Chemical Composition of the Cell-Wall Constituent and Acid Detergent Fiber Fractions of Forages

Abstract

For 14 grasses, 4 alfalfas, and 3 alfalfa-grass mixtures, respectively, cellulose plus lignin represented 51, 69 and 58% of the total cell-wall constituent (CWC). Of the original plant content the CWC fraction recovered 95 percent of acid-detergent fiber (ADF), 94 percent of cellulose, 91 percent of lignin, and 27 percent of crude protein. For all forages, cellulose represented a consistent portion (79. Of 0.68 percent) of total ADF. Lignin content of ADF for grasses was 10.6t 0.69 percent, significantly different (P < .01) from 16. 3 [plus or minus] 0. 97 percent of alfalfas and alfalfa-grass mixtures. Cellulose plus lignin accounted for 90. 2 [plus or minus] 0.68 percent for grasses and 94. 2 [plus or minus] 0. 94 percent for alfalfas and alfalfa-grass mixtures of the respective total ADF fractions, and crude protein plus ash residue appeared constant. ADF chemical analyses for cellulose, lignin, crude protein, and ash accounted for 95 percent of the total ADF for grasses and 99 percent for alfalfas and alfalfa-grass mixtures. ADF recovered 92 percent of the original plant cellulose and 6 percent of crude protein. ADF minus lignin was a good predictor for cellulose. CWC and particularly the ADF fraction represented a more complete forage entity than crude fiber.