Effects of Adding Dietary Fiber on the Gut Microbiota, Short-Chain Fatty Acids and Metabolism of Layer Chickens

Dietary fiber is important for the growth performance and health of chickens. However, chickens must rely on fiber-degrading bacteria to grade fiber into monosaccharides due to a lack of endogenous fiber-degrading enzymes. Some of monosaccharides are then fermented into short-chain fatty acids (SCFAs) by SCFA-producing bacteria. SCFAs further regulate the host metabolism via special G protein-coupled receptors (GPRs) such as GPR43. In recent years, more and more research has focused on the impacts of adding dietary fiber on gut microorganisms and microbial metabolites-SCFAs of chickens. However, few works have focused on SCFA receptors and their impacts on metabolism of chickens. Understanding of this would help to explore how the dietary fiber affects chickens’ metabolism via SCFAs and their receptors. Given this, three different levels (0%, 1%, and 2%) of dietary fiber–eubiotic lignocellulose were added to the feed of ISA brown hens (IBH) for 0–8 weeks, with the aim of observing the effects of adding it on the gut microbiota, SCFAs, their receptors and metabolism of chickens. The results showed that the addition of 1% significantly increased the relative abundance of SCFAs-producing bacteria Sutterella, Oscillospira and Lactobacillus panis and the production of SCFAs (P < 0.05). The primer sequences of the GPR43 and reaction conditions designed in this experiment were applied to chickens. However, because the difference of the concentration of SCFAs was not great among groups, there was no significant change in the relative expression of the GPR43 mRNA in the liver and cecum (P > 0.05), resulting in there being no significant difference among groups in the appetite metabolism indexes including glucagon-like peptide-1 (GLP-1) and peptide tyrosine-tyrosine (PYY) and glucose metabolism indexes including blood glucose and liver glycogen of chickens (P > 0.05). The addition of 1% eubiotic lignocellulose is beneficial to increase the relative abundance of some SCFA-producing bacteria and the production of SCFAs at 8 weeks. The effects of added eubiotic lignocellulose on the relative expression of GPR43 mRNA and the metabolism of chickens were slight.