166 Effect of gas production recording system and inoculum volume on in vitro fermentation of corn distillers dried grains with solubles (cDDGS) or soybean hulls using pig fecal inoculum.

摘要

An experiment was conducted to investigate the effect of inoculum volume and recording system on gas production (GP) produced from fermentation of corn distillers dried grains with solubles (cDDGS) or soybean hulls (SBH). A 2 × 2 × 2 factorial design was used and included the factors of 1) ingredients (cDDGS or SBH), 2) inoculum volume (IV30 = 0.2g substrate + 30 ml inoculum or IV75 = 0.5 g substrate + 75 ml inoculum), and 3) GP recording system (MRS = manual recording system or ARS = automated recording system). Feed ingredient samples were pretreated with pepsin and pancreatin, and the hydrolyzed residues were subsequently incubated with fresh pig feces in a buffered mineral solution. The GP was monitored and recorded for 72 h and kinetics were estimated by fitting data in an exponential model. Compared with SBH, cDDGS yielded less ( < 0.01) maximal gas production (G ), required more time ( < 0.02) to achieve half gas accumulation (T/2), and had less ( < 0.01) fractional rate of degradation (µ) and fermentability of dry matter (IVFDM). Using the ARS resulted in less IVFDM ( < 0.01) compared with MRS (79.0% vs. 81.2%, respectively). Interactions ( < 0.05) were observed between GP system and inoculum volume for G and µ, which implies that increasing inoculum volume resulted in decreased ( < 0.05) G and µ in ARS but not in MRS. However, the recorded cumulative GP at 72 h was not influenced by GP inoculum volume or recording system. Average coefficient of variation of all parameters was greater for IV30 (29.5%) compared with IV75 (23.6%). These results suggest that using less inoculum volume (IV30) increases variability in IVFDM and greater inoculum volume (IV75) is recommended for both ARS and MRS to achieve greater repeatability of results.