# Heterosis-Based Identification of Candidate Genes Associated with Lipid Metabolism and Meat Quality in Crossbred Pigs

## TL;DR

This study identifies genes linked to better meat quality in crossbred pigs, showing how crossbreeding improves traits like fat content and tenderness.

## Contribution

The study reveals overdominant gene expression patterns and key metabolic pathways contributing to hybrid vigor in pork quality.

## Key findings

- Crossbred pigs showed improved meat quality traits like color, fat content, and tenderness.
- Transcriptome analysis identified 1358 overdominantly expressed genes linked to lipid metabolism and muscle development.
- Genes like FASN, CPT1A, and PPARG were associated with intramuscular fat and meat tenderness.

## Abstract

Heterosis, or hybrid vigor, refers to the improved traits seen in crossbred animals compared to their purebred parents. This study examined the muscle gene expression of Songliao Black Pig, Large White × Landrace pig, and their crossbred offspring to understand the genetic basis of better meat quality in hybrids. The crossbred pigs showed improved meat color, moderate fat content, and tenderness. Transcriptome analysis revealed key pathways and genes involved in fat metabolism and muscle development, such as mTOR, AMPK, and insulin signaling. These results help explain how crossbreeding improves meat quality and provide important insights for designing breeding programs focused on producing better-quality pork.

Heterosis or hybrid vigor is a well-recognized biological phenomenon, where crossbred progeny exhibit superior growth performance, stress tolerance, and productivity compared to their purebred parents. However, the molecular mechanisms underlying heterosis for meat quality traits in pigs remain poorly understood. In this study, we compared the longissimus dorsi muscle transcriptomes of Songliao Black Pig (SBP), Large White × Landrace pig (LWLDP), and their crossbred progeny (BXW) to uncover genetic mechanisms contributing to hybrid vigor in meat quality. Results identified 4290 differentially expressed genes (DEGs) in SBP vs. BXW and 3820 in LWLDP vs. BXW. Among these, 1358 genes displayed overdominant expression in BXW, indicating potential heterotic activation. Functional enrichment analysis identified key pathways involved in lipid metabolism, energy homeostasis, and muscle growth, including mTOR, AMPK, insulin, PI3K-Akt, MAPK, and calcium signaling. Over dominantly expressed genes such as FASN, CPT1A, PPARG, ACACA, PPARA, SREBF1, FABP4, DGAT1, PPARGC1A, LIPC, ACSL5, PLCG2, and members of the COX family were closely associated with intramuscular fat deposition, oxidative metabolism, and tenderness. Phenotypically, BXW exhibited improved meat color, moderate fat deposition, and lower shear force compared with parental breeds, clearly aligning with transcriptomic findings. These transcriptomic findings offer valuable insights into precision breeding strategies targeting superior meat quality through genomic selection and crossbreeding programs.