The study aimed to adapt the SHIME® model, developed to simulate human digestion and fermentation, to a baby-SPIME (baby Simulator of Pig Intestinal Microbial Ecosystem). What constitutes a unique feature of this model is its twofold objective of introducing an ileal microbial community and mimicking a dietary weaning transition. This model should then be ideally suited to test the dietary weaning strategies of piglets in vitro. Regarding the microbiota, the main phyla making up the model were Firmicutes, Bacteroidetes and Proteobacteria although Bacteroidetes decreased after inoculation (p = 0.043 in ileum, p = 0.021 in colon) and Delta-Proteobacteria were favoured (p = 0.083 in ileum, p = 0.043 in colon) compared to Gamma-Proteobacteria. The designed model led to a low representation of Bacilli - especially Lactobacillus sp. in the ileum and a weak representation of Bacteroidia in the proximal colon. However, Mitsuokella and Prevotella were part of the major genera of the model along with Bifidobacterium, Fusobacterium, Megasphaera and Bacteroides. As a result of weaning, two major changes - normally occurring in vivo - were detected in the system: firstly, Firmicutes diminished when Bacteroidetes increased particularly in the proximal colon; secondly, Bacteroides decreased and Prevotella increased (mean value for four runs). In terms of metabolite production, while a ratio acetate: propionate: butyrate of 60:26:14 was obtained in post-weaned colon, the expected inversion of the ratio propionate: butyrate in the post-weaned ileum was unfortunately not observed. To conclude, the so-called baby-SPIME model meets expectations regarding the resident microbiota of the proximal colon bioreactor and the metabolites produced thereof. In terms of the evolution of major groups of bacteria, the in vitro weaning process appeared to be successful. However, higher concentration of butyric acid would have been expected in ileum part of newly weaned piglets, as observed in vivo. The microbiota in the ileum bioreactor seemed in fact to act like a pre-colon. This suggests that microbial profile in ileum bioreactor had to be improved.

Apple pomace (AP) is known to be rich in biomolecules beneficial for health and it may advantageously be used to overcome the critical step of piglets’ weaning. The study aimed to determine the effect of two levels of incorporation of AP on the performance, intestinal morphology, and microbiota of weaned piglets and investigate this feed ingredient as a weaning strategy. An experiment was performed with 42 piglets from weaning (28 days old) over a five-week period, including three iso-energetic and iso-nitrogenous diets (0%, 2%, and 4% dried AP diets) with seven pen-repetitions per diet (two pigs per pen). AP diets were beneficial for the average daily gain calculated on week 3 (p = 0.038) and some parameters of the intestinal architecture on the 35 post-weaning day. The 4% AP diet was beneficial for the feed conversion ratio (p = 0.002) and the energetic feed efficiency (p = 0.004) on the 35 post-weaning day. AP tended to influence the consistency of feces (softer to liquid, p = 0.096) and increased the counts of excreted pathogens (p = 0.072). Four percent AP influenced the richness of the microbiota and the bacteria profile as observed for the phylum Bacteroidetes or the class Clostridia. The 4% AP diet appeared as an interesting weaning strategy that should be evaluated in a large cohort.

Apple pomace (AP) contains biomolecules that induce changes in intestinal fermentation of monogastrics with positive expected health effects. The weaning of piglets can induce economic losses due to intestinal disturbances; new weaning strategies are, thus, welcome. The purpose of this study was to test the effect of AP on fermentation products by using baby-SPIME, an in vitro multi-compartment model dedicated to piglet weaning. A comparison was done on short chain fatty acid (SCFA) ratio and the microbiota induced in bioreactors between a control culture medium vs. an AP culture medium. The results of 2 preliminary runs showed that AP medium increased the molar ratio of propionate (p = 0.021) and decreased the molar ratio of butyrate (p = 0.009). Moreover, this medium increased the cumulative relative abundance of Prevotella sp. and Akkermansia sp. in bioreactors. AP could promote an ecosystem enriched with bacteria known as next-generation probiotics (NGP)—likely influencing the energy metabolism of piglets by their fermentation metabolites. AP could be used as a dietary strategy to influence bacterial changes in the intestine by stimulating the growth of bacteria identified as NGP.

In vitro digestion and fermentation models are frequently used for human and animal research purposes. Different dynamic and multi-compartment models exist, but none have been validated with representative microbiota in the distal parts of the small intestine. We recently developed a dynamic and multi-compartment piglet model introducing microbiota in an ileum bioreactor. However, it presented discrepancies compared to in vivo data. Recommendations are available to standardize studies in this field. They target the digestion model but include elements of a fermentation model. But no recommendation is given concerning control of the atmosphere. The gastrointestinal tract is generally associated with anaerobiosis to conduct a good fermentation process. In this study, we attempted to improve the ileal microbiota of the piglet model by testing inoculation: real intestinal content vs feces; the latter being generally used for ethical and economical aspects. Results showed a positive effect of using real intestinal content. Fusobacteriia were less abundant in the model, Bacteroidia were better maintained in the colon. But for the ileum, results showed that anoxic conditions in the ileum bioreactor conditioned the microbial profile probably more than the type of inoculum itself, leading to the general conclusion that in vitro dynamic and multi-compartment models probably have to get oxygenated to improve microbiome studies of the small intestine.

The conversion of agro-industrial co-products and unsold organic plant-based residues into black soldier fly (BSF; Hermetia illucens (L. 1758)) proteins was assessed for use in organic post-weaning piglet diets in Belgium. A total of 72 crossbred female piglets (Landrace × Pietrain) were enrolled in a 5-week feeding trial. Experimental diets consisted of a common energy core (81.2% of the feed) and a protein core (18.8%) composed of organic soybean meal, pea meal, and potato protein, partially replaced by defatted BSF meal at inclusion levels of 15%, 25%, and 35%. All diets were formulated to be isoenergetic and isonitrogenous, with standardized ileal digestibility values for lysine, methionine, threonine, and tryptophan held constant. Incorporating 15% defatted BSF meal can substitute conventional organic protein sources without compromising growth performance in post-weaning piglets. However, economic modelling based on a cumulative feed conversion ratio expressed on a dry matter (DM) basis showed that break-even prices for organic BSF meal remained well below the price of the control protein nucleus (€1039·t⁻¹, excluding VAT), indicating that economic parity could not be achieved at typical market prices under the observed feed efficiency.