[Objective] To explore the expression pattern of SRY-box transcription factor 5 （SOX5） in different physiological stages of the mammary gland in Chinese Holstein cows, and to clarify its protein structure characteristics and its regulation role in milk fat synthesis. [Methods] Quantitative real-time reverse transcription PCR （qRT-PCR） was used to detect the expression of SOX5 mRNA in bovine mammary gland tissues during the puberty, lactation and dry periods and mammary epithelial cells treated with sodium acetate and oleic acid. RNA interference technology was used to silence SOX5, combined with lipid droplet staining and triglyceride （TAG） content determination to analyze its effect on milk fat synthesis. Bioinformatics methods were performed to analyze the homology, physicochemical properties of the protein, secondary/tertiary structure, conserved domains and interacting protein of the SOX5 gene. [Results] The expression of SOX5 in mammary gland tissue during lactation period was extremely significantly higher than that in puberty and dry periods （P<0.01）. Treatment with 12 mmol/L sodium acetate or 100 μmol/L oleic acid extremely significantly up-regulated the expression of SOX5 in mammary epithelial cells （P<0.001）. After silencing SOX5, the expression of PPARγ （P<0.001）, a key transcription factor of milk fat synthesis, and the expression of SREBP1 （P<0.01） were extremely significantly down-regulated; the number and size of lipid droplets were reduced, and the content of TAG was extremely significantly reduced （P<0.01）. SOX5 is highly conserved among species and has the highest homology with goat （99.3%）. It contains a HMG-box domain and is a soluble hydrophilic protein that can interact with SOX6, SOX9, SATB2 and other proteins. [Conclusion] SOX5 is highly expressed in dairy cows during lactation period and is induced by fatty acids, which can promote the synthesis of lipid droplets and triglycerides. This study provides an important basis for analyzing the regulation mechanism of bovine milk fat synthesis.

Biological rhythms are endogenous periodic regulatory systems formed by terrestrial organisms during long-term evolution to adapt to the Earth′s rotation and revolution, mainly including behavioral patterns such as circadian rhythms and annual rhythms. The transcription-translation feedback loop （TTFL） mechanism, elucidated by research related to the 2017 Nobel Prize in Physiology or Medicine, has laid the core theoretical foundation for analyzing the molecular regulation of biological rhythms. In mammals, the biological clock is centered in the suprachiasmatic nucleus （SCN） of the hypothalamus and synergistically regulates the expression of rhythmic genes in peripheral tissues such as the liver, heart, and adipose tissue through light signals, neural pathways, and endocrine signals such as melatonin （MT）, thereby maintaining the body′s circadian rhythm homeostasis. External signals such as light, temperature, and feeding can influence the operation and phase adjustment of the biological clock system through central and peripheral synchronization mechanisms. The biological clock widely participates in the temporal metabolic processes of animal feeding, sleep, energy metabolism, reproduction, and macronutrients （glucose, lipids, and proteins） by regulating the transcriptome, hormone secretion, and key metabolic pathways. Its disruption can lead to metabolic abnormalities, cardiovascular dysfunction, decreased reproductive performance, and various metabolism-related diseases. Reasonable use of environmental interventions such as light and feeding time can optimize biological rhythms to improve animal health and production efficiency. This paper reviews the molecular basis of the biological clock, environmental regulation, synchronization mechanisms, physiological effects, and metabolic regulation, aiming to provide theoretical references for further analysis of biological rhythms and biological clock regulatory mechanisms in female animals, and to promote the application of rhythm regulation in livestock production and health fields.

[Objective] To explore the effects of cutting length on the silage quality of rice straw from different varieties. [Methods] Fresh straw from five rice varieties （Xinxiang S/R8029 Xiang, Xinxiang S/8X001, Xinxiang S/7W1446, Xinxiang S/9WH401 and Xinxiang S/R382） was used as materials, and cut into three lengths of 1-2 cm, 2-3 cm and 3-4 cm, respectively. After 60 days of sealed fermentation in vacuum bags, the microbial populations, nutritional components and fermentation characteristics were determined. Membership function analysis was used to comprehensively evaluate nutritional components and silage fermentation indexes. [Results] In terms of microbial content, different varieties, cutting length, and their interaction had significant effects on the number of lactic acid bacteria and aerobic bacteria （P<0.05）. No mold and yeast was detected in all treatments. In the 1-2 cm treatments of Xinxiang S/9WH401 and Xinxiang S/R382, the number of lactic acid bacteria was significantly lower than that in the 3-4 cm treatments （P<0.05）. In the 1-2 cm treatments of all varieties, the number of aerobic bacteria was significantly lower than that in other treatments （P<0.05）. In terms of nutritional components, under the same cutting length, there was no significant difference in crude protein content between Xinxiang S/R382 and Xinxiang S/8X001 （P>0.05）, but both were higher than those of other varieties; there was no significant difference in soluble carbohydrate content of Xinxiang S/R382 among three cutting lengths （P>0.05）, and the soluble carbohydrate contents of 1-2 cm and 2-3 cm were higher than those of other varieties. In terms of silage fermentation quality, the pH values of all varieties under the 1-2 cm treatment were significantly lower than those under the 3-4 cm treatment （P<0.05）, and the pH value slightly increased with increasing cutting length. Except for Xinxiang S/9WH401, there were no significant differences （P>0.05） in propionic acid content among treatments for the other varieties. Butyric acid was detected only in Xinxiang S/9WH401, and its content significantly increased with increasing cutting length （P<0.05）. The V-score values of Xinxiang S/R8029 Xiang, Xinxiang S/R382, Xinxiang S/8X001, and Xinxiang S/7W1446 under different cutting lengths were all above 90, with Xinxiang S/R382 showing the highest average ranking under different cutting lengths. [Conclusion] Xinxiang S/R382 is an ideal material for silage production, and the cutting length of 1-2 cm can effectively improve the silage quality of rice straw.

[Objective] To explore the effects of selenium-enriched black soldier fly on growth performance, serum biochemical indices, antioxidant indices and tissue selenium content of Micropterus salmoides. [Methods] A single-factor completely randomized experimental design was adopted. A total of 270 juvenile M. salmoides with an average weight of （50.31±0.21） g were selected and randomly divided into 3 groups, with 3 replicates in each group and 30 fish in each replicate. The control group （CN） was fed a basal diet supplemented with non-selenium-enriched black soldier fly; the sodium selenite group （SS） was supplemented with 0.30 mg/kg selenium on the basis of the control group; the selenium-enriched black soldier fly group （Se-BSF） was fed a basal diet supplemented with 2% selenium-enriched black soldier fly. The experiment lasted for 60 days. Growth performance data were recorded before and after the experiment. Blood, liver, muscle, and whole-body samples were collected to determine serum biochemical indices, antioxidant indices, and selenium content in each tissue. [Results] In terms of growth performance, compared with the control group （CN）, the final body weight, specific growth rate and feed efficiency of M. salmoides in the selenium-enriched black soldier fly group （Se-BSF） were significantly improved （P<0.05）; other indices showed improvement trends but no significant differences （P>0.05）; compared with the control group （CN） and the selenium-enriched black soldier fly group （Se-BSF）, there was no significant difference in all indices in the sodium selenite group （SS） （P>0.05）. In terms of serum biochemical indices, compared with the control group （CN）, the total protein （TP）, albumin （ALB） and high-density lipoprotein cholesterol （HDL-C） in the serum of M. salmoides in the selenium-enriched black soldier fly group (Se-BSF) were significantly increased （P<0.05）; the serum triglyceride （TG） and low-density lipoprotein cholesterol （LDL-C） of M. salmoides in the selenium-enriched black soldier fly group (Se-BSF) were significantly （P<0.05） lower than those in the sodium selenite group （SS） and the control group （CN）. In terms of serum antioxidant indices, compared with the control group (CN), the total antioxidant capacity （T-AOC）, total superoxide dismutase （T-SOD） and glutathione peroxidase （GSH-Px） in the serum of M. salmoides in the selenium-enriched black soldier fly group （Se-BSF） were significantly increased （P<0.05）; the serum malondialdehyde （MDA） of M. salmoides in the selenium-enriched black soldier fly group （Se-BSF） was significantly （P<0.05） lower than that in the sodium selenite group （SS） and the control group （CN）. In terms of tissue selenium content, compared with the control group （CN）, the selenium content of muscle, liver and whole body of M. salmoides in the selenium-enriched black soldier fly group （Se-BSF） were significantly increased （P<0.05), and the selenium content in each tissue in the sodium selenite group （SS） showed an increasing trend, but the difference was not significant （P>0.05）; there was no significant difference between the selenium-enriched black soldier fly group （Se-BSF） and the sodium selenite group （SS） （P>0.05）. [Conclusion] Dietary supplementation with selenium-enriched black soldier fly can significantly enhance the growth performance of M. salmoides, improve serum biochemical indices, strengthen the body′s antioxidant capacity, and effectively promote the deposition of selenium in various tissues. This provides a reference for the healthy breeding of M. salmoides and the development of high-quality selenium-enriched products.

With the development of global animal husbandry, the restrictions on the use of feed antibiotics have gradually increased. Microecological preparations can replace antibiotics in livestock and poultry production due to their green, safe, highly efficient, non-toxic, and low drug-resistance-inducing characteristics. Microecological preparations can promote the development of the animal immune system and intestinal tract, improve the body's immune performance, and enhance the mucosal physical barrier. They also possess multiple functions of regulating the composition and activity of intestinal microbiota, maintaining intestinal microbiota balance, improving digestive function, enhancing feed digestibility and utilization efficiency, promoting growth and development, and alleviating stress. The period from birth to weaning is a crucial period in the life cycle of calves. The health status of calves at this stage is directly related to their adult productivity, overall health and breeding efficiency. Based on this, with summarizing the different types and functions of microecological preparations, this paper reviews the regulatory mechanisms of microecological preparations in the growth and development of calves from the aspects of enhancing growth performance, improving body immunity and regulating intestinal microbiota balance and health, aiming to promote microecological preparations to play a greater role in advancing the development of calf breeding industry and accelerating the green transformation of animal husbandry.

[Objective] To investigate the effects of dietary supplementation with Clostridium butyricum culture on the production performance, serum biochemical indices of lactating Hu ewes producing twin lambs, and the growth performance of lambs. [Methods] Twenty-four lactating twin-bearing Hu ewes （7 days postpartum） from the same production batch with similar age and body weight, together with forty-eight of their healthy twin F1 Dorper × Hu crossbred lambs with similar average birth weights, were selected and randomly assigned to four groups （6 ewes and 12 lambs per group）: a basal diet （CK）, a basal diet supplemented 0.1% C. butyricum culture （CB1）, a basal diet supplemented 0.2% C. butyricum culture （CB2）, and a basal diet supplemented 0.4% C. butyricum culture （CB4）. The experimental period lasted for 53 days. Production performance indices of ewes and growth performance indices of lambs were measured on days 9, 24, 39, and 53, respectively. The body weight of ewes was measured at the start and end of the experiment. Serum biochemical indices of ewes were determined at the end of the experiment. [Results] ① C. butyricum culture had no significant effects on body weight and average daily gain of ewes （P>0.05）, but dry matter intake in the CB4 group was extremely significantly higher than that in the other groups （P<0.01）. ② C. butyricum culture had no significant effect on milk yield and milk composition of ewes （P>0.05）. ③ C. butyricum culture significantly improved growth performance of lambs （P<0.05）; body weight of lambs in the CB4 group during 24-53 days was extremely significantly higher than that in the CK group （P<0.01）, and starter feed intake of lambs in the CB4 group during the whole experimental period was significantly higher than that in the CK group （P<0.05）. ④ Interleukin-2 （IL-2） content in the CB1 group was significantly higher than that in the CB4 group （P<0.05）, and interleukin-6 （IL-6） content in the CB4 group was extremely significantly lower than that in the CK group （P<0.01）. The total antioxidant capacity （T-AOC）, superoxide dismutase （SOD） activity, and glutathione peroxidase （GSH-Px） activity in the CB4 group were extremely significantly higher than those in the CK, CB1, and CB2 groups （P<0.01）. C. butyricum culture had no significant effects on serum total protein （TP）, albumin （ALB）, globulin （GLB）, total cholesterol （TC）, triglyceride （TG）, blood urea nitrogen (BUN), aspartate aminotransferase （AST）, alanine aminotransferase （ALT）, glucose （GLU）, or prolactin （PRL） levels （P>0.05）. However, progesterone （P） content in the CB4 group and estradiol （E2） content in the CB2 group were significantly higher than those in the CK group （P<0.05）. [Conclusion] Dietary supplementation with C. butyricum culture does not significantly improve body weight, milk yield, or milk composition of ewes; however, it extremely significantly increases dry matter intake during the middle and late experimental stages through multi-component synergistic effects （P<0.01）, regulates immune and antioxidant functions of ewes, and significantly improves growth performance of lambs （P<0.05）. Considering all indices, 0.4% is the optimal supplemental level of C. butyricum culture.

Oxidative stress is an important cause of body damage, decreased immunity and reduced production performance in livestock and poultry. Therefore, the development of green and safe natural antioxidants has become a research hotspot in the healthy breeding of livestock and poultry. Bioactive peptides are a class of small molecule substances with antibacterial, antioxidant, immunomodulatory and other physiological functions. They are widely found in animal and plant proteins and organisms. Among them, antioxidant peptides can alleviate or inhibit oxidative damage in the body. Due to their high activity and multi-target characteristics, antioxidant peptides have good development prospects in the fields of functional food, biomedicine and animal husbandry. This review systematically summarizes the related research results and comprehensively discusses the classification and sources, preparation technologies, antioxidant mechanisms, and activity evaluation methods of bioactive peptides. The material is mainly classified into two categories: plant-derived and animal-derived, with a wide range of raw material sources; the preparation methods mainly include direct extraction, enzymatic hydrolysis, microbial fermentation, chemical synthesis and recombinant DNA technology. Different preparation processes have their own advantages and disadvantages, among which enzymatic hydrolysis and microbial fermentation are more suitable for large-scale production. The antioxidant mechanism mainly includes scavenging free radicals, chelating metal ions, increasing the levels of endogenous antioxidants and regulating antioxidant-related signaling pathways. Its activity can be assessed by chemical evaluation and biological evaluation. In addition, this review discusses the practical application effects of bioactive peptides in livestock and poultry production, analyzes the shortcomings of current research, and provides perspectives on the optimization of preparation process and the realization path of action mechanism, aiming to provide theoretical references for the rational application and in-depth study of bioactive peptides.

Pork is an important meat product consumed by Chinese residents, and its quality directly affects the consumer experience and the high-quality development of the animal husbandry industry. As an essential trace element for humans and animals, selenium exerts its biological functions primarily through the synthesis of selenoproteins such as glutathione peroxidase, thioredoxin reductase, selenoprotein W, and deiodinase, playing a critical role in regulating pork quality. This review summarizes the existing forms, metabolic characteristics and core selenoprotein family functions of selenium, as well as the molecular mechanisms by which selenium and selenoproteins improve pork color, water-holding capacity, tenderness, lipid stability, and shelf life through pathways such as antioxidant pathways, mitochondrial function, muscle fiber remodeling, protein metabolism, and immune-inflammatory responses. Furthermore, it systematically analyzes the regulatory effects of different selenium sources, additive amounts, growth stages and synergistic nutrition on pork quality. The review highlights that organic selenium has high bioavailability and good safety, which can significantly increase muscle selenium deposition, enhance antioxidant capacity and retard post-slaughter quality deterioration. Appropriate levels of selenium can promote the transformation of muscle fibers into oxidative type, maintain mitochondrial structure and energy metabolism, inhibit inflammation and excessive protein degradation, and then improve the comprehensive quality of pork, providing references for selenium and selenoproteins in high-quality and efficient breeding of pigs and standardized production of selenium-enriched pork.

[Objective] To explore the differences in serum biochemical indices, oviducts and intestinal microbiota between laying hens producing dark-spotted eggs and normal eggs. [Method] A total of 120 60-week-old Dawu Jinfeng laying hens were selected and divided into the normal egg group and the dark-spotted egg group. The differences of serum antioxidant indices, lipid metabolism indices, oviduct length and weight, and intestinal microbiota structure of laying hens were compared. [Result] Compared with the normal egg group, the activities of catalase （CAT）, glutathione peroxidase （GSH-Px）, superoxide dismutase (SOD), total antioxidant capacity （T-AOC） and malondialdehyde （MDA） content in serum of laying hens in the dark-spotted egg group increased to varying degrees, but the differences were not significant （P>0.05）. Serum alanine aminotransferase （ALT） activity significantly increased （P<0.05）, whereas there were no significant differences （P>0.05） in the contents of high-density lipoprotein cholesterol （HDL-C）, low-density lipoprotein cholesterol （LDL-C）, triglyceride （TG）, total cholesterol （TC）, aspartate aminotransferase （AST） activity or other indices. Oviduct weight significantly decreased （P<0.05）, while there was no significant difference （P>0.05） in oviduct length. There were no significant differences in the richness or phylum-level diversity of the intestinal microbiota （P>0.05）; at the genus level, the relative abundance of unclassified Bacteroidetes significantly increased （P<0.05）. [Conclusion] The occurrence of dark-spotted eggs is not related to the body′s antioxidant capacity and lipid metabolism level, but the relationship with liver health, oviduct development status and intestinal microbiota composition deserves attention.

In recent years, due to the dual effects of African swine fever and the COVID-19 epidemic, the pig breeding industry has been seriously affected. The batch production management model has been widely used in pig farms, which has greatly improved the efficiency of pig production. Timed artificial insemination is a key technology to realize batch production of sows and can effectively increase the annual number of farrowings per sow, save semen consumption, and simultaneously reduce the risk of disease transmission among pigs, thus showing broad application prospects. This paper reviews the commonly used hormones, technical applications, influencing factors, existing problems and corresponding solutions of timed artificial insemination in sows, aiming to provide technical references for the batch production mode of pig farms. Timed artificial insemination technology can be divided into simplified timed artificial insemination and precise timed artificial insemination. The former requires estrus detection and is easy to operate, while the latter does not require estrus detection and is more commonly used in batch production. The effectiveness of this technique is affected by factors such as semen quality, hormone quality and safety, the number of inseminations, and feeding management. At present, there are still problems such as high incidence of follicular cysts, high number of white stillborn piglets, and reduced farrowing rate in gilts. These problems can be improved through the establishment of puberty for gilts, optimization of hormone use, and precision feeding and management. In the future, the timed artificial insemination technology can be further improved by developing new semen extenders, optimizing insemination procedures, improving the accuracy of estrus and ovulation detection, developing new deep artificial insemination catheters, and enhancing hormone potency, thereby promoting the healthy development of batch production.

[Objective] To explore the correlation among plant productivity, nutritional quality and soil physicochemical properties under different combined nitrogen and phosphorus applications in mixed grassland of Medicago sativa L. and Elymus sibiricus L. in arid and semi-arid regions of Inner Mongolia, and to screen the optimal fertilization ratio. [Methods] The arid and semi-arid regions of Inner Mongolia were selected, and the artificial grassland mixed with Zhongmu No. 3 M. sativa and E. sibiricus was used as the research object. Nine fertilization treatments were designed. Potassium （K） fertilizer was set at two gradients: 0 and 180.00 kg/hm², designated as K0 and K2, respectively. Nitrogen fertilizer was set at four gradients: 0, 146.67, 300.00, and 446.67 kg/hm², designated as N0, N1, N2, and N3, respectively. Phosphorus fertilizer was set at four gradients: 0, 266.67, 540.00, and 806.67 kg/hm², designated as P0, P1, P2, and P3, respectively. Each group was combined with different application rates of nitrogen, phosphorus and potassium to form a gradient experiment group. By measuring the plant productivity, nutritional quality and soil physicochemical properties, and analyzing the correlation between the indicators, a comprehensive evaluation was performed. [Results] ① Soil available nitrogen and available phosphorus were significantly positively correlated with the average height of plant communities, biomass and dry-to-fresh ratio （P<0.05）, significantly negatively correlated with the average stem-to-leaf ratio of the plant community （P<0.05）, significantly positively correlated with plant crude fat content and relative feed value （P<0.05）, and negatively correlated with neutral detergent fiber and acid detergent fiber （only the negative correlation between soil available nitrogen and neutral detergent fiber was not significant）.soil available phosphorus was extremely significantly positively correlated with plant crude protein （P<0.01）. ② Comprehensive evaluation using the entropy weight-TOPSIS model combined with grey relational analysis showed the fertilization effect was: N2P2K2>N2P3K2>N3P2K2>N1P2K2>N2P1K2>N0P2K2>N1P1K2>N2P0K2>N0P0K0. [Conclusion] It was preliminarily determined that N2P2K2 and N2P3K2 （the application rate of nitrogen fertilizer was 300.00 kg/hm², the application rate of phosphorus fertilizer was 540.00-806.67 kg/hm², and the application rate of potassium fertilizer was 180.00 kg/hm²） were the best fertilization ratios for legume-grass mixed grassland in arid and semi-arid regions of Inner Mongolia.

[Objective] To study the effects of different cultivation practices on plant height, fresh forage yield and seed yield of Medicago sativa cv. Zhongke No. 1, and to clarify the optimal row spacing and seeding rate for its production and cultivation in the desert steppe regions of central and western Inner Mongolia. [Methods] The experiment was carried out in Jining District, Inner Mongolia using M. sativa cv. Zhongke No. 1 as the experimental material. A randomized complete block design was adopted with three row spacings （50, 60, and 70 cm, designated as H1, H2, and H3, respectively） and four seeding rates （18, 24, 30, and 36 kg/hm², designated as P1, P2, P3, and P4, respectively）, which generated a total of 12 treatments, with three replicates per treatment. Sowing was carried out in late May 2021. Plant height of M. sativa was measured in mid-August, and fresh forage yield and seed yield were measured in late September from 2022 to 2024 for three consecutive years. [Results] ①In terms of plant height, when the row spacing was 60 cm and the seeding rate was 24 kg/hm², the plant height of M. sativa cv. Zhongke No. 1 was the highest, with a three-year average plant height of 84.90 cm. ②In terms of fresh forage yield, when the row spacing was 50 cm and the seeding rate was 36 kg/hm², the fresh forage yield of M. sativa cv. Zhongke No. 1 was the highest, with an average fresh forage yield of 14.39 t/hm², which was 48.05% higher than that of the lowest treatment. ③In terms of seed yield, the seed yield of M. sativa cv. Zhongke No. 1 was the highest when the row spacing was 70 cm and the seeding rate was 24 kg/hm², and the average seed yield was 85.87 kg/hm², which was significantly （P<0.05） higher those of other treatments. ④The results of grey relational analysis and ranking showed that the combination of H3P2 （row spacing of 70 cm, seeding rate of 24 kg/hm²）, H2P2 （row spacing of 60 cm, seeding rate of 24 kg/hm²） and H1P4 (row spacing of 50 cm, seeding rate of 36 kg/hm²） ranked the top three. [Conclusion] Different cultivation practices have significant effects on the growth and yield of M. sativa cv. Zhongke No. 1, and the optimal single factor combinations of plant height, fresh forage yield and seed yield are different. Comprehensively considering the production and application values of M. sativa （balancing seed propagation and sustainable grassland utilization）, the optimal cultivation conditions for M. sativa cv. Zhongke No. 1 planted in the desert steppe region of central and western Inner Mongolia （Jining region） is a row spacing of 70 cm and a seeding rate of 24 kg/hm².

Cepharanthine is an alkaloid isolated from the rhizomes of plants such as Stephania japonica and Stephania epigaea in the genus Stephania of the family Menispermaceae. This compound has a broad spectrum of pharmacological activities and shows great potential for application and development in the field of human medicine and veterinary medicine. With the core pharmacological effects of anti-inflammation, anti-virus, anti-parasite and immune regulation, cepharanthine can effectively address the current problems of frequent viral diseases, prominent parasite resistance and low immunity of livestock and poultry in the animal husbandry and veterinary industry. It is an alternative drug with great development value. However, cepharanthine exhibits poor water solubility and low oral absorption efficiency, and has obvious low in vivo bioavailability, which seriously restricts its clinical translation and large-scale application. In order to overcome the shortcomings of the above formulations, a variety of new drug delivery systems such as suspensions, pellets, microemulsions and nanoemulsions have been gradually applied to the optimization and development of cepharanthine formulations. This paper systematically discusses the core pharmacological activities and mechanisms of action of cepharanthine, sorts out its research value and application prospect in related fields, and summarizes the technical strategies of its formulation optimization, aiming to provide scientific reference and theoretical insights for the scientific research promotion and clinical application of cepharanthine in veterinary fields such as animal disease prevention and control and livestock and poultry health breeding.

[Objective] To investigate the drug resistance and pathogenicity of Salmonella from ticks in grazing sheep in Emin County of Xinjiang Uygur Autonomous Region. [Methods] Ten live ticks were collected from the body surface of grazing sheep in Emin County. Morphological methods were used to identify the tick species. Bacteriological culture was employed to isolate the pathogenic bacteria in ticks. Morphological identification and molecular biology methods were applied to identify the isolated strains. The Kirby-Bauer disk diffusion method was used to perform drug susceptibility testing on the isolated strains. PCR amplification was employed to detect the carriage of drug resistance genes and virulence genes. [Results] Through morphological observation of ticks, 10 ticks were all female Hyalomma asiaticum. Three strains of Salmonella were isolated from 10 ticks based on morphological observation, biochemical tests and molecular biological identification, and were designated as isolate 1, isolate 2 and isolate 3, respectively, with an isolation rate of 30.0% (3/10). The results of drug susceptibility testing showed that isolate 1 was resistant to streptomycin and meropenem, isolate 2 was resistant to meropenem, ertapenem and trimethoprim-sulfamethoxazole, and isolate 3 was resistant to amikacin and meropenem. All three isolates carried qnrS, qnrA, sul1, sul2 and aadA1 resistance genes. A total of 10 virulence genes were detected, and all isolates carried rck, spvB, sopE virulence genes. [Conclusion] Salmonella from H. asiaticum in grazing sheep in Emin County have certain drug resistance and pathogenic risks. The research results provide data support for the study of tick-borne pathogens.

[Objective] To identify the bacterial pathogen of Tibetan pigs with respiratory diseases in a Tibetan pig farm in Garze Prefecture, Sichuan Province, and to clarify its biological characteristics and pathogenicity. [Methods] The pathogenic bacteria in the diseased samples were isolated and cultured, followed by morphological observation, 16S rDNA molecular identification and whole-genome sequencing. Drug susceptibility testing, biofilm formation assay and mouse pathogenicity analysis were carried out to clarify its biological characteristics and pathogenicity. [Results] The isolated strain exhibited non-hemolytic activity on 5% sheep blood agar plates, with colonies approximately 1 mm in diameter, grayish-white, and smooth-edged; microscopic examination revealed Gram-positive cocci arranged in chains; PCR amplification was carried out using the universal primers for the bacterial 16S rDNA gene, and a target band of approximately 1,500 bp was obtained. Based on the phylogenetic tree constructed by 16S rDNA gene and the whole genome identification analysis, it was identified as Streptococcus gallolyticus.Drug susceptibility testing showed that the isolated strain was susceptible to ampicillin, penicillin, cephalexin, norfloxacin, vancomycin, imipenem, levofloxacin, chloramphenicol, ceftazidime and florfenicol, and resistant to gentamicin, polymyxin B, tetracycline and azithromycin. In addition, the isolated strain showed strong biofilm formation ability in vitro (+++) . The pathogenicity study in mice showed that the isolated strain was pathogenic to 6-week-old mice, and could cause depression, loss of appetite and acute death in mice after intraperitoneal injection. Necropsy revealed typical lesions such as liver congestion and lung congestion. Pathological tissue sections showed liver cell necrosis, lung inflammatory cell infiltration and cell damage. [Conclusion] A strain of S. gallolyticus from Tibetan pig was successfully isolated. The isolated strain has strong biofilm formation ability, resistance to certain antibiotics, and strong pathogenicity. The study results can provide a reference for the precise prevention and control of bacterial diseases in Tibetan pigs, as well as for public health safety.