LESHEM, Y., Agricultural Research Organization, Volcani Center, Israel
GOLDMAN, A., Agricultural Research Organization, Volcani Center, Israel
YULZARI, A., Agricultural Research Organization, Volcani Center, Israel

Ammonia and sodium hydroxide (NaOH) have been used to improve the dry matter (DM) digestibility of roughages or to conserve them. These treatments have had incidental effects on pH alone or both the pH and nitrogen contents of the roughages. in the present study, the effects of pH and NH4OH on the in vitro dry‐matter digestibility (IVDMD) of eight roughages—four legumes and four grasses—were investigated. The pH levels of approximately 5, 7, 9 and 12 were achieved by adding appropriate amounts of NH4OH or NaOH and H2SO4. Nitrogen levels of approximately 20, 30, 40 and 50 g kg−1 on a DM basis were obtained by adding NH4OH. Results of a multiple regression showed that increasing the pH caused a linear increment in IVDMD and that the added NH4OH reduced the increment of IVDMD. The effects of both pH and N on IVDMD were found to be specific to the individual roughage; the response of grasses to both pH and NH3 was greater than that of legumes Copyright © 1984, Wiley Blackwell. All rights reserved