[Effects of Different Forms of Nitrogen Addition on Soil Physical and Chemical Properties and Microbial Community Structure of Perennial Alpine Cultivated Grassland].

This study aimed to investigate the impact of different nitrogen forms on soil physicochemical properties and microbial community structure in perennial alpine cultivated grasslands, in order to provide scientific basis for developing nitrogen addition strategies for perennial alpine cultivated grasslands. In June 2022, a 4-year-old Qinghai grassland mixed with Poa pratensis Qinghai and Festuca sinensis Qinghai was established at the Bakatai Farm in Gonghe County, Hainan Tibetan Autonomous Prefecture, Qinghai Province. The study was conducted without fertilization as a control (CK), and three different forms of nitrogen treatments were set up, namely, U:urea (amide nitrogen), A:ammonium sulfate (ammonium nitrogen), and N:calcium nitrate (nitrate nitrogen); the nitrogen application rate for each treatment was 67.5 kg·(hm2·a)-1, and the composition and diversity of soil nutrients and microbial communities under different treatments were analyzed. The results showed that the input of exogenous ammonium nitrogen significantly increased NH4+-N content, AP content, and EC; amide nitrogen input significantly increased SOC content and TN content; and nitrate nitrogen input significantly increased NO3--N content, AN content, and TC content. Exogenous nitrogen input changed the structure of soil bacterial and fungal communities, as well as the relative abundance of dominant phyla and genera, but it did not significantly affect the alpha diversity of bacterial and fungal communities. Principal coordinate analysis (PCoA) showed that different forms of nitrogen addition had a significant impact on the Beta diversity of bacterial communities, whereas the impact on fungal communities was not significant. Redundancy analysis (RDA) indicated that nitrogen addition mainly changed the composition and structure of microbial communities through soil ammonium nitrogen. Overall, ammonium nitrogen fertilizer should be given priority in the soil remediation process of perennial cultivated grasslands in the Qinghai Tibet Plateau.

Effects of yak and Tibetan sheep grazing on soil arthropods community in an alpine meadow on the Qinghai-Tibet Plateau, China.

We investigated the responses of community structure of soil arthropods to yak and Tibetan sheep grazing based on a manipulated grazing experiment at the alpine meadow livestock Adaptive Management Platform, which locates in Haiyan County, Qinghai Province. The results showed that the obtained soil arthropods belonged to 26 families, 8 orders, and 4 classes, with Acaroidae and Oribatida as the dominant groups. Yak and Tibetan sheep grazing decreased the abundance but increased Shannon index, Margalef index and Pielou index of soil arthropods. Yak grazing significantly increased the quantity of the predatory soil arthropod groups. Yak and Tibetan sheep gra-zing significantly increased the quantity of the detritivore soil arthropod groups, but did not affect the quantity of the omnivorous and phytophagous soil arthropod groups. Yak and Tibetan sheep grazing significantly reduced the abundance of soil mites. Soil bulk density, available potassium, and available nitrogen were the main abiotic factors affecting soil arthropods community composition.

Effects of Different Livestock Grazing on Foliar Fungal Diseases in an Alpine Grassland on the Qinghai-Tibet Plateau.

In grassland ecosystems, the occurrence and transmission of foliar fungal diseases are largely dependent on grazing by large herbivores. However, whether herbivores that have different body sizes differentially impact foliar fungal diseases remains largely unexplored. Thus, we conducted an 8-year grazing experiment in an alpine grassland on the Qinghai-Tibet Plateau in China and tested how different types of livestock (sheep (Ovis aries), yak (Bos grunniens), or both)) affected foliar fungal diseases at the levels of both plant population and community. At the population level, grazing by a single species (yak or sheep) or mixed species (sheep and yak) significantly decreased the severity of eight leaf spot diseases. Similarly, at the community level, both single species (yak or sheep) and mixed grazing by both sheep and yak significantly decreased the community pathogen load. However, we did not find a significant difference in the community pathogen load among different types of livestock. These results suggest that grazing by large herbivores, independently of livestock type, consistently decreased the prevalence of foliar fungal diseases at both the plant population and community levels. We suggest that moderate grazing by sheep or yak is effective to control the occurrence of foliar fungal diseases in alpine grasslands. This study advances our knowledge of the interface between disease ecology, large herbivores, and grassland science.

Symbiotic diazotrophs in response to yak grazing and Tibetan sheep grazing in Qinghai-Tibetan plateau grassland soils.

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.

Grazing practices affect phyllosphere and rhizosphere bacterial communities of Kobresia humilis by altering their network stability.

The primary utilization strategy for meadow grasslands on the Qinghai-Tibet Plateau (QTP) is livestock grazing. This practice is considered as one of the major drivers of plant-associated bacterial community construction and changes in soil properties. The species of Kobresia humilis is considered as the most dominant one in grasslands. However, how different grazing practices affect the phyllosphere and rhizosphere bacterial communities of K. humilis is unknown. To address this issue, the effects of the grazing enclosure (GE), single-species grazing (YG and SG, representing yak only and sheep only, respectively), and different ratios of grazing (ratio of yak to sheep is 1:2, 1:4, and 1:6, represented by MG1:2, MG1:4, and MG1:6, respectively) on the dominant plant of K. humilis, it's phyllosphere and rhizosphere bacteria, and soil properties were investigated using artificially controlled grazing and grazing enclosure. Our data showed that grazing enclosure enhanced vegetation coverage, and rhizosphere bacterial richness and diversity, while reduced plant number and bacterial network stability of K. humilis. The NO3--N, K+, and Cl- concentrations were lower under grazing compared to GE. SG reduced the concentration of NH4+-N, TN, K+, and Na+ compared to YG. Moderate grazing intensity had a lower relative abundance of the r-strategists (Bacteroidota and Gammaproteobacteria) with higher bacterial network stability. Yak and sheep grazing showed reversed impacts on the bacterial network stability between the phyllosphere and rhizosphere of K. humilis. Proteobacteria and Actinobacteriota were identified in the molecular ecological network analysis as keystone taxa in the phyllosphere and rhizosphere networks, respectively, under all treatments. This study explained why sheep grazing has more adverse effects on grazing-tolerant grass species, K. humilis, than yak grazing, and will contribute to a better understanding of the impacts of different grazing practices and grazing enclosure on alpine grassland ecosystems on the QTP.

Herbivore assemblages affect soil microbial communities by altering root biomass and available nutrients in an alpine meadow.

Three different herbivore grazing assemblages, namely, yak grazing (YG), Tibetan sheep grazing (SG) and yak and Tibetan sheep co-grazing (MG), are practiced in alpine meadows on the Qinghai-Tibetan Plateau (QTP), but the effects of the different herbivore assemblages on soil microbes are relatively unknown. The microbial community plays an important role in the functional stability of alpine grassland ecosystems. Therefore, it is important to understand how the microbial community structure of grassland ecosystems changes under different herbivore grazing assemblages to ensure their sustainable development. To fill this gap, a field study was carried out to investigate the effects of YG, SG, and MG on plant communities, soil physico-chemical properties and microbial communities under moderate grazing intensity in alpine meadows. Grazing increased the ß-diversity of the bacteria community and decreased the ß-diversity of the fungal community. The herbivore assemblage affected the microbial community diversity, but not the plant community diversity. Total phosphorus, soil bulk density, root biomass, and plant α-diversity were correlated with both the bacterial and fungal community composition, available phosphorus and soil moisture were correlated only with the bacterial community composition, while available potassium and above-ground net primary production (ANPP) were correlated only with the fungal community composition. Soil available nitrogen, soil available phosphorus and soil bulk density were highest in SG, while ANPP was highest in MG. It was concluded that MG can improve ANPP and stabilize the soil microbial community, suggesting that MG is an effective method for sustainable use and conservation of alpine meadows on the QTP.

Effect of Chinese Herbs on Serum Biochemical Parameters, Immunity Indices, Antioxidant Capacity and Metabolomics in Early Weaned Yak Calves.

Chinese traditional herbs are used widely as feed supplements to improve the immune response and antioxidant capacity of livestock. Twenty early-weaned 4-month-old yak calves (72.3 ± 3.65 kg) were divided randomly into four groups (n = 5 per group); three groups were provided with supplementary 80 mL/kg DMI of the root water extracts of either Angelica sinensis, Codonopsis pilosula or Glycyrrhiza uralensis, and one group (control) was not provided with a supplement. Compared to control calves, calves consuming the three herbal extracts increased serum concentrations of albumin (ALB) and glutathione peroxidase (GSH-Px), but decreased serum concentrations of free fatty acids (FFAs) and malondialdehyde (MDA) (p < 0.05). Calves consuming A. sinensis decreased (p < 0.05) serum concentration of total cholesterol (TC), and increased (p < 0.05) serum concentration of total proteins (TP). Serum FFA concentrations increased (p = 0.004) linearly with time in the control group, but not in the groups consuming herbs. Serum metabolomic data demonstrated that A. sinensis and C. pilosula regulate mainly amino acid metabolism, while G. uralensis regulates mainly carbon and amino acid metabolism. It was concluded that the three herbal root extracts, as dietary supplements, improved energy and nitrogen metabolism, and enhanced the antioxidant capacity of yak calves.

[Effects of livestock grazing on the C:N:P stoichiometry in global grassland ecosystems: A meta analysis]. / æ”¾ç‰§å¯¹å ¨çƒè‰åœ°ç”Ÿæ€ç³»ç»Ÿç¢³æ°®ç£·åŒ–å­¦è®¡é‡ç‰¹å¾å½±å“çš„Meta分析.

In order to clarify the influence of livestock grazing managements on C:N:P stoichiometry of grassland ecosystem and improve grassland management ability at global scale, 83 Chinese and English papers were selected for meta-analysis in this study. We explored the effects of grazing herbivore assemblage (sheep alone, cattle alone, and mixed cattle and sheep) and grazing intensity (light grazing, moderate grazing and heavy grazing) on leaf, litter, root and soil C, N and P stoichiometry of grassland ecosystems. The results showed that grazing significantly decreased C content, C/N and C/P, and increased N, P content and N/P in leaf and litter. C content, N content, C/P and N/P were significantly reduced, and P content and C/N were increased in root and soil. Leaf and litter stoichiometry were more sensitive to cattle and sheep grazing alone, while root and soil stoichiometry were more sensitive to mixed grazing. Heavy grazing had a greater impact on the stoichiometry of grassland ecosystems. Grazing reduced soil N content and increased P content, indicating that grazing had different pathways of influence on grassland N and P content. Further research on the mechanisms of N and P content changes in response to unbalanced grazing activities and the incorporation of the effects of grazing herbivore assemblage and intensity into models for predicting and managing grassland ecosystems could effectively improve grassland ecosystem management.

Astragalus membranaceus Alters Rumen Bacteria to Enhance Fiber Digestion, Improves Antioxidant Capacity and Immunity Indices of Small Intestinal Mucosa, and Enhances Liver Metabolites for Energy Synthesis in Tibetan Sheep.

Natural, non-toxic feed additives can potentially replace chemical medications and antibiotics that are offered sheep to improve performance. In the present study, Tibetan sheep were supplemented with the root of Astragalus membranaceus (AMT), a traditional herb used widely in China. Twenty-four male Tibetan sheep (31 ± 1.4 kg; 9-month-old) were assigned randomly to one of four levels of supplementary AMT: 0 g/kg (A0), 20 g/kg (A20), 50 g/kg (A50) and 80 g/kg (A80) dry matter intake (DMI). The A50 and A80 groups increased the diversity of rumen bacteria on d 14 and the relative abundances of fiber decomposing bacteria. Supplementary AMT upregulated the metabolism of vitamins, nucleotides, amino acids and glycan, and downregulated the metabolism of lipids and carbohydrates. In addition, supplementary AMT enriched rumen bacteria for drug resistance, and reduced bacteria incurring cell motility. In general, AMT supplementation increased the concentrations of catalase (CAT), superoxide dismutase (SOD) total antioxidant capacity (T-AOC) and secretory immunoglobulin A (sIgA) in the small intestinal mucosa and CAT and SOD in meat tissue. The liver tissue metabolome response showed that AMT in the A80 lambs compared to the A0 lambs upregulated the metabolites for energy synthesis. It was concluded that supplementary A. membranaceus increased the relative abundances of fiber decomposing bacteria and improved the antioxidant capacities and immunity indices of small intestinal mucosa and meat tissue in Tibetan sheep.

Identification and characterization of satellite DNAs in Poa L.

BACKGROUND: Poa L. is a large genus of grass in Gramineae, among which P. pratensis is widely cultivated as turf and forage. Satellite DNA is the main components of the plant genome. Information of satellites will helpful for dissection the genome composition and definition of the phylogeny relationship of these species. However, the knowledge about the satellites in genus Poa is still limited. RESULTS: Four satellite DNAs were identified using the Repeat Explorer pipeline in HiSeq Illumina reads from diploid plants in P. malaca (2n = 26). Two satellites showed high similarity with the previously identified PpTr-1 and PpTr-3, whereas two others are newly identified with the monomer of 326 bp (Poa-326) and 353 bp (Poa-353) respectively. The clone DNAs of PpTr-1 and PpTr-3, and oligonucleotides designed representing satellites Poa-326 and Poa-353 were probed to test on chromosomes across 13 Poa speceis with different polyploidy level by fluorescent in situ hybridization (FISH). PpTr-1, PpTr-3, and Poa-362 were stably positioned in the subtelomeric regions in nearly all species with the variation of hybridization sites number. However, Poa-353 showed different FISH patterns of multiple regions with the variation of hybridization intensity and distribution sites across species. In addition, 5S rDNA and 45S rDNA were used to characterize the genome of the Poa species. Four rDNA FISH patterns were revealed in the tested species. CONCLUSION: Four identified satellite were high conservable across Poa species. Genome distribution of these satellites can be characterized by FISH. The variation of satellite DNAs and rDNA chromosomal distributions between species provide useful information for phylogenetic analysis in genus Poa.

Characterization of the complete chloroplast genome of Poa pratensis L. cv. Qinghai (Gramineae).

This study provides a chloroplast genome of Poa pratensis L. cv. Qinghai. The complete genome is 135,606 bp in length with a G + C content of 38.28%, which contains 32 tRNA genes, and 8 rRNA genes. The phylogenetic analysis indicated that P. pratensis L. cv. Qinghai is closely related to Festuca arundinacea cultivar KY-31. These results contribute to explore the genetic evidence for adaptation to the Qinghai-Tibet Plateau.

Characterization of the complete chloroplast genome of Poa poophagorum (Gramineae), a native grass from the Qinghai-Tibetan Plateau.

This study provides a chloroplast genome of Poa poophagorum. The complete cp genome was135,664 bp in length with typical quadripartite structure, containing a pair of inverted repeats (IR) of 21,552 bp each, a large single-copy (LSC) region of 79,790 bp, and a small single-copy (SSC) region of 12,770 bp. The overall G + C content of the cp genome was 38.30%, which encompassed 119 genes including 79 protein-coding genes,8 rRNA genes, and 32 tRNA genes. The phylogenetic analysis indicated that P. poophagorum was closely related to Festuca arundinacea cultivar KY-31in Gramineae. This study would contribute to enrich the Poa L. cp genome resource and promote biological research.

Characterization of the complete chloroplast genome of Festuca sinensis (Gramineae).

The complete chloroplast genome from Festuca sinensis, an important perennial bunchgrass of the Gramineae, is determined in this study. The whole chloroplast genome sequence of F. sinensis has been characterized by Illumina pair-end sequencing. The circular genome is 134,177 bp long, containing a large single-copy region (LSC) of 79,367 bp and a small single-copy region (SSC) of 12,510 bp, which are separated by a pair of 21,150 bp inverted repeat regions (IRs). It encodes a total of 150 genes, including 93 protein-coding genes (75 PCG species), 49 tRNA genes (30 tRNA species) and eight ribosomal RNA genes (4 rRNA species). The most of gene species occur as a single copy, while 30 gene species occur in double copies. The overall A + T content of is 61.6%, while the corresponding values of the LSC, SSC, and IR regions are 63.7, 67.4, and 56.0%, respectively. Phylogenetic analysis suggested that Festuca sinensis was relatively close to Festuca ovina compared with other species of Festuca genera in Gramineae among the species analyzed. This complete chloroplast genome will provide valuable insight into conservation and exploitation efforts for this species as well as useful resources for studying the Gramineae phylogeny.

Postpartum oestrous cycling resumption of yak cows following different calf weaning strategies under range conditions.

Early weaning can improve body condition and reproductive performance of cows. The objectives of this study were to examine and compare oestrous cycling resumption, behaviour and blood parameters of yak cows following four different strategies of calf weaning. Twenty-six yak cows (4-8 years) and their calves (94.3 ± 2.4 days) were studied in which calves were: weaned naturally with free access to their mothers (NW; n = 13); weaned abruptly and separated permanently from their mothers (PW; n = 5); separated temporarily from their mothers for 15 days (TW; n = 5); and fitted with nose plates for 15 days, but allowed free access to their mothers (NP; n = 3). Yak cows with sucking calves (NW) spent more time grazing in the cold season (from d 39 to 84). Based on serum progesterone concentrations, none of nine NW yak cows resumed oestrous cycling during the study, while seven of nine yak cows with weaned calves resumed cycling (3/3 for PW; 2/3 for TW; and 2/3 for NP yaks). We concluded that early weaning improved postpartum reproductive performance of yak cows on the Qinghai-Tibetan plateau and that abrupt and permanent weaning was an appropriate strategy.