In situ ruminal kinetics of DM and NDF disappearance for the biomass forages Amur silvergrass and big bluestem

Authors: ROBINETTE, J - Morehead State University; WILLIAMSON, B - University Of Arkansas; FLORES, R - University Arkansas For Medical Sciences (UAMS); Woolley, James - Brent; BAILEY, C - University Of Tennessee; THAREL, L - Natural Resources Conservation Service (NRCS, USDA); KING, J - Natural Resources Conservation Service (NRCS, USDA); Burner, David; CARVER, P - Bical; Coblentz, Wayne; WISTUBA, T - Morehead State University; ROSENKRANS, C - University Of Arkansas; Looper, Michael

Submitted to: Arkansas Agricultural Experiment Station Special Reports
Publication Type: Experiment Station
Publication Acceptance Date: 7/31/2010
Publication Date: 12/15/2010
Citation: Robinette, J.A., Williamson, B.C., Flores, R., Woolley, J.B., Bailey, C.R., Tharel, L.M., King, J.R., Burner, D.M., Carver, P., Coblentz, W.K., Wistuba, T.J., Rosenkrans, C.F., Looper, M.L. 2010. In situ ruminal kinetics of DM and NDF disappearance for the biomass forages Amur silvergrass and big bluestem. Arkansas Agricultural Experiment Station Special Reports. December 2010. Research Series 584.

Interpretive Summary: Alternative strategies need to be determined that minimize economic risk associated with biomass production to small farms. Minimal research is available that describes the nutritive value of many bioforages. Researchers University of Arkansas, Fayetteville and Little Rock; Morehead State University; University of Tennessee, Martin; USDA-NRCS, Booneville; and USDA-ARS, Booneville, AR; and Marshfield, WI used four ruminally-cannulated steers to determine disappearance of dry matter and fiber for Amur silvergrass (AS) and ‘Hampton’ big bluestem (BB). Crude protein was similar between the two forages; however, fiber was greater for AS than BB. Amount of dry matter and fiber readily available to the animal was greater in AS compared to BB. It appears that AS has adequate nutritive value during the early summer, and livestock grazing of AS could be an alternative to biomass production. This information is important to agronomists, animal scientists, extension personnel, and small farm producers.

Technical Abstract: Alternative strategies, such as grazing, could minimize economic risk associated with biomass production. Minimal research is available that describes the nutritive value of biomass forages, specifically Amur silvergrass (AS; Miscanthus sacchariflorus (Maxim.) Benth., proprietary clone Msanag). Four ruminally-cannulated steers were used to determine ruminal in situ disappearance kinetics of DM and NDF for AS and ‘Hampton’ big bluestem (BB; Andropogon gerardii Vitman) harvested at vegetative growth stage on three dates (4 June, 8 July, and 31 July) in west-central Arkansas. Crude protein was greater (P < 0.01) on 4 June (13.0 ± 0.3%) than either 8 July (9.5 ± 0.3%) or 31 July (9.5 ± 0.3%) for both forages, and similar (P = 0.84) for forage type across sampling dates. Neutral detergent fiber was greater (P = 0.03) for AS (72.8 ± 0.8%) compared to BB (69.3 ± 0.8%). Effective DM degradability was greatest for BB on 8 July (56.5 ± 4.2%) and 4 June (55.6 ± 4.2%) sampling dates and least for AS on all three sampling dates (mean = 39.1 ± 4.2%). Within sampling date, rate (Kd) of DM disappearance (/h) was slower (P < 0.02) for AS than BB on 4 June (0.039 vs. 0.056 ± 0.001/h) and 8 July (0.033 vs. 0.048 ± 0.001/h), but similar between forages on 31 July (0.038 vs. 0.035 ± 0.001/h). Effective NDF degradability was greater (P < 0.01) for BB (42.5 ± 4.7%) than AS (28.9 ± 4.7%). As observed for disappearance of DM, Kd for NDF disappearance was slower (P < 0.02) for AS (0.041 ± 0.01/h) than BB (0.050 ± 0.01/h). It appears that AS has adequate nutritive value during the early summer, and livestock grazing of AS could be an alternative to biomass production.