PSVI-13 Yield and quality of conventional and reduced lignin alfalfa harvested at different maturity stages in the Southeast United States

Abstract The objective of this study was to evaluate the effect of conventional and reduced lignin alfalfa on forage dry matter (DM) yield and quality when harvested at different maturity stages. The study was conducted in field plots (1.5 m x 6.1 m) as randomized complete block designs with a split-plot arrangement of treatments. Two conventional (Ameristand 455TQ, TQR; Alfagraze 600, ALFA) and one reduced lignin (Ameristand 480 HarvXtra, HVX) alfalfa varieties were harvested at 28 (Early), 35 (Mid), and 42 (Late) d intervals in three consecutive years. Samples were analyzed for NDF, ADF, and ADL (as % DM). Average DM yield was greater for TQR than ALFA and HVX (8,335 vs. 7,119 kg/ha, P < 0.01). The DM yield of alfalfa harvested at Mid stage was significantly greater (8,888 kg/ha) compared with alfalfa harvested at Early (6,961 kg/ha) or Late stage of maturity (6,726 kg/ha). The reduced lignin alfalfa had reduced NDF and ADF concentrations than TQR and ALFA (36.1 vs. 37.4 and 29.4 vs. 30.9%, respectively). The two conventional varieties did not differ in NDF and ADF content. The HVX alfalfa tended (P = 0.06) to have reduced ADL concentration than TQR and ALFA (9.97 vs. 10.62%). Compared with Early alfalfa, forage NDF, ADF, and ADL concentration were greater (P < 0.01) in Late harvested alfalfa (35.3 vs. 39.3%, 28.7 vs. 32.1%, and 10.0 vs. 10.8%, respectively). Under the conditions of this study, results suggest that the evaluated reduced lignin alfalfa has a greater forage quality than the conventional varieties but at the expense of decreased DM yield.