| Popis: |
Objective Dual-flow continuous culture (DFCC) fermentor systems have been historically used to simulate ruminant fermentation, but one most commonly used system was discontinued by the manufacturer. In response, modifications were made to construct new cost-effective units. Our objective was to evaluate the modifications relative to the original DFCC fermentors. Our hypothesis was that experiments using newly modified DFCC units would have decreased variance estimates for common dependent variables: nutrient digestibilities, VFA production, and bacterial N flow. Materials and Methods To evaluate impeller orientation, DFCC fermentors were randomized to either clockwise or counterclockwise fan blades on a counterclockwise-rotating motor. Fermentors (n = 8) were fed 37.2 g of DM of a pelleted 50:50 alfalfa:concentrate diet and run for 11 d with 7 d of adaptation and 4 d of sampling. To evaluate variance estimates, data were accumulated from 4 published fermentor experiments (n = 68) using original fermentors (The Virtis Company) and 2 fermentor experiments using modified DFCC units (n = 42). An F-test was conducted on the modified:original variance ratio, and a significant decrease in variance was declared at P Results and Discussion Impeller orientation decreased NDF digestibility in the clockwise rotation, whereas ADF digestibility was not affected. The modified DFCC system decreased variance of NDF and nonstructural carbohydrate digestibility. Variances of other measures were unaffected by the new system. Implications and Applications These data indicate the potential for the modified DFCC to primarily improve reliability of fiber digestibility, but more work may be needed to reduce variance of concentration-based fermentation parameters. |
