Difference in in vitro fermentability of four carbohydrates and two diets, using ileal and faecal inocula from unweaned piglets

Abstract

An experiment was conducted to examine differences in the in vitro fermentability of four carbohydrate-rich feed ingredients and two weaning piglet diets with and without these ingredients, using both the ileal contents and the faeces of unweaned piglets as inocula. In the first part of the experiment, cumulative gas production was measured over time, using faecal inocula mixed from nine specially raised crossbred piglets (no creep feed or antibiotics) at 3 weeks of age. Inulin, lactulose, unmolassed sugar beet pulp, wheat starch and the two diets were used as substrates and fermented in vitro for 72 h. Gas production was measured as an indicator of the kinetics of fermentation. Fermentation end-products, including volatile fatty acids and ammonia, and organic matter loss, were also measured. For the fermentations of feed ingredients, samples were also collected for polymerase chain reaction/denaturing gradient gel electrophoresis analyses initially and after the fermentation process, to study changes in the composition of the bacterial community. This procedure was repeated 1 week later, using ileal contents from the same piglets as inoculum. There were significant differences between the inocula, in terms of both overall fermentation characteristics and composition and between the substrates. There was also a significant interaction between inocula and substrates, which suggests that there were potentially important differences in the microbial activity occurring in these two areas of the gastrointestinal tract (GIT). For the two diets, one with and one without addition of these fermentable ingredients, there were significant differences in terms of the kinetics, but less so in terms of the end-products of fermentation. It was concluded that inocula from both the small and large intestine should be used to obtain a more accurate assessment of potential feed ingredients which will stimulate fermentation in the piglet GIT.

The effect of betaine on in vitro fermentation of carbohydrate and protein combinations under osmotic stress in pigs

“…It has been already shown in previous in vitro studies featuring normally buffered conditions,23, 31, 32 that differences in fermentability among carbohydrates can be attributed to variations in their chemical composition and structure 33, 34. This is in agreement with the results of an in vitro study , conducted under osmotic stress conditions, which also revealed differences in fermentability among carbohydrates of different structures 35.…”

“…As expected, ammonia production was higher for assay substrates containing the protein source casein consisting of more and easily available CP in comparison to soybean meal. Similarly, for the carbohydrate‐rich by‐products wheat bran, sugar beet pulp and distiller's wheat grains, ammonia production after in vitro fermentation was higher compared to the pure carbohydrate sources, due to their inherent content of CP which is in agreement with previous in vitro studies 13, 19, 23. Under in vivo conditions, protein fermentation results in the formation of ammonia, which may exert toxic effects on the host, but also may impair function and diversity of the gut microbiota and may predispose piglets to diarrhoea 43.…”

“…Acetic, propionic, butyric and valeric acids as well as total SCFAs are expressed as acetic acid equivalents (mg AAE g −1 DM), which allows individual acids to be compared according to their carbon and energy content. The proportion of the branched‐chain SCFAs (isobutyric + isovaleric) to total SCFAs (in mg AAE g −1 DM) was calculated as follows:23 where BCP (in %) is the branched‐chain proportion. Branched‐chain fatty acids are generally related to protein degradation from the metabolism of branched‐chain amino acids 3…”

Effects of fermentable starch and straw-enriched housing on energy partitioning of growing pigs

“…Others (De Lange et al, 2006) also reported a decrease in methane losses in pigs following ingestion of straw, and suggested either that straw reduces fermentation by methanogenic bacteria or that some of the methane produced might be adsorbed by faecal material of the pigs. NS consumption did not increase methane emission as compared to PS, possibly due to a high production of propionic acid relative to other fermentable carbohydrates (Awati et al, 2006).…”