Alfalfa-containing diets alter luminal microbiota structure and short chain fatty acid sensing in the caecal mucosa of pigs

Jiawei Wang,Ning Jiao,Chunfu Qin,Wenjuan Sun,Ting He,Weiyun Zhu,Jingdong Yin,Kai Qiu,Xin Zhang

doi:10.1186/s40104-017-0216-y

Abstract

BackgroundPork produced by outdoor-reared pigs raised mostly on alfalfa pastures attracts increasing population of consumer from most of the world. In China, pigs were raised with alfalfa-containing diets to seek for good quality pork. However, the influence of dietary alfalfa involving high level of insoluble dietary fiber (IDF) on pig intestinal luminal microbiota composition remains unclear. The objective of this study was to investigate the effects of alfalfa on luminal microbiota and short chain fatty acids (SCFA) production, and gene expressions involved in SCFA sensing, transporting and absorbing in pig caecal mucosa.ResultsTwenty-four growing pigs were randomly allotted to four diets containing 0%, 5%, 10% and 15% alfalfa meal for a 28-d experiment. Ingestion of alfalfa meal-contained diets significantly increased the ratio of body weight gain to feed consumption. Illumina MiSeq sequencing of the V3 region of the 16S rRNA genes showed that alfalfa-containing diet significantly decreased the relative abundance of genera Turicibacter, Acidiphilium, Paracoccus, Propionibacterium, Corynebacterium, Pseudomonas, Acinetobacter, and Staphylococcus, and increased the relative abundance of genera Lachnospira, Marvinbryantia, and Desulfovibrio in the caecal digesta. Butyrate concentration was significantly increased in the hindgut by the supplementation of alfalfa meal in diets. The mRNA gene expressions of FFAR3, SMCT1, MCT1, PYY, and GCG were significantly increased in the caecal mucosa of pigs fed alfalfa meal.ConclusionsOur results suggested that alfalfa-containing diet has exerted significant impacts on caecal microbiota composition, butyrate concentration and significantly upregulated mRNA expression of host caecal mucosal genes involved in SCFA sensing and absorption as well as regulation of satiety.

Highlights

Pork produced by outdoor-reared pigs raised mostly on alfalfa pastures attracts increasing population of consumer from most of the world
The diets supplemented with 5, 10 and 15% of alfalfa meal increased the gain:feed (G:F) ratio compared with the control diet while no difference was observed among the three alfalfa meal contained diets
Because major variation of dietary fiber contents among treatments derived from insoluble dietary fiber (IDF) (Table 1), we deduced that differences observed in gut microbiota, short chain fatty acids (SCFA), and gene expression may be due to the specific effect of alfalfa-derived IDF

Summary

Introduction

Pork produced by outdoor-reared pigs raised mostly on alfalfa pastures attracts increasing population of consumer from most of the world. In China, pigs were raised with alfalfa-containing diets to seek for good quality pork. The influence of dietary alfalfa involving high level of insoluble dietary fiber (IDF) on pig intestinal luminal microbiota composition remains unclear. A high-fiber diet can increase the activity of fiber-degrading related bacteria in the large intestine of growing pigs [3, 4]. Along with increasing demand of these styles of pork, the effect of alfalfa on gut microbial community of pigs rapidly drew more attention

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