In vitro fermentation of feed ingredients by fresh or frozen pig fecal inocula

Abstract

In vitro techniques can offer a rapid, repeatable and cost-effective alternative to in vivo experiments. We investigated the gas production (GP) of nine different feeds commonly used in Italian and Maltese pig farms in order to assess the use of the Ankom system in this species and to compare the in vitro microbial activity fresh or frozen inocula derived from piglet feces. Proximate and polyphenolic analyses were determined for all substrates. Fermentation profiles were measured according to the cumulative GP technique. Analysis of GP values revealed significant differences in the fermentation patterns mainly due to substrate and inoculum effects. Fermentation parameters varied significantly according to the substrate ingredients. The frozen inoculum generally led to more total GP than for fresh, with the exception of hard wheat bran pellets (HWBP), pelleted pulp and mature carob. Conversely the fresh fecal inoculum had an earlier maximum time to reach maximum GP than the frozen, showing a higher maximum rate of GP in all substrates excepting for HWBP. A significant difference in frozen and fresh inocula was found for the complete formulation. Further studies are required to confirm the variation between fresh and frozen fecal inocula to a wider range of feed, including those that could have negative biological effects.

Effects of Gas Production Recording System and Pig Fecal Inoculum Volume on Kinetics and Variation of In Vitro Fermentation using Corn Distiller’s Dried Grains with Solubles and Soybean Hulls

“…One possible explanation for the lack of differences may be due to the differences between the headspace volumes to fermentation inoculum ratio between the systems, which was 4.9 for ARS compared to 2.8 for MRS in the current experiment. This ARS ratio is greater than the ratio used in a previous in vitro study conducted using swine fecal inoculum with ARS (ratio: 3.2, Pastorelli et al [24]). However, the optimal ratio between headspace and fermentation inoculum has not yet been established.…”

Effect of in vitro cultivation on human gut microbiota composition using 16S rDNA amplicon sequencing and metabolomics approach

“…The combined faecal inocula are assumed to have a more heterogeneous population and are, therefore, more representative microbiota for the whole population 30 . Moreover, the use of pooled GM as an inoculum for in vitro cultivation models allows using standardized inoculum for multiple different trials and ensures reproducibility between experiments 19 , 51 , 52 The suitability of pooled microbiome samples in cultivation in vitro models has been reported in human adults 19 and infants’ faecal 31 as well as human milk 53 , 54 .…”

Heat Stress Increases In Vitro Hindgut Fermentation of Distinct Substrates in Iberian Pigs

“…Feces are highly representative of the microbial activity of digesta from the whole large intestine [28] and can be used as a source of inoculum instead of intestinal contents for in vitro fermentation techniques [29,30]. The frozen cecal content and feces of pigs [31,32], horses [33], and rabbits [34] have successfully been used as inoculum to study hindgut fermentation. Finally, we used 24 h incubation time, which is both convenient in the laboratory and close to the estimated transit time of digesta in the large intestine of pigs fed cereal-based diets [35,36].…”