• Chemical composition of old world bluestem grasses as affected by cultivar and maturity

      Dabo, S. M.; Taliaferro, C. M.; Coleman, S. W.; Horn, F. P.; Claypool, P. L. (Society for Range Management, 1988-01-01)
      Old world bluestem (OWB) grasses (Bothriochloa spp.) have been used for herbage in the southern Great Plains for over 60 years, but release of new, well-adapted cultivars has led to a dramatic increase in use of these grasses in Oklahoma and adjacent areas during the last 15 years. Little information is available on the chemical composition of OWB grasses. The purpose of this study was to obtain information on the chemical composition of OWB grasses as affected by cultivar and maturation. Forage samples for chemical analyses were obtained from a 2-year field experiment conducted on a Kirkland silt loam soil (Udertic Paleustoll). Ten harvest dates (1-week interval between harvests) and 3 plant parts (whole plant, leaf, and stem) were imposed by split-split plot arrangement on established stands of 'Caucasian', 'Ganada', 'Plains', and 'WW-Spar' bluestem. Responses of variables were neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and crude protein (CP). Concentrations of NDF, ADF, and ADL increased in whole plant and stem samples during the 10-week sampling periods of both years. Quadratic equations best described changes in ADF during both years and in NDF and ADL in 1983, whereas linear equations best fitted changes in NDF and ADL in 1982. Concentration of NDF in leaves changed very little with maturation, but its change in whole plant and stems paralleled that described for ADF and ADL. Concentrations of CP decreased in all plant parts through harvest date eight (11-week old growth), with the changes best described by quadratic equations. Changes in all constituents were less affected by advancing maturity in leaves than in stems. Maturity had a much greater effect on concentration of all the chemical constituents than did cultivar. Initial concentrations of NDF in all plant parts exceeded the level (ca 600 g kg-1) at which intake would likely be affected. Concentrations of CP also declined to levels by the 5th to 6th harvest dates, particularly in whole plant and stem parts, insufficient to supply daily requirements for most classes of mature beef cattle. The results point to the need to maintain and utilize these grasses to the extent possible in a juvenile, actively growing state to provide nutrition for growing livestock.
    • Yield and Digestibility of Old World Bluestem Grasses as Affected by Cultivar, Plant Part, and Maturity

      Dabo, S. M.; Taliaferro, C. M.; Coleman, S. W.; Horn, F. P.; Claypool, P. L. (Society for Range Management, 1987-01-01)
      Old World bluestems (Bothriochloa spp.) have been used in the U.S. for over 60 years but few data are available on effects of management or cultivar differences for forage yield and quality. Field experiments were conducted on a Kirkland silt loam (Uderic Paleustoll) soil for 2 years (1982-83), in order to assess the yield and quality of 4 such cultivars as affected by maturation and plant part. The experimental design was a split-split plot, in a randomized complete block, with 4 replications, 4 cultivars ('Caucasian', 'Ganada', 'Plains', 'WW Spar'), 10 harvest dates, and 3 plant parts (whole plant, stem, and leaf). Cultivars were main plots; harvest dates and plant parts were sub and sub-sub plots, respectively. Response variables were dry matter yield (DMY), in vitro dry matter disappearance (IVDMD), leaf to stem ratio (L/S), and in vitro digestible dry matter yield (IVDDMY). Ganada consistently had the lowest leaf, stem, and whole plant DMY and IVDDMY. Caucasian had higher leaf, stem, and whole plant DMY and IVDDMY than Plains and WW-Spar in 1983, but the DMY and IVDDMY of these cultivars were similar in 1982. Quadratic and linear equations were satisfactorily fit to the DMY and IVDDMY data in 1982 and 1983, respectively. The IVDMD in whole plant samples decreased at average rates of 4.2 and $5.5 g kg ha-1 daily in 1982 and 1983, respectively, during harvest week one. Among cultivars, Caucasian had the highest rate of decline and Ganada the lowest. The decline was quadratic in nature and faster in stem fractions. Cultivar IVDMD differences were consistent over plant parts. Ganada and Caucasian had the highest and lowest IVDMD concentrations, respectively. Plains and WW-Spar had IVDMD values of similar magnitude and intermediate to those of Ganada and Caucasian. Cultivar leaf to stem ratios were similar in 1982 but different in 1983 with Plains and Caucasian having higher L/S ratios than Ganada and WW-Spar. For these cultivars leafiness was a poor indicator of digestibility.