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Cool season grasses, including tall fescue, are dominant plants within managed grassland systems. A symbiotic relationship between tall fescue (Lolium arundinaceum) and the fungal endophyte Epichloë coenophiala can affect grassland response to perturbations, including changing rainfall patterns and increasing temperatures associated with climate change. Because E. coenophiala reproduces asexually, there is concern that climate change may negatively impact vertical transmission, resulting in subsequent fescue stands with lower infection frequencies and reduced grassland resiliency. This 3-year field study evaluated the impact of increased temperature, altered precipitation, and their combination on vertical transmission, seed number, and seed weight in tall fescue clones containing common toxic (CTE) or novel nonmammalian toxic (NTE) E. coenophiala. NTE clones exhibited greater transmission than CTE clones. Temperature did not affect transmission, but altered precipitation reduced transmission in CTE clones. On average, NTE clones responded to increased temperatures by reducing seed number, while CTE clones responded oppositely. NTE clones produced seeds of similar masses across all growing years, suggesting greater stability under varying environmental conditions. Our work illustrates that both plant and endophyte genetics influence vertical transmission and that climate change is unlikely to significantly impact endophyte transmission in the southeastern transition zone of the United States. [Graphic: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Abstract 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. Highlights • Mare hormone concentrations were not different from control mares. • Foal growth rates were not different from foals of control mares. • Novel endophyte tall fescue was a satisfactory pasture forage for foaling mares. [ABSTRACT FROM AUTHOR]

Replacing toxic, wild-type Neotyphodium coenophialwn-infected tall fescue (E+) with nontoxic, N. coenophialum-mfected tall fescue (NE+) has improved cow performance, but producer acceptance of NE+ lias 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 x 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+ (SI00); 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 approxi-mately 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, SI00, 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 x 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 SI00. The calving season x NE+ % interaction affected (P < 0.05) calving rates. Preweaning calf BW gain, actual and adjusted wean-ing 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 concentra-tions of serum prolactin at breeding and serum NEFA at the end of breeding were affected (P <0.05) by the calving season x NE+ % interaction. Serum Zn and Cu concen-trations 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 prolac-tin, and NEFA concentrations during certain times in the production cycle, particularly in spring-calving cows. [ABSTRACT FROM AUTHOR]

Abstract: A 3-year experiment was conducted to determine pasture and cattle responses to tall fescue–endophyte association (free, novel, and wild endophyte associated with ‘Jesup’ cultivar) and fertilization source (inorganic and broiler litter). Fertilization source had only minor or no effects on botanical composition, forage mass, cattle stocking rate, and yearly cattle performance and productivity. However, cattle performance and production were greater with broiler litter than with inorganic fertilization during summer, but lower in autumn and winter, suggesting a difference in timing of nutrient availability to forage due to mineralization of organic nutrients in broiler litter. Pastures with wild endophyte association either had higher forage mass during some periods or were able to carry more cattle than other endophyte associations. Cattle performance was lower with wild than with other endophyte associations at all times of the year, except in summer. Cattle gain in winter was not different among endophyte associations (64kgha−1; p =0.43), was lower in spring with wild endophyte than with other endophyte associations (244kgha−1 versus 302kgha−1; p =0.04), was higher in summer with wild endophyte (147kgha−1 versus 117kgha−1; p <0.001), and was lower in autumn with wild endophyte (97kgha−1 versus 129kgha−1; p =0.10). Seasonal differences in pasture responses to fertilization and endophyte association suggested that management options could be developed to avoid or limit toxic cattle responses to wild endophyte. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Consumption of endophyte-infected tall fescue results in poor reproductive performance. The objective of this study was to examine physiological changes in pregnant cows grazing tall fescue to develop a better understanding of the factors that contribute to the poor reproductive performance attributed to fescue toxicosis. Pregnant Angus and Simmental-Angus cows were blocked by age (2-3, 4-7, and >7 y), BW, and breed; and then randomly assigned to graze either novel (E-; <5% infection rate; n=27) or endophyte-infected tall fescue (E+; 79.5% infection rate; n=27). Weekly BW, BCS, hair coat scores (HCS), and hair shedding scores (HSS) were collected from mid-April through July when ergot alkaloid concentrations are greatest in the forage. Blood samples were collected to measure progesterone concentrations. Forage samples were taken every 2 wks to determine forage quality and composition. Data were analyzed using the MIXED procedure of SAS with repeated measures examined for effects of age, treatment (E- or E+) and time. Statistical significance was determined at P<0.05 and a tendency at 0.057 y) cows having higher scores when compared to younger cows (6.0, 6.1, and 5.7, respectively; P<0.05). The HCS and HSS were greater in cows on E+ pastures compared to cows on E- pastures (P<0.05). The HSS were greater in the >7 y cows (2.69) compared to other age groups (2.40, 2.51, for 2-3 and 4-7 y, respectively, P<0.05) on E+ pastures, whereas no age differences in HCS were observed in cows on E- pastures. By d21 of the grazing period, cows on E- pastures displayed a greater ability to shed hair compared to cattle on E+ pastures (P<0.0001), which continued throughout the remainder of the grazing period. Progesterone concentrations in E+ cows (3.75 ng/ml) were decreased throughout the grazing period compared to E- cows (6.53 ng/mL, P<0.05). The impact of reduced progesterone concentrations, greater HCS and HSS and tendency for decreased ADG in cows grazing E+ during mid-gestation, compared to cows grazing E-, on calf development remains unknown. [ABSTRACT FROM AUTHOR]