# Preliminary Study on Sexual Maturation Pattern of Shenxian Pigs and Molecular Characteristics of Sexual Precocity in Boars

## TL;DR

This study examines the sexual maturation of Shenxian pigs and identifies genes linked to early sexual development in boars.

## Contribution

The study identifies candidate genes SRD5A1 and CYP11B2 associated with sexual precocity in Shenxian pigs.

## Key findings

- Boars reach sexual maturity at an average of 116 days in winter and 129 days in summer.
- Transcriptome analysis identified 6016 upregulated genes related to reproduction and sperm function.
- SRD5A1 and CYP11B2 are candidate genes influencing precocious puberty in Shenxian pigs.

## Abstract

This study aimed to determine the sexual maturation pattern of Shenxian pigs by combining observation, teaser boar testing, and back-pressure methods, and to apply this pattern for early breeding to shorten the generation interval and increase production efficiency. Subsequently, high-throughput transcriptome technology was used to compare gene expression levels in testicular tissues of Shenxian pigs before and after sexual maturity, as well as between sexually mature Shenxian pigs and Shenxian × Large White crossbred pigs. Functional analysis of differentially expressed genes (DEGs) was conducted to screen candidate genes related to sexual maturation and precocity in Shenxian pigs. The results showed that boars reached sexual maturity at an average age of 116 days in winter and 129 days in summer. For sows, the first estrus occurred at 114 days, the second at 134 days, and the third at 154 days in winter; corresponding ages in summer were 125, 144, and 164 days, respectively. The duration of estrus was around 3 days, and the estrus interval was approximately 20 days for both seasons. Comparative trials revealed no significant change in production performance when selection and first mating were conducted at 5 months of age compared to previous practices. Transcriptome sequencing of testicular tissues before and after sexual maturity in Shenxian pigs identified 6016 upregulated genes, primarily associated with reproduction and sperm function, influencing sexual maturation. The comparison between sexually mature Shenxian pigs and crossbred pigs identified 582 upregulated genes, mainly involved in hormone synthesis, affecting the onset of puberty in Shenxian pigs. After intersecting and functionally analyzing the upregulated genes from both sets, SRD5A1 and CYP11B2 were selected as the most likely candidate genes to affect precocious puberty in Shenxian pigs.