CONTENT AND DEPOSITION RATES OF CELLULOSE, HEMICELLULOSE, AND LIGNIN DURING REGROWTH OF FORAGE GRASSES AND LEGUMES

Cell-wall (CW) components greatly influence digestibility of forages as they mature. There is only limited information on the timing of rates of deposition of CW components. This investigation examined differences in CW and CW component deposition in greenhouse-grown alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifolium pratense L.), orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), and switchgrass (Panicum virgatum L.). Plant material was sampled from the basal 10 cm of forage after harvesting at 3-5 cm above the soil level. Samples analyzed included sheaths from orchardgrass, sheaths and stems from bromegrass and switchgrass, and stems from all legumes. After establishment and herbage removal. samples were collected biweekly between 2 and 10 wk of regrowth. Results indicated that, except for orchardgrass, maximum rates of CW and CW component deposition usually occurred earlier in legumes compared with those of grasses. Maximum CW deposition for all species occurred within 1-3 d of maximum dry weight deposition. Among CW components in grasses and legumes, maximum deposition of hemicellulose occurred first, followed by that of cellulose (1-6 d later), and then lignin (up to 14 d after maximum hemicellulose deposition). Maximum cellulose deposition in all species occurred at the same time as maximum CW deposition.