Search Results (78)

Reproductive efficiency determines the economic benefits of the sheep industry, yet the molecular mechanisms underlying prolificacy remain incompletely understood. To investigate transcriptomic differences associated with sheep prolificacy, we performed Oxford Nanopore Technologies (ONT) full-length transcriptome sequencing on ovarian tissues collected during the estrous phase from high-prolificacy Small-tailed Han sheep and comparatively lower-prolificacy Wadi sheep (n = 3 biological replicates per group), with an average sequencing depth of approximately 6.3 Gb per sample. With screening thresholds of |log2FoldChange| > 1 and p < 0.05, transcriptomic analysis identified 457 differentially expressed genes (DEGs; 207 upregulated, 250 downregulated) and 1033 differentially expressed transcripts (DETs). In total, 55% of DETs exhibited expression changes independent of overall gene abundance, highlighting the potential role of alternative splicing (AS)-mediated post-transcriptional regulation. We detected 55,478 AS events and screened 96 significant differential alternative splicing (DAS) events (|∆PSI| > 0.1, p < 0.05) across 78 differentially spliced genes (DSGs). Functional enrichment showed DEGs were primarily associated with reproduction pathways (e.g., TGF-β, MAPK, and ovarian steroidogenesis), whereas DSGs were enriched in p53 signaling and ribosome pathways. Protein–protein interaction network analysis highlighted highly connected candidate genes, including INHBA, CYP19, TNFAIP6, TK1, RRM2, BIRC5, BCL2, ISG15, PCLAF, and MX1, potentially involved in follicular development and reproductive signaling. The results of this study enrich the full-length transcriptomic resources for Small-tailed Han sheep and Wadi sheep, and provide candidate genes and transcriptomic resources for further functional investigation of sheep prolificacy. Full article

Accurate sheep detection supports counting, tracking, behavior analysis, and health monitoring in intelligent livestock farming. However, occlusion, scale variation, nighttime low light, and background interference can cause missed detections and inaccurate localization. This study proposes GMS-YOLO11n, an improved YOLO11n-based detector for fixed-view sheep monitoring. A spatially gated bottleneck convolution module was introduced at key backbone downsampling stages to strengthen local structural cues, while a multi-scale attention fusion module combined deep semantic information with shallow-to-intermediate details through feature alignment, cross-scale attention, and channel-wise learnable gating. A dataset of 3531 images of Small-tailed Han sheep, containing 8167 annotated instances, was used for evaluation. Across six independent runs, GMS-YOLO11n achieved precision, recall, F1-score, mAP@0.5, and mAP@0.5:0.95 of 93.62% ± 0.12%, 91.03% ± 1.37%, 92.30% ± 0.75%, 96.53% ± 0.49%, and 76.32% ± 0.57%, respectively. Compared with the COCO-pretrained YOLO11n baseline, the corresponding improvements were 1.05, 4.38, 2.79, 2.76, and 6.92 percentage points. Subset analysis showed mAP@0.5:0.95 gains of 9.83 and 7.62 percentage points under nighttime low-light and obvious-occlusion conditions. These results demonstrate improved detection performance under the challenging visual conditions represented in the evaluated single-farm, fixed-view dataset; broader generalization requires external validation. Full article

Reliable individual identification is essential for precision livestock management, but sheep facial appearance changes substantially during growth, weakening non-contact recognition. This study evaluated whether early-life facial images can support longitudinal identification at later growth stages. A monthly face dataset of 30 Small-tailed Han sheep was collected from 1 to 12 months of age. Images from months 1–8, 9–10 and 11–12 were used for training, validation and independent testing, respectively. An identity-preserving generative alignment framework was developed to reduce growth-related appearance mismatch while maintaining discriminative facial information. On the independent test set, the proposed method achieved 95.6% Top-1 accuracy and 93.9% macro-F1, outperforming convolutional, augmentation-based, feature-alignment, CycleGAN-based and Transformer baselines. Verification analysis achieved an area under the receiver operating characteristic curve (AUC) of 0.978, an equal error rate (EER) of 4.2%, and a true accept rate (TAR) of 94.5% at a false accept rate (FAR) of 1 × 10⁻⁴. Genuine similarity decreased with growth interval but remained separated from impostor similarity. Robustness tests covering time gaps, device changes, viewpoint shifts and image perturbations showed remaining deployment challenges. A mobile prototype achieved 32-bit floating point (FP32) and 16-bit floating point (FP16) latencies of 210 and 150 ms. Full article

Barley hay (BH), characterized by high crude protein, neutral detergent fiber, and various bioactive compounds, is hypothesized to optimize ruminal microbiota and enhance systemic immune responses in sheep. This study assessed how the graded substitution of traditional forage with BH impacts ruminal fermentation, microbiota composition, and blood immune and antioxidant status in sheep. Forty-five male Dorper × Small-tailed Han crossbred lambs (aged 110 ± 10 days, BW 33.93 ± 1.11 kg) were stratified into five cohorts (n = 9 each), including a control (CON) and four experimental groups (BH25, BH50, BH75, and BH100), where BH replaced 25%, 50%, 75%, and 100% of their forage mixture, respectively. Results showed that BH supplementation consistently increased ruminal acetate concentrations. Specifically, BH75 and BH100 significantly enhanced the acetate-to-propionate ratio (p < 0.05) and concurrently reduced NH₃-N concentrations in BH50 and BH100 (p < 0.05). Regarding ruminal microbiota, BH treatment did not alter alpha diversity but significantly enriched fiber-degrading bacteria, including Clostridia, Bacteroidales, and Prevotella, whereas the CON group favored Eubacterium. Blood analysis indicated a time-dependent modulation of immune and antioxidant markers. At day 30, BH treatment resulted in elevated immunoglobulin A (IgA), immunoglobulin G (IgG), interleukin-6 (IL-6), and malondialdehyde (MDA) levels (p < 0.05), whereas catalase (CAT) concentrations were markedly reduced (p < 0.05). By day 60, BH continued to enhance IgA, IgG, and IL-6 levels; meanwhile, tumor necrosis factor α (TNF-α) levels were up-regulated by BH25-BH75 (p < 0.05), while supplementation with BH75 and BH100 led to a decline in interleukin-4 (IL-4), CAT, and interleukin-10 (IL-10) (p < 0.05). Correlation analysis showed that a positive correlation was observed between total volatile fatty acids and Prevotella UCG-003/001, which conversely displayed a negative relationship with IgM. The norank f Eubacterium coprostanoligenes group showed an inverse association with valerate and IgG, but a positive correlation with interleukin-1β (IL-1β). In parallel, the norank f Bacteroidales RF16 group exhibited an inverse association with NH₃-N and CAT, while unclassified c Clostridia was positively correlated with IL-1β. In conclusion, BH substitution modulates ruminal fermentation and immune responses by enriching fiber-degrading bacteria, though it may trigger oxidative stress. Given that BH100 maximized acetate and immunoglobulin production while minimizing MDA levels, complete replacement appears superior to partial substitution. Full article

This study investigated the effects of fermented Chinese chive (FCC) juice supplementation on growth performance, blood parameters, meat quality, and fresh meat volatile compounds in Small-Tailed Han sheep. Sixty sheep were randomly assigned to a control group (CG; basal diet) or an FCC juice treatment group (TG; basal diet supplemented with 1.0 mL/kg feed offered on an as-fed basis), with three pens per treatment and 10 sheep per pen. FCC juice significantly increased average weight gain (AWG) and average daily gain (ADG) (p < 0.05), whereas carcass traits were not significantly affected (p > 0.05). Most meat quality traits, antioxidant indices, and serum biochemical parameters were unchanged, although serum glucose (GLU) and cholesterol (CHO) decreased in the FCC juice treatment group (p < 0.05). GC × GC-TOF/MS analysis showed that FCC juice altered the volatile profile of fresh sheep meat. Compared with the control group, the FCC juice treatment group showed higher relative contents of aldehydes, ketones, and heterocyclic compounds, but lower contents of hydrocarbons and acids. Seventeen differential volatile compounds were identified using VIP > 1 and FDR-adjusted p < 0.05, with esters representing the major upregulated class. Based on the published odor descriptors of the identified volatile compounds, the FCC juice treatment group showed stronger green and apple-like aroma-associated characteristics. Overall, FCC juice showed a modest positive effect on growth performance and altered the volatile compound profile of fresh sheep meat; however, flavor-related findings should be regarded as preliminary because of the limited slaughter sample size and the absence of direct sensory validation. Full article

Deposition of three key 4-alkyl branched-chain fatty acids (KBCFA), including 4-methyloctanoic acid (MOA), 4-ethyloctanoic acid (EOA), and 4-methylnonanoic acid (MNA), causes the gamey flavor in sheep meat. This study integrated metagenomics and metabolomics to evaluate how Allium mongolicum Regel (AMR) supplementation (15 g/d) and rumen fluid transplantation (RFT) modulate rumen microbiota and hepatic metabolism to reduce KBCFA in lamb longissimus thoracis muscle. The experiment consisted of two phases. In Phase I, twelve 3-month-old male Dorper × Small Tailed Han sheep (25 ± 1 kg) were selected as the rumen donor group. These sheep were supplemented with 15 g/d/head of AMR powder in their basal diet until the end of the experiment. In Phase II, thirty 3-month-old male Dorper × Small Tailed Han sheep (23 ± 2 kg) were randomly assigned to one of three groups (n = 10 per group): the control group (STG), which was fed the basal diet and received a physiological saline transplant; the AMR group, which was fed the basal diet supplemented with 15 g/d/head of AMR powder and received a physiological saline transplant; and the rumen fluid transplant group (RTG), which was fed the basal diet and received a rumen fluid transplant from the donor group. Compared to the STG, results showed that the MOA, EOA, and MNA in the AMG decreased by 64.51%, 54.72%, and 49.34%, respectively. Similarly, the MOA, EOA, and MNA in the RTG were reduced by 63.13%, 56.17%, and 49.60%, respectively (p < 0.001). For the rumen metagenome, AMR enriched the genus Prevotella, while RFT increased Butyrivibrio. Hepatic metabolomics revealed a distinct shift where AMR elevated amino acid derivatives and RFT enhanced carnitine-related metabolites. These alterations indicate a potential metabolic shift associated with amino acid metabolism and mitochondrial β-oxidation, rather than lipid elongation. We postulate that this coordinated regulation across the rumen–liver–muscle axis may alter the availability of lipogenic precursors for KBCFA synthesis, ultimately contributing to improved meat flavor. Full article

This study explored the differences in slaughter performance, blood biochemical indices, and ruminal and colonic microbiota between 6-month-old male and female Small-tailed Han sheep, a typical meat-wool dual-purpose breed in China. Twenty weaned lambs (10 males and 10 females) with uniform body condition were reared under unified feeding management until 6 months of age, followed by slaughter sampling and microbial sequencing detection. Results showed that male lambs had significantly higher pre-slaughter live weight, carcass weight and serum ALP content than females (p < 0.05), with lower BUN and β-BHBA levels (p < 0.05). High-throughput sequencing of the 16S rDNA gene in rumen fluid and colon contents revealed that microbial alpha diversity in the rumen was extremely significantly higher than that in the colon (p < 0.01), and their microbial community structures were distinctly separated (p = 0.001). Sex had no significant effect on overall microbial diversity, but altered specific flora and functional pathways: male rumen had higher Actinobacteriota abundance, while female colon had enriched galactose metabolism and male colon had enhanced folate-mediated one-carbon pool pathway. These findings clarify the tissue specificity of gastrointestinal microbiota and sex-related phenotypic differences, providing a theoretical basis for sex-specific feeding of Small-tailed Han sheep. Full article

The Huang-huai sheep (Dorper × Small-tailed Han), certified in China in 2019, initially exhibited issues with genetic uniformity and meat quality. A six-year (2020–2025) breeding program was conducted at two core farms (collectively housing ~2400 breeding ewes representing 12 bloodlines) using the custom “Yuyang Muxin” 10 K SNP chip containing functional markers for reproduction (FecB), growth (CLPG, ACTC1), and meat quality (FABP3, CIDEa). Genotyping and marker-assisted selection were integrated with BLUP breeding values. After six years, favorable FecB genotype frequency increased from 68.97% to 82.58% (p < 0.05), while genetic diversity remained stable (F_IS < 0.05). Mixed model analysis accounting for farm and year random effects revealed significant genetic gains: 6-month ram body weight increased by 9.1% (58.50 to 63.80 kg, p < 0.05), dressing percentage improved from 56.02% to 57.8% (p < 0.05), and loin muscle area expanded by 9.4% (24.50 to 26.8 cm², p < 0.05). Meat quality was enhanced, with shear force decreasing by 14.1% (38.65 to 33.20 N, p < 0.05) and intramuscular fat increasing by 40.0% (2.0% to 2.8%, p < 0.05). Lambs weaned per ewe per year increased from 2.38 to 2.56 (p < 0.05). EBV trend analysis confirmed that improvements were primarily genetic. After Bonferroni correction, CIDEa expression was strongly correlated with intramuscular fat (r = 0.89, p < 0.001) and FABP3 expression with arachidonic acid (r = 0.70, p < 0.001). Nine months was identified as the optimal slaughter age. The “Yuyang Muxin” breeding chip effectively accelerated genetic improvement in Huang-huai sheep, enabling synergistic enhancement of multiple traits. Full article

Tail fat deposition constitutes a distinctive adaptive phenotype in sheep. The Large-tailed Han (LTH) and Small-tailed Han (STH) breeds display pronounced divergence in tail fat storage, offering an ideal model for elucidating lipid metabolism regulation. Integrated sRNA-Seq and RNA-Seq analysis identified 521 differentially expressed genes and 144 miRNAs, which were significantly enriched in lipid metabolism pathways, including fatty acid metabolism and PPAR signaling. Key candidate genes (ADIRF, LPL, ACSL5) were highlighted as pivotal regulators. Additionally, 23 miRNA-mRNA regulatory networks were constructed, revealing complex interaction patterns from ‘one-to-one’ to ‘many-to-one’ relationships. For example, six miRNAs collectively targeted LTA4H. Collectively, this study advances understanding of the genetic network underlying tail fat deposition and provides candidate targets for modulating lipid metabolism. Functional validation is warranted to delineate causal mechanisms. Full article

Background: Sheep (Ovis aries) exhibit significant diversity in adipose tissue deposition, which influences meat quality, environmental adaptation, and economic value. Tail fat, in particular, varies widely among breeds, yet the transcriptomic basis of this variation remains incompletely understood. This study aims to systematically compare the transcriptional profiles of five adipose depots across five sheep breeds to identify molecular mechanisms underlying fat deposition and tail phenotype divergence. Methods: We analyzed 250 publicly available RNA-seq samples from five adipose tissues (caul, subcutaneous, perirenal, intermuscular, and tail fat) of five sheep breeds (Altay, Tibetan, Merino, Wadi, Small-tailed Han). Data were processed using FastQC, STAR, and featureCounts. Differential expression analysis was performed with DESeq2, followed by GO and KEGG enrichment analyses. Breeds were grouped into three tail phenotypes: fat-tailed, short fat-tailed, and thin-tailed. Cross-tissue and phenotype-specific pathway analyses were conducted to identify key regulatory genes. Results: Transcriptional divergence was most pronounced in subcutaneous and intermuscular fat, while tail fat exhibited both conserved and phenotype-specific pathways. Fat-tailed breeds showed enrichment in mitochondrial oxidative phosphorylation and lipid biosynthesis genes (TAFAZZIN, GPAM, COQ family). Short fat-tailed breeds were characterized by extracellular matrix remodeling genes (MMP9, MMP12, MMP19). Thin-tailed sheep lacked these pro-lipogenic and structural remodeling pathways. A dual-axis model of tail fat development is proposed to explain phenotypic diversity. Conclusions: This study reveals that distinct molecular mechanisms underpin tail fat phenotypes in sheep: fat-tailed breeds prioritize metabolic efficiency, short fat-tailed breeds rely on ECM remodeling, and thin-tailed breeds lack these enhancements. The identified candidate genes may serve as potential targets for molecular breeding strategies aimed at optimizing fat deposition and adaptive traits in sheep. Full article

Mastitis is a common mammary gland disease in mammals that severely impairs lactation function, with Staphylococcus aureus (S. aureus) being the primary pathogenic bacterium. However, the molecular mechanisms underlying S. aureus-induced mastitis in sheep remain incompletely elucidated. This study employed RNA sequencing (RNA-SEq) technology to systematically analyze the dynamic transcriptomic characteristics of mammary tissue in small-tailed sheep (SHT) after S. aureus infection, aiming to clarify the molecular regulatory mechanism of the host immune response and its relationship with the occurrence of mastitis. Twelve lactating STH were selected to establish an S. aureus-induced mastitis model. Blood, milk, and tissue samples were collected at 0, 24, 48, and 72 h post-infection (hpi). The infected sheep exhibited typical mastitis symptoms, including exacerbated breast swelling, reduced milk yield, elevated udder temperature, and darker, more viscous milk. Hematoxylin–eosin (HE) staining revealed significant pathological changes over time, such as stromal hyperplasia, extensive inflammatory cell infiltration, severe necrosis and sloughing of mammary epithelial cells, and compromised tissue integrity. RNA-Seq analysis identified 1299 differentially expressed genes (DEGs), among which 75 core genes maintained stable expression throughout the infection time (24 hpi, 48 hpi, and 72 hpi). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that these DEGs were associated with metabolic processes, protein binding, Toll-like receptor signaling, and the NF-κB pathway. The PPI network analysis identified core hub genes including PTK2B, STAT3, and JAK1/3, providing critical evidence for therapeutic target screening. Furthermore, qPCR verification indicated that the expressions of innate immune receptors TLR2, TLR4, TLR7, and TLR10, as well as pro-inflammatory factors IL-1β, IL-16, TNF-α, type I interferon (IFN-α), and nuclear transcription factor NF-κB were significantly upregulated in a time-dependent manner (p < 0.05). In conclusion, this study delineated the dynamic response of ovine mammary tissue to S. aureus infection, systematically elucidated temporal gene expression patterns, and revealed the molecular mechanisms underlying the tissue’s initial defense against inflammatory challenges. Full article

(1) Background: This study aims to systematically identify key candidate genes and the regulatory networks governing ovarian development in sheep breeds with divergent fecundity. Focusing on elucidating the central regulatory roles of these factors during distinct ovarian developmental stages in highly prolific breeds, the research seeks to reveal the mechanism by which multilevel regulatory networks synergistically determine ewe reproductive capacity. (2) Methods: This study utilized the ovaries from the low-fecundity sheep breed Ujumqin sheep, the high-fecundity breed small-tailed Han sheep, and various developmental stages of small-tailed Han sheep as research subjects. Through whole-transcriptome sequencing analysis, differentially expressed mRNAs(DEGs) and non-coding RNAs (ncRNAs) were screened, and a ceRNA regulatory network was constructed and subjected to bioinformatic analysis. The dual-luciferase reporter gene detection system was employed to validate the targeting relationships within the obtained key circRNA-miRNA-mRNA networks. Finally, qRT-PCR was used to verify the accuracy of the sequencing results. (3) Results: Our analysis constructed two distinct ceRNA networks: one from different fecundity groups (116 DECs, 46 DEMs, 82 DEGs) and another from different ovarian stages (186 DECs, 143 DEMs, 338 DEGs). Functional enrichment revealed key reproduction-related pathways, including Mitogen-Activated Protein Kinase(MAPK), Janus Kinase-Signal Transducer and Activator of Transcription(JAK-STAT), and WNT signaling in the fecundity comparison, and MAPK, Ras, WNT, Hippo signaling in the developmental stage comparison. Integrated analysis identified a core circRNA-miRNA-mRNA network, pinpointing circRNA2058-miR-9226-5p-MET as a central regulatory axis. The dual-luciferase assay confirmed that circRNA2058 acts as a sponge for miR-9226-5p, thereby mediating MET expression. qRT-PCR validation of randomly selected RNAs confirmed the sequencing reliability. (4) Conclusions: this study deciphers a synergistic regulatory network and identifies, for the first time, the pivotal circRNA2058-miR-9226-5p-MET ceRNA axis as an potential critical molecular switch driving follicular dominance in sheep. This discovery provides a molecular foundation for targeting core regulators of ovine reproductive efficiency and offers significant insights for innovative strategies in enhancing sheep reproduction. Full article

Background: Tibetan sheep (Ovis aries) have evolved remarkable adaptations to the extreme high-altitude environment of the Qinghai–Tibet Plateau. While previous studies have identified some genetic features underlying these adaptations, a comprehensive understanding of their population genetics and selection signatures remains incomplete. We hypothesized that Tibetan sheep harbor unique genetic diversity and population structure distinct from low-altitude sheep (Hu sheep and Small Tail Han sheep), and that whole-genome resequencing could identify key positively selected genes driving their high-altitude adaptation and economic trait variation. Thus, this study aimed to characterize the population structure and genetic diversity of Tibetan sheep via whole-genome resequencing and identify genomic regions and candidate genes under positive selection related to high-altitude adaptation and important economic traits (growth, meat quality, wool, reproduction). Results: Using whole-genome resequencing of 90 Tibetan sheep (ZY) compared to 90 Hu sheep (HY) and 90 Small Tail Han sheep (XWHY), we identified significantly higher genetic diversity in Tibetan sheep (Pn = 0.6399, PIC = 0.1731). Population structure analyses revealed distinct clustering of Tibetan sheep, with principal components explaining 20.69% (PCA1), 12.26% (PCA2), and 14.18% (PCA3) of genetic variation. Selective sweep analysis identified 713 genomic regions (containing 207 genes) under positive selection, including key hypoxia adaptation genes (HDAC5, BMP2/BMPR1B, DUOX2) and economic trait genes (FGF9 for growth; SLC27A2 for meat quality; KRTAP for wool; IZUMO1R for reproduction). Functional enrichment highlighted pathways in oxygen transport (EPO regulation), energy metabolism (fatty acid β-oxidation), and vascular remodeling (TGF-β signaling). Conclusions: Our study provides the most comprehensive genomic characterization of Tibetan sheep to date, revealing both their unique genetic diversity and molecular mechanisms of high-altitude adaptation. The identified candidate genes offer valuable targets for marker-assisted breeding to improve productivity while maintaining adaptive traits, supporting sustainable development of plateau animal husbandry. Full article

Since extracorporeal membrane oxygenation (ECMO) is primarily used for patients in a high-risk state and is an invasive procedure, its unique application scenarios make it difficult to recruit suitable cases for clinical trials. Therefore, large animal models have become one of the most important models for preclinical evaluation of the safety and effectiveness of ECMO. This study aims to assess the safety and performance of a novel portable ECMO device with Small-tail Han sheep. Fifteen sheep were divided into a test group (LIFEMOTION, Chinabridge, Shenzhen, China) and control group (NOVALUNG XLUNG kit 230, Xonis, Heilbronn, Germany) with veno-venous ECMO (VV-ECMO) and veno-arterial ECMO (VA-ECMO) modes. Tracheal intubation, arteriovenous access, and ECMO support were performed. Vital signs and blood laboratory tests of the subjects were monitored and recorded. The main organs were examined pathologically at the end of day fourteen. The serum protein expression profile was analyzed by protein quantification techniques. All sheep were successfully weaned from ECMO without transfusion or cannula complications. No significant differences were observed between the two groups in terms of vital signs, oxygenation, hemodynamic stability, and physiological function (p > 0.05). According to the serum protein expression profile, no significant biomarkers associated with ECMO clinical complications were identified. The LIFEMOTION ECMO device demonstrated good safety and efficacy. Full article

Increasing the litter size in sheep is a primary objective in breeding programs, driving sustained interest in identifying candidate functional genes and molecular markers associated with fecundity. The known FecD mutation in the LEPR gene has been shown to regulate reproductive traits by influencing the ovulation rate of Davisdale sheep. However, the relationship between single-nucleotide polymorphisms (SNPs) in the LEPR and litter size remains unknown in Gobi short tail sheep and Sonid sheep. In this research, we found one novel variant and thirteen known variants through direct sequencing in Sonid sheep and Gobi short tail sheep and performed an association study in a large-scale population. The association analysis identified two SNPs (c.240C>T (rs159694506) and c.279C>T (rs159694508)) with significant litter size associations in Gobi short tail sheep (p < 0.01 ). In Sonid sheep, the c.240C>T (rs159694506), c.279C>T (rs159694508), g.41249772C>T (rs412130067), g.41249873A>C (rs425490800), g.41250357T>C (rs424307284), and g.41250358T>C (rs404651806) SNPs were significantly associated with litter size (p < 0.05 ). In addition, in GB sheep, the frequency of the litter-size-associated C allele at the c.240C>T (rs159694506) and c.279C>T (rs159694508) variants were significantly lower than that in Sonid sheep (SN), Mongolia sheep (MG), Ujimqin sheep (UM), Tan sheep (Tan), Hu sheep (Hu), and Small-tailed Han sheep (STH) populations. In SN sheep, the frequency of the litter-size-associated C allele at the c.240C>T (rs159694506) and c.279C>T (rs159694508) variant was significantly lower than that in the DPU. These findings provided valuable molecular markers pertinent to the fecundity of sheep, offering scientific evidence for the genetic improvement of these breeds. Full article