Search Results (41)

Objectives: To evaluate the effects of replacing soybean meal (SBM) with rapeseed meal (RSM) or cottonseed meal (CSM) in finishing lamb diets on meat, untargeted metabolomics were used to explore underlying mechanisms of metabolites related to Volatile Organic Compounds (VOCs) between raw and cooked meat. Methods: Twenty-four lambs were fed isocaloric and isonitrogenous diets for 90 days and longissimus thoracic (LT) meat was sampled for quality evaluation. Results: Results showed that growth performance and most traits of meat were unaffected, including feed intake, average daily growth, pH, cooking loss, shear force, most color values, and fatty acids. However, the yellowness (b*) in RSM and CSM meat, as well as Met and Tyr in CSM meat, were increased. Muscle metabolomics identified five different metabolite-associated flavor precursors that varied, including galactose, L-pyrdosine, and 13-octadecenoic acid. In total, 223 VOCs detected in cooked meat showed no major differences among diets. Key flavor compounds, including 1-octen-3-ol and lipid-derived aldehydes, were consistent across treatments. Conclusions: In conclusion, RSM and CSM are viable SBM alternatives, changes in raw meat metabolites do not alter the volatile compounds of cooked meat. Full article

Intramuscular fat (IMF) content determines marbling levels and influences the sensory and edible qualities of livestock meat. Its deposition is influenced by the animal’s age and gut microbial community. This study assessed age-related differences in IMF deposition and shifts in gut microbiota between yearlings (1-year-old) and mature (4-year-old) grazing Tan sheep. Then correlations among these factors were examined to investigate the potential role of gut bacteria in IMF deposition. The results demonstrated that mature sheep exhibited higher IMF content in shoulder and rump muscles (p < 0.05), elevated serum lipid levels (p < 0.001), and increased lipolytic enzyme abundances in the liver and pancreas (p < 0.05), compared with yearlings. In contrast, the concentrations of acetate and propionate in ruminal and colonic contents were lower in mature sheep (p < 0.05), despite a higher abundance of lipolytic and synthetic enzymes in colonic content (p < 0.05). Gut microbial diversity differed between age groups, particularly in the rumen and colon, with clear shifts in specific bacterial taxa. Correlation analyses revealed that the abundance of Copromorpha and RUG420 in the colon were positively correlated with IMF content in shoulder and rump muscles, and serum lipid levels (including free fatty acids, FFA; low-density lipoprotein, LDL; high-density lipoprotein, HDL; and very-low-density lipoprotein, VLDL), but negatively correlated with propionate content (|r| > 0.45, FDR < 0.05). Conversely, the abundance of Cryptobacteroides in the colon was negatively correlated with IMF content in shoulder muscle (r < −0.6, FDR < 0.05), and with the levels of triglyceride (TG), LDL, HDL, and VLDL, while showing positive correlations with acetate and propionate contents (r > 0.45, FDR < 0.05). These findings highlight the potential role of specific colon bacteria (Copromorpha, RUG420, and UBA5905) in IMF deposition, identifying them as candidate bacteria for further investigation regarding their effects on meat quality. Full article

In livestock farming, the reproductive function and breeding performance of Tan sheep are crucial for enhancing farming efficiency. Despite advances in research on sheep germ cells, studies on the identification of markers for spermatogonia, spermatocytes, and spermatozoa in Tan sheep remain limited and inadequate. In this study, Tan sheep were used as research subjects to investigate the morphological characteristics of testicular tissues, the developmental status of germ cells, and potential novel markers for spermatogonia, spermatocytes, and spermatozoa across different ages (0 days, 60 days, 180 days, and 365 days). Homology of the SMC3, G3BP1, and AKAP4 genes was analyzed via NCBI alignment. The localization and expression characteristics of these genes in the testis tissues of Tan sheep were investigated using HE staining, qPCR, and immunofluorescence double staining. The results showed that from 0 to 365 days of age, with increasing age, spermatogonia, spermatocytes, and spermatids exhibited an orderly distribution, and mature spermatozoa appeared in the tubular lumen, marking the initial establishment of the spermatogenic process. The homology of SMC3, G3BP1, and AKAP4 was 90%, 85%, and 81%. The mRNA levels of SMC3 and G3BP1 in the testes of 60-day-old Tan sheep were significantly increased, while AKAP4 expression showed a gradual increase with advancing age. SMC3 was co-localized with PLZF in undifferentiated spermatogonia, G3BP1 was co-expressed with SYCP2 in spermatocytes, and AKAP4 was co-expressed with PNA in spermatozoa. The findings of this study provide further supportive evidence for novel markers of spermatogonia, spermatocytes, and spermatozoa in Tan sheep. Full article

Tan sheep are a characteristic and economically important local breed in the Ningxia Hui Autonomous Region of China, where respiratory diseases continue to pose challenges to animal health and production. In this study, a Pasteurella multocida strain (P6) was isolated from the lung tissue of a single Tan sheep presenting with severe and fatal respiratory disease, and subjected to case-based genomic and pathogenic characterization. The isolate was identified as capsular serotype A based on biochemical profiling, 16S rRNA gene sequencing, kmt-1 PCR, and capsular typing. To provide supportive evidence of virulence potential, a murine infection model was employed, in which P6 induced acute clinical signs and severe pulmonary lesions, including congestion, edema, hemorrhage, and fibrinous inflammatory exudation. Whole-genome sequencing revealed that strain P6 possesses a 2,289,251 bp genome with a GC content of 40.2%, encoding 2155 predicted genes and multiple mobile genetic elements, including genomic islands, prophages, transposons, and a CRISPR locus. Phylogenetic analysis based on seven housekeeping genes placed P6 in close relationship with strains 166CV and 103220, distinct from several rodent- and avian-derived isolates. Functional genomic analyses identified numerous genes associated with carbohydrate metabolism, secondary metabolite biosynthesis, host–pathogen interaction, virulence-related functions, and antimicrobial resistance. Comparative genomic analysis with the reference strain PM70 indicated a largely conserved functional framework, accompanied by a significant enrichment of mobilome-associated genes, suggesting enhanced genomic plasticity. Overall, this study provides a descriptive genomic overview of a P. multocida isolate associated with respiratory disease in Tan sheep and highlights its genetic features and potential adaptive capacity, while acknowledging the limitations inherent to a single-case investigation. Full article

Background/Objectives: In the context of increasing consumer demand for high-quality meat, this study aimed to evaluate the effects of 4% fermented goji berry residue supplementation on meat quality and flavor characteristics in finishing Tan sheep. Methods: Thirty-six male lambs were randomly assigned to a control and FGB group and fed for 68 days. Results: FGB supplementation significantly enhanced Longissimus Dorsi (LD) brightness (L*), redness (a*), and crude protein content, while reducing crude fat (p < 0.05). Amino acid analysis revealed significant increases in lysine, methionine, histidine, glycine, proline, arginine, cysteine, and total sweet-tasting amino acids in the FGB group (p < 0.05). Lactate and inosine monophosphate (IMP) levels were significantly elevated, whereas hypoxanthine levels decreased (p < 0.05). Metabolomics identified 189 metabolites, with 12 differentially expressed, mainly enriched in butanoate metabolism, glycolysis/gluconeogenesis, PI3K-Akt, and HIF-1 signaling pathways. Transcriptomics revealed 382 differentially expressed genes, including key regulators of lipid metabolism (FOXO1, SLC2A4, LPIN1, IGF1, SPP1) and amino acid metabolism (COL3A1, GLUL, PSMC1). Conclusions: Fermented goji residue altered amino acid and lipid metabolism in the LD muscle of Tan sheep, affecting meat quality and flavor traits. However, effects on color (L*, a*, b*), protein content, and shear force varied across the four muscles studied, indicating that responses to supplementation are muscle-specific. These findings offer a sustainable strategy for improving meat quality and provide insights into the molecular mechanisms underlying flavor development in ruminants. Full article

Understanding the drivers of average daily gain (ADG) is key to enhancing the productivity of Tan sheep. This study employed an integrated multi-omics approach to compare rumen microbial communities (16S rRNA sequencing) and metabolomic profiles between Tan sheep with high (HADG) and low (LADG) ADG. The novelty of this work lies in the systems-level identification of functional linkages between specific rumen bacteria and metabolites that underlie divergent growth phenotypes. The results revealed no significant difference in initial body weight between the two groups (p > 0.05). However, the HADG group showed significantly higher final body weight (p < 0.05), markedly greater ADG and Average Daily Dry Matter Intake (ADFI) (p < 0.01), and a substantially lower FCR (p < 0.01). Plasma Total Antioxidant Capacity (T-AOC) and Superoxide Dismutase (SOD) levels were significantly elevated in the HADG group (p < 0.05), while Malondialdehyde (MDA) concentration was significantly reduced (p < 0.05). In contrast, plasma Globulin (GLB), Glucose (GLU), and Triglycerides (TG) concentrations were significantly lower in HADG sheep (p < 0.05). Rumen metabolomics identified 265 differentially abundant metabolites between groups, with 64 down-regulated and 201 up-regulated in LADG compared to HADG sheep. These metabolites were significantly enriched in tyrosine metabolism, β-alanine metabolism, and thiamine metabolism pathways. Receiver Operating Characteristic (ROC) curve analysis identified 15 key differential metabolites, including succinic acid, 2-hydroxyglutarate, and pyridoxal phosphate. 16S rRNA sequencing indicated significant differences in microbial genera such as UCG-002, Blautia, norank_f__Bacteroidales_UCG-001, and norank_f__norank_o__Rhodospirillales. Correlation analysis revealed that UCG-002 and norank_f__Bacteroidales_UCG-001 were highly negatively correlated with succinic acid (p < 0.01), and significantly negatively correlated with 1-aminocyclopropanecarboxylic acid, pyridoxal phosphate, and 2-hydroxyglutarate (p < 0.05). Conversely, beta-alanine, ureidoacrylic acid, L-proline, and 2′-deoxyguanosine showed a highly significant positive correlation with norank_f__Bacteroidales_UCG-001 (p < 0.01), and a significant positive correlation with UCG-002 (p < 0.05). These findings elucidate the molecular mechanisms behind growth differences in Tan sheep and provide actionable insights for developing targeted nutritional strategies. Full article

This study aims to elucidate the quality differences among Tan lamb from three major production regions and investigate the influence and regulation of lipids on regional sheep meat quality. The Ningxia Tan lamb exhibited higher pH values, lower lightness and yellowness, better water-holding capacity and more polyunsaturated fatty acids compared to the other regions. GC-IMS revealed different flavor profiles of Tan lamb from different regions. A total of 1080 lipids across 41 lipid subclasses were identified, with 10 lipid molecules, including PC (16:0_16:1), Carnitine C3:0 and Carnitine C5:1, serving as key differentiators among the regions, as determined by the Random Forest method. Correlation analysis revealed strong associations between acyl lipid characteristics and pH, lightness and centrifugal loss, while glycerophospholipid characteristics were significantly correlated with basic nutritional indices. Lipid metabolic pathway analysis indicated that thermogenesis, glycerophospholipid metabolism and metabolic pathways as crucial for Tan lamb growth, serving as major pathways for distinguishing different regional Tan lamb. These findings indicate that origin influences lamb quality and lipid composition and that a relationship may exist between lamb quality and lipid variations. This provides a comprehensive understanding of how lamb quality is formed and contributes to future identification of lamb origins, as well as control and enhancement of meat quality. Full article

The keratin-associated proteins (KAPs) are a class of wool proteins. They form a matrix that cross-links the wool intermediate filament keratins. The KAPs are thought to affect wool fibre structure and properties and have been associated with variation in wool fibre traits. There are many KAP genes in sheep, but not all have been identified. Recently a second member of the KAP22 gene family, KRTAP22-2, was identified in goats, and variation in this caprine gene was associated with cashmere fibre traits. In this study, we identified ovine KRTAP22-2. To ascertain the extent of variation in KRTAP22-2, sheep from eight breeds were investigated using polymerase chain reaction (PCR) followed by single-strand conformational polymorphism (SSCP) analysis. This revealed two unique banding patterns, which upon sequencing gave two novel DNA sequences. These differed by two single nucleotide polymorphisms in the coding region. Three genotypes of the novel KRTAP22-2 sequences were observed in the eight sheep breeds studied. The ovine KRTAP22-2 variant sequences were similar to a goat KRTAP22-2 variant, but a search of ovine expressed sequence tags revealed no matching mRNA sequences in the ovine databases. In a second part of the study, no association was found between the KRTAP22-2 genotypes and mean fibre diameter, fibre diameter standard deviation, coefficient of variation in fibre diameter, and mean fibre curvature, for either the fine wool or heterotypic hair fibres of 255 Chinese Tan lambs. These results suggests that sheep have a KRTAP22-2 gene, but that there may be species-specific differences in the gene’s expression or function. The gene may not affect wool traits in the way that it appears to in goats. Full article

The Lop sheep (LOP), a unique local breed from Xinjiang, exhibits remarkable resilience to the harsh conditions of a desert arid climate and frequent sandstorms, alongside notable fecundity characteristics. This study aims to investigate the adaptability of LOP within this challenging environment by collecting whole blood samples from 110 LOP individuals in the Lop Nur region of Xinjiang for genome resequencing. The resulting data will be compared with whole genome resequencing information from 22 local sheep breeds worldwide to analyze the origin and evolution of LOP. Additionally, comparisons will be made with HUS sheep from warm and humid regions to identify genomic differences through selection signal analysis, thereby assessing the impact of a desert arid climate on the extreme living conditions of LOP. Finally, qPCR was used to preliminarily analyse the impact of the desert arid climate on the genome of the Bactrian sheep. Genetic diversity results indicate that LOP exhibits a relatively stable genetic structure alongside high genetic diversity. The results of population structure analysis and gene flow indicate that we can tentatively posit that LOP is a breed that originated from the Middle East, subsequently mixing with MGS upon its arrival in Xinjiang. Chinese local sheep breeds trace their origins to AMS, with the gene flow evolving from west to east, progressing through mountainous hills (BSBS), basins (LOP, HTS, CLHS, DLS), plains (MGS, TANS), and coastal areas (HUS). LOP is associated with ALTS, BSBS, HTS, CLHS, and DLS, as well as with MGS, HUS, TANS, WDS, and SSSP, in a context of gene exchange, with the degree of exchange diminishing in that order. Selection signal analysis revealed that the candidate genes identified are closely related to adaptation to desert arid climates and disease resistance (PDGFD, NDUFS3, ATP1B2, ITGB8, and CD79A), using HUS as the reference group. qPCR results demonstrated that LOP was significantly upregulated in cardiac, splenic, and lung tissues compared to HUS, suggesting that LOP plays a crucial role in cardiac function, immune response, and respiratory capacity. 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

Tan sheep, a valuable indigenous breed in China, are vulnerable to coccidiosis caused by Eimeria ovinoidalis. In this case-control study, four 8-month-old Tan sheep raised under identical conditions were enrolled, including two with confirmed E. ovinoidalis infection (the Eo group) and two healthy controls (the HC group). Integrated metagenomic and untargeted metabolomic analyses were performed to assess gut microbiota and metabolic alterations. Results showed reduced alpha diversity and a distinct microbial composition in the Eo group. LEfSe identified 38 differentially abundant bacterial species, with Prevotella sp. and Fusobacterium necrophorum enriched in the Eo group and Faecalibacterium sp. and Lachnospira sp. enriched in the HC group. KEGG and VFDB analyses revealed significant differences in microbial functional pathways and virulence factor profiles. A total of 543 metabolites were differentially expressed, involving pathways related to inflammation, stress response, and amino acid metabolism. Microbiome–metabolome correlation analysis showed that Eo-associated bacteria were positively linked to pro-inflammatory metabolites, while HC-associated taxa correlated with markers of metabolic homeostasis. These findings provide new insights into the pathogenesis of ovine coccidiosis and may inform targeted interventions. Full article

Wool has distinctive biological, physical, and chemical properties that contribute to its value both for the sheep and in global fibre and textile markets. Its fibres are primarily composed of proteins, principally keratin and keratin-associated proteins (KAPs). To better comprehend the genes that underpin key wool traits, this study examined the keratin-associated protein 36-1 gene (KRTAP36-1) in Chinese Tan lambs. We identified three previously reported alleles of the gene (named A, B and C) that were present in the lambs studied, with genotype frequencies as follows: 2.0% (n = 5; AA), 6.9% (n = 17; AB), 13.8% (n = 34; AC), 8.9% (n = 22; BB), 33.4% (n = 82; BC) and 35.0% (n = 86; CC). The frequencies of the individual alleles in the Chinese Tan lambs were 12.4%, 29.1% and 58.5% for alleles A, B and C, respectively. The three alleles were in Hardy–Weinberg Equilibrium. In an association analysis, it was revealed that allele C was associated with variation in the mean fibre curvature of the fine wool of the Chinese Tan lambs, but this association was not observed in their heterotypic hair fibres. This finding suggests that KRTAP36-1 might be differentially expressed in the wool follicles that produce the two fibre types, and that along with other KRTAP genes, it may be involved in determining fibre curvature and the distinctive curly coat of the lambs. Full article

This study identified four new keratin-associated protein genes (KRTAP19-n) in sheep: sKRTAP19-1, sKRTAP19-2, sKRTAP19-4, and sKRTAP19-6. These genes are closely related to the previously identified sheep genes KRTAP19-3 and KRTAP19-5, as well as to human KRTAP19-n genes. However, no clear orthologous relationships were found, suggesting complex evolutionary dynamics for this gene family. Extensive nucleotide sequence variation was observed across the four genes. sKRTAP19-1 had four variants, defined by four synonymous single-nucleotide polymorphisms (SNPs) and a variable number of “GGCTAC” hexanucleotide repeats. sKRTAP19-2 had five variants involving seven SNPs, three of which were non-synonymous. sKRTAP19-4 had five variants with nine SNPs (three being non-synonymous) and a three-nucleotide deletion. sKRTAP19-6 had eight variants, defined by 13 SNPs and a two-nucleotide consecutive substitution, with four of the SNPs being non-synonymous. One distinct variant each of sKRTAP19-4 and sKRTAP19-6 was found exclusively in Yanchi Tan sheep, with seven unique nucleotide differences compared to other variants. These unique variants were identical to the Romanov sheep genome in the region amplified (excluding the primer binding regions), suggesting a shared ancestral origin. The findings highlight considerable genetic diversity in ovine KRTAP19-n and lay a foundation for future research into their role in regulating wool fibre characteristics. Full article

The rumen and intestinal microbiota play a pivotal role in the digestion and absorption processes of ruminants. Elucidating the mechanisms by which gastrointestinal microbiota influence the feed conversion ratio (FCR) in ruminants is significantly important for enhancing feed utilization efficiency in these animals. In this study, RT-qPCR, 16S rRNA sequencing, and metabolomic techniques were systematically employed to compare the microbial community structures in the rumen, cecum, and rectum, as well as the differences in rumen metabolites between high- and low-FCR Tan sheep. The results showed that, compared to the HFCR group of Tan sheep, the LFCR group exhibited a significant reduction in unclassified_f__Selenomonadaceae, Blvii28_wastewater-sludge_group, and Papillibacter in the rumen; a significant increase in Lachnospiraceae_AC2044_group and Sanguibacteroides; a significant reduction in unclassified_f__Peptostreptococcaceae, Clostridium_sensu_stricto_1, and Parasutterella in the cecum; a significant increase in norank_f__Bacteroidales_UCG-001; and a significant reduction in norank_f__Muribaculaceae, Blautia, and Turicibacter in the rectum. There is a significant positive correlation between Parasutterella in the cecum and three microorganisms, including unclassified_f__Selenomonadaceae, in the rumen. Additionally, Blvii28_wastewater-sludge_group was positively correlated with Lactobacillus. Furthermore, unclassified_f__Selenomonadaceae in the rumen was positively correlated with Turicibacter, unclassified_f__Peptostreptococcaceae, and Breznakia in the rectum. Blvii28_wastewater-sludge_group also showed positive correlations with Blautia, norank_f__Muribaculaceae, and Clostridium_sensu_stricto_1, while Papillibacter was positively correlated with Faecalitalea. The metabolomic results indicated that, compared to the HFCR group, 261 differential metabolites, including Phenylacetylglutamine and Populin, in the rumen of Tan sheep in the LFCR group were significantly downregulated, whereas 36 differential metabolites, including Glycyl-L-tyrosine, were significantly upregulated. Furthermore, the rumen microbe unclassified_f__Selenomonadaceae exhibited positive correlations with significantly differential metabolites such as L-tryptophan, Etiocholanolone glucuronide, N-acetyl-O-demethylpuromycin, and 6-deoxyerythronolide B. Blvii28_wastewater-sludge_group and Papillibacter also exhibited positive correlations with Icilin. High and low FCRs in the rumen of Tan sheep were investigated, especially in relation to unclassified_f__Selenomonadaceae, Blvii28_wastewater-sludge_group, and Papillibacter. Correlations can be seen with microorganisms such as Parasutatella and Lactobacillus in the cecum; Turicibacter, norank_f__Bacteroideales_UCG-001, and Blautia in the rectum; and metabolites such as L-tryptophan, Etiocholanolone glucuronide, and N-acetyl-O-demethylpuromycin. This reveals the role of microorganisms in the digestion and absorption of Tan sheep feed, thus providing a preliminary basis for further research on the microbial regulation of ruminant animal feed utilization and a theoretical basis for improving Tan sheep feed utilization efficiency. Full article

Tan sheep outperform Dorper sheep in meat-quality traits, including muscle fiber characteristics and fatty acid composition, while Dorper sheep excel in carcass weight. However, the molecular mechanisms underlying these breed-specific traits, especially gut microbiota–bile acid (BA) interactions, remain poorly understood. As host–microbiota co-metabolites, BAs are converted by colonic microbiota via bile salt hydrolase (BSH) and dehydroxylases into secondary BAs, which activate BA receptors to regulate host lipid and glucose metabolism. This study analyzed colonic BA profiles in 8-month-old Tan and Dorper sheep, integrating microbiome and longissimus dorsi muscle transcriptome data to investigate the gut–muscle axis in meat-quality and carcass trait regulation. Results showed that Tan sheep had 1.6-fold higher secondary BA deoxycholic acid (DHCA) levels than Dorper sheep (p < 0.05), whereas Dorper sheep accumulated conjugated primary BAs glycocholic acid (GCA) and tauro-α-muricholic acid (p < 0.05). Tan sheep exhibited downregulated hepatic BA synthesis genes, including cholesterol 7α-hydroxylase (CYP7A1) and 27-hydroxylase (CYP27A1), alongside upregulated transport genes such as bile salt export pump (BSEP), sodium taurocholate cotransporting polypeptide (NTCP), and ATP-binding cassette subfamily B member 4 (ABCB4), with elevated gut BSH activity (p < 0.05). DHCA was strongly correlated with g_Ruminococcaceae_UCG-014, ENSOARG00000001393, and ENSOARG00000016726, muscle fiber density, diameter, and linoleic acid (C18:2n6t) (|r| > 0.5, p < 0.05). In contrast, GCA was significantly associated with g_Lachnoclostridium_10, g_Rikenellaceae_RC9_gut_group, ENSOARG0000001232, carcass weight, and net meat weight (|r| > 0.5, p < 0.05). In conclusion, breed-specific colonic BA profiles were shaped by host–microbiota interactions, with DHCA potentially promoting meat quality in Tan sheep via regulation of muscle fiber development and fatty acid deposition, and GCA influencing carcass traits in Dorper sheep. This study provides novel insights into the gut microbiota–bile acid axis in modulating ruminant phenotypic traits. Full article