Integrated Transcriptomic-Metabolomic Analysis Reveals the Effect of Different Light Intensities on Ovarian Development in Chickens

Abstract

Light is a key environmental factor regulating reproduction in avians. However, the mechanism of light intensity regulating ovarian development is still unclear. In this study, 5-week-old (5 wk) partridge broiler breeders were randomly divided into a low-light-intensity group (LL group) and a natural-light-intensity group (NL group) (n = 100). In the rearing period (5 wk to 22 wk), the light intensity of the LL group and NL group were 0.41 ± 0.05 lux and 45.39 ± 1.09 lux, and in the laying period (23 wk to 32 wk) they were 23.92 ± 0.06 lux and 66.93 ± 0.76 lux, respectively. Samples were collected on 22 wk and 32 wk. The results showed that the LL group had a later age at first egg and a longer laying period than the NL group. Serum P4 and LH levels in the LL group were higher than in the NL group on 22 wk (p < 0.05). On 32 wk, P4, E2, LH and FSH levels in the LL group were lower than in the NL group (p < 0.05). Ovarian transcriptomics and metabolomics identified 128 differentially expressed genes (DEGs) and 467 differential metabolites (DMs) on 22 wk; 155 DEGs and 531 DMs on 32 wk between two groups. An enrichment analysis of these DEGs and DMs identified key signaling pathways, including steroid hormone biosynthesis, neuroactive ligand-receptor interaction. In these pathways, genes such as CYP21A1, SSTR2, and NPY may regulate the synthesis of metabolites, including tryptamine, triglycerides, and phenylalanine. These genes and metabolites may play a dominant role in the light-intensity regulation of ovarian development and laying performance in broiler breeders.

Keywords: light intensity; metabolomics; ovarian development; partridge chicken; transcriptomics.

Figure 1

Effect of different light intensities on laying performance. (A) Experimental design of this study. Two hundred 5-week-old (5 wk) partridge broiler breeders with similar body weights were selected and randomly divided into low-light-intensity group (LL group) and natural-light-intensity group (NL group) (n = 100). The light intensity of the LL group and NL group from 5 wk to 22 wk were 0.41 ± 0.05 lux and 45.39 ± 1.09 lux, respectively; and from 23 wk to 32 wk, they were 23.92 ± 0.06 lux and 66.93 ± 0.76 lux, respectively. Tissue and blood samples were collected on 22 wk and 32 wk. (B) Laying rate.

Figure 2

Effects of different light intensities on GSI% and numbers of follicles. (A) GSI% (GSI% = gonadal weight/body weight × 100%); (B) Number of large yellow follicles (LYFs, follicle diameter > 8 mm); (C) Number of small yellow follicles (SYFs, follicle diameter = 6–8 mm); (D) Number of white follicles (WFs, follicle diameter < 6 mm). Data are presented as the mean ± SEM, n = 10. ** indicates p < 0.01.

Figure 3

Transcriptomic analysis in ovaries under different light intensities on 22 wk. (A) PCA plot; (B) DEGs bar plot; (C) Gene volcano plot; (D) DEGs clustering heatmap; (E) DEGs GO enrichment analysis plot; (F) DEGs KEGG enrichment analysis plot.

Figure 4

Transcriptomic analysis in ovaries under different light intensities on 32 wk. (A) PCA plot; (B) DEGs bar plot; (C) Gene volcano plot; (D) DEGs clustering heatmap; (E) DEGs GO enrichment analysis plot; (F) DEGs KEGG enrichment analysis plot.

Figure 5

Metabolomic analysis in ovaries under different light intensities on 22 wk. (A) PCA plot; (B) OPLS-DA scores plot; (C) OPLS-DA model validation plot; (D) DM clustering heatmap; (E) DM bar plot; (F) metabolites’ volcano plot; (G) DM KEGG enrichment analysis plot.

Figure 6

Metabolomic analysis in ovaries under different light intensities on 32 wk. (A) PCA plot; (B) OPLS-DA scores plot; (C) OPLS-DA model validation plot; (D) DM clustering heatmap; (E) DM bar plot; (F) metabolites’ volcano plot; (G) DM KEGG enrichment analysis plot.

Figure 7

Integrated analysis of transcriptomics and metabolomics in ovaries under different light intensities. (A) Venn diagram of intersection of DEG and DM enrichment signaling pathways on 22 wk; (B) top 10 pathways of the intersection of DEG and DM enrichment signaling pathways on 22 wk; (C) Venn diagram of intersection of DEG and DM enrichment signaling pathways on 32 wk; (D) top 10 pathways of the intersection of DEG and DM enrichment signaling pathways on 32 wk.