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Effects of Saccharomyces cerevisiae fermentation product on rumen VFA concentrations
Effects of Saccharomyces cerevisiae fermentation product (SCFP; Original XPC, Diamond V, Cedar Rapids, Iowa) on rumen volatile fatty acid (VFA) concentrations were measured in vivo and in vitro. In the in vivo study, eight cannulated Jersey cows (non-lactating, non-pregnant) were utilized in a crossover design experiment consisting of two 28-d periods. Cows were housed in tie stalls containing individual feed bins and an automatic watering system. Cows were fed a TMR diet once daily that was top-dressed with one of two treatments: 14 g Control (grain mix) or 14 g SCFP. Rumen fluid samples were collected from each cow every 9 h from d 26 to 28, which represented every 3 h over a 24-h period (8 samples per cow). Samples were collected from 5 locations within the rumen (cranial dorsal, cranial ventral, central rumen, caudal dorsal, and caudal ventral), composited within cow, and strained. Samples were analyzed for VFA concentrations and pH. The in vitro study, performed concurrently with the in vivo study, utilized the Diamond V Rumen Activity Modifier Model (RAMM). Rumen fluid was collected from the 8 cows used in the in vivo study. The rumen fluid was strained and composited within cow treatment group to create one composite per treatment on d 28 of each period. Incubation bottles containing substrate (ground TMR), treatments (Control or SCFP) and rumen fluid (Control or SCFP) were incubated under anaerobic conditions at 39oC for 16 hours. After incubation, pH and VFA concentrations were determined. Data were analyzed using the fit model procedure of JMP. Cows supplemented with SCFP had greater (P < 0.01) total VFA, acetate, isobutyrate, isovalerate, and valerate concentrations (130.39 vs. 122.79; 81.33 vs. 76.66; 1.74 vs. 1.58; 2.03 vs. 1.70; 1.88 vs. 1.71 mM, respectively). Concentration of propionate tended to be greater (P < 0.06) in cows supplemented with SCFP (23.89 vs. 22.58 mM, respectively). In the in vitro model, SCFP increased (P< 0.001) total VFA, acetate, propionate, and butyrate concentrations (58.76 vs. 56.34; 29.67 vs. 28.53; 20.34 vs. 19.31; 7.76 vs. 7.56 mM, respectively). In both the in vivo and in vitro model, rumen VFA concentrations were greater when SCFP was supplemented.
Keywords: Saccharomyces cerevisiae fermentation product, VFA, dairy