Dietary supplementation of Macleaya cordata extract and Bacillus in combination improve laying performance by regulating reproductive hormones, intestinal microbiota and barrier function of laying hens

Abstract

Background: This study aimed to investigate whether the combination of Macleaya cordata extract (MCE) and Bacillus could improve the laying performance and health of laying hens better.

Methods: A total of 360 29-week-old Jingbai laying hens were randomly divided into 4 treatments: control group (basal diet), MCE group (basal diet + MCE), Probiotics Bacillus Compound (PBC) group (basal diet + compound Bacillus), MCE + PBC group (basal diet + MCE + compound Bacillus). The feeding experiment lasted for 42 d.

Results: The results showed that the laying rate and the average daily egg mass in the MCE + PBC group were significantly higher than those in the control group (P < 0.05) and better than the MCE and PBC group. Combination of MCE and Bacillus significantly increased the content of follicle-stimulating hormone (FSH) in the serum and up-regulated the expression of related hormone receptor gene (estrogen receptor-β, FSHR and luteinizing hormone/choriogonadotropin receptor) in the ovary of laying hens (P < 0.05). In the MCE + PBC group, the mRNA expressions of zonula occluden-1, Occludin and mucin-2 in jejunum was increased and the intestinal epithelial barrier detected by transmission electron microscopy was enhanced compared with the control group (P < 0.05). In addition, compared with the control group, combination of MCE and Bacillus significantly increased the total antioxidant capacity and catalase activity (P < 0.05), and down-regulated the mRNA expressions of inflammation-related genes (interleukin-1β and tumor necrosis factor-α) as well as apoptosis-related genes (Caspase 3, Caspase 8 and P53) (P < 0.05). The concentration of acetic acid and butyric acid in the cecum content of laying hens in the MCE + PBC group was significantly increased compared with the control group (P < 0.05).

Conclusions: Collectively, dietary supplementation of 600 μg/kg MCE and 5 × 10⁸ CFU/kg compound Bacillus can improve laying performance by improving microbiota to enhance antioxidant capacity and intestinal barrier, regulate reproductive hormones and the concentration of cecal short-chain fatty acids of laying hens, and the combined effect of MCE and Bacillus is better than that of single supplementation.

Keywords: Bacillus; Intestinal microbiota; Laying hens; Laying performance; Macleaya cordata extract; Reproductive hormones.

Fig. 1

The relative mRNA expressions of ER-α, ER-β, FSHR and LHCGR were analyzed by real-time qPCR. Data are presented as means ± SEM (n = 3). Different lowercase letters indicate a significant difference (P < 0.05). ER: estrogen receptor; FSHR: follicle-stimulating hormone receptor; LHCGR: luteinizing hormone/choriogonadotropin receptor

Fig. 2

Diversity analyses of microbial communities among groups. (A) Alpha diversity (Ace, Chao1, Shannon and Simpson) (B) Principal coordinates analysis (PCoA) of microbial communities among groups based on Bray–Curtis distance. (n = 6 per group)

Fig. 3

Linear discriminant analysis (LDA) effect size (LEfSe) analysis of the cecum microbial community in the four groups. (A) The cladogram of LEfSe analysis. (B) The histogram of LEfSe analysis. p_: phylum level; c_: class level; o_: order level; f_: family level; g_: genus level; s_: species

Fig. 4

(A–B) Average relative abundance of microbial species in the cecum at the phylum level (A) and genus level (B). (C–D) Relative abundance of microbial communities in the cecum contents at the phylum level (C) and genus level (D). Different lowercase letters indicate a significant difference (P < 0.05)

Fig. 5

Comparison of predicted metabolic pathway abundances between the groups by STAMP. (A) Control vs. MCE; (B) Control vs. PBC; (C) Control vs. MCE + PBC. Confidence Interval was set at 95%

Fig. 6

The concentrations of short-chain fatty acid (SCFAs) in the cecal contents of the laying hens. Data are presented as means ± SEM (n = 6). Different lowercase letters indicate a significant difference (P < 0.05)

Fig. 7

Effects of dietary supplementation with different biological feed additives on the Intestinal physical barrier function. (A) Histomorphology of the jejunum in laying hens. (B) The relative mRNA expressions of ZO-1, Claudin-1, Occludin and MUC-2 were analyzed by real-time qPCR. Data are presented as means ± SEM (n = 3). Different lowercase letters indicate a significant difference (P < 0.05). ZO-1: zonula occluden 1; MUC-2: mucin-2. (C) Transmission electron micrographs of the jejunum microvilli in laying hens

Fig. 8

Effects of dietary supplementation with different biological feed additives on the relative mRNA expression of cytokines (A) and apoptosis factors (B). Data are presented as means ± SEM (n = 3). Different lowercase letters indicate a significant difference (P < 0.05). IL: interleukin; TNF-α: tumor necrosis factor-α

Fig. 9

Heatmap of Spearman’s correlation between the Intestinal microbiota and antioxidant indicators or gonadotropin at the genus level. The intensity of the colors represented the degree of association (red, negative correlation; blue, positive correlation). Significant correlations were marked by *P < 0.05; **P < 0.01; ***P < 0.001

Fig. 10

Graphical summary of the effect of Macleaya cordata extract and Bacillus in combination on the performance and intestinal health of laying hens