EFFECT OF PROCESSING METHODS ON THE IN VITRO DIGESTIBILITY OF SODIUM HYDROXIDE TREATED ROUGHAGES

Abstract

The response of roughages to sodium hydroxide (NaOH) treatment varied with type of roughage. Treatment with NaOH at 23 C for 24 hr increased in vitro dry matter digestibility (IVDMD) by 8,5, 39.6 and 21.5 percentage units for alfalfa stem, barley straw and corn stover, respectively. Increased IVDMD values were brought about, in part, by increased water solubility and decreased cell wall constituents. No significant changes occurred in acid detergent fiber, cellulose or lignin content. The IVDMD values of barley straw ranged from 38% at 0% NaOH to 81% with 12% NaOH at 130 C. At all temperatures and durations, IVDMD increased with increase in concentration of NaOH up to the 8% level. Above 8% NaOH, no further increase in IVDMD occurred. Temperature affected the rate as well as the extent of the response to NaOH. Treatments at 100 C for 90 min resulted in IVDMD values approximately 10 percentage units higher than at 23 C for 24 hr.