The effects of methods of processing soyabean meal (SBM), and low (LRSM) and high (HRSM) gluco-sinolate rapeseed meals on rumen degradability (DG) of dry matter (DM) and nitrogen (N), were determined by the nylon bag method in experiments of Latin Square design with 4 rumen-fistulated heifers. Rumen fractional outflow rates (FOR) for untreated SBM, LRSM and HRSM were determined by the chromium-mordant method in 2 heifers. Effective rumen degradabilities (EDG) for rumen incubation times of 24 h were calculated from DG and FOR.

Methods of processing were formaldehyde (FT, 0.8g HCH0/I6g N), heat (HT, 110°C for 2 h) and untreated (UT). Heifers were given a basal diet of hay (0.55 of DM intake) and mineralized barley with LRSM (0.45 of DM intake). The diet was offered twice a day at 08.00 and 16.00 hours. An adaptation period of four weeks preceded the experiments.