Yak Breeds Research Articles

Impact of weight variation on the microbiome of yak dams and calves.

Limited information exists regarding the microbiome composition of yak calves of varying weights. Therefore, this study aimed to investigate the microbiomes of mother-calf pairs with different weight profiles. Fecal and blood samples were collected from both lower-weight (CB) and higher-weight (HB) yak calves, along with their corresponding female yaks (CA, HA). The results revealed significantly higher levels of T-AOC (total antioxidant capacity) and GSH-Px (glutathione peroxidase) in HB animals (p < 0.001). Sequencing yielded 652,181 and 643,369 filtered reads in female and calf yaks, respectively. Alpha diversity analysis indicated that Chao1, Faith_pd, and Observed species were significantly higher in CA compared to HA (p < 0.01). Furthermore, nine genera were notably different between HA and CA yaks, including Avispirillum, Fimenecus, CAG-1031, Odoribacter 865974, and Jeotgalicoccus A 310962. Compared to CB yaks, CA animals exhibited significant differences in one phylum and six genera, including CAG-485 (p < 0.05), CAG-83 (p < 0.01), Copromorpha (p < 0.01), Phocaeicola A 858004 (p < 0.05), and UBA2253 (p < 0.05). In summary, higher-weight yak calves demonstrated increased oxidative resistance, and weight profiles were linked to the microbiomes of both female yaks and their calves. These findings offer valuable insights for optimizing yak breeding practices in high-altitude regions.

Genetic structure analysis of yak breeds and their response to adaptive evolution

Yaks are crucial genetic resources in the Tibetan Plateau and surrounding regions. Throughout the long process of domestication, natural and artificial selection pressures have enabled yaks to demonstrate adaptive characteristics to the environment in terms of physiological structure and genetic molecules, but no systematic cell analysis has been carried out on this phenomenon of yaks. Here, the population structure and genetic diversity of yak were studied by WGRS, and the genes related to yak adaptability were excavated. Combined with scRNA-seq method, the transcription map of yak lung tissue and skin tissue was constructed, which provided a new comprehensive insight into yak adaptability. The analysis of yak population structure showed that there was obvious genetic differentiation between TZ _ yak and other seven yak populations, while there was significant genetic exchange between PL _ yak and SB _ yak at high altitude. WGRS and scRNA-seq analysis revealed that the gene HIF1A related to high altitude adaptation was expressed in various cell types, while EPAS1 was predominantly expressed in epithelial and endothelial cells of yak lung tissue. Endothelial cells play a critical role in hypoxia-adapted VEGF signaling, which correlates closely with the high expression of KDR and VEGFA genes in endothelial cells and monocytes. Furthermore, in the selection signal of High _ yak vs Low _ yak, 19.8 % of the genes overlapped with the genes screened by skin scRNA-seq, including genes related to coat color such as RORA, BNC2, and KIT. Notably, BNC2 is a gene associated with melanin deposition and shows high expression levels in HS cells. Additionally, GRN in melanocytes and SORT1 in IRS play an important role in cell communication between melanocytes and IRS. These findings offer new insights into the natural polymorphism of yaks and provide a valuable reference for future research on high-altitude mammals, and potentially even human genetics.

Maternal Genetic Diversity, Differentiation and Phylogeny of Wild Yak and Four Domestic Yak Breeds in Qinghai, China Inferred from Mitochondrial Cytb Variations

Maternal Genetic Diversity, Differentiation and Phylogeny of Wild Yak and Four Domestic Yak Breeds in Qinghai, China Inferred from Mitochondrial Cytb Variations

Comparative analysis of intestinal microbiota composition between free-ranged captive yak populations in Nimu County.

The intestinal microbiota assumes a pivotal role in modulating host metabolism, immune responses, overall health, and additional physiological dimensions. The structural and functional characteristics of the intestinal microbiota may cause alterations within the host's body to a certain extent. The composition of the gut microbiota is associated with environmental factors, dietary habits, and other pertinent conditions. The investigation into the gut microbiota of yaks remained relatively underexplored. An examination of yak gut microbiota holds promise in elucidating the complex relationship between microbial communities and the adaptive responses of the host to its environment. In this study, yak were selected from two distinct environmental conditions: those raised in sheds (NS, n=6) and grazed in Nimu County (NF, n=6). Fecal samples were collected from the yaks and subsequently processed for analysis through 16S rDNA and ITS sequencing methodologies. The results revealed that different feeding styles result in significant differences in the Alpha diversity of fungi in the gut of yaks, while the gut microbiota of captive yaks was relatively conserved. In addition, significant differences appeared in the abundance of microorganisms in different taxa, phylum Verrucomicrobiota was significantly enriched in group NF while Firmicutes was higher in group NS. At the genus level, Akkermansia, Paenibacillus, Roseburia, Dorea, UCG_012, Anaerovorax and Marvinbryantia were enriched in group NF while Desemzia, Olsenella, Kocuria, Ornithinimicrobium and Parvibacter were higher in group NS (P<0.05 or P<0.01). There was a significant difference in the function of gut microbiota between the two groups. The observed variations are likely influenced by differences in feeding methods and environmental conditions both inside and outside the pen. The findings of this investigation offer prospective insights into enhancing the yak breeding and expansion of the yak industry.

Polymorphisms of ITGA9 Gene and Their Correlation with Milk Quality Traits in Yak (Bos grunniens).

A single-nucleotide polymorphism (SNP) is a genome-level trait that arises from a variation in a single nucleotide, leading to diversity in DNA sequences. SNP screening is commonly used to provide candidate genes for yak breeding efforts. Integrin Subunit Alpha 9 (ITGA9) is an integrin protein. It plays an important role in cell adhesion, signalling, and other processes. The aim of this study was to discuss the association between genetic polymorphisms in the ITGA9 gene and milk quality traits and to identify potential molecular marker loci for yak breeding quality. We genotyped 162 yaks using an Illumina Yak cGPS 7K liquid chip and identified the presence of polymorphisms at nine SNP loci in the ITGA9 gene of yaks. The results showed that the mutant genotypes in the loci g.285,808T>A, g.306,600T>C, and g.315,413C>T were positively correlated with the contents of casein, protein, total solids (TS), and solid nonfat (SNF) in yak milk. In other loci, heterozygous genotypes had a positive correlation with nutrient content in yak milk. Then, two ITGA9 haplotype blocks were constructed based on linkage disequilibrium, which facilitated a more accurate screening of ITGA9 as a candidate gene for yak milk quality improvement. In conclusion, we identified SNPs and haplotype blocks related to yak milk quality traits and provided genetic resources for marker-assisted selection in yak breeding.

Genetic diversity, phylogeography, and maternal origin of yak (Bos grunniens)

BackgroundThere is no consensus as to the origin of the domestic yak (Bos grunniens). Previous studies on yak mitochondria mainly focused on mitochondrial displacement loop (D-loop), a region with low phylogenetic resolution. Here, we analyzed the entire mitochondrial genomes of 509 yaks to obtain greater phylogenetic resolution and a comprehensive picture of geographical diversity.ResultsA total of 278 haplotypes were defined in 509 yaks from 21 yak breeds. Among them, 28 haplotypes were shared by different varieties, and 250 haplotypes were unique to specific varieties. The overall haplotype diversity and nucleotide diversity of yak were 0.979 ± 0.0039 and 0.00237 ± 0.00076, respectively. Phylogenetic tree and network analysis showed that yak had three highly differentiated genetic branches with high support rate. The differentiation time of clades I and II were about 0.4328 Ma, and the differentiation time of clades (I and II) and III were 0.5654 Ma. Yushu yak is shared by all haplogroups. Most (94.70%) of the genetic variation occurred within populations, and only 5.30% of the genetic variation occurred between populations. The classification showed that yaks and wild yaks were first clustered together, and yaks were clustered with American bison as a whole. Altitude had the highest impact on the distribution of yaks.ConclusionsYaks have high genetic diversity and yak populations have experienced population expansion and lack obvious phylogeographic structure. During the glacial period, yaks had at least three or more glacial refugia.

Establishment of an immortalized yak granulosa cell line: in vitro tool for understanding the molecular processes of ovarian follicle development.

The yak, a unique species of cattle found exclusively on the western plateau of China, is a valuable source of livelihood for local residents. However, their low fecundity restricts the expansion of yak farming, whereas regional factors limit studies on yak breeding. Granulosa cells (GCs), which provide essential steroid hormones and growth factors for oocytes, have been the focus of many studies on the mechanisms of follicular growth and atresia. This study aimed to establish an immortalized cell line model that could serve as a tool for future studies on the mechanisms of ovarian follicle development in yaks. First, we isolated primary yak granulosa cells (yGCs) and evaluated their replicative senescence after continuous in vitro subculturing. Subsequently, an immortalized culture method for primary yGC was explored, and a new cell line model was established to study the mechanism of follicular development in vitro. We used a mammalian gene expression lentivirus vector to transfer the simian virus 40 large T antigen (SV40T) into primary yGC to obtain an immortalized cell line. The immortalized yGCs were morphologically identical to the primary yGCs, and cell proliferation and growth were normal within a limited number of generations. Follicle-stimulating hormone receptor (FSHR), a specific marker for GCs, was positively expressed in immortalized yGCs. Furthermore, the immortalized yGCs retained the ability of GCs to synthesize estradiol and progesterone and expressed genes related to steroid synthesis. The establishment of immortalized yGC opens up a myriad of possibilities for advancing our understanding of yak reproductive biology and improving yak breeding strategies.

Microbial interventions in yak colibacillosis: Lactobacillus-mediated regulation of intestinal barrier.

The etiology of Escherichia coli in yaks, along with its drug resistance, results in economic losses within the yak breeding industry. The utilization of lactic acid bacteria treatment has emerged as a viable alternative to antibiotics in managing colibacillosis. To elucidate the therapeutic mechanisms of Lactobacillus against Escherichia coli-induced intestinal barrier damage in yaks, we employed yak epithelial cells as the experimental model and established a monolayer epithelial barrier using Transwell. The study encompassed four groups: a control group, a model group (exposed to E. coli O78), a low-dose Lactobacillus group (E. coli O78 + 1 × 105CFU LAB), and a high-dose Lactobacillus group (E. coli O78 + 1 × 107CFU LAB). Various techniques, including transmembrane resistance measurement, CFU counting, RT-qPCR, and Western Blot, were employed to assess indicators related to cell barrier permeability and tight junction integrity. In the Model group, Escherichia coli O78 significantly compromised the permeability and tight junction integrity of the yak epithelial barrier. It resulted in decreased transmembrane resistance, elevated FD4 flux, and bacterial translocation. Furthermore, it downregulated the mRNA and protein expression of MUC2, Occludin, and ZO-1, while upregulating the mRNA expression and protein expression of FABP2 and Zonulin, thereby impairing intestinal barrier function. Contrastingly, Lactobacillus exhibited a remarkable protective effect. It substantially increased transmembrane resistance, mitigated FD4 flux, and reduced bacterial translocation. Moreover, it significantly upregulated the mRNA and protein expression of MUC2, Occludin, and ZO-1, while downregulating the mRNA and protein expression of FABP2 and Zonulin. Notably, high-dose LAB demonstrated superior regulatory effects compared to the low-dose LAB group. In conclusion, our findings suggest that Lactobacillus holds promise in treating yak colibacillosis by enhancing mucin and tight junction protein expression. Furthermore, we propose that Lactobacillus achieves these effects through the regulation of Zonulin.

Whole genome resequencing-based analysis of plateau adaptation in Meiren yak (Bos grunniens)

The Meiren yak is an important genetic resource in Gansu Province, China. In this study, we aimed to explore the evolutionary history and population structure of the genetic resource of Meiren yak and to mine the characteristic genes of Meiren yak. We analysed a total of 93 yaks of eight yak breeds based on whole genome resequencing combined with population genomics and used θπ ratio and Fst method to screen the selected sites in the genome region. The results proved that Meiren yak can be used as a potential genetic resource in Gansu Province. The genes in Meiren yak with positive selection in selection signal analysis were subjected to the Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses, which indicated that the genes were related to the adaptability to high altitude and hypoxic environment. By analysing the genetic variation of Meiren yak at the genome-wide level, this study provided a theoretical basis for genetic improvement of Meiren yak and for the development of high-quality yak resources.

Whole-genome resequencing reveals genetic diversity, differentiation, and selection signatures of yak breeds/populations in southwestern China.

The Sichuan-Yunnan region is the main production area of yaks in southwestern China, with rich genetic resources of Yaks. Nevertheless, there have been limited study on the genetic characteristics of the entire yak populations in Tibet and southwestern China. In this study, we performed whole-genome resequencing to identify genetic variation information in a total of 198 individuals from six yak breeds (populations) in Sichuan (Muli yak, Jinchuan yak, Changtai yak, Maiwa yak), Yunnan (Zhongdian yak), and Tibet (Tibetan yak). The aim was to investigate the whole-genome genetic diversity, population genetic structure, and genome selection signatures. We observed that all six populations exhibit abundant genetic diversity. Except for Tibetan yaks, which showed low nucleotide diversity (0.00104), the remaining yak populations generally displayed high nucleotide diversity (0.00129-0.00153). Population genetic structure analysis revealed that, among the six yak populations, Muli yak exhibited greater differentiation from other yak populations and formed a distinct cluster independently. The Maiwa yak population displayed a complex genetic structure and exhibited gene exchange with Jinchuan and Changtai yaks. Positive selection signals were detected in candidate genes associated with growth (GNB4, HMGA2, TRPS1, and LTBP1), reproduction (PI4KB, DYNC1I1, and GRIP1), immunity (CD200 and IL1RAP), lactation (SNX13 and CPM), hypoxia adaptation (NDUFB6, PRKN, and MRPS9), hair (KRT24, KRT25, and KRT26), meat quality (SUCLG2), digestion and absorption (CLDN1), and pigment deposition (OCA2) using the integrated Pi and F ST methods. This study provides significant insights into understanding the whole-genome genetic characteristics of yak populations in Tibet and southwestern China.

Features of blood morphological and biochemical parameters of yaks of the new Bay-Talsky type in the Republic of Tyva

The purpose of this research was to study the morphological and biochemical parameters of Bay-Talsky type yaks bred in the Bay-Tal yak breeding enterprise located in the Bay-Taiga mountain range. The BayTal type yak was created on the basis of purebred breeding in the Sarlyk breed in 2021. 43 heads of yaks of 18 months of age were used as experimental animals, from which two groups of yaks were formed, of which 23 heads of a new intra-breed Bay-Tal type and 20 heads of yaks of the Sarlyk breed. Of the yaks indicated in this experiment, blood counts were previously studied only in yaks of the Sarlyk breed. We have conducted the study of morphological and biochemical parameters of the Bay-Tal type yaks for the first time. As a result of the study, it was revealed that the average values of blood parameters in yaks were within the physiological norm. Nevertheless, the Bay-Tal yaks showed a higher level of hemoglobin – by 9.8% (P&lt;0.05), the content of erythrocytes – by 10.9% (P&lt;0.05) and leukocytes – by 34.4% (P&lt;0.01) compared with Sarlyk yaks. Along with morphological parameters, the yaks of the new Bay-Tal type are characterized by a high content of biochemical blood parameters: total protein - by 16.4% (P&lt;0.05), urea – by 40.6% (P&lt;0.01), cholesterol and glucose – by 60% (P&lt;0.001). The results obtained are important for establishing the average population level of a number of morphological and biochemical blood parameters in Bay-Tal yaks.

Advancing Yak Breeding in China: Harnessing Genetic Resources and Marker-Assisted Selection for Improved Production Traits

Advancing Yak Breeding in China: Harnessing Genetic Resources and Marker-Assisted Selection for Improved Production Traits

Polymorphisms of CCSER1 Gene and Their Correlation with Milk Quality Traits in Gannan Yak (Bos grunniens).

Coiled-coil serine-rich protein 1 (CCSER 1) gene is a regulatory protein gene. This gene has been reported to be associated with various economic traits in large mammals in recent years. The aim of this study was to investigate the association between CCSER1 gene single nucleotide polymorphisms (SNPs) and Gannan yaks and to identify potential molecular marker loci for breeding milk quality in Gannan yaks. We genotyped 172 Gannan yaks using Illumina Yak cGPS 7K liquid microarrays and analyzed the correlation between the three SNPs loci of the CCSER1 gene and the milk qualities of Gannan yaks, including milk fat, protein and casein. It was found that mutations at the g.183,843A>G, g.222,717C>G and g.388,723G>T loci all affected the fat, protein, casein and lactose traits of Gannan yak milk to varying extents, and that the milk quality of individuals with mutant phenotypes was significantly improved. Among them, the milk fat content of AG heterozygous genotype population at g.183,843A>G locus was significantly higher than that of AA and GG genotype populations (p < 0.05); the casein and protein content of mutant GG and CG genotype populations at g.222,717C>G locus was significantly higher than that of wild-type CC genotype population (p < 0.05); and the g.388,723G>T locus of the casein and protein contents of the mutant TT genotype population were significantly higher (p < 0.05) than those of the wild-type GG genotype population. These results provide potential molecular marker sites for Gannan yak breeding.

Quantitative proteomics analysis reveals the key proteins related to semen quality in Niangya yaks

BackgroundProteins related to sperm motility and sperm morphology have an important impact on sperm function such as metabolism, motility and fertilisation etc. An understanding of the key proteins related to semen quality in Niangya yaks would help to provide support for breeding. However, the key proteins that affect semen quality in Niangya yaks remain unclear.MethodsHerein, we applied tandem mass tag (TMT) labeling and liquid chromatography-tandem mass spectrometry (LC‒MS/MS) to analyze the expression levels of sperm proteins in groups of high- and low-quality semen from Niangya yaks. And fifteen differentially expressed proteins (DEPs) were randomly selected for expression level validation by parallel reaction monitoring (PRM).ResultsOf the 2,092 quantified proteins, 280 were identified as DEPs in the high-quality group versus the low-quality group. Gene Ontology (GO) analysis revealed that in terms of biological pathways, the DEPs were mainly involved in metabolic processes, cell transformation processes, and single organism metabolic processes. In terms of cell composition, the DEPs were mainly located in the cell membrane, organelle, molecular complex. In terms of molecular functions, the most abundant functions of the DEPs were catalytic activity, binding activity, transport activity, and enzyme regulation activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the DEPs were mainly involved in the cytokine and cytokine receptor interaction, notch signaling pathway, lysine biosynthesis, renal function-related protein and proteasome pathway. From protein-protein interaction (PPI) analysis of DEPs involved in important pathways, 6 related proteins affecting the semen quality of Niangya yaks were identified. And the results of the PRM and TMT analysis were consistent.ConclusionsThe differential sperm proteomic analysis of high- and low-quality semen from Niangya yaks, revealed 6 proteins (PSMC5, PSMD8, PSMB3, HSP90AA1, UGP2 and HSPB1), were mainly concentrated in energy production and metabolism, might play important roles in semen quality, which could serve as candidates for the selection and breeding of Niangya yaks.

CURRENT STATUS AND DEVELOPMENT PROSPECTS YAK BREEDING IN THE REPUBLIC OF ALTAI

The yak is a late-maturing animal compared to cattle. However, the yak has precious properties in terms of endurance to harsh climatic conditions, the ability to make long transitions along inconvenient rocky mountain paths and feed all year round in the pasture, including during the winter. The local population of the Altai Republic has been breeding yaks since ancient times, as evidenced by archaeologists’ finds. Although the maximum number of yaks in the Altai Republic reached in 1990 - 18468 heads and were bred in the farms of five administrative districts, at present, the number of yaks totals only 6043 heads, and they are concentrated mainly in the farms of one municipality - the Kosh-Agachsky district. The authors propose measures for the effective development of yak breeding, increasing the number and rational use of these unique animals, considering natural and climatic conditions, land resources and the existing potential of agricultural producers in the Altai Republic. It is necessary to carry out selection and breeding work to create a highly productive breed to improve the breeding and practical qualities of the Altai population of yaks. The development of gastroecological tourism is the most promising for the Altai Republic. The need for high-quality, environmentally friendly meat, including barley, is constantly growing. Therefore, it is necessary to increase the number of yaks to develop a system at the farm level that ensures the rational use of available pasture lands. One of the critical issues is the development of State Standards (GOST) for meat and all by-products of yaks. Creating a marketing and advertising system for yak products remains an urgent problem.

Basic behavior recognition of yaks based on improved SlowFast network

The yak is a symbol of the Tibetan Plateau and an indispensable livestock resource at high altitudes, with important ecological, economic, and cultural values. When yaks are sick, their excrement can cause serious damage to the highland ecosystem, so real-time monitoring of their health status is essential for ecological conservation. The daily behaviors of yaks, such as eating, lying, standing, and walking, contains a wealth of health information. By recognizing the behavior of yaks using computer vision technology, real-time monitoring of yak health status can be achieved, thus, effectively protecting the ecological environment while maintaining the economic benefits of yak breeding. This study proposes a non-contact yak behavior recognition method based on the SlowFast model. The method uses two paths with different sampling rates (i.e., Slow and Fast) to extract spatial and action features from the input video. The 3D Resnet50 network is selected as the backbone network of the SlowFast dual path after comparative analysis. The size of the 3D convolutional kernel is increased to improve the perceptual field of feature extraction, which in turn effectively improves the recognition accuracy of the algorithm. A total of 318 videos of yaks in different scenes and poses were captured for testing. Six different networks were selected to verify the performance of the proposed method: SlowFast-3DResnet50, SlowFast-3DResnet101, SlowFast-3DResnet152, 3DResnet50, C3D, and I3D. The experimental results show that the method achieves 96.6% recognition accuracy, 91.3% recall, and 90.5% precision in classifying the basic behaviors of yaks in natural scenes, and 97.3%, 99.1%, 95.9% and 94.1% for the four basic behaviors, respectively. These results are comprehensively better than the other six methods. In addition, compared with other 3D convolutional neural networks used for video classification, the method proposed in this paper can classify the target behavior from each video frame, which has a broader implications and application. The algorithm meets the needs for basic behavior recognition of yaks and lays the foundation for real-time monitoring of yak health status.

Evolutionary origin of genomic structural variations in domestic yaks

Yak has been subject to natural selection, human domestication and interspecific introgression during its evolution. However, genetic variants favored by each of these processes have not been distinguished previously. We constructed a graph-genome for 47 genomes of 7 cross-fertile bovine species. This allowed detection of 57,432 high-resolution structural variants (SVs) within and across the species, which were genotyped in 386 individuals. We distinguished the evolutionary origins of diverse SVs in domestic yaks by phylogenetic analyses. We further identified 334 genes overlapping with SVs in domestic yaks that bore potential signals of selection from wild yaks, plus an additional 686 genes introgressed from cattle. Nearly 90% of the domestic yaks were introgressed by cattle. Introgression of an SV spanning the KIT gene triggered the breeding of white domestic yaks. We validated a significant association of the selected stratified SVs with gene expression, which contributes to phenotypic variations. Our results highlight that SVs of different origins contribute to the phenotypic diversity of domestic yaks.

Eimeria zuernii (Eimeriidae: Coccidia): mitochondrial genome and genetic diversity in the Chinese yak

BackgroundCoccidiosis caused by Eimeria zuernii (Eimeriidae: Coccidia) represents a significant economic threat to the bovine industry. Understanding the evolutionary and genetic biology of E. zuernii can assist in new interaction developments for the prevention and control of this protozoosis.MethodsWe defined the evolutionary and genetic characteristics of E. zuernii by sequencing the complete mitogenome and analyzing the genetic diversity and population structure of 51 isolates collected from eight yak breeding parks in China.ResultsThe 6176-bp mitogenome of E. zuernii was linear and encoded typical mitochondrial contents of apicomplexan parasites, including three protein-coding genes [PCGs; cytochrome c oxidase subunits I and III (cox1 and cox3), and cytochrome b (cytb)], seven fragmented small subunit (SSU) and 12 fragmented large subunit (LSU) rRNAs. Genome-wide comparative and evolutionary analyses showed cytb and cox3 to be the most and least conserved Eimeria PCGs, respectively, and placed E. zuernii more closely related to Eimeria mephitidis than other Eimeria species. Furthermore, cox1-based genetic structure defined 24 haplotypes of E. zuernii with high haplotype diversities and low nucleotide diversities across eight geographic populations, supporting a low genetic structure and rapid evolutionary rate as well as a previous expansion event among E. zuernii populations.ConclusionsTo our knowledge, this is the first study presenting the phylogeny, genetic diversity, and population structure of the yak E. zuernii, and such information, together with its mitogenomic data, should contribute to a better understanding of the genetic and evolutionary biological studies of apicomplexan parasites in bovines.Graphical

Characterization of Staphylococcus aureus and methicillin‐resistant S. aureus from yak

AbstractStaphylococcus aureus, particularly methicillin‐resistant S. aureus (MRSA), is an important zoonotic pathogen which not only causes significant economic loss in livestock production but also emerges as a potential threat to public health. Compared with bovines, the information on the colonization of S. aureus and MRSA in yaks, the only bovine species providing meat and other necessities for Tibetans living at high altitude, is very limited. Therefore, in the current study, S. aureus and MRSA prevalence, virulence genes, and antibiotic and antiseptic resistance properties in yaks from 18 counties of Ganzi Prefecture, Sichuan province, China were investigated. The results revealed that the overall prevalence of S. aureus during yak breeding was 7.10% among 1281 samples (91/1281), containing 9.44% from nasal (62/657) and 4.65% from anus (29/624). Nearly all of the S. aureus isolates carried at least one staphylococcal enterotoxin (SE) gene and the predominant enterotoxin gene was selx (51.65%). In addition, virulence genes (hlα, hlβ, pvl, and tsst‐1), antiseptic resistance genes (qacA/B, qacC, and qacG), and heavy metal resistance genes (copA, arsB, cadD, and arsA) were also found. Furthermore, 24 MRSA strains were identified. SCCmec, spa, and multilocus sequence typing typing revealed that the predominant types of MRSA were ST59‐IVa‐t437 and ST59‐III‐t437. It was noteworthy that all these methicillin‐resistant strains were resistant to two or more antibiotics and possessed virulence genes. The minimal inhibitory concentration (MIC) values of antiseptic peroxyacetic acid, sodium hypochlorite, and benzalkonium bromide against these MRSA strains were measured and the MIC values of benzalkonium bromide (1.22–9.77 μg/mL) were relatively low. Furthermore, the challenge with 1/4 MIC of oxacillin sodium or ofloxacin or benzalkonium bromide for 216 h increased the resistance of the MRSA strain YB786 to these antibiotics but decreased the MIC value of benzalkonium bromide. The results provide an indication of the health risks associated with these S. aureus strains, especially methicillin‐resistant strains from yaks and new approaches are needed to treat these strains.

Comparative analysis of whey proteins in yak milk from different breeds in China using a data-independent acquisition proteomics method

Yak milk is rich in essential milk proteins of nutritional and therapeutic value. In this study, whey proteins of milk from 3 yak breeds (Gannan, GN; Huanhu, HH; Maiwa, MW) in China were comprehensively identified and compared using a data-independent acquisition quantitative proteomics approach. A total of 632 proteins were identified in yak milk whey samples, in which immune-related proteins were abundant. Compared with other milks, more proteins were involved in oxidation-reduction process and with ATP binding. In addition, we identified 96, 155, and 164 differentially expressed proteins (DEP) for GN versus HH, GN versus MW, and HH versus MW, respectively. "Phagosome" and "complement and coagulation cascades" were the most significant pathways for DEP of GN versus HH and GN or HH versus MW yak milk based on the Kyoto Encyclopedia of Genes and Genomes pathway analysis. Protein-protein interaction network analysis showed that DEP for the 3 comparisons had significant biological interactions but were associated with different functions. The results provide useful information on yak milk from different breeds in China, and elucidate the biological functions of yak milk proteins.