Deyin Zhang

Population stratification based on gut microbiota composition has revealed several enterotypes in humans and animals, providing valuable tools for studying the gut microbiota landscape, which is crucial for animal health and production. However, knowledge about rumen enterotype identification in sheep, its influencing factors, and its association with growth performance and host genetics remains limited. Here, we investigated host genetic effects and phenotypic landscapes of rumen bacterial enterotypes in a large sheep population. Ruminal contents from 1150 healthy sheep were analyzed using 16S rRNA gene sequencing and genus-level clustering, complemented by extensive phenotypic data covering 47 traits spanning growth, feed efficiency, meat yield, and ruminal fermentation, along with whole-genome resequencing data. We identified two distinct enterotypes: Enterotype 1 (E1), a mixture of multiple genera, and Enterotype 2 (E2), dominated by Prevotella. E2 sheep exhibit superior growth and meat production performance, but lower feed efficiency and increased fat deposition. Two-part beta-regression models and co-occurrence network analyses revealed the extensive impact of enterotypes on microbial community structure, with E1 displaying a higher frequency of unique bacterial interactions. The estimated heritability of the enterotype was 0.47, and a GWAS identified five key genetic markers associated with rumen enterotype, localized to two candidate genes: CHODL and ENPP6. These markers significantly influence 58 ruminal bacterial genera, including key taxa and driving genus. Overall, our data provide new insights into sheep rumen-enterotype characteristics, contributing to a better understanding of microbial interactions that are crucial for improving ruminant growth performance.

Body weight (BW) is a critical economic trait closely linked to livestock meat production performance and producer profitability. In the present study, we measured individual BW of 1070 male Hu sheep at six growth stages (80, 100, 120, 140, 160, and 180 days of age) and conducted descriptive statistical analyses. Results showed that the coefficient of variation (CV) for BW at each stage was higher than 13%. Additionally, we investigated the expression patterns of the FGF9 gene and its associations with single nucleotide polymorphisms (SNPs) and BW. Quantitative real-time PCR (qRT-PCR) revealed FGF9 is significantly higher expressed in the hypophysis tissues that in the other tested tissues. Association analyses indicated that the SNP FGF9:c.382-1264C>T was significantly associated with BW across different measurement periods. Finally, we performed assay for transposase-accessible chromatin using sequencing (ATAC-seq) and cleavage under targets and tagmentation (CUT&Tag) techniques to identify the OCRs (open chromatin regions) and regulatory regions in the hypophysis tissues of Hu sheep, and we obtained an average of 221243, 52692, and 20957.5 peaks in the ATAC-seq, H3K27ac, and H3K4me3 data per sample. Simultaneously, by integrating the SNPs of FGF9 and hypophysis tissue’s epigenomic data, we found that the SNP FGF9:c.382-1264C>T was located in the adjacent OCR- and H3K27ac-modified peaks. Therefore, we propose that the SNP FGF9:c.382-1264C>T plays an important role in regulating body weight in sheep. Overall, this study generated a valuable epigenetic dataset (ATAC-seq, H3K27ac, and H3K4me3) in sheep hypophysis tissue and identified a novel functional regulatory variant for improving body weight in sheep.

Mycoplasmal pneumonia of sheep (MPS), caused by Mesomycoplasma (Mycoplasma) ovipneumoniae, profoundly impacts ovine productivity and survival. Although gut–lung microbiota interactions are increasingly recognized in respiratory diseases, whether similar crosstalk occurs between the lung and rumen microbiota in MPS-affected sheep remains unknown. To investigate alterations in the lung and rumen microbiota of sheep with MPS, the crosstalk between these microbial communities, and their impacts on growth phenotypes. From a cohort of 414 naturally infected six-month-old male Hu sheep, we selected 10 individuals with severe pulmonary pathology and 10 healthy controls for detailed phenotypic and microbiome analyses. Assessment of 359 phenotypic traits revealed that MPS significantly impairs feed efficiency and growth rate (p < 0.05). Through 16S rRNA gene sequencing, we found that MPS significantly altered the pulmonary microbiota community structure (p < 0.01), with a noticeable impact on the rumen microbiota composition (p = 0.059). Succinivibrionaceae_UCG-001 was significantly depleted in both the rumen and lungs of diseased sheep (p < 0.05) and strongly associated with reduced average daily feed intake (p < 0.05). In addition, pulmonary Pasteurella and ruminal Succinivibrionaceae_UCG-002 were significantly enriched in MPS-affected sheep, showed a strong positive correlation (p < 0.05), and were both negatively associated with feed efficiency (p < 0.05). Notably, Pasteurella multocida subsp. gallicida may act as a keystone species influencing feed efficiency. These findings point to a previously unrecognized rumen-lung microbial axis that may modulate host productivity in sheep affected by MPS. This work provides new insights into the pathogenesis of MPS and offers potential targets for therapeutic intervention and management.

Meat quality is a critical determinant of consumer preference and economic value in the livestock industry. However, the relationship between carcass performance and meat quality remains poorly understood. In our study, we conducted an integrative analysis of transcriptomics and metabolomics to investigate the molecular mechanisms underlying meat quality differences in Hu sheep with high (HHS, n = 10) and low (LHS, n = 10) carcass performance. Phenotypic analysis revealed that the HHS group exhibited superior meat quality traits, including higher intramuscular fat (IMF) content (reflected in elevated marbling scores), along with lower shear force, drip loss, and cooking loss, compared to the LHS group. Transcriptomic analysis identified 376 differentially expressed genes (DEGs) enriched in pathways linked to lipid metabolism, such as the PPAR signaling pathway and long-chain fatty acid metabolic process. Weighted gene co-expression network analysis (WGCNA) revealed important modules and key genes (e.g., ELOVL6, PLIN1, and ARHGEF2) associated with meat quality traits. Metabolomic profiling identified 132 differentially accumulated metabolites (DAMs), with significant enrichment in amino acid metabolism pathways, including D-amino acid metabolism, arginine biosynthesis, and glycine, serine, and threonine metabolism. Integrative analysis of transcriptomic and metabolomic data highlighted six co-enriched pathways, such as the mTOR signaling pathway and amino acid metabolism, underscoring their role in regulating meat quality. These findings provide valuable insights into the genetic and metabolic networks driving meat quality variation and offer potential biomarkers for genetic selection and nutritional strategies to enhance both carcass yield and eating quality in Hu sheep. This research enhances knowledge of the molecular basis of meat quality and supports precision breeding in livestock production.

Meat quality traits, particularly WHC and tenderness, are pivotal for consumer satisfaction and economic value in the sheep industry. However, their genetic regulatory mechanisms remain unclear. We used RNA-Seq and WGCNA to identify genes regulating WHC and tenderness. Sixty longissimus thoracis samples were classified into high/low WHC (HWHC vs. LWHC) and high/low tenderness (HTN vs. LTN) groups. Comparative transcriptomics identified 270 differentially expressed genes (DEGs) linked to WHC, enriched in pathways like the regulation of the ATP metabolic process and the inhibition of canonical Wnt signaling. Key DEGs (e.g., SORBS1, FOXO1, PDE4B, CDH1) correlated significantly with WHC-associated traits. For tenderness, 165 DEGs were identified, including LEP, FABP4, PLIN1, and GLP1R, enriched in PPAR signaling, fat cell differentiation, and cAMP signaling pathways. WGCNA revealed modules associated with WHC and tenderness, with hub genes (ATP2C1, GSKIP, PATL1, PPARA, CYLD) involved in ATP metabolism, lipid biosynthesis, and myofibril assembly. Tissue-specific gene integration prioritized muscle-enriched candidates (METTL21C and ACTC1) with strong trait correlations. Our findings unveil interconnected gene networks governing WHC and tenderness, highlighting some candidate genes as potential biomarkers for precision breeding. This study provides novel insights into the molecular determinants of meat quality, offering actionable targets to enhance mutton production sustainability and consumer appeal.

Early mammal gut microorganism colonization affects host health, the feed conversion rate, and production performance. Herein, we explored how fecal microbiota develops and the interactions between microorganisms and nutrients. The lambs were separated from ewes at 7 days old, artificial feeding with milk replacer completely replaced lactation, and the starter diet was added. At 21 days old, the lambs were fed with complete starter and milk replacer was stopped. At day 7, 21, 35, and 49 after birth, fecal samples were collected. Then 16S rRNA gene sequencing in the fecal samples revealed that the alpha diversity increased significantly with age. Principal coordinates analysis showed clear clustering by age (p < 0.05). At the genus level, the relative abundance of 8 genera declined, 12 genera increased (p < 0.1), and 4 genera changed dramatically with age (p < 0.05). The apparent digestibility of dry matter, protein, fat, neutral detergent fiber, and acid detergent fiber significantly decreased by 21.77%, 23.15%, 23.62%, 19.38%, and 45.24%, respectively, from 7 to 35 days of age (p < 0.05), but not thereafter (p > 0.05). Fecal nutrient contents affected the abundance of bacterial genera (p < 0.05). Enterobacteriaceae_unclassified, Clostridium XlVb, Bifidobacterium, and other genera had no relationship with the fecal nutrient content; however, they were closely related to nutrient intake and digestibility, possibly promoting nutrient digestion. Our results suggested that nutrient digestion of young lambs changed rapidly, which was closely related to intestinal microbial colonization.