Tall fescue [Schedonorus arundinaceus (Shreb.) Dumort.; (TF)] is the primary forage species used by cow-calf producers in grazing systems in Tennessee. It is an excellent cool-season perennial grass due to its great forage mass (FM), nutritive value, and extensive growing season. Orchardgrass [Dactylis glomerata L.; (OG)] is also a widely used cool-season grass in the U.S. This study compared TF and OG cultivars under continuous stocking in terms of FM, nutritive value, and animal performance over two grazing seasons (2022 to 2023) in Spring Hill, Tennessee, U.S. Treatments were: 1) OG cv. Persist I (OG-P1), 2) OG cv. Persist II (OG-P2), 3) TF cv. Kentucky 31' (TF-K31), and 4) a novel endophyte TF cv. Max Q (TF-NE). Forage mass was not affected by treatments (P = 0.0519), with an average of 2979 kg DM ha-1. Crude protein (CP) and neutral detergent fiber (NDF) concentrations were also unaffected by treatments (P = 0.6728, P = 0.1300), averaging 106 and 687 g kg-1, respectively. However, TF-NE had the lowest acid detergent fiber (ADF) (P = 0.0258; 380 g kg-1) and the greatest in vitro dry matter digestibility in 48 hours (INVDMD48) (P < 0.0001; 680 g kg-1), while OG-P2 had the greatest ADF (400 g kg-1) and the lowest INVDMD48 (661 g kg-1). Total gain and average daily gain (ADG) were affected by treatment × year interaction (P = 0.0314 and P = 0.0161, respectively). In 2022, TF-NE, TF-K31, and OG-P1 outperformed OG-P2, but no differences were observed in 2023 (total gain: 78.6 kg animal-1; ADG: 0.78 kg animal-1 day-1). Ergovaline concentrations in TF-K31 were low, which likely minimized its negative effects. These findings indicate that both TF and OG can sustain beef cattle production under continuous stocking, with TF offering potential advantages in botanical composition and forage nutritive value over time.

Tall fescue toxicosis negatively impacts blood flow, elevates body temperature, and reduces beef cattle’s average daily gain (ADG). In previous studies, isoflavones have diminished the symptoms of tall fescue toxicosis in ruminants. Therefore, this dataset determined the impact of low concentrations of isoflavone doses on animal vasculature, body temperature, ADG, and rumen microbial communities in beef cattle. A 21-day experiment with Angus cattle consisted of four isoflavone doses: 0 g, 2 g, 4 g, and 6 g, along with a control group. Isoflavones were mixed with 0.5 kg of dried distiller’s grains (DDGs). Daily individual rectal temperatures were recorded. Weekly blood serum was collected via coccygeal venipuncture, blood vasculature data were measured via color Doppler ultrasound, and body weight (BW) was recorded. Approximately 100 mL of rumen content was collected at the end of the trial. The pulsatility index (PI) decreased in the control group compared to the 2 g and 4 g groups (p = 0.01). Animals in the isoflavone treatment groups recorded a higher rectal temperature (p < 0.05). ADG was reduced in animals undergoing isoflavone treatments (p < 0.001). Finally, there was no impact on the rumen microbial communities (p > 0.05). Isoflavone supplementation may mitigate tall fescue toxicosis and improve animal performance at greater doses.

The rising prices of N fertilizer led to exploring cost-saving efforts, such as intercropping cool- or warm-season legumes serving as alternative sources of N for managing fall-stockpiled tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.; TF]. We aimed to evaluate red clover (Trifolium pratense L.; RC) and sunn hemp (Crotalaria juncea L.; SH) mixed with TF as alternative sources of N for stockpiling TF to increase productivity and animal performance. The experiment was conducted in Crossville, TN, in 2020 and 2021 and consisted of TF pastures mixed with RC (TRC) or SH (TSH), and TF fertilized with urea (TU). The experiment was divided into two periods: the pre-grazing period (stockpiling) (April-October) and the grazing period (October-December). After the stockpiling period, Black Angus beef (Bos taurus) steers were used for the grazing period. The study evaluated the botanical composition, herbage mass (HM), nutritive value, steer average daily gain (ADG), and net returns (NR). The TRC pastures had a greater proportion of legumes compared to TSH plots in May, October, November, and December of both years. There were no differences among treatments for the total HM and nutritive value in 2020; however, in 2021, TU had greater HM at the beginning of the grazing period and greater average crude protein values compared to the other treatments. In both years, there were no differences among treatments for ADG or NR. Therefore, producers can make the same profit considering the beef steer price and the cost of conventional and alternative N sources. Legumes have the potential to suppress weeds when mixed with grasses. Nitrogen is the most important nutrient that contributes to forage production. Stockpiling forages contributes to the extension of grazing season. Grass and legume mixtures can increase the nutritive value and, consequently, improve animal performance.

Pasture systems that include cool- and warm-season species have the potential to enhance tall fescue (TF) [Schedonorus arundinaceus (Schreb.) Dumort.] forage systems beyond their typical season. The objectives of this study were to incorporate crabgrass (Digitaria ciliaris Retz.) into TF swards and compare the production of monoculture TF to a binary mixture of crabgrass and TF as well as its effect with different sources of nitrogen (such as red clover [Trifolium pratense L.] or sunn hemp [Crotalaria juncea L.]). The experiment was conducted in Crossville, TN, in 2020 and 2021. The treatments were as follows: (1) TF + 0 N (T), (2) TF + ammonium nitrate (TA), (3) TF + red clover (TR), (4) TF + sunn hemp (TS), (5) TF + crabgrass + 0 N (TFC), (6) TF + crabgrass + ammonium nitrate (TCA), (7) TF + crabgrass + red clover (TCR), and (8) TF + crabgrass + sunn hemp (TCS). The plots containing red clover indicated a greater herbage mass (HM) and crude protein (CP) along with lesser neutral detergent fiber compared to the other treatments. Sunn hemp performed best during the mid-summer, contributing to the increase of HM. Tall fescue swards that were mixed with crabgrass and a source of N (legumes or N fertilizer) had greater HM during the warm season, having the potential to decrease the stationarity of production. Thus, including crabgrass, red clover, and sunn hemp (grass and legumes, respectively) in TF pasture can be a great strategy to increase HM and improve nutritive value. Inclusion of cool- and warm-season grasses increases the seasonality of production. Crabgrass is a warm-season grass that improves nutritive value in mixed pasture. Nitrogen fertilizer increases forage mass and nutritive value. Increasing the use of legumes in pastures may decrease the use of synthetic N fertilizer.

Cellulosic biomass derived from switchgrass can be an alternative source to produce renewable bioenergy. However, the bioenergy production from switchgrass is not economically viable unless the genotypes with high yield potential and acceptable biofuel quality are available. To identify switchgrass genotypes with good biofuel quality, ten high biomass yielding hybrids derived from crosses between two lowland cultivars, Alamo (A) and Kanlow (K) were evaluated in this study. The experiment was planted in 2018 in two field environments, the East Tennessee Research and Education Center, Knoxville, and the Plateau Research and Education Center, Crossville, in a randomized complete block design with two replications per location. Tillers were collected in the Fall of 2020 and 2021 and analyzed for biomass compositions using the near-infrared reflectance spectroscopy technique. The crosses and their parents were different in biomass compositions across the environments (locations and years) (P<0.05). The crosses’ total ethanol yield (EtOH) ranged from 63.5 to 70.4 mg g-1, and the total sugar yield varied from 725 to 737 mg g-1 across the environments. Average cellulose, hemicellulose, lignin, and ash content were 395.8, 333.9, 178.4, and 49.3 mg g-1, respectively. The estimated non-structural carbohydrates were found as good predictors of EtOH (R2=0.67) (P<0.05). The crosses 12A-259 × 12K-247 and TN13006-04 (A) × TN13009-08 (K) exhibited high predicted EtOH and low ash. Crosses 11A-88 × 12K-35, 12A-261 × 12K-245, and 12A-263 × 12K-250 exhibited high cellulose. These results indicate significant genetic heterogeneity for bioenergy traits within and between these two lowland switchgrass cultivars.

Living mulch (LM) production systems are gaining traction as an alternative to the use of annual cover crops in the southeastern United States, warranting research on the viability and functionality of this system. Our objective was to evaluate the benefits of LM in corn silage and grain production and to evaluate the potential of LM grazing during the corn (Zea Mays L.) growing season. The experiment was conducted in Spring Hill, TN in 2020 and 2021 and consisted of two mulch species, white clover (WC) (Trifolium repens L.) and a mixture of crimson clover (Trifolium incarnatum L.) and cereal rye (CCCR) (Secale cereale L.). Cull cows were used for the grazing periods (4 weeks before planting and after the harvest of corn). The study evaluated the botanical composition, mulch mass, nutritive value, corn silage and grain production, and cow average daily weight gain (ADG). The WC treatment had a greater weed control than CCCR. In 2020, when differences in mulch mass were observed, CCCR had greater mass than WC mass due to the weed presence. Meanwhile, in 2021, the mulch mass did not differ between WC and CCCR, with both treatments showing less mass in spring and early summer. Grain production was 30% less than silage in 2020 and 90% less in 2021. The ADG was only observed for WC (0.5 kg(-1)) paddocks. It was concluded that WC as LM has greater corn production than CCCR treatments. The LM for grazing is a beneficial strategy if feeding costs are greater than $2.22 head day(-1).

The use of living mulch (LM) in corn (Zea mays L.) production must be evaluated under different N fertilization levels. The objective of this study was to determine the optimum amount of N fertilization in white clover (Trifolium repens L. (WC)) LM in corn. The study was conducted in Spring Hill, TN, from 2020 to 2021. The treatments were [C-0] no LM + no N, [C-135] no LM + 135 kg/ha N, [CLM-0] LM + no N, [CLM-45] LM + 45 kg/ha N, [CLM-90] LM + 90 kg/ha N, and [CLM-135] LM + 135 kg/ha N. We evaluated the LM mass and corn production (silage and grain). In general, the LM mass was higher with CLM-45, CLM-90, and CLM-135 during both years. Corn silage production was higher in 2020 compared with 2021 (6.8 and 2.8 Ton/ha, respectively), and showed differences among treatments. The production of corn grain showed the same response pattern with a higher value in 2020 than in 2021 (1.8 and 0.1 Ton/ha, respectively). Thus, the use of LM did not increase corn silage or grain production, even receiving a high N rate as in conventional systems.

Across much of the eastern United States, tall fescue [TF; Schedonorus arundinaceus (Schreb.) Dumort.], a cool-season (i.e., C-3) perennial grass, is the primary forage for pasture systems, thereby leaving producers vulnerable to reduced summer forage production and drought. Warm-season (i.e., C-4) forages can complement existing production systems by supplementing summer forage production and drought resiliency. Therefore, our objective was to compare five, C-4 forage options in a grazing trial: switchgrass (SW; Panicum virgatum L.), eastern gamagrass (EG; Tripsacum dactyloides L.), a big bluestem (Andropogon gerardiiVitman) and indiangrass (Sorghastrum nutans L. Nash) blend (BBI), bermudagrass (BG; Cynodon dactylon L. Pers), and crabgrass (CG; Digitaria sanguinalis L. Scop.). Research was conducted 2014-2016 at two locations in Tennessee. Weaned beef heifers (237-242 kg initial weight) grazed 1.2-ha pastures with three replications per species and location. Average daily gains (kg d(-1)) (0.62 [BBI], 0.41 [BG], 0.44 [CG], 0.42 [EG], 0.51 [SW]), grazing days (d ha(-1)) (412 [BBI], 459 [BG], 455 [CG], 664 [EG], 617 [SW]), and total gain (kg ha(-1)) (259 [BBI], 186 [BG], 200 [CG], 276 [EG], 315 [SW]) all varied among forages (P <.001). Similarly, forage nutritive values differed (P <.001) among forages: season-long crude protein ranged from 94 (BG) to 115 (CG and EG) g kg(-1), neutral detergent fiber (NDF), 601 (CG)-680 (SW) g kg(-1), and acid detergent fiber (ADF) 379 (BG)-417 (EG) g kg(-1). These forage options should be evaluated in the context of TF pastures to establish a broader understanding of their contribution within an overall forage system.

Dual-use cover crops as forage for livestock could offer ecological and economic benefits when incorporated into rotations with corn (Zea mays L.) and soybean (Glycine max (L.) Merr) in the Mid-South USA; however, information on implementation and impact is limited. A factorial of sixteen cool-season species and a no-cover control by two management systems (forage harvest and residue left in the field) was repeated under two cover crop planting/termination timings: long-season (Oct. through May; corn/cover-crop/soybean) and short-season (Nov. through Apr.; soybean/cover-crop/corn), two locations (Spring Hill and Knoxville, TN), and two growing seasons (2017/2018 and 2018/2019). Data were analyzed using a mixed model ANOVA (SAS 9.4.). The forage biomass did not differ by species within the short-season (415 to 1583 kg ha−1) but did in the long-season (475 to 4282 kg ha−1). Within the long-season, crimson clover (Trifolium incarnatum L.) and winter pea (Pisum sativum subsp. arvense (L.)) had crude protein and acid detergent fiber values within the range for prime forage and were among the highest biomasses. The forage harvest did not negatively affect soil properties or succeeding crop yield and quality. If appropriate species are selected, cover crops within a corn/cover-crop/soybean rotation can provide quality forage, without reducing the short term ecological benefits.

Limited work has been done to develop organic forage programs in humid subtropical regions despite growing demand for high-value forage and organic products. Alternative crops were compared for optimizing forage production and nutritive value under organic conditions in the southeastern United States. The study was conducted at the Middle Tennessee AgResearch and Education Center, in Spring Hill, Tennessee. Forage treatments consisted of (a) monoculture tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.], (b) monoculture bermudagrass [Cynodon dactlyon (L.) Pers.], (c) tall fescue and alfalfa (Medicago sativa L.) mixture, (d) bermudagrass and alfalfa mixture, and (e) an annual rotation of winter wheat (Triticum aestivum L.) mixed with winter pea (Pisum sativum L.) followed by sorghum-sudangrass [Sorghum bicolor (L.) Moench x S. sudanese (Piper) Stapf.] mixed with cowpea [Vigna unguiculata (L.) Walp.] mixture. Perennial treatments were established during the 2017-2018 growing season. Monthly production was measured in the 2018-2019 and 2019-2020 growing seasons. Botanical composition of forage mass fluctuated due to establishment dynamics and weed competition, affecting forage quantity and quality. The annual rotation was the highest-yielding treatment, producing more than 6,000 kg(-1), though each tall fescue and tall fescue-alfalfa treatments produced similar to 4,000 kg ha(-1). Nutritive value was sufficient for most livestock operations, with forage crude protein concentration averaging similar to 150 g kg(-1) across treatments and growing seasons. For transitioning organic producers, a perennial forage will likely favor long-term sustainability, whereas the annual rotation may be useful during the transition period to reduce weed pressure before transitioning to a perennial forage system.

Research on the use of forages to transition cropland to organic production is limited. Our objective was to determine the cost of transitioning from conventional to organic production using perennial and annual forage systems. The study was conducted at the Middle Tennessee AgResearch and Education Center, in Spring Hill, TN. Five forage treatments were compared: tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] monoculture, bermudagrass [Cynodon dactlyon (L.) Pers.] monoculture, tall fescue and alfalfa (Medicago sativa L.) mixture, bermudagrass and alfalfa mixture, and an annual rotation of a cool-season mixture, including winter wheat (Triticum aestivum L.) and winter pea (Pisum sativum L.), and a warm-season mixture of sorghum-sudangrass [Sorghum bicolor (L.) Moench x S.orghum sudanese (Piper) Stapf] and cowpea [Vigna unguiculata (L.) Walp.]. Perennial forages were established in 2017 and 2018 following orchard removal and a fallow period. Regular production measurements began in 2019 when the plots achieved full organic certification status. Tall fescue had the lowest cost for the overall transition period. However, on a cost per unit of dry matter (DM) forage mass and on a cost per unit of crude protein (CP) basis, all treatments were similar, with a range between US$0.02 and $0.03 lb(-1) for DM forage mass and between $0.15 and $0.20 lb(-1) for CP, except for the more costly bermudagrass monoculture that was $0.06 lb(-1) DM forage mass and $0.40 lb(-1) CP. Given the lack of a premium during the transition period, tall fescue was the most cost-effective transition forage.

Spring establishment of cool-season annual grasses into poorly producing orchardgrass (Dactylis glomerata L) (OG) swards may improve forage production and nutritive value in the southeastern United States following a fall drought. A randomized complete block experiment was conducted where annual ryegrass (Latium multiflorum Lam.) (AR) or forage oat (Avena sativa L.) (FO) was interseeded into an existing OG stand over three seeding dates with (+) or without (-) a burndown herbicide (BD) treatment and compared with an OG monoculture (control). In 2017, after a warm and wet winter, the OG monoculture (control) was able to produce sufficient forage mass (FM) without significant reduction in nutritive value as compared with OG interseeded with AR or FO. In 2018, OG had approximately 2,600 1b acre(-1) less FM than in 2017, suggesting that recurrent fall drought with unfavorable winter conditions resulted in long-term damage to the perennial sward. Meanwhile, treatments without BD did not show higher FM in the beginning of the season. Burndown treatment in general increased FM and nutritive value. An economic analysis of the study also revealed results suggesting that interseeding AR and FO in the spring is not economically viable, as it may cost up to 10 times as much as the control.

Strong interest in organic produce has warranted great demand in organically produced forages. However, extremely limited research has focused on organic forage production and its ecological contribution. Grass-legume biculture has been suggested to reduce dependency on external N inputs, control weed encroachment, and achieve better soil health. A 2-year study was designed as a conservative organic system with minimum tillage and no external inputs to investigate productivity, botanical composition, nutritive value, mineral concentration, economic benefit, and soil total carbon changes in five certified forage biculture systems; including (1) one annual rotation of winter wheat-Austrian winter pea biculture followed by sorghum-sudangrass hybrid-cowpea biculture, and four perennial systems of (2) bermudagrass-alfalfa, (3) tall fescue-white clover, (4) old world bluestem-sainfoin, and (5) orchardgrass-alfalfa bicultures. Annual systems indicated the greatest productivity (12.7 Mg ha−1) followed by old world bluestem-sainfoin (11.3 Mg ha−1) and bermudagrass-alfalfa (10.3 Mg ha−1) bicultures; but with very limited nutritive value advantages, low mineral concentration, and poor economic return. Perennial systems, particularly old world bluestems-sainfoin biculture, indicated great adaptation, soil carbon enhancement capacity. Monthly biomass production was influential on several nutritive value indices (P < 0.05, R2 ≈ 0.5) within many forage systems. No treatment effects were detected on soil total carbon (P = 0.27), but significant year-wise increase was found under old world bluestems-sainfoin biculture (P < 0.05). Soil moisture levels were affected by treatments and correlated well to botanical composition. Path analysis indicated that Radiation Use Efficiency is the key driver for determining forage yield in the temperate environment.

Winter cover crops can improve the soil’s moisture-holding capacity, reduce soil water evaporation, and mitigate water-induced soil erosion; however, economic studies show mixed results on cover crop impacts on profits. One way to potentially increase the profits from planting cover crops is to harvest the cover crop for hay. The objective of this study was to determine the profitability of planting and harvesting cover crops when planting corn (Zea mays) or soybean (Glycine max (L.) Merr.) as a cash crop. We determined the difference in net returns among 15 cover crop species when planted before corn and soybeans. We then calculated the breakeven hay price if the cover crop was harvested. Data were collected from an experiment in Tennessee, from 2017 to 2019, at two locations. There was no difference in net returns across cover crop treatments for both corn and soybeans, thus indicating that planting a cover crop does not reduce profits. The breakeven prices for harvesting cover crops suggest that this system would not likely be profitable for corn but might be profitable if planting soybeans, depending on labor availability and local demand for hay.

Context: With prevailing economic concerns facing the conventional dairy industry, organic production is a potential alternative for dairy producers as evidenced by a substantial number of operations pursuing organic markets in an effort to improve profitability. However, economic research is limited and the long-term economic sustainability of the system has been questioned. Objective: The objectives of this study were to determine the economically optimal mix of forage and supplemental feed to maximize net returns, identify opportunities and considerations regarding production and feed management, and determine the sensitivity of returns relative to changes in milk prices for an organic dairy operation. Methods: A linear programming model was developed to represent a whole-farm organic dairy operation in the Southeastern United States. The representative farm modeled was based on actual organic dairy operations in Kentucky and Tennessee, partnering with University personnel on this project. The model was employed to explore and optimize enterprise and feed options for the operation. Results and conclusions: Results demonstrated a degree of substitutability of ration components, including representative forage species mixes for grazing, as well as hay and purchased concentrates. Profit potential was found to exist at assumed organic milk price levels, although organic milk price trends and the cost of transitioning to organic production create significant challenges. While a considerable reliance on grazing was a costeffective feeding decision for organic production (a minimum of 30% dry matter intake from grazing is required), increased milk volumes justified the production and purchasing of additional supplemental feeds. Thus, evidence of increased profit potential by targeting higher production levels was suggested under the scenarios examined. Results also indicated a relatively narrow range of break-even milk prices across varying production levels for organic dairies. Finally, a business life of twenty years was generally needed to justify the transitioning of an existing conventional dairy to an organic dairy operation. Significance: This work has implications for existing dairy operations as findings suggest profit potential and some ability to withstand moderate erosion of milk price. The work also informs dairy producers interested in transitioning to organic production by quantifying the cost of this transition and the potential return on that investment over time.

In order to utilize alfalfa (Medicago sativa L.), alone or in mixtures with grasses, defoliation management practices must be evaluated to assess their performance. The objective was to determine the forage accumulation (FA) and nutritive value of alfalfa grown as a monoculture (ALF) and in mixtures with tall fescue [Lolium arundinaceum (Schreb.) Darbyish] (ATF) or bermudagrass [Cynodon dactylon (L.) Pers] (ABG) subjected to four harvest intervals (clipped every 21, 28, 35, and 42 d). The study was conducted in Crossville, TN, and Charleston, OH, during the 2016 and 2017 growing seasons, and in Salisbury, NC, during the 2017 and 2018 growing seasons. Harvest intervals of 35 d or greater showed optimal FA, with greatest productivity in spring. In summer, the plot productivity of ATF was not different from ABG. The ATF mixture was superior to ABG in FA for the entire season. Although tall fescue can be very competitive with alfalfa in mixtures, it results in greater FA while reducing weed competition. Botanical composition indicated greater weed infestation in ALF than in mixtures. Growing alfalfa-grass mixtures can increase sward crude protein compared with grass monocultures (average of 128 g kg(-1) for ATF and 161 g kg(-1) for ABG). We conclude that harvest intervals of 35 d or longer should be adopted to provide greater FA, and the ALF and ATF treatments resulted in superior FA compared with ABG in the southern United States.

Continuous, season-long (May-August) grazing is the most commonly used grazing strategy among tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] belt beef (Bos taurus) producers. However, little information is available regarding the feasibility of managing native warm-season grass (NWSG) pastures in this region with continuous, season-long grazing. We compared stand sustainability, beef cattle performance, and pasture production between continuous (CONT), season-long grazing and heavy-early (HEAVY), a modified continuous grazing strategy, on mixed-NWSG pastures. Heavy-early was designed to match the growth curve of NWSG, with an initial stocking target of 1.25 times the CONT density until 25 June, at which time stocking was reduced to 0.75 times the CONT density. Pastures were mixed big bluestem (Andropogon gerardii Vitman), indiangrass [Sorghastrum nutans (L.) Nash], and little bluestem [Schizachyrium scoparium (Michx.)]. The plant population (plants m(-2)) was similar between treatments, but years differed (P < .001), with a 35% reduction from 2017, the third and final year of grazing, to 2018. Despite the decline in plant density, overall tiller density (tillers m(-2)) increased 14%, indicating that the grazing strategies were likely sustainable. The grazing strategies had similar (P > .05) average daily gain (ADG; kg d(-1)), animal-days ha(-1), and total gain (kg ha(-1)). Weaned steer ADG was 0.98 kg d(-1) for CONT and 0.89 kg d(-1) for HEAVY. Total gain was 379 kg ha(-1) for CONT and 334 kg ha(-1) for HEAVY. Continuous grazing appears to be an appropriate strategy for managing NWSG pastures in the Fescue Belt.

Abstract Fescue toxicosis reduces animal performance, costing approximately $2 billion dollars to the beef industry annually. Emerging research has demonstrated effects of fescue toxicosis can be reduced by consumption of red clover isoflavones. The objective of the current study was to evaluate the effect of isoflavone supplementation with endophyte infected seed consumption on serum metabolites in beef steers. Angus steers (n = 36) were randomly allocated to treatments in a 2×2 factorial arrangement of endophyte-infected (E+) or endophyte-free (E-) tall fescue seed, with (P+) or without (P-) a red clover isoflavone supplement. For the 21d trial, steers were provided a basal diet supplemented with fescue seed head targeting a minimum of 0.011 mg×kg of body weight−1×d−1 of total alkaloids. A total of 943 mg isoflavones were administered daily via bolus. Following the 21d trial, blood samples were collected for metabolite analysis. Metabolites were filtered from serum and extracted using 0.1% formic acid in acetonitrile:water:methanol (2:2:1) for analysis on the Dionex UltiMate 3000 UHPLC system and Exactive Plus Orbitrap MS. The Metabolomic Analysis and Visualization Engine program was used to determine peaks and identify metabolites. Resulting metabolite data were analyzed in MetaboAnalyst 4.0 and SAS 9.4 with significance at P≤0.05. Principle component analysis indicated separation of metabolomes between E+P+ and E-P- steers. Orthogonal partial least squares discriminant analysis depicted distinct separation between P+ and P- steers and partial separation between E+ and E- steers. The variation between P+ and P- metabolomes were mainly due to differences in citrulline (r = 0.47, P = 0.003), and AMP (r = -0.35, P = 0.03) between E+ and E- metabolomes. A total of 13 and 8 metabolic pathways were impacted from differences in seed type and isoflavone treatment, respectively (P ≤ 0.05). Therefore, metabolism is altered by isoflavone supplementation that may improve animal performance during fescue toxicosis.

For alfalfa (Medicago saliva L.) to be profitable in the southeastern United States, enhanced persistence is required. However, studies assessing alfalfa's persistence in monoculture or mixtures in the region are limited. We aimed to determine the persistence and productivity of alfalfa and alfalfa-grass mixtures subjected to different harvest intervals. Three species combinations were established in 2015: alfalfa (A), alfalfa-tall fescue [Schenodorus arundinaceus (Schreb.) Dumort] (ATF), and alfalfa-bermudagrass [Cynodon dactylon (L.) Pers.] (AB). These were subjected to four harvest intervals (21, 28, 35, and 42 d) during the 2016, 2017, and 2018 growing seasons. Total forage accumulation (FA) was quantified during 2017 and 2018 and nutritive value and stem density were measured at the first and last harvests in those years. Forage accumulation decreased in all species combinations after 2 yr of management (A: 21 d, -63%; 28 d, -66%; 35 d, -50%; 42 d, -31%; AB: 21 d, -22%; 28 d, -59%; 35 d, -34%; 42 d, -19%; ATF: 21 d, -41%; 28 d, -62%; 35 d, -64%; 42 d, -41%), reflecting decreased alfalfa stem density, especially for A and AB. The differences in alfalfa stem density between the first and last harvests depended on the species. No differences were observed in ATF mixtures but for AB and A, longer harvest intervals had up to 90% fewer stems, thus decreasing alfalfa's persistence in the field. Lower stem density was observed for the 21-d harvest interval; therefore, longer intervals could result in better field performance.

Improved summer forage production is important in forage systems dominated by cool-season perennial grasses. Improved forage may be especially important for heifer [Bos taurus (L)] development. Therefore, we compared two summer forage options, a perennial, eastern gamagrass [Tripsacum dactyloides (L.) L.], and a widely used summer annual, sorghum [Sorghum bicolor (L.) Moench] x sudangrass [Sorghum bicolor (L.) Moench ssp. drummondii (Nees ex Steud.) de Wet & Harlan] hybrid, as options for providing summer pasture for bred heifers (418 +/- 31 kg initial body mass). We used put-and-take grazing (i.e., routine adjustment of stocking to maintain target canopy conditions) to evaluate pasture characteristics, animal performance, and pasture productivity, 2013-2015. Crude protein of eastern gamagrass (EG) exceeded (P = 0.01) that of the sorghum x sudangrass hybrid (SXS), but FM, ADF, and NDF were all similar between the two forage types. Although SXS provided greater ADG (P = 0.03) in two of three years, EG provided twice as many AD ha(-1) (P = 0.03) and consequently, greater (P < .001) GAIN in two of three years. Calving rates (89%) did not differ between the two forages. Increased N rates (67 vs.137 kg ha(-1) N) did not alter EG pasture characteristics but appeared to improve GAIN (279 and 355 kg ha(-1), respectively). Cost of gain was greater for SXS in 2014 and 2015 ($1.71 and $1.64 kg(-1)) than for EG ($0.62 and $0.62 kg(-1)). Both EG and SXS could be useful for providing summer forage for bred heifers.