ABSTRACTNative North American warm‐season bunchgrasses have the potential to provide both forage and cellulosic bioenergy in drier regions of the southern Great Plains. Almost no information is available on the potential accumulations of many of these species under forage, bioenergy, or combined system harvests. Multiflower false rhodesgrass (MFR; Chloris pluriflora Fourn.), pink pappusgrass (PPG; Pappophorum bicolor Fourn.), shortspike windmill grass (SSWG; Chloris × subdolichostachya Müll. Berol. (pro sp.) [cucullata × verticillata]), and plains bristlegrass (PBG; Setaria vulpiseta Scribn. and Merr.) were harvested during 4 yr at Stephenville, TX, USA. Seedlings were transplanted into a Windthorst sandy loam soil fertilized in Year 1 with 0 or 67 kg N and P ha−1 yr−1 plus 67 kg N ha−1 yr−1 in the spring of Years 2 to 4. Fertilizer improved N and dry matter (DM) accumulations (P ≤ 0.05) except for SSWG and improved (P ≤ 0.05) accumulations of October regrowth following July harvest in greater rainfall years. Multiflower false rhodesgrass produced greater (P ≤ 0.05) accumulation the first year (up to 4.38 Mg ha−1) while PPG had the most consistent accumulation across years with variable precipitation. Results indicate that MFR and PPG bunchgrasses native to the North American Great Plains have potential for bioenergy or forage and bioenergy production systems.

The Penn State particle separator (PSPS) was used to determine if molasses can reduce sorting of ground juniper when juniper is used as a feed intake limiter for lambs. Rambouillet wether lambs (n=21) were fed ad libitum treatments in the morning that consisted of coarse-ground juniper material, dried distillers grains with solubles (DDGS), and either no water or molasses (CNTL; 50:50:0), water (WAT; 45:45:10), or a 50:50 water:cane molasses solution (MOL; 45:45:10); lambs were fed an ad libitum basal pelleted diet in the afternoon. Lamb body weight, average daily gain, basal diet and total dry matter intake (DMI), and gain to feed efficiency were similar (P>0.17) among treatments, but DMI of MOL was greater than CNTL (P<0.09). Particle size distributions of each treatment and feed refusals were determined by the PSPS, which contains a series of 3 sieves and a solid bottom pan. Treatment×sieve interactions (P<0.001) were observed for g/kg of dry matter (DM) under and retained on sieves and for neutral detergent fiber (aNDF) expressed as g/kg of total DM. The WAT and MOL had less (P<0.001) DM under and greater (P<0.001) DM retained on the 8.0- and 1.18-mm sieves than CNTL, suggesting that molasses adhered to small and large juniper particles and DDGS. When material >19.0mm was excluded from calculations, geometric mean length and standard deviation decreased for all treatments, but CNTL still had less (P<0.001) geometric mean length than WAT or MOL and MOL had less material in the bottom pan (<1.18mm; P<0.001) than WAT. For treatment refusals, treatment×sieve interactions (P<0.04) were observed for g/kg of DM under and retained on sieves, but g/kg of DM under and retained on the 19.0- and 8.0-mm sieves were similar (P>0.10) among treatments. The CNTL and MOL had greater (P<0.001) DM under the 1.18-mm sieve (bottom pan) as compared to WAT, suggesting that lambs sorted WAT more than CNTL or MOL. However, chemical composition of treatment refusals suggested that lambs sorted the treatments at similar extents. The PSPS was effective in determining particle size distribution of diets and feed refusals containing coarse-ground woody forage material. Removing coarse-ground juniper material greater than 19-mm from the treatments does not currently seem warranted, but should be considered if it is going to be ground finer and included in non-agglomerated or pelleted diets that reduce or eliminate sorting, respectively.

ABSTRACTNative warm‐season grasses have the potential to provide summer grazing because of their adaptation and persistence. Little nutritive value information is available, however, on the effects of maturity and soil amendments for native North American warm‐season grasses during establishment. Multiflower false rhodesgrass (Chloris pluriflora E. Fourn.), pink pappusgrass (Pappophorum bicolor E. Fourn.), and plains bristlegrass [Setaria vulpiseta (Lam.) Roem. & Schult.] were harvested monthly during the first 2 yr after establishment on a Windthorst sandy loam soil and fertilized with 0 or 67 kg N and P ha−1 yr−1 Spring application of fertilizer resulted in early season herbage N concentrations 58 to 79% greater (p ≤ 0.10) than unfertilized herbage and maintained N concentrations (p ≤ 0.10) above the 11.2 g kg−1 considered minimum for cattle maintenance through September for most entries. Multiflower false rhodesgrass had the least (p ≤ 0.10) fiber and greatest N and in vitro organic matter disappearance (IVOMD). During Year 1 and early in Year 2, IVOMD was sometimes greater (p ≤ 0.10) when goat rumen liquid was used compared to steer liquid. This relationship was nullified or even reversed as plants matured in Year 2, indicating that donor species of rumen liquid should be considered when interpreting IVOMD results for native warm‐season grasses.

Anthelmintic effects of plant secondary compounds may be occurring in the rumen, but in vitro larvae migration inhibition (LMI) methods using rumen fluid and forage material have not been widely used. Forage material added to an in vitro system can affect rumen pH, ammonia N, and volatile fatty acids, which may affect larvae viability (LV). Validating a LMI assay using rumen fluid and a known anthelmintic drug (Ivermectin) and a known anthelmintic plant extract (Quebracho tannins; QT) is important. Rumen fluid was collected and pooled from 3 goats, mixed with buffer solution and a treatment (1 jar/treatment), and placed into an anaerobic incubator for 16 h. Ensheathed larvae (<3 months old) were then anaerobically incubated with treatment rumen fluid for 2, 4, or 16 h depending on the trial. Larvae (n = 15–45) were then transferred onto a screen (n = 4–6 wells/treatment) within a multi-screen 96-well plate that contained treatment rumen fluid. Larvae were incubated overnight and those that passed through the 20-μm screen were considered viable. Adding dry or fresh juniper material reduced (P < 0.05) pH, ammonia N, and isobutyric, butyric, isovaleric, and valeric acids, and increased (P < 0.001) acetic, propionic, and total VFA. Including 4.5% (w/v) polyethylene glycol (PEG) in rumen fluid mixture with or without forage material reduced (P < 0.01) LV. However, LV was similar at all PEG concentrations tested (0–2%, w/v; 89.4, 78.9, 76.5, 75.5, and 77.5% viable). Q. tannin concentrations from 0 to 1.2% (w/v) quadratically reduced (P < 0.001) LV; 89.4, 65.5, 22.8, and 9.2%. Ivermectin concentrations from 0 to 15 μg/mL quadratically reduced (P < 0.001) LV; 90.2, 82.6, 73.6, 66.3, 51.9, 56.5, 43.5, 41.9, 29.3, and 19.9% viable, respectively. Effects of altering in vitro rumen fluid pH, ammonia N, and VFA and using PEG when evaluating LV need to be further investigated. In vitro rumen fluid assays using QT and Ivermectin resulted in decreased LV, validating the efficacy of this technique for measuring Haemonchus contortus larval viability.