Meat quality is influenced by genetic, nutritional, and microbial factors, with increasing attention on the role of gut-derived metabolites. In this study, we conducted untargeted metabolomics of 10 gut tract sites and RNA sequencing (RNA-seq) of longissimus dorsi muscles in Meigu goats and Liangshan black sheep raised under standardized conditions. Results showed that goat muscle contained significantly higher levels of essential amino acids (e.g., methionine) and specific fatty acids (e.g., C18:3_N6, C20:4_N6), suggesting improved nutritional quality. Transcriptomic analysis identified 3133 differentially expressed genes (DEGs), among which ADCY1 and SLC38A4 were upregulated in goats and strongly associated with meat traits. Using integrative correlation analysis, we uncovered 17 genes and 19 gut metabolites that were significantly correlated with more than eight meat quality parameters across multiple gut sites. Notably, these metabolites included bioactive compounds such as L-tyrosine ethyl ester and pelargonidin 3-O-glucoside, while genes were enriched in pathways related to amino acid transport, cAMP signaling, and muscle development. Together, these findings highlight a potential gut–muscle axis involving metabolite-mediated modulation of muscle gene expression, contributing to breed-specific differences in meat composition and quality. This study provides a valuable framework for improving ruminant meat quality through integrative multi-omics analysis.

N the study, we successful constructed a library from the ovine testis using next-generation sequencing technology, and identified 219 novel miRNAs by bioinformatics. Two of the novel miRNAs (ovis_aries_testis-m0052_5p and ovis_aries_testis-m0165_5p), which were expressed in the sheep testis and ovary, and were confirmed by real-time PCR and northern blotting. Ovis_aries_testis-m0052_5p was 23 nucleotides in length, was located on chromosome 15, and had 100% similarity to mmu-miR-34c-5p, hsa-miR-34c-5p, gga-miR-34c-5p, and cfa-miR-34c. Ovis_aries_testis-m0165_5p was 21 nucleotides in length, located on chromosome 5, and had 100% similarity to mmu-miR-145a-5p, hsa-miR-145-5p, ssc-miR-145-5p, and bta-miR-145. The pre-miRNAs for Ovis_aries_testis-m0052_5p and Ovis_aries_testis-m0165_5p were 75 and 81 nucleotides in length, and both had a standard hairpin stem-loop structure. From the consistency of the sequence and structure, we speculated that ovis_aries_testis-m0052_5p had a function similar to hsa-miR-34c-5p, mmu-miR-34c-5p, and ovis_aries_testis-m0165_5p had a function similar to hsa-miR-145-5p, which were involved in the fine regulation of cell survival, spermatozoon generate, breeding activities. Therefore, we defined the identified miRNAs as oar-miR-34c-5p and oar-miR-145-5p. The results will enrich the miRNA database, and provide the basis for research into the regulatory mechanisms of miRNA in relation to breeding activities.

Background: The Dolang sheep is a well-known indigenous breed from Xinjiang, China. Two of its main advantages are year-round estrus and high prolificacy. Although the molecular regulatory mechanisms of reproductive processes have been studied in other animals and humans, relevant information on its year-round estrus and high prolificacy remains limited, particularly for Dolang sheep breeds from Xinjiang. Methods: To obtain differentially expressed genes (DEGs) and proteins that might be responsible for the year-round estrus and high fecundity, ovaries from Dolang sheep were studied at different periods using an integrative strategy of transcriptomics and proteomics via high-throughput sequencing and iTRAQ technologies. Result: RNA-seq yielded 28,717 unigenes, 987 candidate genes and 308 DEGs in the ovaries (at estrus) of Dolang sheep compared with the dioestrus and gestation period (about 45 days of pregnancy). GO and KEGG analysis revealed that the gene products were mainly involved in metabolism, hormone secretion and regulation, ovulation, estrus and regulation of reproduction. At the protein level, a total of 4847 proteins and 470 differentially expressed proteins were identified. The latter were potentially associated with metabolism, endocytosis, the glycolytic pathway and skeletal muscle growth. In conclusion, the current study provides a basis and prospective understanding of the molecular regulatory mechanism underlying the high prolificacy and year-round estrus of Dolang sheep.