Fermented Aronia melanocarpa pomace improves the nutritive value of eggs, enhances ovarian function, and reshapes microbiota abundance in aged laying hens

Abstract

Introduction: There is a decline in the quality and nutritive value of eggs in aged laying hens. Fruit pomaces with high nutritional and functional values have gained interest in poultry production to improve the performance.

Methods: The performance, egg nutritive value, lipid metabolism, ovarian health, and cecal microbiota abundance were evaluated in aged laying hens (320 laying hens, 345-day-old) fed on a basal diet (control), and a basal diet inclusion of 0.25%, 0.5%, or 1.0% fermented Aronia melanocarpa pomace (FAMP) for eight weeks.

Results: The results show that 0.5% FAMP reduced the saturated fatty acids (such as C16:0) and improved the healthy lipid indices in egg yolks by decreasing the atherogenicity index, thrombogenic index, and hypocholesterolemia/hypercholesterolemia ratio and increasing health promotion index and desirable fatty acids (P < 0.05). Additionally, FAMP supplementation (0.25%-1.0%) increased (P < 0.05) the ovarian follicle-stimulating hormone, luteinizing hormone, and estrogen 2 levels, while 1.0% FAMP upregulated the HSD3B1 expression. The expression of VTG II and ApoVLDL II in the 0.25% and 0.5% FAMP groups, APOB in the 0.5% FAMP group, and ESR2 in the 1% FAMP group were upregulated (P < 0.05) in the liver. The ovarian total antioxidant capacity was increased (P < 0.05) by supplementation with 0.25%-1.0% FAMP. Dietary 0.5% and 1.0% FAMP downregulated (P < 0.05) the Keap1 expression, while 1.0% FAMP upregulated (P < 0.05) the Nrf2 expression in the ovary. Furthermore, 1.0% FAMP increased cecal acetate, butyrate, and valerate concentrations and Firmicutes while decreasing Proteobacteria (P < 0.05).

Conclusion: Overall, FAMP improved the nutritive value of eggs in aged laying hens by improving the liver-blood-ovary function and cecal microbial and metabolite composition, which might help to enhance economic benefits.

Keywords: aged laying hens; fermented Aronia melanocarpa pomace; microbiota; nutritive value; ovarian function.

Figure 1

FAMP affected the number of follicles, hormone levels, and gene expression related to hormone synthesis/receptors. The number of follicles (A), hormone levels in plasma (B) and ovary (C), and gene expression related to hormone synthesis (D) and receptor (E) of the ovary. The hens in the CON, 0.25%, 0.5%, and 1.0% groups were fed the basal diet supplemented with 0, 0.25%, 0.5%, and 1.0% fermented Aronia melanocarpa pomace (FAMP), respectively. Data are represented as means with SEM; n = 8. Values with different lowercase letters in the histogram differ significantly (P < 0.05). CYP11A1, cytochrome P450 family 11 subfamily A member 1; HSD3B1, 3 beta- and steroid delta-isomerase 1; CYP17A1, cytochrome P450 family 17 subfamily A member 1; HSD17B1, hydroxysteroid 17-beta dehydrogenase 1; CYP19A1, cytochrome P450 family 19 subfamily A member 1; ESR1, estrogen receptor 1; ESR2, estrogen receptor 2; FSHR, follicle stimulating hormone receptor; LHCGR, luteinizing hormone/choriogonadotropin receptor.

Figure 2

FAMP affected plasma biochemical indicators and egg yolk precursors synthesis and transport of the liver. The plasma biochemical indicators (A) and expression of genes related to egg yolk precursor synthesis (B) and transport (C) of the liver. The mRNA expression of VLDLR of the ovary (D) and ESR1 and ESR2 of the liver (E). The hens in the CON, 0.25%, 0.5%, and 1.0% groups were fed the basal diet supplemented with 0, 0.25%, 0.5%, and 1.0% fermented Aronia melanocarpa pomace (FAMP), respectively. Data are represented as means with SEM; n = 8. Values with different lowercase letters in the histogram differ significantly (P < 0.05). ACC, acetyl-CoA carboxylase; APOB, apolipoprotein B; ApoVLDL II, apo very low-density lipoprotein II; ESR1, estrogen receptor 1; ESR2, estrogen receptor 2; FAS, fatty acid synthase; MTTP, microsomal triglyceride transfer protein; PPARα, peroxisome proliferator-activated receptor alpha; PPAR-γ, peroxisome proliferator-activated receptor gamma; SCD1, stearoyl-CoA desaturase 1; SREBP1, sterol regulatory element binding protein 1; TC, total cholesterol; TG, triglyceride; VLDLR, very low-density lipoprotein receptor; VTG II, vitellogenin 2.

Figure 3

FAMP-affected the antioxidant capacity of the plasma and ovary. The plasma (A) and ovary (B) redox level and gene expression in the Keap1/Nrf2 signaling pathway of the ovary (C). The hens in CON, 0.25%, 0.5%, and 1.0% groups were fed the basal diet supplemented with 0, 0.25%, 0.5%, and 1.0% fermented Aronia melanocarpa pomace (FAMP), respectively. Data are represented as means with SEM; n = 8. Values with different lowercase letters in the histogram differ significantly (P < 0.05). T-AOC, total antioxidant capacity; SOD, superoxide dismutase; GSH, glutathione; GPX, glutathione peroxidase; MDA, malondialdehyde; Keap1, Kelch-like ECH-associated protein 1; Nrf2, NF-E2-related factor 2; HO-1, heme oxygenase 1; GPX1: glutathione peroxidase 1; SOD1, superoxide dismutase 1; SOD2, superoxide dismutase 2.

Figure 4

FAMP affected the cecal microbiota composition. The α- (A) and β-diversity (B) indices and community composition of cecal microbiota of aged laying hens at the phylum (C, E) and genus (D, F) levels. The hens in the CON, 0.25%, 0.5%, and 1.0% groups were fed the basal diet supplemented with 0, 0.25%, 0.5%, and 1.0% fermented Aronia melanocarpa pomace (FAMP), respectively. Data are represented as means with SEM; n = 8. *P < 0.05.

Figure 5

FAMP affected the predicted microbiota functions in cecal contents. Linear discriminant analysis effect size (LEfSe analysis, LDA score ≥ 2) for taxonomic abundance analysis (A), random forest for identifying microbial markers (B), different enrichment pathways for predicted function (C), and correlation analysis (|R| > 0.50, P < 0.05) between microbiota (top 50 genera) and differential fatty acid indices (D) of cecal microbiota of aged laying hens. The hens in the CON, 0.25%, 0.5%, and 1.0% groups were fed the basal diet supplemented with 0, 0.25%, 0.5%, and 1.0% fermented Aronia melanocarpa pomace (FAMP), respectively.

Figure 6

FAMP affected the concentrations of short-chain fatty acids in cecal content. The hens in CON, 0.25%, 0.5%, and 1.0% groups were fed the basal diet supplemented with 0, 0.25%, 0.5%, and 1.0% fermented Aronia melanocarpa pomace (FAMP), respectively. Data are represented as means with SEM; n = 8. Values with different lowercase letters in the histogram differ significantly (P < 0.05).

Figure 7

Effects and potential mechanisms of fermented Aronia melanocarpa pomace on performance, quality, and nutritive value of eggs, ovarian function, and cecal microbiota composition of aged laying hens.