Mucosal Microbiota and Metabolome in the Ileum of Hu Sheep Offered a Low-Grain, Pelleted or Non-pelleted High-Grain Diet.

Ruiyang Zhang,David M Irwin,Huiting Ma,Fei Xie,Limei Lin,Shengyong Mao,Zhe Wang,Zhiqiang Zhong,Shuyi Zhang

doi:10.3389/fmicb.2021.718884

Ruiyang Zhang, David M Irwin + Show 7 more

Open Access

https://doi.org/10.3389/fmicb.2021.718884

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Abstract

Alterations in mucosal microbiota and metabolites are critical to intestinal homeostasis and host health. This study used a combination of 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC/MS) to investigate mucosal microbiota and their metabolic profiles in the ileum of Hu sheep fed different diets. Here, we randomly allocated 15 Hu sheep to three diets, a non-pelleted low-grain diet (control diet; CON), a non-pelleted high-grain diet (HG), and a pelleted high-grain diet (HP). After 60 days of treatment, ileal mucosal samples were collected for microbiome and metabolome analysis. The results of principal coordinate analysis and permutation multivariate analysis showed that there was a tendency for microbial differentiation between the CON and HG groups (P < 0.1), although no significant difference between the HG and HP groups was observed (P > 0.05). Compared with the CON diet, the HG diet decreased (P < 0.05) the abundance of some probiotic species (e.g., Sphingomonas and Candidatus Arthromitus) and increased (P < 0.05) the abundance of acid-producing microbiota (e.g., Succiniclasticum, Nesterenkonia, and Alloprevotella) in the ileal mucosa. Compared with the HG diet, the HP diet decreased (P < 0.05) the abundance of Alloprevotella and increased (P < 0.05) the abundance of Mycoplasma in the ileal mucosa. Furthermore, partial least squares discriminant analysis and orthogonal partial least-squared discriminant analysis indicated that different dietary treatments resulted in different metabolic patterns in the ileal mucosa of the CON, HG, and HP groups. The HG diet altered (VIP > 1 and P < 0.05) the metabolic patterns of amino acids, fatty acids, and nucleotides/nucleosides (such as increased amounts of ornithine, tyrosine, cis-9-palmitoleic acid, and adenosine) compared with the CON diet. However, 10 differential metabolites (VIP > 1 and P < 0.05; including tyrosine, ornithine, and cis-9-palmitoleic acid) identified in the HG group exhibited a diametrically opposite trend in the HP group, suggesting that the HP diet could partially eliminate the changes brought upon by the HG diet. Collectively, our findings demonstrate that different diets altered the ileal mucosal microbiota and metabolites and provide new insight into the effects of high-grain diets on the intestinal health of ruminant animals.

Highlights

A high-grain (HG) feeding is often used during the breeding of ruminant species as it improves production performance and has economic benefits
Rarefaction curves of the ileal mucosal microbiota were conducted, and the results showed that the samples provided sufficient sequences to detect most of the microbial species (Supplementary Figure 1)
To further evaluate the effects of different diets on ileal mucosal microbiota, we conducted a statistical analysis at different microbial taxonomic levels

Summary

Introduction

A high-grain (HG) feeding is often used during the breeding of ruminant species as it improves production performance and has economic benefits. The application of HG diets while ensuring the health of ruminant animals is an important issue that needs to be resolved for the breeding of ruminants. With the development of lamb breeding programs with increased productivity, feeding of the animals with pelleted concentrates has been promoted and implemented in many modern fattening systems (Islam et al, 2017). Accumulating evidence has indicated that the application of pelleted concentrates is an effective method to avoid selective eating, reduce nutrition wastage during storage and feeding, save labor, and increase rearing profitability (Blanco et al, 2015; Zhong et al, 2018; Li et al, 2021b). Previous studies have demonstrated that pelleted HG diets improve rumen fermentation and amplify the use of simple sugars by rumen microbiota (Trabi et al, 2019), information regarding the impact of pelleted HG diets on the small intestine is limited

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