre-grazing forage biomass was greatest (P = 0.0157) in 3-CM (3261 kg/ha) and lowest in C (2523 kg/ha), with 3-SM (2813 kg/ha) and 1-SM (2779 kg/ha) being intermediate. Post-grazing forage biomass was greatest (P = 0.0063) in 3-CM (1982 kg/ha), C (1916 kg/ha), 1-SM (1900 kg/ha), but lower in 3-SM (1592 kg/ha). Prior to grazing, body condition score (BCS) was higher (P = 0.0029) for animals grazing C (5.48), but change in BCS of animals within treatments was not different (P = 0.798). Hair shedding scores (HS) were not different on d-0, with all treatments near 5. However, HS were highest (P &amp;lt; 0.0001) in C (4.75), and lowest in 1-SM (1.75), 3-SM (2), and 3-CM (2) after 56-d. Data suggest animal performance for NE was improved compared to TF during spring grazing in years following renovation.

Animal safety of a tall fescue endophyte (Epichloë sp.) in a perennial ryegrass (Lolium perenne) host

ABSTRACT Aims To assess animal health and production in sheep grazing perennial ryegrass (Lolium perenne) infected with a tall fescue endophyte (Epichloë sp.). Methods Three replicates of pure perennial ryegrass pastures infected with AR501 tall fescue endophyte (AR501 HE), AR1, AR37 or standard endophyte (STD) (all >85% infection) and a low endophyte control (AR501 LE) were grazed by 10 lambs for 7 weeks during late summer/early autumn, 2017. AR501 HE and AR501 LE were in the same tetraploid cultivar and the remaining treatments were in the same diploid cultivar. Lambs were weighed on Days 0, 19, 37 and 48 and assessed for ryegrass staggers on a 0–4 tremor scale nine times from Day 13. On Days 14 and 20, rectal temperatures and respiration rates were measured in lambs grazing AR501 HE, AR501 LE and STD under heat load. Pasture samples from each treatment were taken regularly (8 times) for analysis of known endophyte secondary metabolites. Results Peak mean ryegrass staggers scores for lambs grazing STD and AR37 treatments were 3.9 and 2.7, respectively, indicating environmental conditions were conducive to toxicity. Lambs grazing AR501 HE showed no ryegrass staggers at any date. The liveweight of STD lambs was up to 6.6 kg less than some or all other treatments on Days 19, 34 and 48, but there was no evidence of a difference between the liveweight of AR501 HE lambs and AR501 LE, AR37 or AR1 lambs on any date. Rectal temperatures and respiration rates of STD lambs were higher than AR501 HE lambs by 0.2°C and 26 breaths/minute, respectively. Apart from lower rectal temperature of AR501 HE lambs on Day 14, there was no evidence of differences between the AR501 HE and AR501 LE lambs. N-Formylloline was the only loline present in AR501 HE herbage (350–860 mg/kg). Peramine in AR501 HE herbage (42–77 mg/kg) was greater than that in STD and AR1 herbage on five and seven of the eight sampling dates, respectively. Conclusion Lambs grazing AR501 HE showed no ryegrass staggers, exacerbated heat stress or suppressed liveweight gain compared with lambs grazing AR501 LE in a season when endophyte-induced toxicity was evident in STD and AR37 pastures. This suggests AR501 tall fescue endophyte does not produce toxic concentrations of secondary metabolites. Clinical relevance This study suggests that there are no secondary metabolites produced by the tall fescue AR501 endophyte-perennial ryegrass association which affect animal health or production.

Újabb szempontok a legeltetéses állattartás értékelésében

The first part of this review papers presents the history of tall fescue endophyte toxicosis, which used to be a real constraint on grazing beef industry in southern US. The second part reviews some up-dated scientific publications, dealing with vitamins, fats and fatty acids in grass, grass products as well as in animal products produced on these feedstuffs. The papers cited prove that inclusion of grass or conserved (hay, silage) grass in the diets for cattles (beef and dairy) pigs or poultry (broiler chicken and leying han):&#x0D; - reduces the fat content of the body- improves some vitamin contents of animal products (milk, butter, meat, eggs)- improves the unsaturated fatty acid contents of the same animal products.&#x0D; The consumption of these high quality animal products consequently may contribute to better human health status of consumers.

PSI-4 Animal and agronomic performance while grazing winter stockpiled novel endophyte tall fescue established with three pasture renovation strategies

Abstract Comparing animal and agronomic performance following renovation of toxic-infected tall fescue (TF) to novel endophyte tall fescue (NE) is fundamental to evaluating economic returns and increasing adoption of NE. In 2018, three NE renovation strategies were implemented in a randomized complete block design in Bahama, NC. Strategies included: 1) control (C), 2) renovation to NE after one season of a single specie cover crop (1-SM), 3) renovation to NE after three seasons of a single specie cover crop (3-SM), and 4) renovation to NE after three seasons of a multi-specie cover crop (3-CM). Sixty-four Angus heifers (initial BW 290 kg ± 88) were randomly assigned to treatments and strip-grazed stockpiled fescue for 56-d, two years after NE establishment. Forage yield and nutritive value was measured every 14-d. Data were analyzed using proc GLIMMIX of SAS v9.4. Average daily gain was greatest (P = 0.0024) for cattle grazing 1-SM (0.67 kg/d), and least for 3-CM (0.54 kg/d) and C (0.44 kg/d), which did not differ. 3-SM (0.57 kg/d) did not differ from other treatments. Within the grazing period, forage yield was greatest (P = 0.0001) in 3-CM, 3-SM, and C compared to 1-SM (3053, 2941, 2856 and 2465 kg/ha, respectively). Prior to the initiation of grazing, crude protein concentration was greater (P = 0.0089) for 3-CM (17.5%) compared to C, 1-SM, and 3-SM (15.8%, 15.8% and 15.3%, respectively). Neutral detergent fiber was greater (P = 0.0135) for 3-SM (57%) than C (55.1%) and 3-CM (54.5%), but did not differ from 1-SM (54.6%). Concentration of total digestible nutrients was greater (P = 0.0187) for 3-CM (73.2%) compared to 1-SM (72.1%) and 3-SM (71.9%), but did not differ from C (72.5%). Data suggest animal and agronomic performance for NE was improved compared to TF during winter stockpile grazing in years following renovation.

PSXI-19 Impact of toxic-infected tall fescue renovation strategies on second-year hay yield, botanical composition, and nutritive value

Abstract Renovating toxic-infected tall fescue (Lolium arundinaceum) (TF) pastures to novel endophyte tall fescue (NE) is a solution to mitigate the negative associated effects of toxic fescue in beef cattle. However, beef cattle producers are uncertain of the payback period for costs associated with renovation techniques in terms of farm profitability and agronomic performance. In 2018, three renovation strategies were implemented in a randomized complete block design in Bahama, NC. Strategies included: 1) control (C), 2) renovation to NE after one season of a single specie cover crop (1-SM), 3) renovation to NE after three seasons of a single specie cover crop (3-SM), and 4) renovation to NE after three seasons of a multi-specie cover crop (3-CM). Each treatment plot (0.81 ha) was evaluated for botanical composition and hay was harvested in May and August of 2020. Round bales from each treatment were weighed to determine yield and core sampled to determine nutritive value. Data were analyzed using proc GLIMMIX of SAS v9.4. Combined forage yield was greater (P = 0.0226) for 3-CM (8,816 kg/ha) compared to 3-SM (7,191 kg/ha) and C (6,920 kg/ha), but did not differ from 1-SM (7,775 kg/ha). Crude protein concentration was greater (P = 0.035) for C (10.2%) in comparison to 3-SM (9.35%) in harvest 1, but was not different (P = 0.93) in harvest 2. Percentage of fescue in the sward was greatest (P = 0.0002) for 3-SM and least for C (84.9 and 62%, respectively). Similarly, presence of undesirable plants was greater (P &amp;lt; 0.0001) for C (37.5%) than 1-SM, 3-CM and 3-SM (23.7, 15.2 and 12.7%, respectively). Percentage of bare ground did not differ among treatments (P = 0.31). Data suggest agronomic performance for 3-CM and 3-SM was improved compared to C in years following pasture renovation.

Effects of Tall Fescue Endophyte Type and Dopamine Receptor D2 Genotype on Cow-Calf Performance during Late Gestation and Early Lactation.

Grazing endophyte-infected, toxic tall fescue reduces cow/calf production; therefore, this study examines alternate strategies such as use of novel endophyte fescue varieties during late gestation and early lactation or genetic selection of resistant cows. Pregnant cows (n = 75) were randomly assigned to fescue endophyte type: 1) endophyte-infected ergot alkaloid producing tall fescue (E+) or 2) novel endophyte-infected, non-toxic tall fescue (NOV) within maternal (A|A, n = 38 and G|G, n = 37) DRD2 genotype to examine changes in cow/calf performance and milk production during late gestation and early lactation. Grazing E+ fescue pastures during late gestation reduced cow body weight gain but did not alter calf birth weight compared to NOV. Milk production and calf ADG during the first 30 day of lactation were lower for E+ than NOV. The calving rate was reduced, but not calving interval for E+ cows. The adjusted 205-day weight of calves was lower in those grazing E+ with their dams compared to NOV. There were no interactions between DRD2 genotype and fescue endophyte type indicating that genotype was not associated with response to E+ fescue in this study. Overall, grazing NOV tall fescue pastures rather than E+ during critical stages of production improved cow gain during late gestation, calving rate, early milk production and calf growth.

Assessing Remote Sensing Vegetation Index Sensitivities for Tall Fescue (Schedonorus arundinaceus) Plant Health with Varying Endophyte and Fertilizer Types: A Case for Improving Poultry Manuresheds

Tall fescue (Schedonorus arundinaceus) is a common perennial forage in cattle pastures of the southeastern United States. A mutualistic fungal endophyte normally infects the grass and produces ergot alkaloids toxic to livestock, but fungal biotypes that have no ergot alkaloid production have been developed. Here remote sensing methods were used to assess plant health in 1 ha grazed paddocks with application amongst different combinations of fertilizer sources (inorganic and broiler litter) and endophyte associations (wild, novel–tall fescue MaxQ type with novel endophyte, and free). Broiler litter fertilization is common in the region due to the presence of many chicken farms. Moreover, broiler litter costs are comparable to inorganic fertilizer depending on distance from source to application. Incorporating remote sensing, we tested the sensitivity of three indices: normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and land surface water index (LSWI) to assess fescue plant health. Indices were obtained from satellite imagery provided by Landsat 7 ETM+ between the years 2005 and 2009. Sensitivity analytics suggested that LSWI was the optimum index to determine fescue plant health. The year experiencing drought (determined by annual precipitation) showed significant difference between fertilizer types (p = 0.05) and a nearly significant difference between endophyte associations (p = 0.08). There was no significant difference in years with normal or wet precipitation rates due to tall fescue endophyte association or type of fertilization. Limited availability of satellite imagery during parts of the five years of study might have influenced outcomes of statistical analyses. Nevertheless, the data and findings point to the potential use of satellite imagery in assessing grazingland tall fescue health and advancing the concept of poultry manureshed in the region or elsewhere where poultry manure production is extensive.

75 Effects of endophyte-infected tall fescue on performance of genotyped pregnant beef cows and heifers supplemented with rumen-protected niacin

Abstract Fescue toxicity is the result of cattle consuming fungal (Ergot spp.) endophyte tall fescue, a perennial forage widely used in the United States. Ergot alkaloids produce vasoconstriction; however, rumen-protected Niacin (RPN), known by its vasodilation ability, may act as an alleviator for fescue toxicity. Our objective was to assess the effects of a genetic test for fescue toxicity susceptibility, and RPN supplementation on animal performance, hepatic gene expression, and uterine arteries blood flow of Angus × Simmental pregnant animals consuming endophyte-infected tall fescue seeds. Ninety days prior to calving, genotyped pregnant cows (n = 11) and heifers (n = 17) were stratified by body weight (BW; 540 ± 207 kg) and genetic resistance to fescue toxicity (susceptible or tolerant); and randomly assigned to dietary treatments: 1) Susceptible Control (SC); 2) Susceptible Niacin (SN); 3) Tolerant Control (TC); and 4) Tolerant Niacin (TN). Animals’ BW and liver samples were obtained on days 0 and 29. Uterine arteries blood flow was measured using Doppler ultrasonography on treatment days 3, 10, 17, and 23. Messenger RNA was extracted from liver samples for RT-qPCR. Gene expression and BW data were analyzed using the PROC MIXED procedure of SAS, and uterine arteries blood flow was analyzed with the GLIMMIX procedure of SAS. Between day 0 and 29, SOD1 and CYP2E1 were upregulated (P &amp;lt; 0.05) in TC and SC, respectively. Furthermore, SOD2 expression in SC was significantly lower (P &amp;lt; 0.05) on day 29. Genetic test and RPN did not affect uterine arteries’ blood flow. TN animals had a greater decrease in BW compared with other treatments (P &amp;lt; 0.01). In conclusion, Doppler ultrasonography did not detect any changes in uterine arteries blood flow and, supplementation with RPN may influence the oxidative status of cows’ liver consuming endophyte-infected fescue seeds.

Endophyte-Infected Tall Fescue Affects Rumen Microbiota in Grazing Ewes at Gestation and Lactation.

Tall fescue (Schedonorus arundinaceus) is a cool-season perennial grass that is widely used as a forage for many livestock species including sheep. An endophyte (Neotyphodium coenophialum) in tall fescue produces ergot alkaloids that enhance plant survival but produce toxicosis in animals. The objective of this study was to investigate the rumen microbiota from gestation and lactation in ewes grazing tall fescue pastures with high (HA) or moderate (MA) levels of endophyte infection, and their relationship with serum parameters. Data were collected at the beginning of the study (d1), the week before initiation of lambing (d51), and at the end of the trial (d115). The rumen microbiota was evaluated using 16S rRNA gene sequencing. Ewes grazing HA had greater serum non-esterified fatty acid (NEFA) (P = 0.024) levels compared with ewes in MA pasture at d115. Both the number of observed OTUs and Shannon diversity index tended (P = 0.08, P = 0.06) to be greater for HA than for MA on d115. At the genus level, Prevotella relative abundance increased with time in both MA and HA (on d1, d51, and d115: 15.17, 25.59, and 24.78% in MA; 14.17, 18.10, and 19.41% in HA). Taxa unclassified at the genus level including (unclassified) Lachnospiraceae, Coriobacteriaceae, and Veillonellaceae exhibited higher abundances in HA at d51 (3.72, 2.07, and 11.22%) compared with MA (2.06, 1.28, and 7.42%). The predictor microbiota for HA and MA were identified by a random forest classification model. The HA predictors included bacteria associated with unclassified Coriobacteriaceae and Ruminococcaceae. Other OTUs classified as Prevotella and Clostridiales could be microbial predictors for MA. The OTUs classified as Prevotella and Lachnospiraceae were negatively correlated with serum concentration of prolactin. Negative correlations with NEFA were observed in the microbiota such as species affiliated to unclassified Clostridiales and Prevotella. OTUs classified as Bacteroidetes and Coriobacteriaceae exhibited a positive correlation with NEFA. Our study confirmed that the rumen microbiota populations were affected by high levels of toxins in endophyte-infected tall fescue and were associated with host hormone and energy metabolism.

Effect of Epichloë endophyte-tall fescue symbiosis on rhizosphere aggregate stability and quality indicators under oxygen–limited conditions

Endophytic fungus-tall fescue symbiosis can improve the rhizosphere physical quality, but contribution of oxygen-limited conditions on this change, particularly in semiarid and arid regions has not been established yet. Therefore, the objective of this study was to evaluate the effects of endophyte-tall fescue symbiosis on the rhizosphere quality indicators under different aeration conditions in a greenhouse pot experiment. The treatments were seven levels of air-filled porosity, AFP (0, 0.025, 0.050, 0.750, 0.100, 0.125 and 0.150 m3 m−3) in a sandy loam soil, and two genotypes (75C and 75B) of tall fescue (Festuca arundinacea = Schedonorus arundinaceus Schreb.) each with endophytic fungus Epichlöe coenophiala (E+) and without endophyte (E−). Soil biophysical properties were determined on the intact soil aggregates from rhizosphere zone: structural stability (by HEMC, high energy moisture characteristic), percent of water-stable aggregates, water repellency, basal soil respiration and soil organic matter. The results showed that by decreasing the AFP, and reducing redox potential to <300 mV, (i) all biophysical indices, and the activity and population of soil microorganisms (especially fungi) significantly decreased, (ii) the role of biological and chemical aggregators was reduced and soil structure degradation was intensified, and (iii) aggregate stability indices and water repellency were associated with the quality of soil organic matter, rather than its quantity. Soil structural stability under genotype 75B was higher and lower than genotype 75C for the oxygen-limited and non-limited conditions, respectively. Stability indices, water repellency and soil organic matter content were greater in the rhizosphere of E+ plants compared to E− ones. No significant differences were observed for the HEMC stability indices between 75B and 75C genotypes for E+ plants, whereas for the E− plants, they were significantly greater in genotype 75C. Endophytic fungi increased the rhizosphere aggregate stability through the water-repellent exudates, extension of root system and enhanced organic carbon storage especially under oxygen-limited conditions.

A Tale of Two Grass Species: Temperature Affects the Symbiosis of a Mutualistic Epichloë Endophyte in Both Tall Fescue and Perennial Ryegrass.

Many cool-season grasses form permanent, mutualistic symbioses with asexual Epichloë endophytes. These fungal symbionts often perform a protective role within the association as many strains produce secondary metabolites that deter certain mammalian and invertebrate herbivores. Although initially a serious issue for agriculture, due to mammalian toxins that manifested in major animal health issues, selected strains that provide abiotic stress protection to plants with minimal ill effects to livestock are now commercialized and routinely used to enhance pasture performance in many farming systems. These fungal endophytes and their grass hosts have coevolved over millions of years, and it is now generally accepted that most taxonomic groupings of Epichloë are confined to forming compatible associations (i.e., symptomless associations) with related grass genera within a tribe. The most desired compounds associated with Epichloë festucae var. lolii, an endophyte species associated with perennial ryegrass, are peramine and epoxy-janthitrems. No other major secondary metabolites with invertebrate bioactivity have been identified within this association. However, other agriculturally beneficial compounds, such as lolines, have been discovered in related endophyte species that form associations with fescue grasses. A rationale therefore existed to develop novel grass-endophyte associations between loline-producing endophytes originally isolated from tall fescue with elite cultivars of perennial ryegrass to achieve a wider spectrum of insect bioactivity. A suitable loline-producing endophyte strain of Epichloë sp. FaTG-3 was selected and inoculated into perennial ryegrass. We hypothesed that endophyte transmission frequency, endophyte mycelial biomass and endophyte-derived alkaloid production would differ between the original tall fescue host and the artificial association. Consistent with our hypothesis, our data strongly suggest that plant species significantly affected the plant-endophyte association. This effect became more apparent for transmission frequency and endophyte biomass as the plants matured. Overall, the viable endophyte infection frequency was greater in the tall fescue host than in perennial ryegrass, at all sampling dates. Additionally, temperature was found to be a significant factor affecting endophyte transmission frequency, endophyte mycelial biomass and alkaloid production. Implications for the development of novel grass-endophyte associations are discussed.

Interactions between putatively endophytic bacteria and tall fescue (Festuca arundinacea): plant growth promotion and colonization in host and non-host cultivars

Tall fescue (Festuca arundinacea) is a forage grass highly used in prairies. Cultivar SFRO Don Tomas has excellent drought and cold resistance, characteristics which are influenced by the native endophytic bacterial community. The aims of this work were to deepen the characterization of a selected group of putatively endophytic strains with different plant growth promoting (PGP) traits and to analyze the relationship between colonization and PGP abilities. PGP with single inoculations in pots containing a mixture of sterile sand and field soil and with paired inoculations in field soil cores were carried out. Colonization of plants inoculated singly or co-inoculated under gnotobiotic conditions was quantified. Confocal laser microscopy was used to visualize the colonization and infection processes of strain Streptomyces sp. UYFA156 in cultivars SFRO Don Tomas and Tacuabe. Tall fescue cultivars displayed different responses to single bacterial inoculation. Inoculation with two strain pairs which included UYFA156 were successful in promoting growth in soil cores. Higher bacterial densities did not correspond to higher PGP. Strain UYFA156 was observed colonizing both fescue cultivars. UYFA156 is a true endophyte of tall fescue. Its PGP activity is cultivar-specific and may be related to the modulation of other endophytes.

141 The Alliance for Grassland Renewal presents workshops to enhance the understanding and adoption of Novel Endophyte Tall Fescue

Abstract The Alliance for Grassland Renewal (the Alliance) is a collaborative multi-state effort to enhance the understanding of fescue toxicosis and the adoption of Novel Endophyte Tall Fescue (NETF). The Alliance includes academic institutions, companies marketing NETF, allied companies, governmental agencies, and non-profits. The Alliance initially focused on the state of Missouri. After 2014, it expanded efforts with one-day workshops in MO, KY, OK, KS and UKY joined the board in 2017. In 2018, Clemson and NCSU joined the board, and workshops were expanded to the east coast, with five workshops in MO, KY, SC, NC and VA. In 2019, workshops will repeated in those states in addition GA. Key presentations included managing fescue toxicosis, establishment and first year management, second year management, and economics of conversion. Additionally the agenda included microscope viewing of the endophyte, quality control and endophyte testing, industry update, drill calibration, producer panel, and a tour of NETF plots. There were 214 paid attendees in 2018 (locations ranged 26 to 59; 75% farmers), and 146 evaluations were submitted. Attendees owned 9592 beef or dairy cows, 1997 stocker cattle, 121 horses, 545 sheep and goats, and 151 alpacas. Thirty percent of the audience had planted NETF in the past, while 55% intended to plant NETF in the future. Reasons given for not planting included: unclear cost/benefit (9%), limited financial resources (4%), lack of knowledge (5%), rented or unsuitable land (15%) and forage reserves lacking (5%). Registration fee was $60, and 45% of the audience said they would have paid $95, suggesting the registration fee was appropriate. The Alliance is a growing and successful partnership between academic institutions and industry. This approach is a model that could be applied to adoption of other new technologies.

Pregnant Mares Grazing a Novel Endophyte-Infected Tall Fescue Foal Normally

These experiments were conducted to determine if pregnant mares grazing a novel endophyte tall fescue (NETF) pasture would have satisfactory foaling outcomes. The hypotheses tested were that mares grazing the NETF pasture or an orchardgrass/Kentucky bluegrass (OGBG) pasture would have statistically equivalent (1) serum progesterone, estradiol, and prolactin concentrations, (2) blood chemistry analyte concentrations, and (3) palmar artery sizes. In addition, foals born on the respective pastures would grow at comparable rates. Over 4.5 months, during each of two summers, 12 foaling mares were placed on either NETF or OGBG pastures (n = 6 mares/pasture/year). There were no differences in the blood sample concentrations of progesterone, estradiol, prolactin, and chemistry analytes between the groups. Combined uterine placental thickness and placental weights were not different between the two groups of mares, and foals grew at equivalent rates. The diameter of the palmar artery of each mare was measured via Doppler ultrasonography as a bioassay for consumption of ergot alkaloids of fescue pastures. Diameters were not different between mares grazing NETF versus OGBG pastures. However, palmar artery diameters of nonpregnant mares grazing a pasture of toxic Kentucky 31 tall fescue were reduced compared to mares on the NETF or OGBG pastures. Pasture analyses demonstrated that the NETF was endophyte infected but produced no or trace amounts of ergovaline. In summary, there were no differences in any variable tested between mares grazing the new, NETF fescue pasture, compared with mares grazing a standard OGBG pasture.