PSXI-27 - Live yeasts enhance ruminal fermentation of fibrous feedstuffs

Abstract: Since the beginning of the present century, research results have shown that ruminant researchers have explored the idea of manipulate ruminal fermentation, trying to improve a much better metabolism of nutrients in the rumen, all of this with the aim to increase the productivity of ruminants. The main goal of this experiment was to evaluate the potential use of a savage yeast strain (Pichia guilliermondii) on the ruminal fermentation of maize stover. To accomplish the objective two in vitro treatments were examined: (a) filtered rumen liquid + powdered maize stover + yeast-free culture medium and (b) filtered rumen liquid + powdered maize stover + culture medium inoculated with yeast. Samples were collected at different time, 0, 6, 12, and 24 h and examined for effects on culture pH, ammonia nitrogen (NH₃-N), the fiber digestibility percentages of neutral detergent fiber (NDFD) and acid detergent fiber (ADFD), as well the digestibility of dry matter (DMD), and the concentration of volatile fatty acids (VFAs). The results showed that the addition of Levica 27 had no effect on the ruminal pH, NH₃-N or the digestibility indicators (p > 0.05). However, at 12 h, the inclusion of Levica 27 increased (p < 0.05) the molar levels of total VFAs and acetic and propionic acids in ruminal fluid and decreased (p < 0.05) the C2:C3 ratio. Our conclusion was that Pichia guilliermondii had a stimulating effect on the in vitro ruminal fermentation over a range within 6 and 12 h, a result that should be taken into account when in vivo studies are replicated with this yeast strain.