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Forage source and maturity effects on enzymatic digestion rate of isolated cellulose

Fairbrother, T.E., Brink, G.E.
Crop science 1989 v.29 no.1 pp. 209-212
Lolium multiflorum, Festuca arundinacea, Cynodon dactylon, Paspalum dilatatum, Paspalum notatum, Trifolium subterraneum, Trifolium alexandrinum, Trifolium vesiculosum, Trifolium repens, Trifolium pratense, Trifolium incarnatum, Macroptilium lathyroides, Aeschynomene americana, Lespedeza cuneata, crop quality, cellulose, in vitro digestibility, hydrolysis, maturity stage, cellulases
This study was conducted to determine the rate of enzymatic hydrolysis of isolated cellulose from grass and legume forages important to the southeastern USA, and to compare the difference in hydrolysis rate between grasses and legumes at two stages of maturity. Cellulose from six grass and nine legume species harvested at two stages of maturity were isolated using an acid chlorite delignification procedure followed by hemicellulose extraction with 0.12 M NaOH solution. Residual dry matter from isolated cellulose samples was determined to contain between 901 and 958 g kg-1 glucose. Cellulose samples were incubated at 40 degrees C in a solution of commerically obtained cellulase enzyme for 8 h. Solutions were sampled at hourly intervals and analyzed for glucose concentration. Results indicated that glucose production was linear during the sampling period for all cellulose samples. The rate of enzymatic hydrolysis was greater (P less than 0.01) for cellulose isolated from grass samples than from legume samples (8.06 and 6.94 mg kg-1 s-1, respectively). Stage of maturity also affected enzymatic digestion rate (P less than 0.01). Rates for enzymatic digestion of cellulose from immature and mature forage were 8.61 and 8.06 mg kg-1 s-1, respectively. Even though enzymatic digestion rates between grasses and legumes were significantly different, the differences were small. Correlation between cellulose digestion rate and in vitro dry matter digestion of forage was not significant, indicating that cellulose digestion rate was not important in determining digestibility of whole plant tissue.