Yeast Culture Improves Egg Quality and Reproductive Performance of Aged Breeder Layers by Regulating Gut Microbes

Abstract

This study aimed to investigate the effects of dietary yeast culture (YC) supplementation on egg production, egg quality, reproductive performance, immune functions, antioxidant capacity, and intestinal microbial structure of aged hens. A total of 224 Hy-Line Brown layers (54 weeks old) were randomly assigned to two dietary treatments. The control group was fed a basal diet and the YC group was supplemented with YC at 2.0 g/kg of their diet. Each group had seven replicates with 16 hens each. The study was conducted over a period of 8 weeks. Results indicated that YC addition had no significant effect on laying performance. However, it significantly improved egg quality and hatching rate, enhanced ileum crude fat digestibility, increased the serum parameters of lysozyme (LZM) and total antioxidation capacity (T-AOC) (P < 0.05), and reduced serum aspartate aminotransferase (AST) levels (P < 0.05). Using 16S rRNA analysis, we found that addition of YC significantly altered ileum microbial composition. Linear discriminant analysis of effect size (LEfSe) showed significant enrichment of Bacilli and Lactobacilli in the YC group. PICRUSt analysis of the ileal microbiota found that glutathione metabolism, ubiquinone, and other terpenoid-quinone biosynthesis and lipopolysaccharide biosynthesis protein pathways were highly enriched in the YC group compared with the basal diet group. In summary, the addition of YC can improve egg quality, immune functions, antioxidant capacity, reproduction efficiency, and digestive absorption by increasing the abundance of Lactobacilli and Bacilli. Furthermore, it also improves the biosynthesis of lipopolysaccharide proteins, glutathione metabolism, and the synthesis of ubiquinone and other terpenoid-quinone metabolic pathways.

Keywords: aged layer; egg quality; microbiome; performance; reproduction; yeast culture.

FIGURE 1

The overall description of gut microorganism in basal diet control group (DC) and yeast culture (YC) group. (A) The alpha diversity rarefaction curve of 16S rRNA gene sequence to estimate the rationality of sequencing depth (at 97% similarity). X-axis was the sequencing sampling depth, and the Y-axis was the corresponding Good’s Coverage index. Different sample curves were represented by different colors. (B) Species accumulation curve is used to estimate the rationality of sequencing sample quantity. The X-axis is the number of sequencing samples, and the Y-axis is the number of operational taxonomic unit (OTU) detected. (C) Alpha-diversity evaluation of ileum flora richness and evenness. (D) Venn diagram is used to represent the amount of OUTs that is unique or common to each group.

FIGURE 2

Principal coordinate analysis of ileal microbial community. (A) (PCoA)-2D. (B) (PCoA)-3D.

FIGURE 3

The microbial community structure in DC and YC groups. (A) Stacked bar chart of ileum microbial structure at phylum level. Top15 bacterial are shown in the graph. (B) Stacked bar chart of ileum microbial structure at genus level. Top15 bacterial are shown in the graph. (C) Relative abundance of microbial which was greater than 1% between DC and YC groups.

FIGURE 4

Ileal marker microbial in DC and YC groups. (A,B). Linear discriminant analysis coupled with effect size (LEfSe) is used to explore differences between treatment groups. (A) Cladogram plot of LEfSe analysis. (B) Histogram of LDA value distribution between DC and YC groups. (C) Indicator analysis is used to search for Indicator OTUs. The first column is phylum level annotation information, the second column is genus level annotation information, the third column represents the corresponding OTU, the fourth column represents the relative abundance of each OTU, and the bubble diagram represents the indicator values. Only significant (P < 0.05) OTUs are shown.

FIGURE 5

Microbial community network analysis is used to explore the relationship between the two groups. Each genus is represented by different nodes, the size of which represents the relative abundance of the genus, and the color of the nodes represents the degree. The thickness of the edges represents the correlation coefficient, the thicker, the greater of correlation. The red line represents positive correlation, and the cyan line represents negative correlation.

FIGURE 6

The microorganism function prediction in DC and YC groups. The second level (A) and third level (B) of Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway are shown in the extended error bar. The corrected p-value is listed at the right. Blue and yellow represent DC and YC, respectively.