BackgroundThe rapid emergence of multidrug-resistant bacterial pathogens has created an urgent demand for alternative antimicrobial agents. Bovine lactoferricin (Lfcin B), a cationic antimicrobial peptide derived from bovine lactoferrin, exhibits potent broad-spectrum antibacterial activity. Although truncated derivatives of Lfcin B retain partial antimicrobial effects, their efficacy relative to full-length Lfcin B and the structural mechanisms governing their function remain poorly understood.MethodsFull-length Lfcin B and three truncated variants (Lfcin B15, Lfcin B9, and Lfcin B6) were synthesized using solid-phase peptide synthesis and characterized by RP-HPLC and MALDI-TOF-MS. Circular dichroism spectroscopy was employed to evaluate secondary structural changes under different ionic and hydrophobic environments. Tertiary structures were predicted using AlphaFold3. Antibacterial activities were assessed against multidrug-resistant Gram-negative and Gram-positive pathogens, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhimurium, Salmonella gallinarum, Shigella flexneri, Staphylococcus aureus, and Trueperella pyogenes, using MIC, MBC, and agar diffusion assays.ResultsCircular dichroism spectroscopy revealed that ionic strength and hydrophobic environments modulate the secondary structures of the peptides, with increased ionic strength consistently reducing random coil ratios across all variants. Structural stability progressively diminished with peptide truncation, as shorter variants exhibited less conformational complexity. AlphaFold3-predicted tertiary structures identified two distinct conformations for full-length Lfcin B, an α-helix-rich state and a β-sheet-dominant topology, whereas truncated variants adopted simpler structural ensembles, primarily α-helical or random coil conformations. Antibacterial activity decreased markedly with peptide truncation. Lfcin B demonstrated the strongest and broadest-spectrum antibacterial activity, showing substantially lower MIC and MBC values and larger inhibition zones than truncated peptides. In contrast, Lfcin B6 exhibited only limited activity against T. pyogenes. Structural analyses indicated that the intact sequence and intramolecular disulfide bond of Lfcin B are essential for maintaining conformational stability, membrane interaction capacity, and antibacterial potency.ConclusionsThe antibacterial efficacy of bovine Lfcin B is strongly associated with its full-length sequence, conformational adaptability, and disulfide bond-mediated structural stability. Progressive truncation compromises structural plasticity and significantly attenuates antimicrobial activity. These findings support Lfcin B as a promising structural scaffold for the development of next-generation therapeutics against antibiotic-resistant bacterial infections.

Fat deposition plays an important role in yak metabolism, reproduction, and meat quality, and male yaks are often castrated to facilitate management and improve production performance. The effect of castration on the characteristics of fat deposition in male yaks and the molecular mechanisms of action was explored in this study. The subcutaneous fat thickness in castrated and common male yaks was measured, further the content of fatty acids in yak subcutaneous fat was detected using gas chromatography-mass spectrometer (GC-MS); the transcriptome, metabolome in the yak subcutaneous fat were detected using mRNA-Sequencing, ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), respectively; the integrative analyses of differentially expressed genes (DEGs), different metabolites (DMs), fatty acids and fat thickness were carried out. The results showed that castration can strengthen the ability of fat deposition and improve the content of fatty acids, especially PUFAs, in male yaks, and both transcriptome and metabolome were significantly different between castrated male yaks and common male yaks. The effect of castration on the male yak fat deposition was closely related to the PPAR signaling pathway, citrate cycle, and insulin resistance. Data suggests that FASN, ACACA, AGPAT2, ACLY, ACSL5, SCD, GSK3B, and SLC2A4 may be the crucial control genes for the fat amount in yaks, and that FADS2, LPL, and ACSL4 may be the crucial control genes for the polyunsaturated fatty acids (PUFAs) content in yak adipose tissue. Further functional studies will be conducted to determine the specific role of each gene in regulating fat deposition and fatty acid composition in yaks.

Domestic yaks are a crucial livestock species on the Qinghai-Tibet Plateau and its surrounding regions, providing indispensable resources for local residents’ livelihoods and production. China harbors the world’s largest yak population and possesses exceptionally rich yak genetic resources. In this study, we performed whole-genome resequencing on 200 individuals representing 19 indigenous yak breeds. Sequencing of DNA samples generated approximately 4.3 terabytes (TB) of raw data, with an average sequencing depth of 8.36×. High-quality sequencing reads were successfully mapped to the reference yak genome, achieving an average alignment rate of 98.4%. Following stringent quality control and filtering, we identified a total of 13.41 million high-confidence single nucleotide polymorphisms (SNPs). These genome-wide SNP markers provide a valuable resource for in-depth investigation into the demographic history and adaptive evolutionary mechanisms of Chinese yak populations, offering critical genomic support for the conservation and innovative utilization of yak genetic resources.

Yak meat is valued for its unique flavor and nutrition, but refrigerated storage packaging affects its flavor quality. This study focuses on longissimus thoracis et lumborum (LTL) of yaks and compares the regulatory effects of tray packaging (aerobic environment) and vacuum packaging (low oxygen environment) on the taste and metabolic characteristics of meat products at 3 days (mid-term of short-term storage) and 7 days (end of short-term storage, upper limit of conventional shelf life) under 4 degrees C refrigeration conditions. The relevant mechanisms are analyzed by combining gas chromatography-ion mobility spectrometry (GC-IMS) and gas chromatography-mass spectrometry (GC-MS) techniques. The results showed that GC-IMS detection revealed that tray packaging had significantly higher fresh flavor compounds (alcohols, aldehydes, esters) than vacuum at 3 days, better retaining initial aroma. However, when storage was extended to 7 days, substances imparting undesirable flavors (2-methylbutanal-D, 1-hydroxy-2-propanone, 2-propanethiol, and 2-ethylfuran) accumulated significantly in tray packaging meat, while vacuum packaging effectively inhibited the formation of such substances. GC-MS analysis indicated that the contents of fumaric acid and glutamine in the vacuum packaging groups (3/7 days) were consistently higher than those in tray packaging groups. After 7 days of storage, the content of free amino acids (L-cysteine, L-lysine) in vacuum packaging meat was significantly increased. Furthermore, glyceraldehyde 3phosphate, formamide, and 1-methoxy-2-methylprop-1-en-1-ol were identified as the key differential metabolites between the two packaging methods. KEGG pathway enrichment analysis showed that amino acid metabolism was the core driving pathway for changes in the composition of flavor compounds during the oxidation of yak meat under chilled storage. The selection of yak meat packaging should be adjusted according to storage duration: tray packaging is more suitable for short-term storage (within 3 days) to retain fresh flavor, while vacuum packaging can more effectively maintain meat flavor quality during long-term storage (7 days) by inhibiting oxidative reactions and regulating umami-related metabolism. The results of this study provide experimental support for the targeted optimization of fresh yak meat packaging schemes and the extension of its flavor shelf life.

The reproductive physiology of yaks differs significantly from that of other cattle breeds due to late sexual maturity, low fecundity and short estrus time. How to improve the reproductive efficiency of yaks has become the main research content and goal of yak reproduction technology. In this study, we collected blood samples from adult female yaks (4-8 years old) during different reproductive periods, including the period of anestrus (Y-A), estrus (Y-E) and pregnancy (Y-P), and investigated the changes of RNA expression and steroid hormone levels in yaks during different reproductive periods by using RNA-seq and target metabolomics, and screened for the genes and regulatory pathways. DEGs such as PDK4, ALAS2, GLP1R, SLC25A39, PGAP6, FOS, CD36, MMP9 and BCL-6 were identified to play key roles in ovarian function, follicular development, hormone homeostasis and energy metabolism. Functional annotation and enrichment analysis indicated that DEGs were involved in ovarian angiogenesis, hormone synthesis and follicular development. In order to reveal the deep interaction between steroid hormone metabolism and gene expression, the weighted gene co-expression network analysis (WGCNA) method was used. It was found that SLC25A39 may affect glucocorticoid homeostasis and physiological readiness by regulating energy metabolism during anestrus, MARCHF2 and DHEA may be closely related to reproductive hormone fluctuation and system activation during estrus, glucocorticoid down-regulation in pregnancy and maintenance of hormone homeostasis and regulation of immune tolerance by DHEA. The results of this study provide a theoretical basis for improving the reproductive performance of yaks and further analysing the reproductive characteristics of yaks.

Chilled yak meat is becoming more and more popular with the improvement in living standards, and the flavor of chilled meat is closely related to storage time. The effect of storage time on the flavor of chilled yak meat was explored in this study. We used GC-MS, HS-GC-IMS, and LC-MS/MS to detect changes in the metabolites in yak meat during storage at 4 °C and constructed storage time-dependent metabolite fingerprints of the yak meat. The results showed that low-temperature storage promoted the degradation of proteins and lipids, nucleotide release, and the production of the volatile compounds heptanal, octanal, n-nonanal, benzaldehyde, 2,3-pentanedione, 3-hydroxy-2-butanone, and 2-butanone. With an increase in the chilled storage time of yak meat, the total volatile basic nitrogen and total viable count of the meat were significantly increased. The short-term storage time of yak meat at 4 °C should not exceed 5 days.

Cattle have evolved genetic adaptations to a diverse range of agroecological zones, such as plateaus and arid zones. However, little is known about its genetic basis of adaptation to harsh environments within a short period of time after domestication. Here, we analyzed whole-genome sequence data from three indigenous cattle breeds (Anxi, Qaidam and Zhangmu) in northwest China and five worldwide cattle breeds (Angus, Holstein, Jersey, Gir and N’Dama) to explore their genetic composition and identify selective sweeps in the Chinese cattle breeds. Analyses of phylogenetic and population structure revealed that three indigenous cattle breeds share genomic components from Bos taurus and Bos indicus. A novel set of candidate genes was identified through comparative genomic analyses of cattle from contrasting environments based on SNP and copy number variation (CNV) data. These candidate genes are potentially associated with adaptive phenotypes, including high-altitude adaptability (e.g., ANGPT1, PPARGC1A, RORA), cold climate adaptation (e.g., TSHR, PRKG, OXCT1), and dryland adaptation (e.g., PLEKHA7, NFATC1, PLCB1). This study unravels the unique adaptive diversity of three Chinese indigenous cattle breeds, providing a valuable resource for future research on sustainable livestock breeding strategies to response to climate change.

Short-read RNA sequencing has been used to sequence the transcriptome of the skeletal muscle of yak and cattle-yak; however, full-length transcripts cannot be obtained and alternative splicing (AS) events cannot be inferred using this sequencing approach. Here, we used Oxford Nanopore Technologies (ONT) full-length sequencing to sequence the transcriptome of the longissimus dorsi of yak and cattle-yak. A total of 20,323 novel genes and 172,870 novel transcripts were identified, and 159,700 novel transcripts were successfully annotated. A total of 157,812 AS events, 58,073 simple sequence repeats, 57,468 complete open reading frames, 2296 transcription factors, and 20,404 lncRNAs were detected. Differentially expressed transcripts (DETs) in the longissimus dorsi muscle of yak and cattle-yak were involved in the MAPK and JAK-STAT signaling pathways related to muscle development and growth. Protein-protein interaction analysis of DETs suggested that TNNI2 might make a major contribution to differences in muscle growth and meat quality traits between yak and cattle-yak. The results have enriched the transcriptome data of dorsal muscles, providing new ideas for the study of transcriptional regulation processes, and also providing useful information for the production of higher yields of yak meat.

The Yushu yak is one of China’s distinctive yak breeds, primarily distributed in the Yushu Tibetan Autonomous Prefecture of Qinghai Province and its surrounding areas. Yushu yaks are not only economically and culturally significant but also play a crucial role in protecting the ecosystem of the Qinghai-Tibet Plateau and promoting sustainable development. However, there are no clear records regarding the ancestry, population structure, and unique traits of Yushu yaks. Therefore, this study conducted an analysis of genetic diversity, population structure, and selection signals in Yushu yak populations, aiming to provide references for the conservation and utilization of the breed genetic resources. The results of the analysis showed that the Yushu yak population has high genetic diversity and low inbreeding coefficients, indicating a stable genetic structure. Population structure analysis revealed that the Yushu yak lineage is unique, with limited gene flow between domestic and wild yaks. Functional enrichment analysis of positively selected genes in Yushu yaks indicated prominent selection features related to growth and development as well as energy metabolism. Additionally, we classified the Yushu yak breeding bulls into family lineages based on kinship, which is essential for improving the efficiency of utilizing genetic resources and scientifically managing the population.

The yak is a classic grazing livestock species on the Qinghai–Tibet Plateau, and fat deposition is indispensable for its survival and metabolism. Coding and non-coding RNAs (ncRNAs) play an important role in regulating fat deposition in livestock. In this study, the expression of mRNAs, lncRNAs, miRNAs, and circRNAs in the subcutaneous fat of yaks under grazing and stall feeding was measured using whole-transcriptome sequencing technology. A total of 677 differentially expressed (DE) mRNAs, 120 DE lncRNAs, 2216 DE circRNAs, and 15 DE miRNAs were identified, and their biological function was explored using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Co-expression RNA (ceRNA) networks between DE ncRNAs and DE mRNAs were further constructed, and the crucial RNAs and signal pathways regulating fat deposition in yaks were obtained. The effect of mRNAs and ncRNAs on fat deposition in yaks mainly depended on the PPAR, PI3K–Akt, and cAMP signaling pathways, and the regulatory pathways TCONS00042948, TCONS00012083/bta-miR-2316/MCAT, and NR4A3 may be critical in this process. This study provides some theoretical basis for breeding yak species and promotes improvements in yak production.

BACKGROUND:The distinctive geography and climate of Gansu Province have given rise to three indigenous cattle breeds-Zaosheng, Anxi, and Yangba. Renowned for their superior meat quality and remarkable adaptability, these breeds are crucial for maintaining genetic diversity. However, they are under threat from intensive farming practices, environmental degradation, and genetic drift, which could lead to an irreversible loss of genetic resources. Thanks to natural and artificial selection, these breeds possess genetic markers that enhance their adaptation to extreme environments and improve key economic traits. By integrating comprehensive genome data from multiple breeds, this study aims to analyze population genetics, detect composite selection signals, and perform functional enrichment to uncover the mechanisms behind genetic differentiation and adaptive evolution. This research is pivotal for developing resilient breeds and ensuring sustainable resource management. RESULTS:The genetic background of local cattle breeds in Gansu shows a mix between indicine cattle (Bos indicus) and taurine cattle (Bos taurus), with geographical differentiation: Yangba cattle in the southeast mainly exhibit indicine ancestry (54.43%), while Anxi and Zaosheng cattle in the northwest show a predominance of taurine ancestry (86.51% and 74.81%, respectively). This divergence is closely related to historical ethnic migrations, geographic barriers, and gene flow along the Silk Road. Selection signal analysis has revealed specific adaptation mechanisms in different populations: Yangba cattle exhibit strong selection signals in the T-cell receptor pathway (FYN, FYB1) and skeletal development genes (SOX6), which may be related to their adaptation to hot and humid environments and mountainous terrain; Anxi cattle show adaptive evolution in nitrogen metabolism (CA8, CA10) and adherens junction pathways (CTNNA2), possibly reflecting the genetic basis for their adaptation to arid conditions; Zaosheng cattle display strong selection signals in muscle development (LARGE1, SGCZ) and immune regulation genes (SLAMF family), likely associated with enhanced meat production performance and increased pathogen resistance driven by artificial breeding. CONCLUSION:This study explores the drivers of genetic diversity and adaptive evolution in Gansu's native cattle breeds, emphasizing the impact of geography and human activity on genetic divergence. It provides a theoretical basis for conserving breed resources, identifying functional genes, and developing breeding strategies.

The emergence and development of pathogenic bacterial resistance to antibiotics pose significant challenges to human health. Antimicrobial peptides (AMPs) are considered promising alternatives to conventional antibiotics. Lactoferricin (Lfcin), a cationic AMP located in the N-terminal region of lactoferrin, serves as the antimicrobial active center of the intact protein. The presence of two cysteines in Lfcin allows for the formation of an intramolecular disulfide bond, which may influence its molecular structure and antibacterial function. To investigate this hypothesis, we synthesized, purified, and identified bovine Lfcin along with two derivatives: Lfcin with a disulfide bond (Lfcin DB) and a mutated form that cannot form the disulfide bond (Lfcin C36G). We analyzed the circular dichroism spectra of these peptides under varying ionic and hydrophobic conditions, while their tertiary structures were predicted using AlphaFold3. Results indicated that increased ionic strength reduced the random coil ratios across all peptides. The secondary structure of Lfcin showed similar percentages with Lfcin C36G in the H2O and similar ratios with Lfcin DB under hydrophobic conditions. AlphaFold3-predicted models revealed two distinct structures: one predominantly adopting α-helix conformations and the other characterized by β-sheet topology. Furthermore, we evaluated the antibacterial activity of the peptides against four Gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella gallinarum. The synthetic peptides demonstrated broad-spectrum antibacterial activity, with Lfcin exhibiting superior efficacy compared to its derivatives. Our findings suggest that Lfcin can reversibly interconvert between two distinct molecular states under varying ionic strengths and hydrophobic effects, with the resulting structural transformations enhancing its antibacterial function.

The hybridization of yak with cattle is an effective means to improve the yak’s production performance. The fatty trait greatly affects the meat quality, the growth and development, and the reproduction of bovine. In this study, the thickness of subcutaneous fat in cattle-yaks and yaks was measured, and fatty acid composition was detected by a gas chromatograph-mass spectrometer (GC-MS); the transcriptome and metabolome in fat were detected by mRNA-Sequencing (mRNA-Seq) and an ultra-high performance liquid chromatography-mass spectrometry technique (UHPLC-MS/MS), respectively. The results revealed that the thickness of subcutaneous fat in yaks was greater than the value in cattle-yaks; the content of saturated fatty acids (SFAs), polyunsaturated fatty acids (PUFAs), and Σn-3 PUFAs in cattle-yaks’ fat were higher than the values in yaks’ fat, whereas the unsaturated fatty acids (UFAs) and monounsaturated fatty acids (MUFAs) content in cattle-yaks’ fat were lower. Furthermore, the expression of the SREBF1 gene in the fat deposition of the two bovines was affected by PI3K-Akt and AMPK signal pathways, which led to the expression change of downstream VLDLR, INSIG1, ACACA, LIPE, SLC2A4, CPT1C, SCD, and DGAT2 genes. Therefore, fatty acid synthesis, glucose and lipid transport, and lipid synthesis differed in fat depositions between the two bovines, ultimately leading to differences in the fat quantity in the two bovines. Moreover, the expression of VLDLR, CPT1C, LEP, SCD, and CEBPE genes was closely related to the differences in fatty acid composition between the fat tissues of two bovines. The results can provide some theoretical basis for yak breeding and can also promote the improvement of yak production.

The epididymis is essential for sperm maturation. During sperm maturation, markable alterations of the payload of small noncoding RNAs are observed in the epididymis, which indicated the role of epigenetic alterations in sperm maturation. However, the N6-Methyladenosine (m6A) modification profile of the epididymis remains unelucidated. Therefore, in this study, we assessed the m6A modification levels in the caput, corpus, and cauda of the yak epididymis using a combination of methylated RNA immunoprecipitation and RNA sequencing. The m6A levels were significantly increased in the corpus of the epididymis. Functional enrichment analysis of differentially methylated RNA (DMR) between the corpus and caput group revealed the significant enrichment of DMRs in the gap junction, ErbB signaling pathway, and mTOR signaling pathway, which participate in cell communication and sperm maturation. In addition, the DMRs of cauda-vs-corpus group were enriched in apoptosis, the FoxO signaling pathway, the PI3K-Akt signaling pathway, and the tumor necrosis factor signaling pathway that were associated with sperm autophagy, oxidative stress, and sperm maturation. Furthermore, we identified the key genes exhibiting significant changes in m6A levels but with no differences in RNA levels, including YY1-associated factor 2, forkhead box J2, and forkhead box O1. This finding indicated that m6A modifications affect these genes during translation, thereby participating in sperm maturation. In summary, we generated the m6A profile of the yak epididymis, which will aid in further elucidating the maturation process of sperm and reveal more information related to male infertility.

Cattle–yak, a hybrid of yak and cattle, exhibits significant heterosis but male infertility, hindering heterosis fixation. Although extensive research has been conducted on transcriptional mechanisms in the testes of cattle–yak, the understanding of their translational landscape remains limited. In this study, we characterized the translational landscape of yak and cattle–yak based on Ribo-seq technology integrated with RNA-seq data. The results revealed that gene expression was not fully concordant between transcriptional and translational levels, whereas cattle–yak testes exhibited a stronger correlation across these two regulatory layers. Notably, genes that were differentially expressed at the translational level only (MEIOB, MEI1, and SMC1B) were mainly involved in meiosis. A total of 4,236 genes with different translation efficiencies (TEs) were identified, and the TEs of most of the genes gradually decreased as the mRNA expression level increased. Further research revealed that genes with higher TE had a shorter coding sequence (CDS) length, lower GC content, and higher normalized minimum free energy in the testes of yaks, but this characteristic was not found in cattle–yaks. We also identified upstream open reading frames (uORFs) in yak and cattle–yak testes, and the sequence characteristics of translated uORFs and untranslated uORFs were markedly different. In addition, we identified several short polypeptides that may play potential roles in spermatogenesis. In summary, our study uncovers distinct translational dysregulations in cattle–yak testes, particularly affecting meiosis, which provides novel insights into the mechanisms of spermatogenesis and male infertility in hybrids.

Translation regulation plays a crucial role in testicular development and spermatogenesis, but its dynamic mechanism has not yet been elucidated. This study integrated transcriptome data through ribosomal sequencing (Ribo-seq) to analyze the translation landscape of yak (Bos grunniens) testes at 6 months (Y6M), 18 months (Y18M), and 4 years (Y4Y) of age. The results revealed that the ribosome footprint characteristics of yaks were consistent with those of other mammals. The differentially translated genes during sexual maturity are significantly enriched in the meiotic cell cycle, PI3K Akt, and Notch signaling pathways. From Y6M to Y18M, most of the TE altered genes showed inverse transcription-translation efficiency trends, potentially involved in protein ubiquitination modification. From 18 M to 4Y, translationally altered genes lacked transcriptional changes but associated with acetyltransferase and phosphotransferase activity. PPI analysis identified stage-specific regulatory genes: COL1A2/MEIOB/SYCP3 (6 M-18 M) and STAT1/ITGB5/ERBB2 (18 M-4Y). Additionally, we identified 106 predicted translatable small open reading frames (sORFs), which included annotations for 58 known coding proteins and 1 long non-coding RNA. Sequence feature analysis revealed that higher translation efficiency correlates with longer uORF length, lower GC content, shorter CDS length, and higher NMEF. In conclusion, the results provide new insights into the dynamic regulation of gene translation during testicular development and spermatogenesis, which is highly significant for enhancing yak reproductive performance.

Translation, plays a critical regulatory role in follicular development, ovulation, and corpus luteum formation and degeneration in the ovaries. To better understand the molecular mechanisms of reproductive regulation at the translation level in yaks, the present study analyzed gene expression changes in the ovarian tissues of yaks in different reproductive stages by using ribosome profiling and integrating RNA sequencing data. The small open reading frames (sORFs) of the ovarian tissue were characterized, and the effect of the translation efficiency of the targeted genes on their sequence features was determined. The results showed that over 80% of genes in the two groups exhibited inconsistent changes in their expression at the transcription and translation levels; this finding indicated that the changes in gene expression at both levels were not merely synergistic. The pathway enrichment analysis revealed that these differentially expressed genes were enriched in various pathways, including PI3K-Akt, MAPK, calcium signaling, and ovarian steroidogenesis. Further investigations showed that some genes related to ovarian function displayed inconsistent changes in their expression at both transcription and translation levels and exhibited dynamic changes in translation activity, including PALB2, BMP7, PIK3R2, and WNT2B. Additionally, we identified 66 predicted translatable sORFs and assessed the impact of upstream ORFs on the translation efficiency of downstream major ORFs. The present study systematically revealed the characteristics of gene expression at the translational level in yak ovarian tissues in different reproductive stages for the first time and provided a new perspective for in-depth understanding of the physiological mechanisms of yak reproduction.

This study unveils the unique origins, evolution, and genetic variations of the Yangba cattle, an endangered breed in China, through a comparative genomic analysis involving 202 individuals from 21 domestic and international breeds. Genetic component analysis revealed that the Yangba cattle comprise four ancestral lineages: Eurasian taurine (18%), East Asian taurine (26%), Chinese indicine (39%), and Indian indicine (17%). Their high genetic diversity and low inbreeding coefficient set them apart significantly from mainstream commercial breeds. Gene introgression analysis indicated that the influx of genetic material from East Asian taurine has enhanced the Yangba cattle’s adaptability to environmental stress, while the introgression from Chinese indicine has endowed them with unique advantages in muscle development and tissue repair. A genome-wide selection scan identified strong positive selection signals for genes such as ABCC2, which is involved in immune regulation, and NCOA3, which plays a role in growth regulation, in the Yangba cattle. This study systematically elucidates, for the first time, the composite ancestral composition and mechanisms of adaptive evolution in Yangba cattle. These findings offer critical insights into the conservation and sustainable utilization of endangered cattle resources and underscore the importance of implementing effective breeding programs.

The aim of this study is to determine the effects of a high-concentrate diet on growth performance, serum biochemical indexes, and rumen microbiota in house-fed yaks. Sixteen male yaks (body weight, 151.73 ± 14.11 kg; 18 months) were randomly allocated into two dietary treatments: a group with a low level of concentrate (n = 8, LC, concentrate–forage = 40:60) and a group with a high level of concentrate (n = 8, HC, concentrate–forage = 60:40). We found that compared with the LC group, the average daily feed intake (ADFI), the average daily gain (ADG), and the serum albumin (ALB) concentration in the HC group were significantly increased (p < 0.05). The rumen bacterial compositions also differed significantly between the groups, as indicated by principal coordinate analysis (p < 0.05). Firmicutes and Bacteroidota were the main dominant phyla of rumen bacteria in yaks. Compared with the LC group, the relative abundance of Firmicutes in the HC group was significantly increased (p < 0.05) and the relative abundance of Bacteroidota was significantly decreased (p < 0.05). At the genus level, Rikenellaceae_RC9_gut_group, Succiniclasticum, Prevotella, Christensenellaceae_R-7_group, and NK4A214_group had the highest relative abundance. The relative abundance of Christensenellaceae_R-7_group in the HC group was significantly higher than that in the LC group (p < 0.05). The PICRUSt 2 results showed a significant enrichment in glycosaminoglycan degradation, apoptosis, and ECM–receptor interaction in HC relative to LC (p < 0.05). In conclusion, high-concentrate diets can enhance growth performance and alter the compositions and functions of ruminal bacterial communities in yaks.

Milk lipids greatly affect the volatile flavor of milk, and the relationship between lipids and volatile flavor in yak milk was explored in this study. The volatile flavor compounds (VFCs), lipids profile, fatty acids in yak ordinary milk and colostrum were detected with HP/SPME-GC-MS, the semiquantitative lipidomics based on LC-MS/MS, GC-MS, respectively. The VFCs differences in yak milk were closely related to 1-((1 s,3ar,4r,7 s,7as)-4-hydroxy-7-isopropyl-4-methyloctahloctahydro-1h-inden-1-Yl)-ethanone,2,6,6-trimethyl-2,4-cycloheptadien-1-one, pentanal, 2-phenylethyl propionate, octanoic acid methyl ester, diphosphoric acid diisooctyl ester, (Z)-3,4,4-trimethyl-5-oxo-2-hexenoic acid and acetic acid. The volatile flavor in yak milk was well correlated with milk lipids, and TG(4:0_12:3_18:1), TG(6:0_8:0_18:1), TG(4:0_12:3_18:1), TG(12:0_18:2_18:3) and TG(16:0e_18:1_22:5) were the crucial lipid molecules affecting volatile flavor. The degeneration of above lipids by hydrolysis produced some fatty acids and alcohol, then these compounds were further derived into other VFCs especially above crucial 8 molecules. This study provided a theoretical basis for improving the volatile flavor by controlling lipids in yak milk.