EFFECTS OF INITIAL HARVEST DATE ON DRY MATTER YIELD, IN VITRO DRY MATTER DIGESTIBILITY AND PROTEIN IN TIMOTHY, TALL FESCUE, REED CANARYGRASS AND KENTUCKY BLUEGRASS

Abstract

Timothy, tall fescue, reed canarygrass and Kentucky bluegrass plots were harvested at weekly intervals from the vegetative stage through to seed maturity for 3 yr in order to evaluate the effect of harvest and species on nutrient production. The forage of the early harvest regimes was cut after 5 wk of regrowth and all plots were harvested in the fall. In vitro dry matter digestibility (IVDMD) values ranged from above 80% down to 45%, with an average rate of decrease during June of 0.74, 0.84, 0.85 and 0.45% per day in timothy, tall fescue, reed canarygrass and Kentucky bluegrass, respectively. Similarly, crude protein (CP) in first-cut forage ranged from 28% to 6% and had respective decreases of 0.47, 0.40, 0.39 and 0.28%/day. Regrowth forage in the midsummer and fall harvests averaged from 63 to 59% IVDMD and from 16 to 20% CP, respectively. With the exception of reed canarygrass, delaying the initial cut resulted in continued increases in total annual dry matter (DM) yield, significant increases in total IVDMD yield until flowering, and decreases in total CP yield from stem elongation onwards. Reed canarygrass reached its optimum CP yield at early heading and had significant increases in IVDMD yield until the flowering stage. Harvesting all forages at the stem elongation stage substantially reduced the yield of DM, IVDMD and CP. Although most of the DM was obtained in the initial harvest, almost half of the total CP was obtained in the final harvest.Key words: Timothy, tall fescue, reed canarygrass, Kentucky bluegrass, growth cycle, forage quality