Nutritive value of silages of Elephant grass (Pen-nisetum purpureum, Schum.) mixed with 0; 3.5%; 7.0%; 10.5% and 14.0 % of dehydrated by product from juice industry of cashew fruit (Anacardium occidentale, L) (DBC) was determined. A randomized design was used with four replicates. Silages were opened after 65 days and samples taken for analysis of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose HCEL), cellulose (CEL), lig-nin (LIG), crude energy (CE), ash, neutral detergent inso-luble nitrogen (NDIN) and acid detergent insoluble nitro-gen (ADIN). Were also analyzed, pH, ammonia nitrogen and organic acids (lactic, acetic, butyric and propionic). Regarding fermentative parameters, there was an expected decrease in pH and the increasing levels of DBC did not affect the concentrations of N-NH3/NT and organic acids. It is concluded that dehydrated cashew by product can be ensiled along with Elephant grass without altering its fer-mentative characteristics. On the other side, the increased cell walls and ADIN contents of the silage may affect its nutritional value. Key-words: Cashew byproducts, nutritive value, tropical grass.