Comparison of in vitro digestibility estimates using the DaisyII incubator with in vivo digestibility estimates in horses.

This study examines the efficacy of using the Ankom DaisyII incubator in lab conditions (in vitro) to predict the digestive efficiency of horse’s body (in vivo) for different diets. The results suggest that the Ankom DaisyII incubator, with the methodologies used in the study, could be utilized to estimate the in vivo Dry Matter Digestibility (DMD) of horse feeds.

Research Methodology

• The experiment was designed as a 4 × 4 Latin square involving four mature geldings (male horses).
• The horses underwent a factorial arrangement of diet treatments involving timothy hay, alfalfa hay, timothy hay plus oats, and alfalfa hay plus oats.
• Each horse was housed individually and fed diets according to the design.
• Feces were collected during each 5-day total fecal collection period and used to calculate the in vivo digestibility.

In Vitro Analysis

• The DaisyII incubator was used to evaluate the digestion of the four diet treatments in vitro.
• Each incubation vessel of the DaisyII was assigned to one horse and contained 18 filter bags having different feed samples.
• Three incubation periods were evaluated: 30, 48, and 72 hours.

Comparative Results of In Vivo and In Vitro Digestibility

• Though the digestibility estimates for 30- and 48-hour in vitro analysis were consistently less than the in vivo estimates, they ranked the diets in the same order as the in vivo method.
• The mean 72-hour in vitro DMD and in vivo DMD for the alfalfa oat diet, timothy diet, and the timothy oat diet, were not significantly different.
• However, for the alfalfa diet, the DMD from 72-hour in vitro incubation was less than the in vivo estimate.

NDF Digestibility

• For Neutral Detergent Fiber Digestibility (NDFD), only the timothy diet’s mean 72-hour in vitro NDFD was similar to the in vivo estimate.
• Despite this discrepancy, the in vitro method ranked the alfalfa-based diets to have greater NDFD estimates than the timothy-based diets correctly.
• Among the 3 incubation periods, the 72-hour period yielded digestibility estimates closest to the in vivo data.

The conclusion drawn is that the DaisyII incubator, combined with the methodologies described in the research, can be a plausible way to estimate the in vivo DMD of horse feeds.