Transcriptome analysis reveals the mechanism by which fermented Broussonetia papyrifera influences meat quality of Taihe black-bone silky fowl

Abstract

This study was designed to investigate the effects of Fermented Broussonetia papyrifera (FBP) on growth performance, meat quality, and the expression of meat quality-related genes in Taihe black-bone silky fowl (TBsf). In the present study, 360 ninety-day-old TBsfs (body weight = 781 ± 0.85 g) were divided into 4 groups with 5 replicates (18 hens per replicate), of which the control group was fed the basal diet and the 3 experimental groups were supplemented with 2%, 4%, and 8% FBP. After 75 days, 8 TBsfs in each group were randomly selected to collect their left pectoral muscles for meat quality and transcriptome analysis. Compared with the control group, 4% FBP improved the growth performance and meat quality of TBsf, evidenced by the increasing trend in the ratio of feed intake to body weight gain (P = 0.082), and significantly increased equivalent umami concentration (EUC), amino acid, and nucleotide compositions (P < 0.05). In addition, the remaining meat quality indices including the yellowness of meat color, muscle fiber density, and shear force were also improved in the 4% group (P < 0.05), with consistent improvements in the 8% FBP group. The transcriptome results indicated that FBP may regulate muscle fiber growth and development through the Forkhead box O (FoxO) and mitogen-activated protein kinase (MAPK) signaling pathways, and regulate meat color through the adipocytokine signaling pathway. Weighted gene coexpression network analysis (WGCNA) further revealed the candidate genes involved in amino acid metabolism and nucleotide metabolism, and the trends of these genes were inflecting with the 4% FBP group. Together, these results suggest that FBP significantly improved the growth performance, and meat quality of TBsf, with 4% FBP as the optimal addition ratio, and the transcriptome analysis revealed the mechanism of gene regulation.

Keywords: Fermented Broussonetia papyrifera; Meat quality; Taihe black-bone silky fowl; Transcriptome.

Fig. 1

Morphological characteristics of the pectoral muscle in TBsfs. (A) Histological observations of the pectoral muscle after staining with H&E (20 × magnification). (B) Pectoral muscle fiber density. (C) Pectoral muscle fiber area. (D) Pectoral muscle fiber diameter. Control: basal diet; FBP groups: 2%, 4%, or 8% FBP supplemented in the basal diet to replace equivalent amounts of rice bran. FBP = fermented Broussonetia papyrifera; TBsfs = Taihe black-bone silky fowls; A = ANOVA; L = linear; Q = quadratic. The columns represent the means ± SEMs (n = 8). For each index, bars with a common letter indicate significant differences (P < 0.05).

Fig. 2

Expression profiles of DEGs in the pectoral muscles of TBsf. (A) Venn diagram representing the number and overlapping sets of DEGs obtained from three comparisons. (B) Line graph representing the number of DEGs in three comparisons. Control: basal diet; FBP groups: 2%, 4%, or 8% FBP supplemented in the basal diet to replace equivalent amounts of rice bran. FBP = fermented Broussonetia papyrifera; TBsfs = Taihe black-bone silky fowls; DEGs = differentially expressed genes.

Fig. 3

GO and KEGG functional annotation of target DEGs. (A) GO functional annotations for upregulated target DEGs (top 10 for each ontology). (B) GO function annotations for downregulated target DEGs (top 10 for each ontology). (C) The top 20 enriched GO terms for the target DEGs. (D) The top 20 enriched KEGG pathways of the target DEGs. Control: basal diet; FBP groups: 2%, 4%, or 8% FBP supplemented in the basal diet to replace equivalent amounts of rice bran. FBP = fermented Broussonetia papyrifera; TBsfs = Taihe black-bone silky fowl; BP = biological process; CC = cellular component; MF = molecular function; MAPK = mitogen-activated protein kinase; JNK = c-Jun N-terminal kinase; ErbB = epidermal growth factor receptor; mTOR = mammalian target of rapamycin; FoxO = Forkhead box O.

Fig. 4

Weighted gene coexpression network analysis (WGCNA) of pectoral muscles in TBsf with the addition of different ratios of FBP. (A) Modular clustering tree analysis of genes. (B) Heatmap of module correlations with amino acids and nucleotides. Only modules with P < 0.05 are displayed with Pearson correlation coefficients. (C) Stacked histograms of the KEGG pathways directly related to nucleotide metabolism for the pink and royal blue modules. (D) Stacked histograms of KEGG pathways directly related to amino acid metabolism for the pink, royal blue, black and dark green modules. (E) Interaction network of candidate genes related to amino acid metabolism. (F) Interaction network of candidate genes related to nucleotide metabolism. Node size is positively correlated with degree, edge width is positively correlated with connection strength, and the color of the node is derived from the relevant color module. Control: basal diet; FBP groups: 2%, 4%, or 8% FBP supplemented in the basal diet to replace equivalent amounts of rice bran. FBP = fermented Broussonetia papyrifera; TBsfs = Taihe black-bone silky fowls; EUC = equivalent umami concentration; UMP = 5′-uridine monophosphate; GMP = 5′-guanosine monophosphate; IMP = 5′-inosine monophosphate; AMP = 5′-adenosine monophosphate; FAA = free amino acids; EAA = essential amino acids; NEAA = nonessential amino acids; TAA = total amino acids.

Fig. 5

Heatmap of candidate genes. Up-regulation and down-regulation are separately colored in red and blue. Control: basal diet; FBP groups: 2%, 4%, or 8% FBP supplemented in the basal diet to replace equivalent amounts of rice bran. FBP = fermented Broussonetia papyrifera.