Comparison of In Vivo and In Vitro Digestibility in Rabbits

Area of Science:

• Animal Nutrition
• Digestibility Studies
• In Vitro Assays

Background:

• Accurate measurement of apparent dry matter digestibility (ADMD) is crucial for formulating rabbit diets.
• In vivo digestibility trials are resource-intensive, necessitating reliable in vitro alternatives.
• The Ankom Daisy II Incubator offers a platform for in vitro digestibility assessments.

Purpose of the Study:

• To compare in vivo and in vitro methods for determining apparent dry matter digestibility in rabbits.
• To evaluate the efficacy of different in vitro methods (fecal inoculum and multienzyme) using the Ankom Daisy II Incubator.

Main Methods:

• Four rabbit diets (low fiber, low fiber + 5% fenugreek, low fiber + 10% fenugreek, high fiber) were tested.
• In vivo digestibility was measured using fecal samples from 56 rabbits.
• In vitro digestibility was assessed using fecal inoculum (FA, FB) and multienzyme (ENZ) methods in the Ankom Daisy II Incubator.

Main Results:

• In vitro methods ranked diet digestibility similarly to in vivo results.
• The multienzyme (ENZ) method yielded higher digestibility values than fecal inoculum methods (FA, FB).
• The ENZ method demonstrated superior prediction of in vivo digestibility (R² = 0.69) and higher reproducibility (CV = 3.1%) compared to FA and FB.

Conclusions:

• The Ankom Daisy II Incubator can be utilized with various methods to assess rabbit digestibility.
• The multienzyme method provides a more reproducible and accurate in vitro assessment of rabbit apparent dry matter digestibility compared to fecal inoculum methods.
• Variability in fecal inocula may explain the lower reproducibility observed with FA and FB methods.