Journal of Animal Science, Vol 74, Issue 7 1689-1693, Copyright © 1996 by American Society of Animal Science

JOURNAL ARTICLE

Effect of storage temperature and time on fiber content of fresh and ensiled alfalfa

M. L. Nelson and M. J. Bozich
Washington State University, Pullman 99164-6320, USA.

To determine effects of storage temperature and time on fiber content, fresh alfalfa (late vegetative) was hand-clipped from three locations (blocks) and stored fresh or ensiled at -20 degrees C or +60 degrees C for 0, 24, 48, 96, 168, or 336 h. The experimental design was a randomized complete block with a 2 x 2 factorial arrangement of treatments. Main effects were method of forage conservation (fresh or ensiled) and temperature of storage (-20 degrees C or + 60 degrees C). Length of storage (0, 24, 48, 96, 168, or 336 h) was in the subplot. Conservation method x storage temperature x time interactions were detected (P < .05) for NDF, IVDMD, ADIN, and N content of NDF. Large increases in alfalfa NDF were observed up to 168 h of storage at 60 degrees C, whereas when fresh alfalfa was stored at -20 degrees C, small increases were observed up to 48 h but a large increase was observed after 168 h. Ensiled alfalfa stored at -20 degrees C had no change in NDF content. Contributors to increased NDF seemed due to changes in protein solubility and glycosylamine formation when fresh forage was stored at 60 degrees C, and changes in protein solubility, glycosylamine formation, and Maillard product formation when ensiled forage was stored at 60 degrees C. At -20 degrees C, formation of adducts with arabinose and glucose from nonstructural carbohydrates as well as polymerization and fragmentation of cell wall monosaccharides probably contributed to altered NDF content of alfalfa.