# Ovarian Transcriptome Profile from Egg-Laying Period to Incubation Period of Changshun Green-Shell Laying Hens

## TL;DR

This study explores how the ovaries of a Chinese chicken breed change from egg-laying to incubation, identifying genes and pathways involved in these processes.

## Contribution

The study identifies 1650 differentially expressed genes and key pathways linked to ovarian development during broodiness in Changshun hens.

## Key findings

- 1650 differentially expressed genes were identified, with 429 up-regulated and 1221 down-regulated.
- Key pathways like focal adhesion and MAPK signaling were linked to follicle development in chicken ovaries.
- Eight candidate genes were suggested to play roles in ovarian development during the transition from egg-laying to incubation.

## Abstract

Background/Objectives: The Changshun green-shell laying hen with a strong broodiness is a Chinese indigenous chicken breed. Little is known about the mechanisms responsible for the ovary development of Changshun green-shell laying hens from the egg-laying period (LP) to the incubation period (BP). Methods: A total of six hens were selected from LP (n = three) and BP (n = three) at 28 weeks old. The RNA sequencing (RNA-seq) of ovaries from hens in LP and BP groups was performed to identify candidate genes and pathways associated with broodiness. Results: We identified 1650 differently expressed genes (DEGs), including 429 up-regulated and 1221 down-regulated DEGs, in chicken ovaries between LP and BP groups. Gene ontology term (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that these DEGs were mainly involved in the pathways related to follicle development in chicken ovaries, including focal adhesion, the MAPK signaling pathway, and the FoxO signaling pathway, and vascular smooth muscle contraction, ECM–receptor interaction, and the GnRH signaling pathway were down-regulated in incubating ovaries. Eight candidate genes (EGFR, VEGFRKDRL, FLT1, KDR, PDGFRA, TEK, KIT and FGFR3) related to angiogenesis, folliculogenesis, steroidogenesis and oogenesis in ovaries were suggested to play important roles in the ovarian development of Changshun hens during the transition from LP to BP. Conclusions: This study identified a range of genes and several pathways that may be involved in regulating the broodiness of Changshun green-shell laying hens. These data are helpful to further enrich our understanding of the mechanism of incubation behaviour in chickens.