YIELD AND QUALITY OF WW-IRON MASTER AND CAUCASIAN BLUESTEM REGROWTH

Old World bluestems (Bothriochloa spp.) have been seeded on over a mil lion hectares of marginal farmland in Oklahoma and Texas, yet we know little about their regrowth yield and quality, The objective was to de termine seasonal pattern of forage regrowth yield and quality of leave s and stems of WW-Iron Master (B. ischaemum [L.] Keng) and Caucasian ( B. caucasica [Trin.] C.E. Hubb,) bluestem when 4-week regrowth was har vested at weekly intervals from early May through mid-September, Four plots of each bluestem were established in each of the 4 blocks (32 pl ots total). Harvesting was rotated so that 4-week regrowth of each blu estem was harvested weekly from 1 of the 4 plots in each block during 1988 and 1989 to determine regrowth yield, in vitro dry matter digesti bility (IVDMD), and crude protein (CP) of leaves and stems, Forage reg rowth of both species peaked in June both years, Regrowth during Augus t averaged 10 and 35% of June regrowth in 1988 and 1989, WW-Iron Maste r produced 80 and 45% greater 4-week regrowth than Caucasian in 1988 a nd 1989. WW-Iron Master produced 75 and 28% greater leaf regrowth than Caucasian in 1988 and 1989 and twice as many stems both years, Leaf a nd stem IVDMD of WW-Iron Master averaged 2 to 6 percentage units highe r than Caucasian, Leaf CP of WW-Iron Master averaged 2 percentage unit s higher than Caucasian during May and June, However, stem CP of WW-Ir on Master averaged 1 percentage unit lower than Caucasian. Grazing man agement plans need to consider that the majority of bluestem forage pr oduction was restricted to a 1 month period in June. This technique of sampling 4-week regrowth every week during the growing season was an effective method for determining the seasonal regrowth pattern.