YEASTS ON in vitro DIGESTIBILITY OF DIETS WITH DIFFERENT LEVELS OF ROUGHAGE

The objective of this work was to evaluate the effect of Saccharomyces cerevisiae at levels 0; 0.2; 0.4 and 0.6 g/L on the in vitro digestibility of dry matter (IVDDM), crude protein (IVDCP) and neutral detergent fiber (IVDNDF) in diets containing, in DM, 100, 75, 50 and 25% Cynodon dactylon grass. The experimental design was completely randomized with 4x4 factorial scheme. The rumen fluid was collected from a cannulated cattle and food were incubated by two stages technique (48 hours + 24 hours), in artificial rumen. The data were interpreted by analysis of variance and regression studies. The elevation of the yeast has provided increases in IVDDM, IVDCP and IVDNDF in all treatments, except at the level of 0.6 g/L in the diets containing 100, 75 and 50% roughage for IVDDM and IVDNDF, and 100 and 75% for IVDCP, which presented quadratic behavior. We concluded that in diets with proportion of roughage equal or above 50%, the digestibility can be improved with the use of yeast to the level of 0.4 g/L. In diets with more than 50% of concentrate the improvement in digestibility occurs linearly with increasing levels of yeast.