Fescue toxicosis is a common problem in beef cattle grazing endophyte-infected (E+) tall fescue. Symptoms include decreases in feed intake, weight gain, and reproductive efficiency along with vasoconstriction. The mechanisms by which fescue toxicosis affects the bovine reproductive tract have yet to be discovered. The objective of this study was to determine if the onset of fescue toxicosis conditions would alter the blood perfusion observed in the CL and peripheral concentrations of progesterone in cattle. We hypothesized that during fescue toxicosis, the vasoconstrictive symptoms would lead to a reduction in CL blood perfusion thus decreasing peripheral concentrations of progesterone. Overall, fescue toxicosis was induced as cows fed an E+ treatment diet had greater rectal temperatures and reduced pulse pressure and mean arterial pressure measurements; however, total blood perfusion of the CL and peripheral concentrations of progesterone did not differ in cattle under fescue toxicosis compared to those without.

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Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] is an important forage crop in the United States and covers over 14 million ha. The presence of Neotyphodium coenophialum, an endophytic fungus in tall fescue, is associated with several disorders in grazing livestock, but also increased persistence of tall fescue. These disorders, commonly called fescue toxicosis, are responsible for large economic losses in the beef cattle industry each year. This research examined the effect of three fescue types [endophyte-infected Kentucky 31 tall fescue (E+), endophyte-free Kentucky 31 tall fescue (E-), non-ergot alkaloid-producing endophyte Q4508-AR542 tall fescue (Q)], and Lakota prairie grass (L; Bromus catharticus Vahl.) on animal response, alkaloid appearance, DMI, and copper status. Ergovaline (EV) is the most abundant ergot alkaloid in tall fescue and has previously been considered the causative toxin in fescue toxicosis. More recently it is simpler ergot alkaloids, such as lysergic acid amide (LSA) have been implicated. The objective of the first project was to evaluate animal performance and alkaloid (EV and LSA) appearance in forage and ruminal fluid of steers grazing E-, Q, E+, and L. Average daily gains were greater (P < 0.05) on E-, Q and L compared to E+, and there was a trend (P = 0.11) for gains on E- to be higher than with Q. The seasonal appearance of LSA in ruminal fluid was similar to the seasonal pattern of alkaloids in E+ forage. Ergovaline was not detectable in ruminal fluid of steers grazing E+. Alkaloids were not detectable in forage or ruminal fluid of steers grazing E-, Q, or L. The appearance of LSA in ruminal fluid of steers grazing E+ suggests that this alkaloid may contribute to fescue toxicosis. Low DMI of animals grazing E+ tall fescue is considered a key factor in decreased animal performance compared to other fescue types. The objective of the second project was to evaluate DMI of steers grazing E-, E+, Q, and L pastures using the alkane technique. Dry matter intake of steers grazing E- was greater (P < 0.001) than Q, E+, and L and DMI of steers grazing Q and E+ were similar (P > 0.10) in 2004. In 2005, DMI did not differ (P = 0.23) among fescue types. These results suggest that decreased DMI effects ADG of steers grazing E+ compared to those grazing E-, and lower DMI of Q suggests that the fescue variety Q4508 may not be the optimal variety for the incorporation on non-ergot alkaloid-producing endophytes. Reactive oxygen metabolites such as superoxide (O₂⁻) are produced by both endogenous and exogenous sources and an accumulation of these compounds can result in oxidative stress. Copper/zinc superoxide dismutase (SOD) is a Cu-based antioxidant metalloprotein that acts as a defense against oxidative stress by the scavenging of O₂⁻. <i>Neotyphodium</i>-infected tall fescue is typically lower in Cu which could potentially increase oxidative stress of animals grazing this forage. Therefore the objective of the third project was to investigate the Cu and SOD status of steers grazing E-, E+, Q, and L forages. Copper levels of all forages were below the dietary requirement (10μg Cu/g DM) of growing cattle. In 2004, steers grazing E+ exhibited lower (P <0.05) liver Cu compared to E- and Cu intake was lower (P < 0.001). Cu/Zn SOD enzymatic activity and mRNA relative expression did not differ (P > 0.10) among treatments. Copper intake of steers grazing E+ tall fescue was sufficient to maintain, but not replenish liver Cu, and SOD status did not appear compromised by grazing E+ at these Cu levels. / Ph. D.

Urban development alters the physical and chemical properties of soil which presents challenges for vegetation establishment. Compost, when applied as a soil amendment, can help to ameliorate these challenges. In field trials, we evaluated the effect of surface-applied composts and standard hydroseeding applications on changes in soil properties and turfgrass stand on a highway roadside. The short-term effects of (1) no compost application; (2) 2.5 cm compost surface mulch; (3) 2.5 cm compost application, incorporated; (4) 5.0 cm compost application, incorporated; (5) 0.6 cm compost blanket; and (6) straw mat on turfgrass establishment, quality and changes in soil properties were measured on an urban soil devoid of topsoil. In greenhouse studies, we compared the effect of depth of planting of two variously-sized turfgrass seeds in compost. The soils of the disturbed roadside and the urban soil had increased Mehlich I-extractable soil K, Mg, and P following compost application. Analysis of botanical composition on the highway roadside demonstrated that the percentage of fescue decreased with time, while weed species increased inversely in both treatments. Compost amendments on the urban soil increased turfgrass color over time, whereas turfgrass density was not affected by time. Turfgrass density was greatest in applications of a 5 cm depth compost incorporated 7-10 cm into the soil. No differences were observed in biomass harvested among treatments. Tall fescue seeds had greater germination and establishment than smaller sized bermudagrass seeds when sown below the surface of compost, regardless of depth. Composts help to regenerate topsoil-like functionality in disturbed soils by promoting vegetation establishment, including weeds, on highway roadsides and improving turf quality on urban soils. / Master of Science

The beef cattle marketing structure imposes stress on calves due to weaning, transport, commingling, and adaptation to new diets, resulting in a weakened immune systems at the height of disease risk, frequently causing bovine respiratory disease. Backgrounding programs facilitate opportunities for calves to overcome stressors by building immunity, and adapting the rumen to high concentrate diets for improved feedlot performance. Four experiments were conducted to compare backgrounding strategies and effects of supplementation frequency performance and the effects of the ruminal environment. In Exp. 1, 48 weaned steers were used to investigate the effects of transportation and supplementation frequency, while in Exp. 2, 36 heifers were used to investigate only supplementation frequency. No differences in gains were observed due to transportation stress or supplementation frequency. Weaning stress resulted in elevated (P < 0.05) creatine kinase and neutrophil:lymphocyte ratios during the first week. In Exp. 3, 48 calves were used to compare the effect of tall fescue type on performance and health. Calves on novel endophyte fescue had higher ADG (P = 0.07) than on endophyte-infected fescue. Experiment 4 investigated the changes in ruminal environment due to supplementation frequency. No differences were observed between supplementation frequencies for ruminal pH, ammonia, or VFA concentration, and DM, or CP digestibility. Therefore, the rumen maintained a hospitable environment to promote bacterial protein synthesis and fiber digestion with every 48 h supplementation. Backgrounding calves with high fiber co-product supplements or on novel endophyte fescue can enhance calf performance. / Master of Science

For Virginia, the primary forage base is endophyte-infected tall fescue (Schedonorus phoenix (Scop.) Holub). However, the decreased animal performance and disorders caused by the presence of the fungal endophyte Neotyphodium coenophialum reduces its suitability for many forage-livestock producers. The endophyte, which is found in the inter-cellular space of tall fescue tissues, forms a mutalistic relationship with the plant and helps the fescue tolerate drought, insect predation, and grazing pressure. The production of toxic ergot alkaloids by the endophyte is associated with decreased performance of animals that graze endophyte infected tall fescue. The objective of the current experiment was to determine how tall fescue type (endophyte free vs novel endophyte) and orchardgrass-legume (alfalfa vs clover) mixture affect grazing behavior of weaned steers. Forty-eight weaned steers (218 ± 18 kg) were blocked by frame score (medium and large), and randomly assigned within block to four treatments with three replications in a 2x2 factorial design. Each treatment consisted of 2 paddocks with the combination of tall fescue and legume-orchardgrass mixture as follow: alfalfa-orchardgrass mixture (A)/E-, clover-orchardgrass mixture (C)/E- , A/E++ and C/E++. Each group of 4 steers had 24 h access to both tall fescue stand and legume-orchardgrass mixture. Botanical composition of paddocks was determined on d 0, and forage mass, sward height and nutritive value were determined on d 0, 17 and 33. Behavior of steers was scanned every 5 min on d 24 and 25 from 0700 to 1900. The proportion of legumes was higher (P = 0.001) in A paddocks(37 %) compared to C paddocks (6%), while the percent orchardgrass was lower (P = 0.040) in A (33 %) than C (53 %). The proportion of broadleaf and grassy weeds was higher (P = 0.013) in E- paddocks (11 %) as compared with E++ paddocks (3 %). Sward height and herbage mass were similar between treatments during the experiment (P > 0.05). Nutritive value (CP, NDF and ADF) did not differ between fescue paddocks (P > 0.05). However, within mixed swards, CP was higher and NDF was lower in A compared with C (P < 0.05). Acid detergent fiber was (P < 0.05) lower in A than C only on d 0 and 17. Average daily gain did not differ between treatments (P > 0.05). Steers spent higher (P = 0.002) proportion of the daylight time grazing in treatments with C (56 %) as compared with A (50 %), and in treatments (P = 0.023) with E++ (55 %) compared with E- (52 %). Time spent ruminating, idling and lying, as well as steps taken per day, did not differ between treatments (P > 0.05). Regardless of differences in weeds between E- and E++, these results indicate that fescue type affected grazing behavior of calves. Difference between mixed swards in proportion of ground cover with legumes and orchardgrass, as differences in nutritive value between A and C may have affected grazing behavior of calves between mixed swards, instead of a legume species effect within mixtures. / Master of Science

The Southeastern United States offers a beneficial environment for stocker and cow-calf production. Abundant tall fescue grass offers a feed source that has been underutilized. These studies evaluated how nitrogen rate and source can affect yield and nutritional quality of fall stockpiled tall fescue, and how grazing methods impact weight gains, forage utilization, and forage nutritive value. The first study evaluated the impact of N rate and source on the yield tall fescue stockpiled for winter grazing. In mid-September, seven N sources (ammonium sulfate (AS), ammonium nitrate (AN), urea + Agrotain @ 2.1 l/Mg (AG2), urea + Agrotain @ 4.2 l/Mg (AG4), urea + Agrotain @ 6.3 l/Mg (AG6), Nutrisphere (NuS), and urea) were applied at 0, 45, 90, and 135 kg N/ha. Ammonium sulfate produced the highest nutritive values of all N sources. Only yield in 2012 was found to be influenced by N volatilization inhibitors; said products had no effect on nutritive value. The second study evaluated how grazing methods impact nutritive value, ADG, and utilization of tall fescue stockpiled for winter grazing. Three treatments (continuous grazing, moved once per week, and moved twice per week) were used. In year one, cattle moved once and twice per week showed significantly higher ADG (P < 0.05) than the continuous treatment. In year two, cattle that continuously grazed had higher ADG (P <0.05), than cattle moved once and twice per week. Cattle moved once and twice per week showed greater forage utilization (P < 0.05) than cattle that continuously grazed. / Master of Science

Tall fescue (Lolium arundinaceum) is the principal cool-season species within pastures of the southeastern USA and is known to have a mutualistic relationship with a fungal endophyte (Neotyphodium coenophialum) that produces the ergot alkaloids responsible for tall fescue toxicosis. Management of the reproductive growth of tall fescue is necessary, as the seedheads contain the highest concentrations of ergot alkaloids, and livestock have been documented to selectively graze these tissues. Recently, the herbicide Chaparral™ has been shown to be an effective method to prevent seedhead production in tall fescue pastures while also increasing steer gains at a low stocking rate. The objective of this study was to compare the impact of Chaparral on steer and pasture production under multiple grazing intensities (GI). Chaparral (0 and 140 g ha-1) and two levels of GI (low: 3300±250 kg ha-1 & moderate: 2500±250 kg ha-1) treatments were arranged in a factorial combination as RCBD with three replications. Tall fescue seedhead densities were decreased (P < 0.05) within the Chaparral-treated pastures, but efficiency of the inhibition varied slightly between growing seasons. Chaparral-treated pastures had lower (P < 0.05) forage availabilities and contained forage with higher (P < 0.05) concentrations of crude protein (CP) and in vitro digestible dry matter (IVDDM) during both growing season. Steers within the Chaparral-treated pastures and low GI treatment had higher average daily gains (ADG). Carrying capacities (CC) were lowest and highest within the Chaparral-low GI and control-moderate GI treatments, respectively. Estimates of CC were not different (P > 0.15) between the Chaparral-moderate GI and control-low GI treatments. The higher ADG compensated for the lower CC of the Chaparral and low GI treatments and resulted in no difference (P > 0.60) in total gain per hectare (GPH) between grazing intensities and herbicide treatments in 2011. In 2012, the GPH were higher within the control and moderate GI treatments due to a lessening in the magnitude of difference between the herbicide and GI treatments. The effects of these treatments for alleviating symptoms of tall fescue toxicosis were inconclusive due to the low levels of ergot alkaloids production.

Ergot alkaloids present in endophyte-infected (E+) tall fescue are thought to be the causative agent of fescue toxicosis, a syndrome affecting cattle in the eastern United States. Many of the observed signs of fescue toxicosis are thought to be attributed to peripheral vasoconstriction; however, there are data indicating that ergot alkaloids can alter blood flow to the gut. An experiment was conducted using right ruminal artery and vein collected from heifers shortly after slaughter. Vessels were mounted in a multi-myograph to determine the vasoconstrictive potentials of ergot alkaloids present in E+ tall fescue. Results indicated ergot alkaloids have the potential to induce vasoconstriction of foregut vasculature. A second experiment was conducted to determine if the additional ergot alkaloids present in E+ tall fescue increase the vasoconstrictive response above that of ergovaline. Results indicated that ergovaline is the main alkaloid responsible for vasoconstriction in bovine vessels. A third study was performed to determine the effect of ergot alkaloids on ruminal epithelial blood flow in the washed rumen of steers exposed to E+ or endophyte-free (E-) tall fescue seed. Steers were dosed with seed followed by a washed rumen experiment with differing levels of ergovaline incubated in the rumen. Results indicated that E+ tall fescue seed treatment reduced ruminal epithelial blood flow. Additionally, incubating ergovaline in the rumen during the washed rumen further decreased epithelial blood flow and volatile fatty acid (VFA) absorption. A final study was conducted to determine the acute effects of ergot alkaloids on isolated rumen epithelial absorptive and barrier functions and the potential for ruminal ergovaline absorption. Results indicate that acute exposure to ergot alkaloids does not alter the absorptive or barrier function of rumen epithelium and ergovaline is absorbed from the rumen. Data from this series of experiments have shown that ergot alkaloids from E+ tall fescue can induce vasoconstriction of blood vessels in the foregut of cattle, reduce blood flow to the rumen epithelium, and decrease VFA absorption. The decrease in nutrient absorption could contribute to the observed symptoms of fescue toxicosis, including depressed growth rates and general unthriftiness.

Two experiments were conducted at the University of Kentucky, Eden Shale Farm, Owenton, KY to evaluate the use of MTB-100TM (Alltech, Inc., Nicholasville, KY) to alleviate the symptoms of fescue toxicity when lactating Angus x Beefmaster cows and their calves grazed endophyte-infected KY-31 tall fescue. Experiment 1 provided a carbohydrate based toxin adsorbent, MTB-100TM, ad libitum in a commercial mineral supplement to project a daily consumption rate of 0, 20 or 40 g of MTB-100TM per cow. Cows were weighed, assigned a body condition score (BCS) and hair coat score (HC), rectal temperatures were recorded and fecal grab samples were taken for ergovaline (EV) and lysergic acid (LA) analysis every 35 days for three grazing seasons (May to September). Calves were also weighed and assigned a HC score. Although MTB-100TM did not improve cow or calf performance, cows older than 4 years and those with greater Beefmaster breeding exhibited a higher tolerance to fescue toxicity than 2 and 3-yr-olds and cows with greater Angus breeding. Experiment 2 was conducted to evaluate the response of lactating beef cows and their calves to strategic supplementation with MTB-100TM. MTB-100TM was mixed with a complete mineral so daily intake was projected to be 0 or 20 g/cow. The experimental period extended from May 5 to October 2 and was divided into 3 strategic periods: P1 = May 5 to July 5; P2 = July 5 to August 31; P3 = August 31 to October 2. Treatments were either 0 or 20 g•cow-1•d-1 MTB-100TM within a period (Treatment 1 = 0, 0, 0; Treatment 2 = 20, 0, 20; Treatment 3 = 0, 20, 0; Treatment 4 = 20, 20, 0; and Treatment 5 = 20, 20, 20). Cow and calf performance was measured the same as Exp. 1, but every 21 days. Supplementation early in the grazing season tended to improve cow weight gain and body condition; however, there was no effect on calf performance. Fecal output of EV and LA did not increase in either experiment with supplementation. In conclusion, strategically invoked MTB-100TM consumption can increase performance of cows grazing endophyte-infected tall fescue forage.