Comparative Evaluation of High-Throughput In Vitro Digestion Methods for Predicting In Vivo Digestibility and Fecal...

Area of Science:

• Animal Nutrition
• In Vitro Digestion Models
• Swine Physiology

Background:

• In vivo trials for pig nutrient digestibility are resource-intensive and raise animal welfare concerns.
• Accurate in vitro models are crucial for predicting nutrient digestibility and hindgut fermentation in pigs.
• Existing in vitro methods require improvement for physiological relevance and predictive accuracy.

Purpose of the Study:

• To evaluate and compare the predictive performance of three in vitro digestion methods (shaking, dialysis, and combined shaking-dialysis) for estimating in vivo apparent total tract digestibility (ATTD) and hindgut fermentation in pigs.
• To assess the ability of in vitro models to predict nutrient digestibility and fermentation characteristics across different pig growth stages (weaning, growing, finishing).
• To determine the optimal in vitro method for high-throughput porcine feed evaluation and prediction of fecal nitrogenous odorants.

Main Methods:

• Simulated gastric and small-intestinal digestion using shaking (S), dialysis (D), or shaking-dialysis (SD) methods.
• Inoculation of digesta with pig feces to model hindgut fermentation for 12 and 48 hours.
• Analysis of crude protein digestibility, dry matter digestibility, fermentation metabolites (skatole, indole), and microbial enzyme activities.

Main Results:

• The dialysis (D) method showed the highest crude protein digestibility during the gastrointestinal phase.
• All methods demonstrated strong linear correlations with in vivo ATTD after 48 hours of fermentation (r > 0.93).
• The D method achieved high absolute agreement for dry matter and crude protein digestibility (Lin's CCC > 0.95) and accurately predicted fecal profiles of skatole, indole, and microbial enzymes.

Conclusions:

• The dialysis (D) method provides the most precise predictions of absolute values for nutrient digestibility and fermentation characteristics in pigs.
• The combined shaking-dialysis (SD) method offers a balance between physiological relevance and operational efficiency for high-throughput applications.
• Both D and SD methods show promise as robust platforms for porcine feed evaluation and prediction of fecal nitrogenous odorants, reducing reliance on animal trials.