Comparing Morphological Development and Nutritive Value of Caucasian Old World Bluestem and Native Grasses

Caucasian old world bluestem (OWB) [Bothriochloa bladhii (Retz) S.T. Blake] has been introduced in the southern and central USA for conservation and forage production. It has escaped into some native rangelands, and observations indicate that it is usually avoided by grazing animals. Caucasian OWB matures at a greater rate than some native grasses, and maturity was speculated as being a factor for poor forage quality and avoidance by grazing animals when found in mixed stands with native grasses. This study was conducted to examine if forage quality and morphology of Caucasian OWB and native perennial warm-season grass species differs. Caucasian OWB, big bluestem (Andropogon gerardii Vitman), little bluestem [Schizachyrium scoparium (Michx.) Nash], and sideoats grama [Bouteloua curtipendula (Michx.) Torr] were hand clipped at approximately 3-week intervals each growing season in 2004 and 2005. Caucasian OWB morphologically developed at a greater rate than the native species. Caucasian OWB had equal or greater crude protein and in situ digestibility, and equal or lower neutral detergent fiber at each harvest compared to the native species, even though it was equal or more morphologically developed at each harvest. Avoidance of Caucasian OWB that has invaded native rangelands may be related to other factors that are not tested by standard forage quality analyses.