Acta Veterinaria et Zootechnica Sinica ›› 2025, Vol. 56 ›› Issue (2): 643-656.doi: 10.11843/j.issn.0366-6964.2025.02.016

• Animal Genetics and Breeding • Previous Articles     Next Articles

Comparative Study on Muscle Fiber Development Phenotype and Gene Expression Profile of Two Mongolian Horse Populations

HU Hanwen1(), BAO Tugeqin1, REN Xiujuan1, DING Wenqi1, GONG Wendian1, JIA Zijie1, SHI Lin1, MA Muren2, Baorigele 3, DUGARJAVIIN Manglai1, BAI Dongyi1,*()   

  1. 1. Key Laboratory of Equus Germplasm Innovation of Ministry of Agriculture and Rural Affairs, Inner Mongolia Key Laboratory of Equine Science Research and Technology Innovation, Equus Research Center, Inner Mongolia Agricultural University, Hohhot 010018, China
    2. Xilinhot Agricultural and Animal Husbandry Technology Extension Center, Xilinhot 026000, China
    3. Horqin Left Back Banner Livestock and Fishery Technology Service Center, Horqin 028100, China
  • Received:2024-05-20 Online:2025-02-23 Published:2025-02-26
  • Contact: BAI Dongyi E-mail:havyn0502@qq.com;baidongyi1983@163.com

Abstract:

To investigate the differences in muscle growth among different populations of Mongolian horses, the muscle phenotype and molecular-level differences between the Mongolian horse populations with the most significant environmental differences and the greatest geographical distance(Baerhu horse and Wushen horse) was compared. The experimental animals in this study consisted of 3 Baerhu horses raised in the Chenbaerhu Banner and 3 Wushen horses raised in the Wushen Banner. All horses were healthy stallions, free-range grazing in the wild. The average age of the horses in each population was 5 years, with similar body conditions within each population. The pre-slaughter live weight of the Baerhu horses was (303.10±14.10) kg, and the carcass weight was (148.29±15.43) kg. The pre-slaughter live weight of the Wushen horses was (287.90±37.5) kg, and the carcass weight was (140.83±5.04) kg. The experimental animals were divided into two populations based on their breed, with 3 repetitions per group. All animals were slaughtered, and their gluteus medius muscles were collected. After the muscle samples were embedded in paraffin, HE and immunohistochemistry staining were performed. The muscle fiber area and the proportion of slow-twitch muscle fibers were statistically analyzed. Additionally, transcriptome sequencing was conducted on the collected muscle samples. The sequencing data were analyzed for differentially expressed genes using the DESeq2 software, and GO and KEGG enrichment analyses were performed using the David online tool. Finally, qRT-PCR was used to validate the sequencing results. In this experiment, HE staining and immunohistochemical staining revealed that the average muscle fiber area of the gluteus medius in Baerhu horses was (2 592±180.92) μm2, while in Wushen horses it was (1 997±73.39) μm2, with a significant difference between the two populations (P < 0.05). The proportion of slow-twitch muscle fibers in the gluteus medius of Baerhu horses was (10.34±0.59)%, while in Wushen horses it was (8.14±0.81)%, with no significant difference between the two populations (P>0.05).This study identified a total of 1 103 differentially expressed genes in the gluteus medius of Baerhu and Wushen horses, with 460 upregulated genes and 643 downregulated genes expressed in the gluteus medius of Wushen horses. The study found that MYH15, MYOZ2, several glutamate receptor genes, and several GABAA receptor genes were highly expressed in the gluteus medius of Baerhu horses, while MYH6 and FOXO1 genes were highly expressed in the gluteus medius of Wushen horses. Enrichment analysis of the differentially expressed genes revealed 208 enriched items in the GO analysis and 65 pathways in the KEGG analysis. These enriched items and pathways were mainly associated with glutamate signaling, GABA signaling, and muscle growth and development. This study investigates the gluteus medius muscle of the Baerhu horse and the Wushen horse, finding that the fiber area of the gluteus medius in Baerhu horses is significantly larger than that in Wushen horses, while the proportion of slow muscle fibers shows no significant difference. At the molecular level, there are notable differences between the two populations, particularly in muscle fiber types, fiber area, and neuromuscular signaling in the muscle spindles.

Key words: Baerhu horse, Wushen horse, muscle fiber area, transcriptome

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