This 2-yr experiment evaluated productivity of wild-type, endophyte-infected tall fescue (E+) and novel endophyte-infected tall fescue (NE) summer stockpiled (SS) pastures and the performance of fall-calving beef cow/calf pairs stocked on each cultivar. Fescue cultivars used were KY-31 and MaxQ for E+ and NE treatments, respectively. Pregnant Simmental x Angus cows (128 total, 64 each yr) were stratified by BW, BCS, and expected calving date and then allotted to 1 of 10 pasture groups within each yr (20 groups total, 10 per treatment). Forage growth was stockpiled from April until the initiation of strip-grazing on August 31 of 2017 and 2018. Cows grazed treatment pastures for 52 d from 23 ± 14 d prepartum to 29 ± 14 d postpartum, and calved on treatment pastures. Forage quadrats were clipped from the grazed and ungrazed portions of each pasture to determine weekly forage mass. Total ergot alkaloid (TEA) concentrations were analyzed for all pastures at the beginning of the experiment and every subsequent 2 wk for E+ tall fescue. Cow BW was recorded on 2 consecutive d and BCS determined at the start and end of the experiment. In yr 2, ultrasound 12th rib fat thickness (FT) was measured at the beginning and end of the treatment period Milk production was estimated using the weigh-suckle-weigh technique at 29 ± 14 d postpartum. Initial TEA concentrations for NE (Yr. 1 = 112 µg/kg; Yr. 2 = 632 µg/kg) were decreased (P ≤ 0.01) compared to E+ (Yr. 1 = 1831 µg/kg; Yr. 2 = 2903 µg/kg). TEA concentrations for E+ pastures did not differ (P < 0.23) by sample date. However, average TEA concentrations were greater for yr 2 than yr 1(P ≤ 0.01). Fescue cultivars were not different (P ≥ 0.06) in forage CP, Ash, Ether Extract, and grazed or ungrazed forage mass. However, differences were observed (P ≤ 0.02) for ADF, NDF, and TDN by fescue cultivar. Cow BW, BCS, and FT at the beginning and end of grazing were not different (P ≥ 0.41) by treatment. Milk production was greater (P < 0.01) for cows grazed on E+. Calving date, calf BW, calf ADG were not different (P ≥ 0.65) by treatment. Neither AI nor overall conception rates differed (P ≥ 0.23) between cultivars. Performance of fall-calving cows pre-exposed to E+ was not hindered when grazed on E+ relative to NE in a SS system. / Master of Science / Wild-type, endophyte-infected tall fescue (E+) is the predominant forage of use for producers within the southeastern United States. Endophyte-infected tall fescue gained notoriety due to its drought and pest resistance as well as climate adaptability. These advantages are the result of a symbiotic relationship with an endophytic fungus that has been shown to decrease in animal performance through the production of toxic ergot alkaloids. Development of improved fescue cultivars provided producers with an alternative forage, known as novel endophyte-infected tall fescue (NE), that maintains the agronomic advantages noted with E+ fescue without negative impacts on animal gain and reproductive performance. In adopting NE tall fescue, producers are faced with the financial challenge of renovating existing stands of E+ with NE fescue; leaving pastures unusable during times of normal grazing behavior. This constraint has highlighted the need to explore forage utilization and strategies that can extend the grazing period that do not require the significant cost of total renovation with NE. Fall stockpiled tall fescue has provided producers an option to extend grazing from late November through February when pasture growth ceases and hay supplementation is normally needed. However, a 60 to 90 d period between summer and fall stockpiled grazing leaves producers looking for an additional strategy to provide standing forage for their herds. Summer stockpiling (SS), is a novel grazing strategy that bridges summer and fall stockpiled grazing through proper accumulation of 25 % of total pasture to help extend producers grazing season. The objective of the current experiment is to evaluate both E+ and NE SS pastures and its effect on animal performance, forage availability, and nutritive value. Cow BW and BCS were measured at the initiation, conclusion, and before artificial insemination. Calf BW and ADG were assessed 48 h post-calving and at weaning. Ungrazed and grazed forage mass was collected weekly, while measurements of ADF, NDF, CP, TDN, ether extract, and ash were measured every 2 weeks. After a 52 d treatment period, forage mass was similar across both cultivars, with ADF, NDF, and TDN favoring E+ tall fescue. Additionally, animal performance across both E+ and NE pastures were similar, however increased milk production was observed for cows grazed on E+. This experiment helps shed light on the concept of strategic renovation. Strategic renovation can be best utilized by producers who are interested in maximizing pasture utilization through rotationally grazing E+ and NE tall fescue pastures. By following this renovation strategy, proper allocation of NE tall fescue during times of enhanced ergotism and E+ tall fescue during low thresholds will develop a more specific rotation thus decreasing renovation costs for producers when ergotism is lowest.

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