In Vitro Fermentation Potential of Undigested Dietary Protein

Abstract

This study aimed to investigate the in vitro fermentation potential of ileal digesta from pigs fed seven protein sources with different batches—maize germ meal (MGM), cottonseed meal (CSM), rapeseed cake (RSC), rapeseed meal (RSM), peanut meal (PM), soybean meal (SBM), and sunflower meal (SFM)—to assess their potential impact on hindgut protein fermentation, which can be harmful to animals. Ileal digesta samples were incubated with porcine faecal inoculum under N-free conditions, with whey protein isolate (WPI) as a control. Gas production (GP) resulting from protein fermentation was monitored over 48 hours and analysed using a modified biphasic model to assess substrate fermentation and microbiota turnover dynamics. Significant variations in fermentation characteristics, including maximum GP rates (Rmax), cumulative GP, and microbiota turnover slopes, were observed across the protein sources. Rmax values ranged from 16.8 ± 0.6 to 27.9 ± 0.8 mL/h for MGM and SFM, respectively compared to 12.5 ± 0.4 mL/h for WPI. Solubility and molecular mass analyses showed differences in the proportion of insoluble nitrogenous molecules and the distribution of soluble molecules, reflecting varying fermentability. Standardized hindgut fermentation potential differed significantly among the protein sources, with MGM exhibiting the highest potential (1.18 L/g dietary protein) and SBM the lowest (0.46 L/g dietary protein). These findings provide valuable insights into the differential accessibility of undigested protein to hindgut microbiota, contributing to more effective diet management and optimization of animal and human nutrition strategies.