The objective was to evaluated a propolis based product (LLOS) patented (PI No 0605768-3) which consist of dried extract of propolis ranging in alcohol extraction (1, 2 and 3) and propolis concentration (A, B, C and D ): LLOSC1, LLOSD1, LLOSA2, LLOSB3, LLOSC3, on the biochemical and morphological characterization of isolated bacteria tolerant to products LLOSC1, LLOSB3 in diets with 100% roughage and products LLOSC1, LLOSD1, LLOSA2, LLOSC3 in diets 50% roughage and 50% concentrate and administration of products LLOSB3 and LLOSC1 compared with monensin sodium on intake and total and partial digestibility of dry matter and nutrients, characteristics and rumen microbial efficiency in cattle and buffaloes fed diets based on 80% of roughage. In diets with 100% roughage it was found that the strains tolerant to LLOSC1 were higher in ferment cellobyose (92.4 vs. 78.3%) and cellulose (57.7 vs. 34.8%) compared with strains resistant to LLOSB3 which presented as more specialists. For diet 50:50, roughage:concentrate, it was highlight the product LLOSC3 followed by LLOSA2 that selected a larger number of generalists strains that use the different evaluated carbohydrates: arabinose, cellulose, glucose, celobiose, xylose, fructose, lactose. The product LLOSA2 selected strains that grew until 6:30 h, the others products selected strains that had growth rates ranging from 6:30 to 37:00 h . It was used four Holstein cattle and four Murrah buffaloes in an experimental design Latin square 4 x 4 (4 diets: control, monensin, LLOSC1 and LLOSB3 and 4 periods, for each species). The diets given to cattle roughage containing 72.5% and 27.5% of concentrate, with 14.4% CP and 67% of TDN and buffaloes had given to 80% of roughage and 20% concentrate, with 11. 1% of CP and 66% of TDN. The intake of DM and other nutrients did not differ between the experimental diets, as for buffalo and cattle, except for the TDN intake in cattle that was higher (P0.05) between the diets, but there was a tendency for greater volume rumen (P0,05) entre as dietas, porém houve tendência de maior volume ruminal (P<0,08) para dietas contendo aditivos em relação a testemunha. O aditivo à base de própolis LLOSC1 apresentou a maior eficiência de síntese microbiana (36,6 g N-Mic/kg MOVDR) em relação à testemunha (25,8 g N-Mic/kg MOVDR). Assim, concluiu-se, que as cepas de bactérias tolerantes aos produtos à base de própolis foram mais generalistas ou especialistas na degradação de diferentes substratos avaliados dependendo do produto LLOS utilizado e tipo de dieta, não se recomenda o uso de monensina sódica e produtos à base de própolis em dietas à base de forragem para bovinos em crescimento, porém recomenda-se o uso do produto LLOSC1 em bubalinos alimentados com dietas volumosas.xix, 92
