An assay was conducted in the Animal Nutrition laboratory of the Agronomy Faculty, University of Zulia, Maracaibo, Venezuela, with the purpose of evaluating the effect of different levels of humidity and days of storage on the ammoniation with urea 3% of Brachiaria brizantha hay on the dry matter content (MS), crude protein (CP), ash and in vitro dry matter digestibility (IVDMD). Hay cutted and placed in plastics bags and aditioned with an aqueous solution of urea at 0, 20, 40 and 60% of humidity in relation to the dry weight of the hay. It was stored during 0, 14, 28 and 42 days at ambient temperature. It was used a totally at random desing with a factorial arragement of 4 x 4 with four repetitions. The results obtained shown a significative effect (P<0.05) of the treatment on IVDMD, DM and ash, but it was not significance for the interacction. The IVDMD showed an increased in relation to the humidity content (from 55.33% to 66.35% when humidity was 0% and 60%, respectively) and the days of storage (from 58.74% with 0 day to 64.69% with 42 days), while the DM decreased with the humidity (from 95.94% with 0% to 62.39% with 60% humidity). For CP only days of storage and the treatments interactions were significant (P<0.05). It is concluded that the ammoniation of hay of Brachiaria brizantha respond positively to the application of water and the days of storage and that the ammoniation with urea constitute an alternative of interest in ruminant nutrition.
