In vitro effects of inulin and soya bean oligosaccharide on skatole production and the intestinal microbiota in broilers

Abstract

The experiment was conducted to investigate the in vitro effects of inulin and soya bean oligosaccharide (SBO) on the metabolism of L-tryptophan (L-try) to skatole production, and the intestinal microbiota in broilers. Treatments were as follows: caecal microbiota control (Cc), Cc + inulin, Cc + SBO, rectal microbiota control (Rc), Rc + inulin and Rc + SBO. Microbial suspensions were anaerobically incubated at 38°C for 24 hr. The results showed that concentrations of skatole and acetic acid were significantly lower in caecal microbiota fermentation broth (MFB) than those in rectal MFB (p < .05). Addition of inulin or SBO significantly decreased the concentrations of indole and skatole and rate of L-try degradation (p < .05). Inulin groups had lower indole than SBO groups (p < .05). PCR-DGGE analysis revealed that addition of inulin or SBO decreased the microbiota richness (p < .05), but no significant differences in Shannon index (p > .05). Four distinct bands were detected in inulin and SBO groups, which were related to two of Bacteroides, one of Firmicutes and Bifidobacteria. Six bands were detected only in control groups, which represented uncultured Rikenellaceae, Roseburia, Escherichia/Shigella dysenteriae, Bacteroides uniformis (T), Parabacteroides distasonis and Enterobacter aerogenes. Populations of Lactobacilli, Bifidobacteria and total bacteria in inulin groups were higher than those in control groups (p < .05). For SBO groups, only population of total bacteria increased (p < .05). However, there were no significant differences in Escherichia coli population among treatments (p > .05). These results suggest that reduced concentrations of skatole and indole in the presence of inulin and SBO may be caused by decrease in L-try degradation rate, which were caused by change in microbial ecosystem and pH value. Uncultured B. uniformis (T) and E. aerogenes may be responsible for degradation of L-try to skatole.

Spatial variations in intestinal skatole production and microbial composition in broilers

“…The present study showed that the greater the total bacterial population, the higher the production of skatole and VFAs, which agrees with the findings of Li et al (2009) and Liu et al (2018).…”

“…Similar to Yang et al (2017) and Liu, Hou, Yang, Zhao, and Dong (2018), the findings of the present study indicate that both propionate and butyrate were undetected in most of the intestinal digesta samples. It was reported that the species or culture conditions of intestinal bacteria largely influenced the type and content of VFAs, and in conditions of excessive carbon sources, Bifidobacteria mainly produce acetate and lactate (Chen, Cao, & Liu, 2006;Wolin et al, 1999).…”

“…Liu et al. () showed that an increase in Lactobacilli and Bifidobacterium populations leads to a reduction in indole and skatole levels in an in vitro fermentation broth consisting of broiler cecal or rectal microflora. These findings do not coincide with the observations of the present study.…”

“…Sheng et al (2014) found that the addition of beneficial microbes in the diet reduces skatole levels in an in vitro fermentation broth of pig manure. Liu et al (2018) showed that an increase in Lactobacilli and Bifidobacterium populations leads to a reduction in indole and skatole levels in an in vitro fermentation broth consisting of broiler cecal or rectal microflora. These findings do not coincide with the observations of the present study.…”

Soybean Oligosaccharides Supplementation Attenuates the Fecal Odor Compounds by Modulate the Cecal Microbiota of Broilers

“…Similar study in mice revealed that administration of SBO improved the numbers of bene cal intestinal microbes [16]. In vitro studies have revealed that SBO can improve the gut microbiota balance in colon and modulate its metabolism in pigs [7], changed in the intestinal microbiota and reduced the production of odor compounds in broilers [17,18]. Antibiotics work primarily by reshaping the intestinal microbiota [19], which is known as a unique ecosystem to play a crucial role in host health and metabolism [20][21][22].…”