Endophytic fungi (A. coenophialum and A. lolii) which infect grasses produce ergot alkaloids that serve as the grasses' chemical defenses and enhance the vigor of the grass. Turf-type tall fescue with high endophyte levels has been deliberately developed to produce a greener, more vigorous, pest-resistant turf. Consumption of endophyte-infected grass causes various toxicity symptoms in livestock. Cattle in the southeastern and midwestern United States, where tall fescue is grown on 14 million hectares, often develop signs of toxicosis during summer months from grazing plants in fected by A. coenophialum. A more severe form of the disease, fescue foot, has been associated with cold environment and reported in late fall and winter months not only in the southeastern United States but also in the northwest United States. In New Zealand, where perennial ryegrass is grown on 7 million hectares of pasture, sheep often develop a condition called ryegrass staggers from grazing plants infected by A. lolii. New Zealand reports economic losses grazing plants infected by A. lolii. New Zealand reports economic losses associated with the sheep industry of $205 million per year. In the United States, economic losses associated with the beef cattle industry alone is estimated at $600 million per year. Range finding experiments and case studies of fescue foot and perennial ryegrass staggers (PRGS) were conducted on cattle and sheep under grazing and barn conditions. The main objective was to determine threshold levels of the endophyte toxins, ergovaline (EV) (appendix 1) and lolitrem B (appendix 2), associated with the diseases of fescue foot and PRGS respectively. Fescue foot was experimentally induced in cattle under barn studies in the spring with 825 ppb ergovaline. The ergovaline contaminated feed was given for a period of 42 days. Similar barn studies in sheep in spring to early summer did not produce clinical fescue foot with up to 1215 ppb. Field studies of natural fescue foot in a herd of sheep were conducted, (ie 540 ppb) values of ergovaline in the feed, but clinical disease was not produced in late fall through winter. A case study from a herd of sheep revealed 813 ppb dietary ergovaline had produced fescue foot in the months of fall (November). Fields of perennial ryegrass (PRG) where sheep received 2,135 ppb lolitrem B toxin were associated with clinical cases of PRGS in 42 sheep of 237 sheep (18 percent incidence rate) in the Willamette Valley of Oregon. Three months later, sheep on this same field which then had 1,465 ppb lolitrem B, did not have PRGS. These were the first range finding experiments undertaken in this locale to document threshold levels of endophyte toxins associated with fescue foot and PRGS. / Graduation date: 1994

A wild-type endophyte (Neotyphodium coenophialum [(Morgan-Jones & Gams) Glen Bacon & Hanlin]) that infects tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorous arundinaceum (Schreb.) Dumort.] imparts tolerances to moisture, heat, and grazing stresses, but also produces ergot alkaloids that adversely affect performance and physiology of cattle. Novel endophytes, developed by AgResearch Ltd. NZ, can sustain fescue persistence and productivity, but do not produce toxic ergot alkaloids. University of Kentucky Plant Breeder, T. D. Phillips Ph.D, developed a tall fescue experimental population (KYFA9301) for the upper transition zone. A 2-yr grazing experiment was conducted with steers to evaluate steer performance and physiology, and forage quality and productivity of KYFA9301 infected with AR584 novel endophyte (AR584) compared with KY31 wild-type endophyte (KY31), endophyte-free KYFA9301 (EF9301) and AR542-‘Jesup’ (MaxQ). Fescue-endophyte combinations were assigned to 1.0-ha pastures in a randomized complete block design with three replications. Pastures were grazed with variable stocking (four testers) from 6 May to 23 July 2008 (76 d), and 2 April to 25 June 2009 (84 d). Shrunk bodyweights were taken at initiation and termination of grazing each year. Average daily gains among MaxQ, AR584, and EF9301 were similar and were greater (P < 0.10) than KY31. Rectal and skin temperatures were collected three times each year at approximately days 28, 56, and study completion, along with blood collection for serum prolactin assay. Rectal and skin temperatures among AR584, MaxQ, and EF9301 were similar and were lower (P < 0.10) than KY31. Serum prolactin concentrations were similar among the three nontoxic varieties and higher (P < 0.10) than KY31. Forage collections were taken at 2 week intervals throughout the study each year and nutritive quality analysis were conducted through wet chemistry to determine forage acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), and In-Vitro Dry Matter Digestibility (IVDMD). Nutritive analyses indicated no differences between fescue-endophyte combinations with the exception of EF9301 having higher ADF concentrations (P = 0.031) than KY31 during the dry year of 2008. Results indicated steer performance and physiological responses for KYFA9301, with and without AR584 were enhanced compared to KY31 and similar to those for MaxQ.

Endophyte-infected (E+) tall fescue grass has been associated with fescue toxicosis, a costly syndrome characterized by poor cattle performance and health resulting in significant production losses. The fungal endophyte produces ergot alkaloids, which help the grass thrive in poor conditions but are toxic to mammals. A number of symptoms of fescue toxicosis can be related to vasoconstriction of bovine core, peripheral, and foregut vasculature. The first part of this series of experiments demonstrated ergot alkaloids were also vasoactive in midgut vasculature, with the exception of lysergic acid. Additionally, prior dietary exposure to ergot alkaloids decreased the contractile response of mesenteric vasculature to many of the ergot alkaloids tested. In the second part of this series, a non-invasive method was developed for measuring rumen motility in cannulated cattle. Using this technology without different dietary treatments, it was determined that 8 to 16 h after feeding was the least variable between animals and would provide the best opportunity to measure differences in motility. Application of this technique in the third part of this series investigated the effect of ruminally dosed ergot alkaloids on rumen motility. Treatments were not effective at inducing fescue toxicosis, and no differences in rumen motility variables were detected.

Thesis (Ph. D.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on June 7, 2006). Thesis advisor: Thomas C. Mueller. Vita. Includes bibliographical references.

Sustainable farming is an integrated practice of crop and livestock production system (integrated crop-livestock system; ICLS) that aims to reduce the environmental impacts of agricultural practices while maintaining the productivity and profitability. The use of one step's byproducts by another is a crucial component of this practice. The continuity and effectiveness of sustainable farming greatly rely on deep understanding of each component and good management strategy. One essential aspect involved in all farming components is the role of microorganisms in mediating the biological processes therein. Thus, understanding the composition and activities of these communities would open up ways to engineer them and optimize the respective processes for better sustainable farming practices. The research presented in this dissertation aimed to characterize the microbial metabolism involved in the ICLS with a broader goal of manipulating these systems to improve sustainable agriculture. We focused on two systems that are widely used in the United States, and employed the analysis of 16S rRNA-V4 element for this purpose. In our first system, we characterized the rumen microbiomes of beef cattle alternately grazing nontoxic MaxQ and toxic KY-31 tall fescue pasture, to understand how these cultivars shape the rumen microbiome and identify microbial species potentially capable of degrading ergot alkaloids for better feed utilization. We found that KY-31 grazing remodeled the rumen microbiome substantially at the cellulolytic and saccharolytic guilds. It suppressed the abundances of Fibrobacter, a major ruminal cellulolytic bacterium, as well as those of Pseudobutyrivibrio and Butyrivibrio, and these losses were compensated by increased occurrences of Eubacterium species. Parts of these new communities lingered once developed, and a different guild composition surfaced upon transfer to MaxQ. We also discovered that most of the observations were not evident at the whole microbiome levels but was identified by analyzing the sessile and planktonic fractions separately. Thus, it showcased the need for analyzing sessile and planktonic segments separately while interrogating a heterogenous microbiome. Finally, we identified several potential ergovaline degrading bacteria such as Paraprevotella and Coprococcus. In our second system, we studied the microbiome composition and associated transformation pathways mediating nitrogen loss in two dairy manure storage systems, the clay-lined Earthen Pit (EP) and aboveground concrete storage tank (CS) on two commercial dairy farms, to develop strategies to minimize these losses. We first developed a catalog of the archaea and bacteria that were present therein based on the 16S rRNA-V4 amplicons from manure samples collected from several locations and depths of the storages. Then, we inferred the respective metabolic capabilities via PICRUSt2 and literature curation, and developed schemes for nitrogen and carbon transformation pathways operating at various locations of EP and CS. Our results showed that the stored manure microbiome composition was more complex and exhibited more location-to-location variation in EP compared to CS. Further, the inlet and a location with hard surface crust in EP had unique consortia. With regards to nitrogen transformation, the microbiomes in both storages had the potential to generate ammonia but lacked the organisms for oxidizing it to nitrate and further to gaseous compounds such as anammox and autotrophic nitrifiers. However, microbial conversion of nitrate to gaseous N2, NO, and N2O via denitrification and to stable ammonia via dissimilatory nitrite reduction (DNRA) seemed possible. Minor quantity of nitrate was present in manure, potentially originating from oxidative processes occurring on the barn floor. Higher prevalence of nitrate-transforming microbes at the near-surface locations and all depths of the inlet were found as a result of this instance. These findings suggested that ammonia oxidation to nitrate started on the barn floor and as manure is being stored in EP and CS, nitrate was lost to the environment via denitrification. For carbon transformation, hydrogenotrophic Methanocorpusculum species were the primary methane producers, and it exhibited higher abundance in EP. / Doctor of Philosophy / Sustainable farming is an integrated practice of crop and livestock production systems that aims to reduce the environmental impacts of agricultural practices while maintaining the productivity and profitability. The use of one step's byproducts by another such as the utilization of arable land to grow forages for livestock grazing or the use of manure as organic nitrogen amendments for crops is a crucial component of this practice. The continuity and effectiveness of sustainable farming greatly rely on deep understanding of each component and good management strategy. One essential aspect involved in all farming components is the role of microorganisms in mediating the biological processes therein. Thus, understanding the composition and activities of these communities would open up ways to engineer them and optimize the respective processes for a better sustainable farming practice. The research presented in this dissertation aimed to characterize the microbial metabolism involved in the integrated crop-livestock system with a broader goal of manipulating these to improve sustainable agriculture. We focused on two systems that are widely used in the United States, and employed bioinformatic analysis of a genetic marker for this purpose. In our first system, we characterized the rumen microbiomes of beef cattle grazing alternately on KY-31 tall fescue, a major grass used in Virginia that carry a toxin-producing fungi, and nontoxic MaxQ tall fescue pasture, to understand how these cultivars shape the rumen microbiome and identify potential microbial species capable of degrading the toxin for better feed utilization. We found that KY-31 grazing remodeled the rumen microbiome substantially, especially affecting microbes responsible for degrading cellulose and starch. Some of these communities lingered once developed, and a different microbial population surfaced upon transfer to MaxQ. Several potential toxin-degrading bacteria were also identified. In our second system, we studied the microbiome composition and associated transformation pathways mediating nitrogen loss in two dairy manure storage systems, the clay-lined Earthen Pit (EP) and aboveground concrete storage tank (CS), to develop strategies to minimize these losses. We first develop a catalog of the archaea and bacteria that were present in the manure samples collected from several locations and depths of the storages based on a genetic marker. Then, we inferred the respective metabolic capabilities and developed schemes for nitrogen and carbon transformation pathways operating at various locations of EP and CS. Our results showed that the stored manure microbiome exhibited more location-to-location variation in EP compared to CS. Oxygen exposure, continuous addition of fresh manure, and the presence of crust at the storage surface gave rise to these unique populations. With regards to nitrogen transformation, the microbiomes in both storages had the potential to generate ammonia but lacked the organisms for oxidizing it to nitrate and further to gaseous compounds. However, microbial conversion of nitrate to gaseous N2, NO, and N2O seemed possible. These observations showcased that ammonia is stable during storage. Nitrate, on the other hand, can be converted into volatile nitrogen compounds via various processes. Thus, it is imperative to limit the level of nitrate in manure prior to placement in the storage, which is potentially originating from oxidative processes occurring on the barn floor.

<p>  </p> <p>Kentucky bluegrass is the most common cool-season turfgrass grown in the northern US. <br> The fact that Kentucky bluegrass requires s high quantity of fertilizers, pesticides, and irrigation to produce high quality turf has led to environmental concerns among policymakers, researchers, and consumers. To address this concern, turfgrass breeders have developed improved cultivars of low-input turfgrass species that aim to improve the sustainability of US lawns (Ghimire et al., 2019). For instance, tall fescue [(<em>Festuca arundinacea </em>Schreb.; syn. <em>Schedonorus arundinaceus</em> (Schreb.) Dumort., nom. cons.] and fine fescues (<em>Festuca </em>spp.) may represent viable options for residential and commercial buildings due to their outstanding performance under lower amounts of inputs such as irrigation, pesticides, and fertilizers (Watkins et al., 2011). Thus, adopting improved cultivars of low-input species may be a step towards reducing the use of inputs in landscapes (Simmons et al., 2011; Pooya et al., 2013). Yet, the production of low-input turfgrasses in the northern US is slow and limited, which leads to marketing and education obstacles that support their adoption. Thus, understanding factors that influence sod buyers to purchase low-input turfgrasses is imperative to increase the market share and the adoption of these turfgrasses. </p> <p>This study investigated the factors influencing sod buyers to purchase low-input turfgrass in the northern US, using tall fescue and fine fescue as low-input sod species. Using a logistic regression model, we assessed the determinants of low-input turfgrass purchase among sod buyers (i.e., athletic facilities, landscape contractors, garden centers, general contractors, lawn care, golf courses, and municipal parks). The logit model assumed the adoption decision to be driven by the buyers’ perception of the utility of buying low-input turfgrass species. Thus, the dependent binary variable Y equals 1 if the firm purchased tall or fine fescue in 2020, and 0 otherwise. The adoption is then expressed as a function of determinants, including the firm’s characteristics, supplier characteristics, sod attributes, and buyer’s perceptions. </p> <p>Data for this study came from a 2021 web-based survey of sod buyers located in 19 states of the Northern US. A total of 200 buyers completed the survey, including landscape contractors, golf courses, general contractors, lawn care services, and landscape maintenance firms who have purchased sod in 2020. The significant mean comparisons between adopters and non-adopters showed that adopters of low-input turfgrasses purchased most of their sod through contract agreements. The main suppliers of adopters were located at a closer distance to on-site delivery than the non-adopters. The logit regression results showed that low-input turfgrass adoption was positively influenced by the number of sod suppliers and managerial experience of the sod buyer. Landscapers were more likely to purchase tall fescue and fine fescue compared to golf courses and municipal parks. We found that distance from sod supplier to on-site delivery negatively impacted the purchase of low-input turfgrasses. Similarly, Kentucky bluegrass buyers were less likely to purchase low-input turfgrass species.</p>

Animal welfare is a major concern among livestock producers in the U.S. Heat stress, particularly, compromises animal welfare and productivity, causing >$2B annual economic loss to producers. The presence of toxic alkaloids within tall fescue (Schedonorus phoenix syn Lolium arundinaceum, syn Festuca arundinacea) plants induces a complex of disorders collectively known as fescue toxicosis. Summer slump, a reduction in animal performance due to heat stress, is common and evident of the symptoms. Various techniques for assessing animal physiological and behavioral responses to heat stress were explored in this dissertation, with particular emphasis on fescue toxicosis and its mitigation strategies. In the first study, the physiological and behavioral responses of heifers was evaluated when grazing either toxic tall fescue with wildtype endophyte (WE) or tall fescue with a novel endophyte (NE). Heifers (n = 24) were assigned to either WE or NE pastures for a 56-d grazing study during the summers of 2020 and 2021. Heifer average daily gain (ADG), intravaginal temperature, and degree of hair shedding were recorded during the grazing period. Blood samples were collected through coccygeal venipuncture and hair was collected from the left rump for cortisol analysis. Ear, tail, and hoof temperatures were collected for each heifer using an infrared thermal imaging camera. In 2020, heifers that grazed NE tall fescue had greater (P = 0.0160) ADG over the season (0.22 vs. 0.12 kg day-1). Hair retention score was greater (P = 0.0029) for heifers that grazed WE tall fescue compared to heifers that grazed NE tall fescue across both years. Heifers that grazed WE tall fescue had decreased ear skin temperature (P = 0.0001), tail skin temperature (P = 0.0058), and hoof surface temperature (P = 0.0075) compared to heifers that grazed NE. Heifers that grazed WE had 0.3-0.9 ºC hotter intravaginal temperatures than heifers that grazed NE, especially during daytime. Hair cortisol levels of heifers that grazed WE tall fescue were greater (P < 0.0001) compared to hair cortisol levels of heifers that grazed NE tall fescue. From 1200h-1700h each day, heifers that grazed WE tall fescue spent 1.5 more (P = 0.0003) hours standing and 0.9 fewer (P = 0.0402) hours lying down compared to heifers that grazed NE tall fescue. These results suggest that heat stress and other physiological changes in heifers grazing WE tall fescue could be mitigated by renovating pastures with NE tall fescue that does not impose any negative effects on grazing animals. The second study explored the potential benefits of consuming condensed tannins as a means of negating the effects of toxic alkaloids in tall fescue. Twelve fall-born steers were assigned to one of the two diet supplement treatments - sericea lespedeza pellets (LES) or sericea lespedeza pellets mixed with polyethylene glycol (LES+PEG) for 12 weeks during the summers of 2020 and 2021. The LES+PEG treatment served as a positive control since polyethylene glycol binds tannins, rendering them inactive in the gastrointestinal system. Animal body weight (BW), hair retention score (HRS), rectal temperature, and thermographic images were collected every 4 weeks. Hair and blood samples were also collected for cortisol analysis. Fecal and urine samples were collected and analyzed for total ergot alkaloid (TEA) concentration. Steers on LES had greater (P = 0.0033) ADG compared to steers on LES+PEG in 2021, but not in 2020 (P = 0.8707). In 2021, HRS was greater (P < 0.05) for steers fed LES+PEG compared to steers fed LES. In 2020, ear skin temperature (P < 0.0001) and hoof surface temperature (P = 0.0382) was greater in steers on LES compared to steers on LES+PEG. Rectal temperatures were lower (P = 0.02905) for steers fed LES compared to steers fed LES+PEG in 2021. Plasma cortisol levels did not differ (P ≥ 0.1566) between LES and LES+PEG treatments for both years. In 2020, hair cortisol levels did not differ (P = 0.8295) between treatments while in 2021, the hair cortisol level of steers on LES+PEG was greater (P = 0.0221) compared to hair cortisol levels of steers on LES. This study indicated some changes in animal physiology in response to dietary supplements containing condensed tannins, but results were inconsistent and further studies are needed to better understand the potential benefits of tannins in reducing the effects of toxic alkaloids consumption. In the third study, behavioral and physiological responses of ewes that grazed either mid-stage hardwood silvopastures or open pasture (OP) were compared. The study site consists of 0.27-ha of black walnut (Juglans nigra; BSP) and honeylocust (Gleditsia triacanthos; HSP) silvopastures and open pasture treatments, each replicated three times. During the summers of 2020 and 2021, thirty-six Katahdin ewes were assigned to one of the treatments for a 6-week summer grazing trial. Ewe weights were recorded for two consecutive days at the beginning and end of the study and intravaginal temperatures were recorded for two consecutive days at every 3-week intervals. Trail cameras captured animal behavior. Blood was collected via jugular venipuncture. Hair grown during the trial was collected from the loin region. Blood and hair cortisol concentrations were determined by ELISA. Ewe ADG was greater in HSP compared to OP (P = 0.0456) but did not differ with BSP (P = 0.4686) across both years. Ewes on OP had hotter (P ≤ 0.0343) intravaginal temperatures than ewes on both silvopasture treatments between 1100h-1700h. Plasma cortisol level was lower in ewes on BSP compared to ewes on OP (P = 0.0400) but did not differ with ewes on HSP (P = 0.6954) across both years. Ewes that grazed OP had greater hair cortisol levels compared to ewes on silvopasture treatments both in 2020 and 2021 (P < 0.0001). In 2020, ewes on BSP spent about 20% more time grazing than ewes on OP (P = 0.0054) while in 2021 ewes on BSP spent about 36% more time grazing than ewes on HSP (P = 0.0014). Ewes on OP spent 400% more time standing than ewes on BSP (P < 0.0001) and 750% more time standing than ewes on HSP (P < 0.0001). Ewe on OP spent 20% less time lying down compared to ewes on BSP (P < 0.0001) and 33% less time lying down compared to ewes on HSP (P < 0.0001). Hair cortisol measures and intravaginal temperature sensors can be utilized as reliable and relatively non-invasive techniques for measuring heat stress response in livestock managed in extensive grazing systems. / Doctor of Philosophy / Heat stress compromises animal welfare and productivity, causing > $2B annual economic loss to producers in the U.S. In the southeastern U.S, heat stress in livestock is largely due both to an environmental condition and to the effect of fescue toxicosis caused by toxic alkaloids. Various management strategies to mitigate the effect of heat stress in livestock due to environmental conditions or due to the effect of tall fescue toxicosis are explored in this dissertation. In the first study, behavioral and physiological responses of heifers that grazed either toxic (WE) or novel (NE) endophyte-infected tall fescue was compared. Heifers that grazed WE tall fescue had lower gains, rough hair coat, higher hair cortisol level (stress measure), cooler extremity temperature, and hotter intravaginal temperature compared to heifers that grazed NE tall fescue. These results suggest that heat stress and other physiological changes in heifers grazing WE tall fescue could be mitigated by renovating pastures with NE tall fescue, a forage cultivar that does not impose any negative physiological effects on grazing animals. In the second study, we tested the effect of condensed tannins in reducing the severity of fescue toxicosis in steers. We fed sericea lespedeza pellets to steers in a study to test this effect. All steers were fed sericea pellets, but pellets for half (6) of the steers were treated with polyethylene glycol, which inactivates the condensed tannins in the sericea lespedeza. In our study, we found that the steers fed the sericea lespedeza had higher temperatures at their extremities (ears and tail), but lower rectal temperatures than the control steers. Interestingly, the steers fed the sericea lespedeza pellets also had slicker hair coats and lower levels of hair cortisol (indicating reduced stress) in the second year compared to the control steers. This study showed some potential of condensed tannins in reducing the effects of fescue toxicosis, but needs further study to better understand the potential benefits of tannins in reducing the post-ingestive effects of fescue toxicosis. In the third study, we compared behavioral and physiological (temperature, hair, and blood cortisol) responses of ewes that grazed either mid-stage hardwood silvopastures or open pastures (OP). Ewes on OP showed signs of heat stress with higher hair cortisol levels and hotter intravaginal temperatures during the daytime compared to ewes on silvopasture treatments. Ewes on OP spent 400% more time standing compared to ewes on BSP and 750% more time standing than ewes on HSP. Ewe on OP spent 20% less time lying down compared to ewes on BSP and 33% less time lying down compared to ewes on HSP. Ewes on silvopasture treatments spent 70% less time drinking water compared to ewes on OP. Trees within the silvopasture systems can alter the micro climatic condition thus creating a suitable environment for livestock. This can ultimately reduce stress and improve overall behavioral and physiological responses of livestock in silvopastures compared to open pastures.

’Kentucky 31’ endophyte-free tall fescue fertilized with 160 kg N ha⁻¹yr⁻¹ was compared to similar fescue grown with ’Cimarron’ alfalfa in a randomized block pasture experiment with four replications. Quality and yield of stockpiled forages and performance and serum minerals of grazing steers were investigated during 1991-92 and 1992-93. Effects of grazing and timing of initiation of stockpiling forages were investigated during autumn of 1992. Rate and extent of release of Ca, Mg, P, S, Cu, and Fe from stockpiled forages were determined in a dacron bag study in 1992-93. In 1991-92, stockpiled N-fertilized fescue improved steer performance over stockpiled fescue-alfalfa (P<0.05); in 1992-93, this result was reversed (P<0.05) due to forage availability. Blood urea nitrogen was higher (P<0.07) and serum Ca and S were higher (P<0.05) in steers which grazed stockpiled fescue-alfalfa. September stockpiling of fescue-alfalfa improved botanical composition, yield, and forage quality, compared to August stockpiling. September stockpiling of N-fertilized fescue improved quality but lowered yield, compared to August stockpiling. Fescue-alfalfa had higher (P<0.05) yield and improved botanical composition when grazing occurred. Nitrogen- fertilized fescue had higher (P<0.05) yield when mechanically harvested. Alfalfa released P, Ca, Mg, S, and Fe to a greater extent and rate than either type of fescue at 24 h and P, Mg, S, and Fe at 72 h (P<0.05). Fescue grown with alfalfa released S to a greater extent and rate than N-fertilized fescue, Fescue-alfalfa produces animal performance as good or better than N-fertilized tall fescue, while eliminating need for N-fertilization. / Master of Science

In Virginia, tall fescue [(Schedonorus phoenix (Scop.) Holub,) formally known as Festuca arundinacea L.] can be found on more than 4 million ac of hay and pastureland. Two separate experiments were conducted at three different geographical locations over two growing seasons. The objective of Experiment 1 was to evaluate the influence of N sources and rates on yield and nutritive value of stockpiled tall fescue. Experiment 2 examined the effect of split spring and fall N applications at various rates on yield and nutritive value of tall fescue pastures. The first experiment was conducted at three locations (Blacksburg, Blackstone, and Steeles Tavern, VA) while the second experiment was conducted only at the Blacksburg and Steeles Tavern locations. In Experiment 1, the N sources included ammonium nitrate, ammonium sulfate, urea, urea + Agrotain®, Environmentally Smart N® (ESN), Nutrisphere (NSN), Nitamin® (Blackstone only), pelleted biosolids (Blackstone only), and broiler litter (Steeles Tavern only) applied at 0, 28, 56, 84, and 112 kg plant available N (PAN) ha-1. Plots were harvested in mid-December (Blacksburg and Steeles Tavern) and late January (Blackstone). The yield of the stockpiled tall fescue in 2006 ranged from 1,300 to 2,900, 1,700 to 3,000, and 2,600 to 3,300 kg DM ha-1 for the Blacksburg, Steeles Tavern and Blackstone locations, respectively. In 2007, however, the yield response to N rate and sources was significantly less than that of 2006 due to low rainfall. At the Blacksburg location, ammonium sulfate and ESN resulted in higher CP concentrations, ranging from 11-14% and 12-20% for 2006 and 2007 growing seasons, respectively. Similar variation (12-20%) was observed for the Steeles Tavern location in 2006. In general, the ADF and NDF content decreased as N rate increased from 0-112 kg ha1. Although the source and rate that resulted in high yield and nutritive value varied across location and years, N rates and sources improved the quality and yield of stockpiled fescue. Experiment 2 utilized urea which was applied in the fall at the rates of 0, 45, 90 or 135 kg N ha-1. followed by spring application of 0, 45, 90 or 135 kg N ha-1. A total of 16 treatment combinations per replication were used. Yields ranged from 1,900 to 3,600 kg DM ha-1 and 700 to 2,500 kg DM ha-1 in 2007 and 2008, respectively. At the Steeles Tavern location, yields ranged from 3,100 to 5,700 kg DM ha-1 and 2,500 to 5,100 kg DM ha-1, in 2007 and 2008, respectively. In both years CP increased with increasing N fertilization. On a dry matter basis, CP values ranged from 14 to 23% for both years. Treatments did not affect on NDF and ADF values. Split fall/spring N applications did not maximize yield of cool-season grass pastures in these experiments. / Master of Science

Demands are placed on cattle producers to provide a steady supply of beef at a competitive price. Producers must maximize beef output while minimizing input expenses without compromising product quality. The use of growth implants has become a common practice among cattle producers. The objective of this study was to evaluate the effects of two implant strategies on the average daily gain of suckling calves rotationally grazed on Kentucky – 31 endophyte-infected tall fescue and Kentucky – 31 non-endophyte-infected tall fescue. Eighteen cows with spring calves (N = 18) were used in this study. Calves were grouped by birth date into four blocks. Within each block, calves were stratified by sex and 45d of age body weight into three implant treatment groups for a total of six calves per treatment (n = 6, control 90.3 ± 9.7 kg, zeranol 102.9 ± 10.9 kg, and progesterone (100 mg) and estradiol benzoate (10 mg) 92.4 ± 10.3 kg). Calves were weighed and re-implanted at 129 d of age (84 d after initial implant). Zeranol treated calves were re-implanted using the same implant as the initial implant. Progesterone and estradiol benzoate treated calves were re-implanted after reaching a minimum body weight of 181 kg with either 200 mg progesterone and 20 mg estradiol benzoate or 200 mg testosterone propionate and 20 mg estradiol benzoate depending on sex. Data were analyzed using the REPEATED function in the MIXED procedure of SAS. No interactions were found among sex and treatments for 84d weight gains and 140d weights. There were also no main effects found for 84d weight gains and 140d weight gains. Forage analysis suggested that low crude protein and energy content may have contributed to the low ADG. Low endophyte concentrations may also have played a role.