Development of a chicken gastrointestinal tract (GIT) simulation model: impact of cecal inoculum storage preservation conditions

A chicken gastrointestinal tract (GIT) simulation model was developed to help predict the potential effects of feed additives supplementation on chicken’ microbiota. The chemical and enzymatic conditions for oral, gastric, intestinal, and cecum fermentation phases were designed to closely resemble the chicken GIT conditions. For cecum fermentation, the inoculum was obtained from the cecal contents of 18 38-day broiler chickens. The impact of inoculum preservation on bacteria viability was assessed by comparing two methods of preservation with fresh inoculum: (1) 5% dimethyl sulfoxide (DMSO) at −80 °C and (2) 30% glycerol at −20 °C. The fermentation with fresh and frozen (DMSO method) inoculums was performed and compared using standard chicken feed (SCF) and SCF with 1% fructooligosaccharides (FOS), and inoculum control (IC) condition without feed matrix was used as a baseline. Inoculum’s viability was assessed throughout 90 days of storage by culture media platting, while bacterial growth and metabolites production during fermentation was evaluated by quantitative polymerase chain reaction (qPCR), high-performance liquid chromatography (HPLC), and total ammonia nitrogen quantification. The DMSO method was shown to be the most suitable for cecal inoculum storage. Higher growth of beneficial cecal bacteria for fresh inoculum was observed in SCF while for frozen inoculum, was the SCF + FOS condition. Also, frozen inoculum had lower activity of butyrate producers and proteolytic bacteria, showing different fermentation profiles. The GIT model developed showed to be useful to test the effect of feed additives supplementation.