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Abstract Racing performance traits are the main indicators for evaluating the performance and value of sport horses. The aim of this study was to identify the key genes for racing performance traits in Yili horses by performing a genome-wide association study (GWAS). Breeding values for racing performance traits were calculated for Yili horses (n = 827) using an animal model. Genome-wide association analysis of racing performance traits in horses (n = 236) was carried out using the Blink, and FarmCPU models in GAPIT software, and genes within the significant regions were functionally annotated. The results of GWAS showed that a total of 24 significant SNP markers (P

This study aims to analyze the whole-genome DNA methylation differences in Yili horses before and after racing, with the goal of identifying differentially methylated genes associated with racing performance and exploring the epigenetic mechanisms underlying exercise in horses. Blood samples were collected from the jugular veins of the top 3 Yili horses in a 5000 m race, which included 25 competitors, both prior to and within 5 min after the race. Genomic DNA was extracted, followed by sequencing using Whole-Genome Bisulfite Sequencing (WGBS) to assess DNA methylation levels, differentially methylated regions (DMRs), and differentially methylated genes (DMGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the identified DMGs to select candidate genes potentially associated with equine exercise. A total of 18,374 differentially methylated CG regions, 254 differentially methylated CHG regions, and 584 differentially methylated CHH regions were identified. A total of 4293 DMGs were anchored in gene bodies and 2187 DMGs in promoter regions. Functional analysis revealed that these DMGs were mainly enriched in terms related to binding and kinase activity, as well as pathways such as PI3K-Akt signaling and Kaposi sarcoma-associated herpesvirus infection. Further analysis indicated that genes such as IFNAR2, FGF4, and DGKH could be potential candidate genes associated with equine athletic performance. The findings of this study contribute to understanding the epigenetic regulatory mechanisms of equine athletic performance, providing a reference for further in-depth research on horse racing.

IntroductionThe Kazakh horse, renowned for its excellence as a breed, exhibits distinctive reproductive traits characterized by early maturity and seasonal estrus. While normal reproductive function is crucial for ensuring the breeding and expansion of the Kazakh horse population, a noteworthy decline in reproductive capabilities is observed after reaching 14 years of age.MethodsIn this study, ovarian granulosa cells (GCs) were meticulously collected from Kazakh horses aged 1, 2, 7, and above 15 years old (excluding 15 years old) for whole transcriptome sequencing.ResultsThe analysis identified and selected differentially expressed mRNAs, lncRNAs, miRNAs, and circRNAs for each age group, followed by a thorough examination through GO enrichment analysis. The study uncovered significant variations in the expression profiles of mRNAs, lncRNAs, miRNAs, and circRNAs within GCs at different stages of maturity. Notably, eca-miR-486-3p and miR-486-y exhibited the highest degree of connectivity. Subsequent GO, KEGG, PPI, and ceRNA network analyses elucidated that the differentially expressed target genes actively participate in signaling pathways associated with cell proliferation, apoptosis, and hormonal regulation. These pathways include but are not limited to the MAPK signaling pathway, Hippo signaling pathway, Wnt signaling pathway, Calcium signaling pathway, Aldosterone synthesis and secretion, Cellular senescence, and NF-kappa B signaling pathway—essentially encompassing signal transduction pathways crucial to reproductive processes.DiscussionThis research significantly contributes to unraveling the molecular mechanisms governing follicular development in Kazakh horses. It establishes and preliminarily validates a differential regulatory network involving lncRNA-miRNA-mRNA, intricately associated with processes such as cell proliferation, differentiation, and apoptosis and integral to the developmental intricacies of stromal follicles. The findings of this study provide a solid theoretical foundation for delving deeper into the realm of reproductive aging in Kazakh mares, presenting itself as a pivotal regulatory pathway in the context of horse ovarian development.

Proper training improves the horse's performance. In the present study, blood transcriptome of the Yili horse was analysed before and after training. Overall, six Yili horses were trained for 3 months; blood samples at rest were collected before and after the training period. Transcriptome libraries were created from the blood samples using high-throughput sequencing; Gene Ontology functional enrichment and Kyoto Encyclopaedia of Genes and Genomes pathway analyses were performed for differentially expressed genes to identify the pathways and candidate genes associated with training and locomotor performance. In total, transcriptome analysis screened 33 significantly differentially expressed genes; of these, 23 and 10 were up-regulated and downregulated after training, respectively. These differentially expressed genes were significantly enriched in metabolic pathways associated with exercise physiology, including sphingolipid metabolism, tryptophan metabolism, and the cGMP-PKG signalling pathway. The results of this study provide a theoretical basis for exploring the molecular mechanisms underlying locomotor performance of the Yili horse as well as a novel insight into the kinematics of this breed. [ABSTRACT FROM AUTHOR]

Many studies have focused on identifying the genes or single nucleotide polymorphisms associated with the athletic ability of thoroughbreds, but few have considered differences in maternal and paternal heritability of athletic ability. Herein, we report on our association study of career race performances of 675 Australian thoroughbreds with their pedigrees. Racing performance data (prize money per start) were collected from the Bloodhound database. The performance of all horses was categorised as either poor or elite athletic achievement. Then, 675 foals were divided by their parents' performance (elite or poor) into four groups: (1) elite dams and elite sires; (2) elite dams and poor sires; (3) poor dams and elite sires; and (4) poor dams and poor sires. The performance of foals was then compared between the four groups. The results show that the heritability of race performance between dams and foals (r = 0.141, P < 0.001) is much higher than that between sires and foals (r = 0.035, P = 0.366), and that this difference is statistically significant (P < 0.05). We also examined the effect of the child-bearing age of dams and sires on the ratio of elite foals. We found a strong correlation between the number of elite foals and dams' child-bearing age (r = -0.105, P < 0.001), with the ratio of elite offspring reaching a high level between a child-bearing age of 8 and 11 years (χ² = 14.31, d.f. = 1, P < 0.001). These findings suggest that the maternal line may play an important role in the selective breeding of athletic performance in thoroughbreds. [ABSTRACT FROM AUTHOR]