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The yak (Poephagus grunniens) has evolved unique adaptations to survive the harsh environment of the Qinghai–Tibetan Plateau, while their gut microorganisms play a crucial role in maintaining the health of the animal. Gut microbes spread through the animal population not only by horizontal transmission but also vertically, which enhances microbial stability and inheritance between generations of the population. Homogenization of gut microbes in different animal species occurs in the same habitat, promoting interspecies coexistence. Using the yak as a model animal, this paper discusses the adaptive strategies under extreme environments, and how the gut microbes of the yak circulate throughout the Tibetan Plateau system, which not only affects other plateau animals such as plateau pikas, but can also have a profound impact on the health of people. By examining the relationships between yaks and their gut microbiota, this review offers new insights into the adaptation of yaks and their ecological niche on the Qinghai–Tibetan plateau. [ABSTRACT FROM AUTHOR]

High-altitude environments present formidable challenges for survival and reproduction, with organisms facing limited oxygen availability and scarce nutrient resources. The yak (Bos grunniens), indigenous to the Tibetan Plateau, has notably adapted to these extreme conditions. This study delves into the genomic basis of the yak's adaptation, focusing on the positive selection acting on genes involved in nutrient assimilation pathways. Employing techniques in comparative genomics and molecular evolutionary analyses, we selected genes in the yak that show signs of positive selection associated with nutrient metabolism, absorption, and transport. Our findings reveal specific genetic adaptations related to nutrient metabolism in harsh climatic conditions. Notably, genes involved in energy metabolism, oxygen transport, and thermoregulation exhibited signs of positive selection, suggesting their crucial role in the yak's successful colonization of high-altitude regions. The study also sheds light on the yak's immune system adaptations, emphasizing genes involved in response to various stresses prevalent at elevated altitudes. Insights into the yak's genomic makeup provide valuable information for understanding the broader implications of high-altitude adaptations in mammalian evolution. They may contribute to efforts in enhancing livestock resilience to environmental challenges. [ABSTRACT FROM AUTHOR]

Simple Summary: Yaks are a major economic source for people in the Tibetan Plateau region. Yaks are rich in nutrients, but their low fat content is not conducive to the large-scale promotion of yak meat, so the study of the mechanism of yak lipid deposition is beneficial to the marketing of yak meat. In this paper, the results of transcriptome sequencing analysis of yak liver showed that it could be determined that the expression levels of genes associated with partial lipid deposition were significantly up-regulated during yak fattening. In addition, this study found that the tenderness of yak meat improved during this process. Fattening significantly affects fat deposition in yaks, which may be realized through its effects on lipid metabolic pathways. Therefore, studying the mechanism of lipid deposition in yaks and fattening yaks will improve the quality of yak meat. Yak meat is nutritionally superior to beef cattle but has a low fat content and is slow-growing. The liver plays a crucial role in lipid metabolism, and in order to determine whether different feeding modes affect lipid metabolism in yaks and how it is regulated, we employed RNA sequencing (RNA-seq) technology to analyze the genome-wide differential gene expression in the liver of yaks maintained under different raising systems. A total of 1663 differentially expressed genes (DEGs) were identified (|log2FC| ≥ 0 and p-value ≤ 0.05), including 698 down-regulated and 965 up-regulated genes. According to gene ontology (GO) and KEGG enrichment analyses, these DEGs were significantly enriched in 13 GO terms and 26 pathways (p < 0.05). Some DEGs were enriched in fatty acid degradation, PPAR, PI3K-Akt, and ECM receptor pathways, which are associated with lipid metabolism. A total of 16 genes are well known to be related to lipid metabolism (e.g., APOA1, FABP1, EHHADH, FADS2, SLC27A5, ACADM, CPT1B, ACOX2, HMGCS2, PLIN5, ACAA1, IGF1, FGFR4, ALDH9A1, ECHS1, LAMA2). A total of 11 of the above genes were significantly enriched in the PPAR signaling pathway. The reliability of the transcriptomic data was verified using qRT-PCR. Our findings provide new insights into the mechanisms regulating yak meat quality. It shows that fattening improves the expression of genes that regulate lipid deposition in yaks and enhances meat quality. This finding will contribute to a better understanding of the various factors that determine yak meat quality and help develop strategies to improve yield and quality. [ABSTRACT FROM AUTHOR]

Simple Summary: The Qinghai–Tibetan Plateau (QTPA), in the northwestern region of China, is characterized by diverse geographical features, earning it the title of "the roof of the world". Despite this, limited information exists on the distribution of tick-borne pathogens in this region. This study aimed to evaluate the infection rates of Babesia and Theileria species in QTPA. Blood samples collected from livestock species (n = 366) were analyzed using different PCR-sequencing techniques. Results showed a high infection rate of Theileria spp. (38.2%). B. motasi-like Lintan/Ningxia/Tianzhu was detected in 0.3% of samples. Notably, this study reported infection rates of Babesia and Theileria species in goats, horses, and donkeys in the Qinghai–Tibetan Plateau for the first time. The northwestern region of China, known as the Qinghai–Tibet Plateau Area (QTPA), is characterized by unique climate conditions that support the breeding of various highly-adapted livestock species. Tick vectors play a significant role in transmitting Babesia and Theileria species, posing serious risks to animal health as well as the economy of animal husbandry in QTPA. A total of 366 blood samples were collected from Tibetan sheep (n = 51), goats (n = 67), yaks (n = 43), cattle (n = 49), Bactrian camels (n = 50), horses (n = 65), and donkeys (n = 40). These samples were examined using conventional and nested PCR techniques to detect Theileria and Babesia species. The overall infection rates were 0.3% (1/366) for Babesia spp. and 38.2% (140/366) for Theileria spp. Notably, neither Babesia nor Theileria species were detected in donkeys and yaks. The infection rates of Babesia and Theileria species among animals in different prefectures were significantly different (p < 0.05). Furthermore, Babesia bovis, B. bigemina, B. caballi, and B. ovis were not detected in the current study. To our knowledge, this is the first documented detection of Theileria luwenshuni infection in Bactrian camels and goats, as well as T. sinesis in cattle and T. equi in horses on the Qinghai plateau. These novel findings shed light on the distribution of Babesia and Theileria species among livestock species in QTPA. [ABSTRACT FROM AUTHOR]

Domestic yak, cattle, and their hybrids are fundamental to herder survival at high altitudes on the Tibetan Plateau. However, little is known about their history. Bos remains are uncommon in this region, and ancient domestic yak have not been securely identified. To identify Bos taxa and investigate their initial management, we conducted zooarchaeological analyses of 193 Bos specimens and sequenced five nuclear genomes from recently excavated assemblages at Bangga. Morphological data indicated that more cattle than yak were present. Ancient mitochondrial DNA and nuclear genome sequences identified taurine cattle and provided evidence for domestic yak and yak-cattle hybridization ~2500 years ago. Reliance on diverse Bos species and their hybrid has increased cattle adaptation and herder resilience to plateau conditions. Ancient cattle and yak at Bangga were closely related to contemporary livestock, indicating early herder legacies and the continuity of cattle and yak husbandry on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Grazing by local livestock is the traditional human practice in Qinghai-Tibetan Plateau grassland, and moderate intensity grazing can maintain high productivity and diversity of alpine grassland. Grazing ecosystems are often nitrogen-limited, but N2-fixing communities in response to yak grazing and Tibetan sheep grazing in Qinghai-Tibetan Plateau grassland have remained underexplored. In this study, we applied quantitative PCR quantitation and MiSeq sequencing of nifH under yak grazing and Tibetan grazing through a manipulated grazing experiment on an alpine grassland. The results showed that the grazing treatments significantly increased the soil ammonium nitrogen (AN) and total phosphorus (TP), but reduced the diazotrophs abundance. Compared with no grazing treatment, the composition of diazotrophs could be maximally maintained when the ratio of yak and Tibetan sheep were 1:2. The foraging strategies of grazing livestock reduced the legumes biomass, and thus reduced the diazotrophs abundance. Data analysis suggested that the direct key factors in regulating diazotrophs are AN and TP, and the changes of these two soil chemical properties were affected by the dung and urine of herbivore assemblages. Overall, these results indicated that the mixed grazing with a ratio of yak to Tibetan sheep as 1:2 can stabilize the soil diazotrophsic community, suggesting that MG12 are more reasonable grazing regimes in this region. [ABSTRACT FROM AUTHOR]

【Objective】The aim of the current study was to investigate the damage of different dietary feeding patterns on Yak jejunal protein composition via proteomic technology during cold season. 【Method】Twelve Datong male Yak with the same age from cold season were randomly selected on different feeding pattern in Tibetan Plateau. Yak jejunum samples were collected after 180 days of feeding, and slaughtered to determine Yak jejunal protein composition by Label-free MS.【Result】96 differentially expressed proteins were identified by Label-free MS. Subcellular localization analysis showed that differentially expression proteins in cytoplasm proteins was 23.54%, nucleus protein was 20.40%, mitochondrion protein was 19.56%, extracell protein was 11.30%, piasma membrane protein was 7.53%, and less in others. Go analysis showed that the major enriched terms of differentially expressed proteins were membrane, cytoplasm and mitochondrion for cellular components. Differentially expressed proteins were enriched of molecular function in oxidoreductase activity, cell-cell adherens junction, adenylate kinase activity, protein bindin and structural molecule activity. Apoptosis, inflammatory response, cellular response to fatty acid, actin cytoskeleton reorganization and adenylate cyclase-inhibiting G protein-coupled receptor were enriched in biological processes. The results of KEGG analysis also showed that the pathways of significant enrichment of jejunal differential expression protein in different feeding modes were tight junction signaling pathway, NF-kB signaling pathway, MAPK signaling pathway, cytokine-cytokine receptor interaction, calcium signaling pathwa, and signaling pathways regulating pluripotency of stem cells. The results of protein-protein interaction analysis showed that the differential proteins formed a complex and powerful interaction network mainly based on structural proteins and inflammatory response proteins.【Conclusion】The jejunum of yak was damaged by the long-term high-precision confinedness feeding patterns. Nine proteins related to the jejunal barrier and function of yaks (Occludin, Claudin, Zo-1, ATP1B3, HKDC1, GPR41, IL-6,TNF-α and CCL5) showed relatively active activity and could be used as candidate proteins for further study. To sum up, the whole house raising with high-precision feed is only suitable for fattening Yak in a short time, but not for raising Yak in a long time. [ABSTRACT FROM AUTHOR]

Simple Summary: Yaks are important for the economy and livelihood of local herders in the Tibetan Plateau and are their primary source of income. Traditionally, the production performance of ruminants is generally improved by increasing the proportion of concentrate feed in the diet. To the best of our knowledge, the optimal proportion of concentrate feed is limited in actual production and research of yak. This study fed three diets with different dietary forage-to-concentrate ratios (50:50, 65:35, and 80:20) to 36 male yaks (Bos grunniens). The changes in the distribution of fecal microorganisms were studied by 16S rRNA gene sequencing and liquid chromatography–mass spectrometry. We found that the dietary forage-to-concentrate ratio significantly impacted yak fecal microorganisms. As such, these studies help us understand the fecal microbiota of yaks, further provide more complete information on the requirements of yak diets in terms of concentrate-to-forage ratio and improve yak growth performance, and provide a theoretical basis for accurate housing of yaks. (1) Background: This study aimed to investigate the effects of different dietary concentrate to roughage ratios on growth performance and fecal microbiota composition of yaks by 16S rRNA gene sequencing. (2) Methods: In the present study, three diets with different dietary forage-to-concentrate ratios (50:50, 65:35, and 80:20) were fed to 36 housed male yaks. (3) Results: The result shows that Final BW, TWG, and ADG were higher in the C65 group than in the C50 and C80 groups, but the difference was not significant (p > 0.05). DMI in the C65 group was significantly higher than in the other two groups (p < 0.05). The DMI/ADG of the C65 group was lower than that of the other two groups, but the difference was insignificant (p > 0.05). At the phylum level, Firmicutes were the most abundant in the C65 group, and the relative abundance of Bacteroidetes was lower in the C65 group than in the other two groups. At the genus level, the relative abundances of Ruminococcaceae_UCG_005, Romboutsia, and Christensenellaceae_R-7 were higher in the C56 group than in the C50 and C80 groups. The relative abundance of Lachnospiraceae_NK3A20 and Rikenellaceaewas_RC9_gut is lower in the C65 group, but the difference was insignificant (p > 0.05). At KEGG level 2, the relative abundance of lipid metabolism and energy metabolism were lowest in the C50 group, and both showed higher relative abundance in the C65 group. (4) Conclusions: In conclusion, the structure of fecal microbiota was affected by different concentrate-to-forage ratios. We found that feeding diets with a concentrate-to-forage ratio of 65:35 improved yaks' growth and energy metabolism. [ABSTRACT FROM AUTHOR]

Tick-borne diseases have become a global health concern in recent decades. Spotted fever group (SFG) rickettsiae have been recognized as important pathogens of human tick-borne diseases worldwide. In this study, Dermacentor everestianus (n = 646) and Haemaphysalis qinghaiensis (n = 172) ticks were collected from yaks (Bos grunniens) in Shiqu county, eastern Tibetan Plateau, China. SFG rickettsiae were identified and characterized in these ticks. A total of 49.9% (408/818) ticks were infected by Rickettsia spp. with infection rates of 58.1% (100/172) and 46.7% (308/646) detected in H. qinghaiensis and D. everestianus ticks, respectively. Furthermore, 95% of Rickettsia spp. were Rickettsia raoultii-like bacteria, and 5% were related to Candidatus Rickettsia longicornii. To the best of our knowledge, this is the first time that SFG rickettsiae infections were firstly reported in Shiqu county for these tick species. Our results indicated that H. qinghaiensis and D. everestianus ticks from Shiqu county became highly infected with a R. raoultii-like bacteria during their feeding process. This observation is alarming because of the zoonotic potentiality of these species. Overall, the present study detected a widespread of R. raoultii-like bacteria in ticks that are considered a serious threat to domestic animals and humans in Shiqu county. The prevalence of R. raoultii-like bacteria in human and wildlife hosts should be further investigated in the future. [ABSTRACT FROM AUTHOR]

Simple Summary: The yak is the largest mammal in the Qinghai–Tibetan Plateau and also supplies necessary sources of food and finance for the Tibetan people. Their body weight is a valuable trait for breeding. In the traditional breeding processes, pedigree data were used to evaluate individual genetic potency ability. However, based on the free range husbandry and random mating in domesticated yaks, the genetic improvement in yaks' body weight is still very slow. In this study, we performed a genome-wide association study using whole genome sequencing data to detect the potential functional genes for body weight in yaks. In total three functional genes were identified as being associated with body weight. The results of this study are important for developing and improving body weight in yaks. The yak is the largest meat-producing mammal around the Tibetan Plateau, and it plays an important role in the economic development and maintenance of the ecological environment throughout much of the Asian highlands. Understanding the genetic components of body weight is key for future improvement in yak breeding; therefore, genome-wide association studies (GWAS) were performed, and the results were used to mine plant and animal genetic resources. We conducted whole genome sequencing on 406 Maiwa yaks at 10 × coverage. Using a multiple loci mixed linear model (MLMM), fixed and random model circulating probability unification (FarmCPU), and Bayesian-information and linkage-disequilibrium iteratively nested keyway (BLINK), we found that a total of 25,000 single-nucleotide polymorphisms (SNPs) were distributed across chromosomes, and seven markers were identified as significantly (p-values < 3.91 × 10−7) associated with the body weight trait,. Several candidate genes, including MFSD4, LRRC37B, and NCAM2, were identified. This research will help us achieve a better understanding of the genotype–phenotype relationship for body weight. [ABSTRACT FROM AUTHOR]

Background: Anaplasma, Babesia and Theileria are tick-borne pathogens (TBPs) that affect livestock worldwide. However, information on these pathogens in yaks (Bos grunniens) and Tibetan sheep (Ovis aries) on the Qinghai-Tibet Plateau (QTP), China, is limited. In this study, Anaplasma spp., Babesia spp. and Theileria spp. infections were assessed in yaks and Tibetan sheep from Qinghai Province. Methods: A total of 734 blood samples were collected from 425 yaks and 309 Tibetan sheep at nine sampling sites. Standard or nested polymerase chain reaction was employed to screen all the blood samples using species- or genus-specific primers. Results: The results showed that 14.1% (60/425) of yaks and 79.9% (247/309) of Tibetan sheep were infected with at least one pathogen. Anaplasma ovis, Anaplasma bovis, Anaplasma capra, Anaplasma phagocytophilum, Babesia bovis and Theileria spp. were detected in this study, with total infection rates for all the assessed animals of 22.1% (162/734), 16.3% (120/734), 23.6% (173/734), 8.2% (60/734), 2.7% (20/734) and 19.3% (142/734), respectively. For yaks, the infection rate of A. bovis was 6.4% (27/425), that of B. bovis was 4.7% (20/425) and that of Theileria spp. was 3.3% (14/425). Moreover, 52.4% (162/309) of the Tibetan sheep samples were infected with A. ovis, 30.1% (93/309) with A. bovis, 56.0% (173/309) with A. capra, 19.4% (60/309) with A. phagocytophilum and 41.4% (128/309) with Theileria spp. Conclusions: This study revealed the prevalence of Anaplasma spp., Babesia spp. and Theileria spp. in yaks and Tibetan sheep in Qinghai Province, China, and provides new data for a better understanding of the epidemiology of TBPs in these animals in this area of the QTP, China. [ABSTRACT FROM AUTHOR]

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. • The basic behavior of yaks is an important indicator to evaluate the health status of yaks. • Compared to contact behavior recognition, non-contact behavior recognition does not cause stress responses in animals. • The video-based behavior recognition method has higher accuracy than the image-based behavior recognition method. • Real-time identification of the basic behavior of yaks can provide a basis for disease prevention and reasonable feeding. [ABSTRACT FROM AUTHOR]

Tibetan yak (Bos grunniens) inhabiting the Qinghai-Tibet Plateau (QTP) where the average altitude is 4000 m, is specially adapted to live at these altitudes. Conversely, cattle (B. taurus) has been found to suffer from high-altitude hypertension or heart failure when exposed to these high altitudes. Two mitochondrial genes, MT-ND1 and MT-ND2, encode two subunits of NADH dehydrogenase play an essential role in the electron transport chain of oxidative phosphorylation (OXPHOS). We sequenced these two mitochondrial genes in two bovine groups (70 Tibetan yaks and 70 Xuanhan cattle) and downloaded 300 sequences of B. taurus (cattle), 93 sequences of B. grunniens (domestic yak), and 2 sequences of B. mutus (wild yak) from NCBI to increase our understanding of the mechanisms of adaptability to hypoxia at high altitudes in yaks compared to cattle. MT-ND1 SNP m.3907 C > T, present in all Tibetan yaks, was positively associated with high-altitude adaptation (p < .0006). Specially, mutation m.3638 A > G present in all cattle, resulting in the termination of transcription, was negatively associated with high-altitude adaptation (p < .0006). Additionally, MT-ND2 SNPs m.4351 G > A and m.5218 C > T also showed positive associations with high-altitude adaptation (p < .0004). MT-ND1 haplotypes H2, H3, H4, H6, and H7 showed positive associations but haplotype H20 had a negative association with high-altitude adaptation (p < .0008). Similarly, MT-ND2 haplotypes Ha1 Ha8, Ha10, and Ha11 were positively associated whereas haplotype Ha2 was negatively associated with adaptability to high-altitudes (p < .0008). Thus, MT-ND1 and MT-ND2 can be considered as candidate genes associated with adaptation to high-altitude environments. [ABSTRACT FROM AUTHOR]

Yak milk fat products constitute the base of Qinghai-Tibetan pastoralists’ daily food intake. Despite the great importance of fat in processing and pastoralists’ health, studies about yak milk fat are scarce. In this study, the lipid composition and the morphological properties of milk fat globule membranes (MFGMs) of yak milk were investigated. The results demonstrated that the yak milk had a higher cholesterol and sphingomyelin content compared to cow milk. In situ structural investigations performed at 25 °C by confocal microscopy showed the presence of lipid domains in yak MFGM, with a larger number and wider size range compared to cow milk. Moreover, the simultaneous localization of glycosylated molecules and polar lipids indicated that glycosylated molecules could be integrated into the lipid domains in yak MFGM. Different characteristics in yak MFGM could be related to the lipid composition and may affect the functions of yak milk lipids during processing and digestion. [ABSTRACT FROM AUTHOR]

Urine deposition by grazing animals, with urea as the major constituent, is an important nitrogen (N) source in grassland ecosystems and may affect the production of three potent greenhouse gases ( GHGs): nitrous oxide (N2O), methane ( CH4) and carbon dioxide ( CO2). However, owing to the greater chemical complexity of urine, the effect of urine on GHG emissions may differ from that of urea, and this difference has not been well reported. A short-term laboratory study was conducted to examine the influence of stored yak urine and urea at addition rates of 350 and 700 mg N m−1 soil on GHG emissions at 20 and 60% water holding capacity ( WHC) in an alpine steppe soil from the Qinghai-Tibetan Plateau. Compared with no N addition, urea led to greater increases in soil ammonium N ( NH4+-N) concentrations, while yak urine resulted in a greater increase in soil dissolved organic carbon concentrations. Greater ( P < 0.05) cumulative N2O and CH4 emissions occurred under 60% than 20% WHC, but soil moisture content did not affect CO2 emissions ( P > 0.05). There were no statistically significant ( P > 0.05) differences in N2O or CH4 emissions between the two N-addition rates, regardless of N type. The increases in N2O and CH4 emissions after N addition were greater in the urine than in the urea treatments, particularly under 60% WHC. The average CO2 emissions for the two soil moisture contents in the urine treatments increased with increasing N-addition rate, but the two urea treatments showed similar values to the control. The greater GHG emissions in the stored yak urine treatments were probably due to the existence of intrinsic organic carbon. Our results suggest that fresh yak urine may also possibly cause more GHG losses than urea under equivalent N application rates in alpine steppe soil on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Bacillus velezensis LM2303 is a biocontrol strain with a broad inhibitory spectrum against plant pathogens, isolated from the dung of wild yak inhabited Qinghai-Tibet plateau, China. Here we present its complete genome sequence, which consists of a single, circular chromosome of 3,989,393 bp with a 46.68% G + C content. Genome analysis revealed genes encoding specialized functions for the biosynthesis of antifungal metabolites and antibacterial metabolites, the promotion of plant growth, the alleviation of oxidative stress and nutrient utilization. And the biosynthesis of antimicrobial metabolites in strain LM2303 was confirmed by biochemical analysis, while its plant growth promoting traits were confirmed by inoculation tests. Our results will establish a better foundation for further studies and biocontrol application of B. velezensis LM2303. [ABSTRACT FROM AUTHOR]

Yak and Tibetan sheep are the major indigenous ruminants on the Qinghai-Tibetan Plateau in China. The aim of this work was to study the differences in ruminal fermentation parameters and rumen prokaryotic community composition between hosts and feeding paradigms. The 16S rRNA genes targeting bacteria and archaea were sequenced using the MiSeq platform. The results showed that the prokaryotic community structure between yak and Tibetan sheep was significantly different ( P < 0.01). A significant difference in structure was also found between groups of yaks barn fed with a total mixed ration (TMR) and those naturally grazing (NG) ( P = 0.034), as well as for Tibetan sheep of the two groups ( P = 0.026). The core prokaryotic populations that existed in the rumen mostly dominated the structure. There was an obvious correlation of the prokaryotic community composition at the phylum and genus levels with the host or the feeding pattern. In addition, Tibetan sheep showed significantly higher yields of volatile fatty acids (VFAs) than yak, as did the NG group compared with the TMR group. In conclusion, both the host and feeding pattern may influence rumen microbial ecology system, with host effects being more important than those of the feeding pattern. [ABSTRACT FROM AUTHOR]

The prevalence of Giardia duodenalis ( G. duodenalis ) assemblages in yaks is poorly known. The present study examined 297 fecal samples from weaned yak, 4–7 months of age, from 3 different farms, in Tibetan Plateau Area (TPA) of the Qinghai Province in Western China. The prevalence of infection was determined by light and immunofluorescence microscopy, and nested-PCR. PCR was performed for the small subunit ribosomal RNA (SSU) amplified 16 positive for G. duodenalis products. The prevalence of Giardia species was 5.0% (15/297) on light microscopic analysis, 6.1% (18/297) on immunofluorescence test (IFT) and 5.4% (16/297) on nested-PCR. The overall prevalence with the three methods was 5.5%. Ten of the 16 PCR products have been successfully sequenced. Sequence results and phylogenetic analysis of the 18S rRNA sequence data using MEGA5.0 and DNAstar7.0 identified all samples of interest as G. duodenalis assemblage E. This study revealed for the first time the presence of G. duodenalis in yaks from the Qinghai province in China and confirmed that yak is a suitable host for Giardia parasites. The results provide useful information about G. duodenalis prevalence and the epidemiological significance of yak a suitable host to harbor Giardia infections. [ABSTRACT FROM AUTHOR]

Dung deposition is an important pathway of nutrient return and redistribution in alpine grasslands of the Qinghai-Tibetan Plateau. To date, information on the greenhouse gas emissions of yak dung on alpine grasslands, especially where there are large amounts of rock fragments, is limited. Our aim, therefore, was to evaluate variations in NO, CH, and CO emissions from yak dung (CCD), and compare it to dung placed on rock fragments (RCD), alpine steppe soil (CSD), and a soil and rock fragment mixture (RSD) over a 30-day incubation period. The results showed that the total NO emissions from treatments without soil were significantly ( P < 0.05) lower than those from treatments with soil. The highest total CH4 emissions were detected in the CSD treatment, while CH losses from treatments without rock fragments were significantly ( P < 0.05) greater than those with rock fragments. The total CO emissions from the RSD treatment was 6.30%-12.0% lower than those in the other three treatments. The soil beneath yak dung pats elevated the global warming potential (GWP), while the addition of rock fragments to the soil significantly ( P < 0.05) decreased the GWP by reducing emissions of the three greenhouse gases. We therefore suggest that interactions between rock fragments and alpine steppe soil are effective in decreasing yak dung greenhouse gas emissions. This finding indicates that rock fragments are an effective medium for reducing greenhouse gas emissions from dung pats, and more attention should therefore be paid to evaluate its ecological impact in future studies. These results should help guide scientific assessments of regional GHG budgets in agricultural ecosystems where the addition of livestock manure to soils with large amounts of rock fragments is common. [ABSTRACT FROM AUTHOR]

Toxocara vitulorum has been rarely reported in yaks at high altitudes and remote areas of Sichuan Province of Tibetan Plateau of China. The current study was designed to investigate the prevalence, associated risk factors, and phylogenetic characteristics of T. vitulorum in yak calves on the Qinghai Tibetan plateau. Fecal samples were collected from 891 yak calves and were examined for the presence of T. vitulorum eggs by the McMaster technique. A multivariable logistic regression model was employed to explore variables potentially associated with exposure to T. vitulorum infection. T. vitulorum specimens were collected from the feces of yaks in Hongyuan of Sichuan Province, China. DNA was extracted from ascaris. After PCR amplification, the sequencing of ND1 gene was carried out and phylogenetic analyses was performed by MEGA 6.0 software. The results showed that 64 (20.1%; 95% CI 15.8-24.9%), 75 (17.2; 13.8-21.1), 29 (40.9; 29.3-53.2), and 5 (7.6; 2.5-16.8) yak calves were detected out to excrete T. vitulorum eggs in yak calve feces in Qinghai, Tibet, Sichuan, and Gansu, respectively. The present study revealed that high infection and mortality by T. vitulorum is wildly spread on the Qinghai Tibetan plateau, China by fecal examination. Geographical origin, ages, and fecal consistencies are the risk factors associated with T. vitulorum prevalence by logistic regression analysis. Molecular detection and phylogenetic analysis of ND1 gene of T. vitulorum indicated that T. vitulorum in the yak calves on the Qinghai Tibetan plateau are homologous to preveiously studies reported. [ABSTRACT FROM AUTHOR]

We examined the nutritional quality of milk from yaks raised at 3016, 3824 and 4750 m above sea level on the Qinghai–Tibetan plateau. The Trolox equivalent antioxidant capacity, vitamin A concentration, fat content, conjugated linoleic acid, γ-linolenic acid, total unsaturated fatty acids and Fe, Zn and Na concentrations of yak milk increased while vitamin C concentration, crude protein content and Cu and Mn concentrations decreased with increasing altitude. Also, the atherogenic index was lower at the middle and highest altitudes than at the lowest altitude. Thus, in general, there was an increase in nutritional quality in the milk with an increase in altitude. We concluded that the observed differences resulted from the combined effects of altitude, forage composition and forage availability. Crude protein in milk and forage both decreased while fat in milk and neutral detergent fibre in forage both increased with increasing altitude. [ABSTRACT FROM AUTHOR]

The yak ( Bos grunniens ) is a long-haired bovid, endemic to the Tibetan Plateau and the adjacent high-altitude regions. The domesticated subspecies of yak ( B . grunniens grunniens ) are abundant and closely associated with the livelihoods of herders, while the wild subspecies of yak ( B . grunniens mutus ) are endangered due primarily to anthropogenic effects. The endangered status of wild yaks calls for consideration, if we are to secure its long term survival, hence this study. Here we hope to provide baseline information necessary for further research and protection of the wild yak resources. We use published data to discuss their evolution, their characteristics as well as their distribution in the Tibetan Plateau and the adjacent high-altitude regions. We were able to come up with a world wild yak distribution map, which may be useful for establishing protected areas, as well as updating the species IUCN Red List Status. From the data available, we were also able to provide an estimate of the wild yak population in China (∼22,000 wild yaks living in China), corresponding to 90% of the total world population. We further discuss the major threats to yaks, and we give some suggestions for future and sustainable conservation. [ABSTRACT FROM AUTHOR]

Several natural anaerobic fungus-methanogen co-cultures have been isolated from rumen and feces source of herbivores with strong fiber degrading ability. In this study, we isolated 7 Neocallimastix with methanogen co-cultures from the rumen of yaks grazing on the Qinghai Tibetan Plateau. Based on morphological characteristics and internal transcribed spacer 1 sequences (ITS1), all the fungi were identified as Neocallimastix frontalis . The co-cultures were confirmed as the one fungus – one methanogen pattern by the PCR-denatured gradient gel electrophoresis (DGGE) assay. All the methanogens were identified as Methanobrevibacter ruminantium by 16s rRNA gene sequencing. We investigated the biodegrading capacity of the co-culture ( N. frontalis + M. ruminantium ) Yaktz1 on wheat straw, corn stalk and rice straw in a 7 days-incubation. The in vitro dry matter digestibility (IVDMD), acid detergent fiber digestibility (ADFD) and neural detergent fiber digestibility (NDFD) values of the substrates in the co-culture were significantly higher than those in the mono-culture N. frontalis Yaktz1. The co-culture exhibited high polysaccharide hydrolase (xylanase and FPase) and esterase activities. The xylanase in the co-culture reached the highest activity of 12500 mU/ml on wheat straw at the day 3 of the incubation. At the end of the incubation, 3.00 mmol–3.29 mmol/g dry matter of methane were produced by the co-culture. The co-culture also produced high level of acetate (40.00 mM–45.98 mM) as the end-product during the biodegradation. Interestingly, the N. frontalis Yaktz1 mono-culture produced large amount of lactate (8.27 mM–11.60 mM) and ethanol (163.11 mM–242.14 mM), many times more than those recorded in the previously reported anaerobic fungi. Our data suggests that the ( N. frontalis + M. ruminantium ) Yaktz1 co-culture and the N. frontalis Yaktz1 mono-culture both have great potentials for different industrial use. [ABSTRACT FROM AUTHOR]

Yak is an important domesticated ruminant on the Qinghai-Tibet Plateau in China. The prokaryotic community of yak remains largely uncharacterized when compared to that of other livestock species. In the present study, high-throughput sequencing of 16S rRNA genes (targeting bacterial and archaeal) and clone library of mcrA gene (targeting methanogenic archaea) were applied to investigate the rumen prokaryotic community structure. High-throughput sequencing results indicated that the rumen prokaryotic community consisted of 29 phyla, 40 classes, 63 orders, 77 families, and 79 genera. Bacteroidetes (59.1%) was the most abundant phylum, followed by Firmicutes , Proteobacteria , Fibrobacteres and Euryarchaeota. Prevotella was the predominant genus, averaging 28.5% of all rumen prokaryotic genera. Archaea accounted for 2.26% of the total prokaryotic community, with their community dominated by Methanobacteriaceae (82%), followed by Methanomassiliicoccaceae , and Methanosarcinaceae . Compared with the clone library of mcrA gene, high-throughput sequencing of 16S rRNA genes yielded a greater coverage of methanogenic archaea diversity. However, both molecular techniques showed that Methanobrevibacter is the predominant archaea of rumen microbiota in yaks grazing natural pastures. Our results should facilitate understanding of the complex rumen ecosystem and the main process of ruminal methanogenesis, which may help to further mitigate CH 4 emissions from ruminants. [ABSTRACT FROM AUTHOR]

The yak is primarily found throughout the Tibetan high plateau and the surrounding mountainous area of south central Asia; among its others attributes, its milk is very important for the local population. A key concern in the field of yak research is the better understanding of which genes control the production and composition of milk. The most accurate and sensitive method for gene expression analysis is quantitative reverse transcription polymerase chain reaction (RT-qPCR). It is essential for reliable RT-qPCR to be able to the normalize the data using internal control genes (ICGs). However, it is critical to assess the reliability of the normalization by testing multiple ICGs. Our objective was to uncover a reliable normalization for RT-qPCR data obtained from yak mammary tissue during the lactation cycle. We assessed the reliability of 10 ICGs (ACTB, EIF6, GAPDH, LRP10, MRPL39, MRPS15, MTG1, RPS8, RPS23, and UXT) using geNorm. The analysis revealed that all of the tested ICGs can be considered to be reliable, but the use of the 6 most stable ICGs should be applied to yield a reliable normalization factor (NF). We compared the results of 3 target genes (CSN1S1, ESR1, and MYC) normalized using 6, 3, or 1 of the best ICGs. We did not observe overall differences between the 3 normalization strategies with the exception of 1 time point in MYC. The use of only a single ICG is not recommended; thus, we concluded that the calculation of the NF using the 3 best ICGs, MRPS15, RPS23, and UXT, is a reliable normalization strategy for RT-qPCR data obtained from yak mammary tissue during pregnancy and lactation. A dilution effect of the ICGs due to a large increase in the mRNA of abundantly expressed genes in bovine and porcine mammary tissue during the lactation cycle was previously observed. To test for the presence of a dilution effect in our study, we evaluated the pattern of non-normalized RT-qPCR data of ICGs from pregnancy to lactation and compared them with the total RNA concentration, milk yield, and non-normalized RT-qPCR data of 3 target genes. With a few exceptions, the non- normalized RT-qPCR data for the tested ICGs was significantly increased by lactation and had a positive correlation with total RNA and the non-normalized RT-qPCR data of CSN1S1. These data clearly indicated the presence of a “concentration effect” of single mRNA that remains unexplained but needs to be accounted for during the normalization of RT-qPCR data. Based on our findings, we recommend that the NF of the MRPS15, RPS23, and UXT genes should be used in the normalization of RT-qPCR data obtained from mammary tissue of lactating yaks during pregnancy and lactation. [ABSTRACT FROM AUTHOR]

Livestock grazing dramatically impacts the belowground community in grasslands by altering resource input from plants, dung and urine return, and soil environments. However, the belowground response pattern as well as the alterations in soil resource input and environments remain uncertain along a grazing intensity gradient. Here, we examined the response pattern of the soil nematode community (abundance, diversity, structure and functions) to grazing intensity by performing a 5-year field manipulation experiment with four levels of yak grazing intensities in a Tibetan alpine meadow. Moderate grazing (i.e., 2 yak/ha) supported the highest abundances of all nematodes, plant feeders and omni-carnivores, and maintained the most closely interspecific interactions within the nematode community. Grazing intensity may affect the belowground community via compensatory growth of forages and bottom-up trophic effects from living roots to the soil micro-food web. Furthermore, moderate grazing increased the functional metabolic footprint index of the nematode community, activated the root energy channel, and maintained the balance between the bacterial and fungal channels, which can optimize soil nutrient cycling. The model averaging results showed that the response of the soil nematode community to grazing intensity was mainly related to the alteration of soil moisture, which also showed a hump-shaped response to increasing grazing intensity. These results indicate that the soil nematode community as well as the soil resource input and environments show a hump-shaped response to increasing yak grazing intensity. Our findings have strong implications in optimizing ecosystem structure and functions of grassland on Tibetan Plateau by managing grazing capacity. [Display omitted] • Belowground responses to yak grazing intensity with four levels are quantified. • Soil nematodes show a hump-shaped response to increasing yak grazing intensity. • Moderate yak grazing maximized abundance and structural complexity of nematodes. • Moderate yak grazing maintains soil nutrient balance by regulating energy channels. • Moderate yak grazing optimizes resource input and habitats to boost soil community. [ABSTRACT FROM AUTHOR]

The Yak ( Bos grunniens ) is a unique species of ruminant animals that is important to agriculture of the Tibetan plateau, and has a complex intestinal microbial community. The objective of the present study was to characterize the composition and individual variability of microbiota in the rumen of yaks using 16S rRNA gene high-throughput sequencing technique. Rumen samples used in the present study were obtained from grazing adult male yaks (n = 6) in a commercial farm in Ganzi Autonomous Prefecture of Sichuan Province, China. Universal prokaryote primers were used to target the V4–V5 hypervariable region of 16S rRNA gene. A total of 7200 operational taxonomic units (OTUs) were obtained after sequence filtering and chimera removal. Within these OTUs, 0.56% belonged to Archaea (40 OTUs), 7.19% to unassigned species (518 OTUs), and the remaining OTUs (6642) in all samples were of bacterial origin. When examining the community structure of bacteria, we identified 23 phyla within 159 families after taxonomic summarization. Bacteroidetes and Firmicutes were the predominant phyla accounting for 39.68% (SD = 0.05) and 45.90% (SD = 0.06), respectively. Moreover, 3764 OTUs were identified as shared OTUs (i.e. represented in all yaks) and belonged to 35 genera, exhibiting highly variable abundance across individual samples. Phylogenetic placement of these genera across individual samples was examined. In addition, we evaluated the distance among the 6 rumen samples by adding taxon phylogeny using UniFrac, representing 24.1% of average distance. In summary, the current study reveals a shared rumen microbiome and phylogenetic lineage and presents novel information on composition and individual variability of the bacterial community in the rumen of yaks. [ABSTRACT FROM AUTHOR]

Six abomasums of yaks (Bos grunniens) were studied with gross dissection and histological methods. It was found that the mucosa of the yak abomasum was covered with simple columnar epithelium. There were lots of spiral folds (≥10) in the fundic glandular area. The developed membrane of lamina propria was occupied by high density glands. According to the morphological characteristics of the glands, the abomasum was divided into the cardiac, gastric and pyloric glands. Cardiac glands were curved tubular glands with the intumescent bottom and small glandular cavity. Fundic glands were simple tubular glands or branched tubular glands, where the chief, parietal and mucous neck cells can be observed clearly. Pyloric glands were curled tubular glands, the closer to the deep of the lamina propria, the more obvious the glands curl. Staining of glycoconjugate revealed that the mucosal epithelium of the cardiac gastric and pyloric glands and gastric pits epithelium mainly secreted neutral glycoconjugate, but other portions of cardiac and gastric glands secreted mixed and acid glycoconjugate respectively. By Gordon-Sweet's reticular fiber staining, it was found that the mucous neck cells possessed the characteristic of argyrophilic phenomenon. There was a large number of argyrophilic granules in the supranuclear cytoplasm in contrast with the chief cells. Furthermore, there were isolated lymphoid nodules and diffuse lymphoid tissue in the abomasum glands, especially in corpus abomasi. Grimelius silver staining showed that the argyrophil cells were located in the glandular epithelium and lamina propria of glands, which can also be observed in connective tissue. These endocrine cells dispersed individually in epithelial cells, occasionally in 3-5 cell groups. Therefore, the yaks were grazed throughout the year on diverse natural grassland and had evolved morphological characteristics of the abomasum enabling them to consume a wide variety of plant species, thereby better adapting them to harsh plateau environment. [ABSTRACT FROM AUTHOR]

The Qinghai–Tibetan Plateau is a very large land unit and an important terrestrial ecosystem within the Eurasian continent. Because of the harsh climate associated with the high altitude, alpine meadows on the plateau are susceptible to degradation from overgrazing. For this region, and for other alpine meadow pastures internationally, there is a need to define the sustainable stocking rate, to develop sound policy pertaining to future land use. Here we report biomass and liveweight gain per animal and per ha for pastures grazed by yaks at high, medium, or low stocking rates over 4 growing seasons from 2010 to 2013. Measures of herbage nutritive value are reported. The influence of inter-year variation in precipitation on standing herbage biomass was also evaluated. Higher precipitation increased standing herbage biomass and herbage nutritive value, indicating that vegetation suffered summer water deficit even in this environment. The sustainable stocking rate in this environment was determined to be approximately 1 yak ha-1 (grown from 80 kg to 120 kg liveweight in 90 d). At this stocking rate, yak weight gain per ha was 88% of that achieved at higher stocking rates typically used by farmers, but with little or no evidence of land degradation. [ABSTRACT FROM AUTHOR]

A simple yak ( Bos grunniens) production model developed in this study was to evaluate the health of the intensive livestock production system in the three rivers headwaters region, on the Qinghai-Tibetan Plateau. An experiment conducted for 3 years showed that individual yak liveweight gain (kg/head) was negatively related to stocking rate (Sr) (head/ha). Yak liveweight gain per hectare (kg/ha) was modeled as a quadratic function of Sr, with an apparent optimum yak stocking rate (Sr). Following the model, the Sr rate was 1.67 heads/ha for the warm-season pasture (WSP), 0.72 head/ha for the cool-season pasture (CSP), and 0.63 head/ha for the yearlong periods grazing pastures, respectively. The corresponding maximum carrying capacity (when individual yak live weight gain was equal to zero) was 3.34, 1.44, and 1.26 head/ha for warm-season, cool-season, and yearlong periods grazing pasture, respectively. In comparison with modeled maximum stock carrying capacity, all the cold-season pasture in the three rivers headwaters region were overgrazed. By contrast, only 37.5 % of the warm-season rangeland area overgrazed. It indicated that reconstruction of the proportion of the seasonal rangeland area may be an effective strategy to prevent serious rangeland degradation in this alpine region. Moreover, adjustment of the stoking rate at optimum values may likely improve the income for local herders. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-1 (IGFBP-1) play a pivotal role in regulating cellular hypoxic response. In this study, we cloned and characterized the genes encoding IGF-1 and IGFBP-1 to improve the current knowledge on their roles in highland Bos grunniens (Yak). We also compared their expression levels in the liver and kidney tissues between yaks and lowland cattle. We obtained full-length 465 bp IGF-1 and 792 bp IGFBP-1, encoding 154 amino acids (AA) IGF-1, and 263 AA IGFBP-1 protein, respectively using reverse transcriptase-polyerase chain reaction (RT-PCR) technology. Analysis of their corresponding amino acid sequences showed a high identity between B. grunniens and lowland mammals. Moreover, the two genes were proved to be widely distributed in the examined tissues through expression pattern analysis. Real-time PCR results revealed that IGF-1 expression was higher in the liver and kidney tissues in B. grunniens than in Bos taurus (p<0.05). The IGFBP-1 gene was expressed at a higher level in the liver (p<0.05) of B. taurus than B. grunniens, but it has a similar expression level in the kidneys of the two species. These results indicated that upregulated IGF-1 and downregulated IGFBP-1 are associated with hypoxia adaptive response in B. grunniens. [ABSTRACT FROM AUTHOR]

A study was conducted to measure the energy balance of free-ranging yak during the four annual seasons in order to elucidate the factors constraining energy utilization by grazing yak. The heat production (HP, kJ/day) of grazing non-lactating female yaks was calculated as the product of heart rate (HR, beats/min) and the amount of O 2 delivered to the body at every heartbeat (O 2 P, μl), and by the constant value of 20.47 kJ/l of O 2 consumed. Heart rates were recorded continuously over 4 days, using modified heart rate monitors. Individual daily fecal output was measured using Cr 2 O 3 as an external marker. Daily herbage dry matter (DM) intake was calculated from fecal output and digestibility of the forage determined in vitro . The greatest herbage mass was measured in August (496 kg DM/ha), and the least in December and May (208 and 226 kg DM/ha). However, the herbage present in both May and August had higher crude protein contents and lower NDF contents than those sampled in October and December. Daily average HR (beats/min) was greater in summer (August) than during the other three seasons (78 vs. 49–52). The greatest O 2 P was recorded in May. The highest metabolizable energy intake (MEI) (1120 kJ/kg BW 0.75 per day) was measured in August when yaks grazed on lush green forage. HP was higher in August than in October and December (715, 548 and 400 kJ/kg BW 0.75 per day, respectively), but did not differ significantly from that measured in May (640 kJ/kg BW 0.75 per day). The animals were in positive energy balance only during August (energy retention (ER) = 405 kJ/kg BW 0.75 per day). Energy balance did not differ between the other seasons: −111 (October), −91 (December) and −13 (May) kJ/kg BW 0.75 per day, respectively. HP and ER were highly correlated with MEI ( R 2 = 0.73 and 0.88, respectively). The formulas calculated through the regression of HP and ER on MEI were used to estimate fasting heat production (FHP = 341 kJ/kg BW 0.75 per day) and maintenance ME requirements (ME m , 545 kJ/kg BW 0.75 per day) of the free grazing yaks. The results showed that free-ranging yaks expended much more energy to resist harsh environmental and sward conditions compared with confined yak or cattle and grazing cattle in low land area. [ABSTRACT FROM AUTHOR]

This study describes the impact of excretal returns derived from livestock dung on nitrous oxide (N2O) emissions in a grazed alpine grassland ecosystem. N2O flux, vegetation and soil characteristics were measured in an alpine steppe on the Qinghai-Tibetan Plateau. Measurements were obtained from control (CK) plot and experimental plot to which either yak dung (YD) or Tibetan sheep dung (SD) was added. We found significantly lower surface soil temperature and higher soil moisture in the YD plot than in either the CK or SD plot. The application of YD resulted in significantly less biomass of aboveground vegetation, lower carbon and nitrogen uptake, and significantly higher cumulative N2O emission in comparison to the CK or SD treatment. N2O from SD treatment was probably mainly produced via nitrification, while N2O from YD treatment was primarily produced by denitrification. Emission factors of N2O for both YD and SD were far lower than the default values proposed by the IPCC and the release of N2O from YD and SD patches is low. [ABSTRACT FROM AUTHOR]

Six forestomachs of yaks (Bos grunniens) were studied with gross dissection and histological methods. It was found that the forestomach of yak consisted of the following three parts, rumen, reticulum and omasum, which were composed of the mucosa, submucosa, muscularis and serosa. In addition, the mucosal epithelium was covered with stratified squamous epithelium, with part of keratinized the shallow cells. Rumen, the mucosa of which formed ligulate papillae varying in size and shape, was no muscularis mucosa. Reticulum, consisted of a surface epithelium that invaginated to various extent into the lamina propria, formed various folds in shape, namely, grid-like small rooms. Furthermore, there are many secondary folds densely covered with keratinized papillae. The most striking feature of the omasum was to be formed the laminae omasi varying in length, with short and rough papillae distributing on both sides. Taken together, there was no glands within the mucosa and lamina propria of forestomach of yak, where diffuse lymphoid tissues can be observed clearly. It is, therefore, believed that the yak forestomach may have evolved those specific structural characteristics in response to the unique living environment and dietary habits impose on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Wild yaks ( Bos mutus) ranged across the Tibetan Plateau in large herds before being forced to remote areas of the plateau. Consequently, little has been published about their behavioral ecology. We present the first extensive study on wild yak behavior during the rut. We gathered data on activity budgets, aggressive/sexual behaviors, and the behavior of bulls inside and outside mixed groups during 11 days in 2010 and 9 days in 2011. Yaks ate less and were more social during the rut than during summer. Males ate less than females and socialized more during the rut. We observed yaks for 234.25 h and recorded 2,078 aggressive/sexual behaviors. Yak bulls inspected and tended cows showing off their profiles during lateral displays, the most common type of indirect aggression. Yak bulls inside mixed sex groups rested less and socialized more than bulls outside. Females initiated intense intra-sexual competition and led at least 25 bulls on chases. Females then incited fight frenzies of numerous bulls from inside and outside the groups before copulations, and fights could be intense. We discuss female choice selecting for large size and fighting ability in males, the similarity of yak and bison (genus Bison) behavior, and conservation implications. [ABSTRACT FROM AUTHOR]

Abstract: The cold, hypoxic conditions of high-altitude habitats impose severe metabolic demands on domesticated yaks (Bos grunniens). Understanding how yaks cope with the combined effects of hypoxia and aerobic metabolism can provide important insights into the process of adaptive evolution. Here, hematological parameters, blood gases and blood volume, as well as enzyme activity, were determined in yaks from different altitudes. A total of 60 yaks, including 16 Tibet Alpine yaks (approximately 5100m a.s.l.), 23 Gannan yaks (3585m a.s.l.) and 21 Tianzhu white yaks (2960m a.s.l.) in the typically alpine meadows for the altitude of the Tibetan Plateau, were compared. The average red blood cell counts (RBC) value (9.34×1012/L) for the Tibet Alpine yaks was significantly higher than those of Gannan yaks (7.34×1012/L) and Tianzhu white yaks (6.77×1012/L) (P<0.05). Similar levels of significance were observed in the hematocrit (HCT), mean cell volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) concentrations in Tibet Alpine yaks. Increases in hemoglobin (Hb) occurred in the Tibet Alpine yaks, with values of 13.21 and 10.67g/dl for the Gannan yaks and Tianzhu white yaks, respectively, which were lower than that of the Tibet Alpine yaks (P<0.05). Gas-tension and pH changes resulting from chronic hypoxia were evident in the reduced O2 and CO2 tensions in both venous and arterial blood and the slight but significant increase in the blood pH. The blood volume displayed a similar pattern of being greater in the Tibet Alpine yaks than in the Gannan yaks and Tianzhu white yaks. Lactate (LA) and lactate dehydrogenase (LDH) activity positively correlated with altitude (P<0.05). These results are interesting in respect to the low-oxygen environment in which yaks live and are consistent with the higher myoglobin (Mb) concentration in yak cardiac muscle, possibly permitting this type of yak muscle to be switched to aerobic metabolism when needed. These results suggest that Hb levels are not a totally conclusive explanation for the yak adaptation to high altitude, and the physiological adaptation was achieved in yaks perhaps by increases in RBC and blood oxygen affinity and decreases in MCV. In addition, enhanced enzymatic activity plays a key role in added metabolic cost and anaerobic metabolism. [Copyright &y& Elsevier]

Yak and Tibetan sheep graze extensively on natural grasslands in the Qinghai-Tibetan Plateau, and large amounts of excrement are directly deposited onto alpine grasslands. However, information on greenhouse gas (GHG) emissions from this excrement is limited. This study evaluated the short-term effects of yak and Tibetan sheep dung on nitrous oxide (NO), methane (CH), and carbon dioxide (CO) emissions from alpine steppe soil at a water holding capacity (WHC) of 40 or 60 % and from alpine meadow soil at a WHC of 60 or 80 % under laboratory conditions. Cumulative NO emissions over a 15-day incubation period at low soil moisture conditions ranged from 111 to 232 μg NO-N kg soil in the yak dung treatments, significantly ( P < 0.01) higher than that of sheep dung treatments (28.7 to 33.7 μg NO-N kg soil) and untreated soils (1.04-6.94 μg NO-N kg soil). At high soil moisture conditions, NO emissions were higher from sheep dung than yak dung and non-treated soils. No significant difference was found between the yak dung and non-treated alpine meadow soil at 80 % WHC. Low NO emission in the yak dung treatment from relatively wet soil was probably due to complete denitrification to N. Yak dung markedly ( P < 0.001) increased CH and CO emissions, likely being the main source of these two gases. The addition of sheep dung markedly ( P < 0.001) elevated CO emissions. Dung application significantly ( P < 0.01) increased global warming potential, particularly for alpine steppe soil. In conclusion, our findings suggest that yak and Tibetan sheep dung deposited on alpine grassland soils may increase GHG emissions. [ABSTRACT FROM AUTHOR]

Shiga toxin (Stx)-producing Escherichia coli (STEC) are recognized as important human pathogens of public health concern. Many animals are the sources of STEC. In this study we determined the occurrence and characteristics of the STEC in yaks (Bos grunniens) from the Qinghai-Tibetan plateau, China. A total of 728 yak fecal samples was collected from June to August, 2012 and was screened for the presence of the stx1 and stx2 genes by TaqMan real-time PCR after the sample was enriched in modified Tryptone Soya Broth. Of the 138 (18.96%) stx1 and/or stx2-positive samples, 85 (61.59%) were confirmed to have at least 1 STEC isolate present by culture isolation, from which 128 STEC isolates were recovered. All STEC isolates were serotyped, genotyped by pulsed-field gel electrophoresis (PFGE) and characterized for the presence of 16 known virulence factors. Fifteen different O serogroups and 36 different O:H serotypes were identified in the 128 STEC isolates with 21 and 4 untypable for the O and H antigens respectively. One stx1 subtype (stx1a) and 5 stx2 subtypes (stx2a, stx2b, stx2c, stx2d and stx2g) were present in these STEC isolates. Apart from lpfAO157/OI-141, lpfAO157/OI-154, lpfAO113, katP and toxB which were all absent, other virulence factors screened (eaeA, iha, efa1, saa, paa, cnf1, cnf2, astA, subA, exhA and espP) were variably present in the 128 STEC isolates. PFGE were successful for all except 5 isolates and separated them into 67 different PFGE patterns. For the 18 serotypes with 2 or more isolates, isolates of the same serotypes had the same or closely related PFGE patterns, demonstrating clonality of these serotypes. This study was the first report on occurrence and characteristics of STEC isolated from yaks (Bos grunniens) from the Qinghai-Tibetan plateau, China, and extended the genetic diversity and reservoir host range of STEC. [ABSTRACT FROM AUTHOR]

Abstract: Topsoil along the altitudinal gradient (2086–4487m above sea level) and yak samples, collected from Wolong high mountain area of Sichuan Province, western China, were analyzed for polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs) and polychlorinated naphthalenes (PCNs) using HRGC–HRMS. The total concentrations of PCDD/Fs, dl-PCBs, and PCNs in soils were: 2.48–4.30pgg−1 dw (dry weight), 7.6–10.5pgg−1 dw, and 13.0–29.0pgg−1 dw, respectively; the greatest concentrations were found at sampling sites of 3927m, 4487m and 3345m, correspondingly. The total PCDD/Fs and dl-PCBs concentrations showed positive correlations with increasing altitudinal gradient. The congener profiles of both 2,3,7,8-PCDD/Fs and dl-PCBs at different altitudes showed similar patterns. PCNs were dominated by Tri-CNs. The long-range atmospheric transport and subsequent aerial deposition are likely the sources for these POPs in area examined. The total TEQs in soils were in the range of 0.28–0.42pgg−1 dw, and the total TEQs in the yak muscle and fatty tissue samples were 3.81–4.09pgTEQg−1 lipid weight. The daily intake of TEQs was estimated to be below the WHO''s tolerable daily intake according to the local people''s dietary habits in Wolong area, which is unlikely to cause any adverse health effects to the yak muscle consuming people. [Copyright &y& Elsevier]

Few data are available on the prevalence of Eimeria spp. in yaks. An observational study was conducted to determine the prevalence of coccidial infection in yaks on the Qinghai-Tibet Plateau of China. A total of 324 fecal samples from 4 counties was examined, and oocysts were identified to the species level on the basis of morphological features. Eimeria oocysts were found in 113 (34.9%) samples. The species detected and their prevalence values included the following: Eimeria zuernii (54.9%), E. pellita (35.4%), E. canadensis (33.6%), E. boris (23.0%), L cylindrica (16.8%), E. subspherica (16.8%), E. ellipsoidalis (14.1%), E. brasiliensis (13.3%), E. wyomingensis (8.0%), E. alabamensis (7.1%), E. illinoisensis (5.3%), E. auburnensis (4.4%), E. bombayansis (3.5%), and E. bukidnonensis (2.7%). Mixed infections of 2 to 7 species were found in 66.4% of the animals. There was an age-related difference in the prevalence of infection. The highest prevalence (53.3%) was observed in calves, an intermediate prevalence in yearlings (36.1%), and the lowest was in adults (15.6%). The number of oocysts per g of feces was significantly higher in calves than in adults. More Eimeria species were indentified in calves. Eimeria zuernii was the most prevalent species in calves and adults, whereas in yearling yaks E. pellita was most common. The majority of calves and yearlings showed mixed infection, but adults tended to be infected with 1 species. The prevalence and intensity of Eimeria species were found to show statistically significant differences among different regions in Qinghai Province. [ABSTRACT FROM AUTHOR]

Yak butter in Tsinghai-Tibet Plateau possesses the characters of high energy, abundant alimentation and a special flavor with certain medical and health care functions. In this paper the organoleptic flavor of yak butter was estimated, and 28 kinds of substance with different flavors were identified with the technique of coupling gas chromatography to mass spectroscopy (GC-MS). The results showed that there are many microorganisms in yak butter with natural inoculation, which contribute to the formation of its special flavors. It was found that three of these 15 microorganisms, identified as Saccharomycetaceae, Penicillium and Asperillus separately, contributed the most to flavors. The microorganisms are expected to be applied in the food industry, especially to produce dairy food with the unique flavor of yak butter. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to screen the bacteriocin-producing lactic acid bacteria (LAB) strains from kurut collected from six regions in Qinghai–Tibet Plateau. Upon the elimination of the effects of organic acids and hydrogen peroxide on tested microorganisms, 5 strains, among a total of 256 presumptive LAB strains screened, belonging to the species of Lactobacillus casei (strains T1, T11 and S9), Lactobacillus lactis (strain S2), and Leuconostoc lactis (strain T14), showed inhibition activities against both Staphylococcus aureus and Escherichia aerogenes. The inhibition activities were destroyed after treated with proteinase K, pepsin and trypsin separately, suggesting the proteinaceous nature of the antimicrobial compounds produced from the strains. The bacteriocins from strains T1 and T14 remained stable for 20 min at 121 °C and after 2 h of incubation at pH values between 3.0 and 11.0, compared with those from strains S2 and T11 that were stable during pH 3.0–6.0, and that from strain S9 stable between pH 3.0 and 9.0. Bacteriocins produced from strains S2, S9 and T11 were resistant to heating treatment at 100 °C for 20 min. Bacteriocins did not adhere to the surface of the producer cells. The results suggest that the extracellular bacteriocins produced from special LAB strains from kurut, of high antibacterial activity, as well as high thermal and pH stability, may be applied to dairy products manufactory to inhibit the growth of spoilage and pathogens during fermentation. [ABSTRACT FROM AUTHOR]

We aimed to examine the phylogeographical structure and demographic history of domestic and wild yaks ( Bos grunniens) based on a wide range of samples and complete mitochondrial genomic sequences. The Qinghai-Tibetan Plateau (QTP) of western China. All available D-loop sequences for 405 domesticated yaks and 47 wild yaks were examined, including new sequences from 96 domestic and 34 wild yaks. We further sequenced the complete mitochondrial genomes of 48 domesticated and 21 wild yaks. Phylogeographical analyses were performed using the mitochondrial D-loop and the total genome datasets. We recovered a total of 123 haplotypes based on the D-loop sequences in wild and domestic yaks. Phylogenetic analyses of this dataset and the mitochondrial genome data suggested three well-supported and divergent lineages. Two lineages with six D-loop haplogroups were recovered for all morphological breeds of domestic yaks across their distributions in the QTP, while one more lineage and more endemic haplogroups or haplotypes were found for wild yaks. Based on the mitochondrial genome data, the divergences of the three lineages were estimated to have occurred around 420,000 and 580,000 years ago, consistent with the geological records of two large glaciation events experienced in the QTP. There are distinct phylogeographical differences between wild and domestic yaks. However, there is no apparent geographical correlation between identified haplogroups and distributions of domestic yaks. Three differentiated lineages of yaks probably evolved allopatrically in different regions during the Pleistocene glaciation events, then reunited into a single gene pool during post-glacial population expansion and migrations before the start of the domestication of yaks in the Holocene. [ABSTRACT FROM AUTHOR]

Using light and scanning electron microscopy, the morphological adaptations of the yak (Bos grunniens) tongue to its foraging environment in the Qinghai-Tibetan Plateau were studied. The tongue of the yak was compared with that of cattle (Bos taurus). Compared with cattle, yak tongues are on average 4 cm shorter (P < 0.001), and yak consume forages using the labia oris, rather than by extending the tongue into the harsh environment. The lingual prominence of yak is greater (P < 0.001) and more developed than in cattle. The conical papillae on the prominence surface of yak are slightly larger (diameter: P = 0.068 and height: P = 0.761) and more numerous (P < 0.001) than in cattle. The lenticular papillae on the prominence surface of yak are larger (diameter: P = 0.002 and height: P = 0.115) and more numerous (P = 0.007) than in cattle. Such characteristics may improve the digestibility of forage by the grinding of food between the tongue and the upper palate. Filiform, conical, lenticular, fungiform, and vallate papillae were observed on the dorsal surface of the tongues studied; no foliate papillae were observed. The papillae were covered by keratinized epithelium, which was thicker (P < 0.001) in the yak than in cattle. It is suggested that the development of characteristic filiform papillae, and more numerous lingual gland ducts and mucus-secreting pores in the lenticular, fungiform and vallate papillae, fungiform papillae, probably having mechanical functions, are all morphological adaptations by yak to diets with greater fiber and DM content as provided by the plants within the Qinghai-Tibetan Plateau environment. On average, yak has 26 vallate papillae and cattle have 28. In the vallate papillae of the yak, the taste buds are arranged in a monolayer within the epithelium, whereas they are multilayered (2 to 4) in those papillae in cattle. The number of taste buds in each vallate papillae was less (P < 0.001) in the yak than in cattle. Therefore, the gustatory function of the yak was weaker than in cattle. Yaks graze throughout the year on diverse natural grasslands and have evolved morphological characteristics enabling them to consume a wide variety of plant species, thereby better adapting them to the typically harsh characteristics of their pastures. [ABSTRACT FROM AUTHOR]

Abstract: Many herders in the Tibetan Plateau still inherit the traditional lifestyle, including living in tents and burning yak dung for fuel. This short correspondence reports a pilot study on indoor air quality in the nomadic tents in the Nam Co region, inland Tibetan Plateau. The results showed very high concentrations of total suspended particles (TSP), averaging at 4.45 mg m−3 during the cooking/heating period (with daily value of 3.16 mg m−3). Elevated concentrations of toxic element Cd, As and Pb were also found within the tents, averaging 3.16 μg m−3, 35.00 μg m−3, and 81.39 μg m−3 for a day, respectively, which were not only far higher than those of WHO indoor air quality guidelines, but also more than 104–106 times higher than the outdoor air level in the Nam Co area. The study raises serious concerns over the health of Tibetan herders following their long-term exposure to the tent air. [Copyright &y& Elsevier]

Two experiments were conducted to determine the urinary purine derivative (PD) excretion rates and to analyze potential variations in PD excretions between yak, Tibetan indigenous cattle, and their crossbreds under similar ecological environment, and to develop prediction equations based on PD excretion for estimating rumen microbial protein supply. Three Tibetan castrated male yaks, and similar numbers of indigenous cattle and their crossbreds, were used in a fasting trial followed by a feeding trial, using three 3 × 3 Latin squares (1 for each breedtype), to measure responses of PD excretion to different feeding levels. The results showed that i) daily endogenous PD excretion for yak, indigenous cattle, and their crossbreds was 134, 163, and 138 μmol/kg of BW0.75 (P = 0.38), respectively; and ii) crossbreds have greater PD excretion rate per unit digestible OM intake than indigenous cattle (P = 0.03). However, there were no significant differences between yaks and the crossbreds (P = 0.24) or between yaks and the indigenous cattle (P = 0.25). The proportion of allantoin to total PD in urine ranged from 0.83 to 0.88, with the crossbreds having greater values compared with the 2 parents (P = 0.03). Daily glomerular filtration rate, calculated using endogenous creatinine as an internal marker, for the above animals was 3.85, 4.23, and 3.61 L/kg of BW0.75, respectively, in fasting trial (P = 0.59). The alpine animals may develop special regulating mechanisms in the kidney in terms of glomerular filtration rate and PD excretion, which would help the animals in adapting to the harsh environment of the Qinghai-Tibetan plateau. [ABSTRACT FROM AUTHOR]

Bos grunniens Linnaeus, 1766, and Bos mutus (Przewalski, 1883) are the domestic and wild forms, respectively, of the bovid commonly called the yak. B. mutus inhabits remote high-elevation alpine meadows and alpine steppe in rolling to mountainous terrain in the Tibetan Plateau, and B. grunniens is maintained widely in China and other parts of Central Asia, and uncommonly elsewhere in the world. Populations of B. mutus are substantially reduced and fragmented throughout its remaining range; the largest numbers occur in northern Tibet and western Qinghai. B. mutus is vulnerable because of poaching and competition with domestic livestock. Although no complete survey of B. mutus has been conducted, there are probably no more than 15,000 remaining in remote areas of the Tibetan Plateau; B. grunniens numbers about 14 million. [ABSTRACT FROM AUTHOR]