Switchgrass (Panicum virgatum L.) may have value as forage and a bioenergy feedstock. Our objective was to evaluate how harvest system and N fertilizer rates affected biomass yield and nutrient composition of young stands of switchgrass (cv. Alamo) in the southern Great Plains, USA. Nitrogen fertilization increased biomass yields from 10.4, 10.8, and 12.2 Mg ha −1 at 0 kg Nha −1 to 13.7, 14.6, and 21.0 Mg ha −1 at 225 kg Nha −1 when harvested after seed set (October), after frost (December), and twice per year after boot stage (July) and frost, respectively. Nutrient concentrations and removal were generally twice as great when biomass was harvested twice versus once per year. Precipitation strongly affected biomass yields across the two years of these experiments. When late-summer precipitation is available to support regrowth in this environment, harvesting switchgrass twice per year will result in greater biomass yields. Harvesting twice per year, however, will increase fertilization requirements and reduce feedstock biomass quality. Switchgrass harvested during mid-summer after boot stage was of poor forage quality. To have value as a dual-purpose forage and bioenergy feedstock, switchgrass would need to be utilized during spring to early summer while in a vegetative stage.

Switchgrass (Panicum virgatum L.) produced for bioenergy is expected to compete with land resources used for stocker cattle (Bos taurus) grazing in the southern Great Plains. The objective was to determine the effect of stocking rate on animal performance, biomass yield, and quality. Three stocking rates (light [2.5 steers ha–1], moderate [4.9 steers ha–1], and heavy [7.4 steers ha–1]) and an ungrazed control were randomly assigned to twelve 0.81‐ha paddocks in 2008, 2009, and 2010. Animal and biomass responses were analyzed using mixed ANOVA models. Average daily gain (P = 0.05) was 0.83, 1.04 and 1.05 kg head (hd)–1 for the light, moderate and heavy stocking rates, respectively. Grazing duration was affected (P < 0.001) by stocking rate treatment, realizing 81, 43, and 28 d of grazing, respectively. Steer grazing days were not different (P = 0.22) between stocking rates treatments, producing 81, 86, and 84 d ha–1, respectively. Total gain by treatment were 167, 215, and 199 kg ha–1, respectively, and were different (P = 0.04). The ungrazed control produced more (P < 0.001) harvested biomass at the end of the growing season (15.3 Mg ha–1) compared to the grazed treatments (10.6, 8.1, and 7.8 Mg ha–1, respectively). Forage quality decreased (P < 0.05) throughout the growing season for all treatments. Results indicate switchgrass has the potential to extend the cool‐season grazing season in the region while also allowing for the production of an annual supply of bioenergy feedstock for conversion into biofuel.

Results suggested that vaccination of beef calves with a 5-antigen modified-live virus vaccine at 67 and 190 days of age was as effective in terms of immunologic responses as was vaccination at 167 and 190 days of age.

Use of cool‐season perennial grasses may decrease annual establishment cost and improve returns to stocker cattle producers. The objective of this 5‐yr field study was to compare the performance of two stocker cattle grazing forage systems: cool‐season annual (rye [Secale cereale L.]–annual ryegrass [Lolium multiflorum Lam.]) vs. cool‐season perennial tall fescue [Schedonorus arundinaceus (Schreb.) Dumort; formerly Festuca arundinacea Schreb., ‘Texoma’], with a nontoxic endophyte (MaxQ II). Paddocks of four replicates consisted of a cereal rye and annual ryegrass mixture that was planted annually in early September 2005 through 2009, whereas tall fescue was planted once in late September 2005. Steers (273 ± 55 kg initial body weight) were weighed every 28 d of each grazing season, and stocking rates were adjusted with put‐and‐take steers based on forage mass. In each 28‐d grazing period, forage mass, forage nutritive value, and stocker average daily gain (ADG) and total gain (TG) were measured. Animals performed well in both systems with ADG of 1.05 and 0.93 kg d−1, and TG of 491 and 349 kg ha−1 for rye–annual ryegrass and tall fescue, respectively. The 5‐yr average annual production cost was less for the tall fescue system ($336 ha−1) than for the rye–annual ryegrass system ($455 ha−1). The assumed amortization of the tall fescue was especially influential on net return; with a 5‐yr amortization, net return was greater for the rye–annual ryegrass ($279 ha−1) than for the tall fescue ($217 ha−1) system, but with 12‐yr amortization, the net return of these two systems was identical.

No abstract