【Objective】 One female pig (ZXWIPIG505) was selected for whole genome resequencing analysis from a new strain of Porcine endogenous retrovirus (PERV) non-transmitting Zhong Xu Wuzhishan Mini-pig Inbred line (ZXWIPIG),in order to further interpret sequence characteristics of the new PERV non-transmitting pig strain at molecular level.【Method】 Genomic DNA of ZXWIPIG505 peripheral blood mononuclear cells was extracted and whole genome resequencing was performed with Illumina hiseq-4000 sequencing platform.Blast and SAMtools-0.1.19 software were utilized to extract the PERV long fragment and PERV-pol gene sequence fragment integrated in ZXWIPIG505 genome,and DNAStar software was used to analyze the integrated PERV structural gene sequence.And then,the integrated PERV-pol gene sequence in ZXWIPIG505 were compared with the PERV-pol gene sequence in the previously identified PERV-pol deficient ZXWIPIG452.【Result】 The average sequencing depth of ZXWIPIG505 whole genome resequencing was 14.32×,and the effective rate of sequencing data was 97.21%.Q20,Q30 and GC content were respectively 94.37%,87.03%,and 43.38%.The above results indicated that the quality of this sequencing data was high.Five long PERV fragments were integrated in ZXWIPIG505 genome,of which only scaffold5028 contained all PERV structural genes but was defective.Eighty-five integrated PERV-pol gene fragments were detected in the ZXWIPIG505 genome,which were all found incomplete and defective by comparison.The PERV-pol gene sequences integrated into the genomes of ZXWIPIG505 and ZXWIPIG452 exhibited high similarity.There were 60 fragments of the same length,75 fragments with identical integration sites in the pig genome,and 42 fragments with the same PERV-pol gene premature termination sites.【Conclusion】 ZXWIPIG505 selected in the early stage was demonstrated to be a PERV-pol gene-deficient pig,and the integrated PERV-pol gene sequences in ZXWIPIG505 and ZXWIPIG452 had high similarity.

Circular RNA (circRNA) is a new type of RNA molecule,which is formed from precursor mRNA by reverse splicing to form a covalently closed ring structure,and the lack of a cap structure and PolyA tail makes it stable and not easily degraded by nucleic acid exonucleases.With the rapid development of high-throughput sequencing and bioinformatics technology,many important regulatory function of circRNA in plant and animal life activity and disease occurrence have been explained,such as competitive binding of microRNA (miRNA),regulation of gene transcription,encoding of polypeptides,interactions with RNA binding protein (RBP),etc.In recent years,circRNA has become a hotspot in livestock and poultry genetic breeding because of their special structure and important regulatory role in gene expression.As an important livestock species with a long history of breeding in China,sheep not only have many varieties,but also are distributed all over the country,and are one of the most common livestock in people’s daily life.circRNA plays a regulatory role in various traits of sheep,such as fleece (wool),meat quality,lactation and reproduction,and circRNA mostly regulates the expression of related genes by acting as molecular sponges of miRNA,thus affecting various traits of sheep.Therefore,the authors summarize the origin,development,synthesis mechanism,biological function of circRNA and their recent applied research progress in important economic traits of sheep,so as to provide a scientific reference for in-depth investigation of the molecular regulatory mechanisms of circRNA in important traits of sheep.

【Objective】 This study was aimed to clone and perform bioinformatics analysis on the stromal cell-derived factor-1 (SDF-1/CXCL12) gene in Hezuo pigs，and detect the expression of CXCL12 gene in different tissues,establishing a foundation for further functional investigation of CXCL12 gene.【Method】 Using cDNA from the heart of Hezuo pigs as a template,the CXCL12 gene CDS sequence was amplified via PCR,cloned and sequenced,the similarity alignment and phylogenetic tree construction for the obtained sequence were performed.Bioinformatics software was used to analyze the physicochemical property and structural function of CXCL12 protein.The expression of CXCL12 gene in different tissues of Hezuo pigs was detected by Real-time quantitative PCR.【Result】 The full-length CDS sequence of CXCL12 gene in Hezuo pigs was 351 bp,encoding 116 amino acids.CXCL12 gene in Hezuo pigs was most closely related to Equus cabllus,and was distantly related to Oryx dammah.CXCL12 protein lacked transmembrane regions and signal peptide,included a low complexity region SCY,with a hydrophilicity index of ―0.347,it belonged to hydrophilic proteins.CXCL12 protein contained 12 phosphorylation sites.The secondary structure was predominantly compose of random coil (54.31%) and alpha helix (32.76%),which was consistent with the tertiary structure.The protein was primarily located in nucleus and mitochondria,and interacted with proteins such as CCL21 and CXCL9.Real-time quantitative PCR results showed that the expression of CXCL12 gene in liver of Hezuo pigs was extremely significantly higher than that in other tissues (P＜0.01),and the expression in kidney and heart was extremely significantly lower than that in other tissues (P＜0.01).【Conclusion】 This study successfully cloned the CDS sequence of CXCL12 gene in Hezuo pigs,encoding 116 amino acids,mainly distributed in nucleus and mitochondria.It was a stable,hydrophilic and secretory protein without transmembrane structures.The highest expression of CXCL12 gene was observed in liver of Hezuo pigs.The results provided a reference for further exploring the regulatory roles of CXCL12 gene in immune mechanisms of Hezuo pigs.

【Objective】 This study was aimed to identify the long non-coding RNA (lncRNA) in longissimus dorsi muscle tissue of Saba pigs with fast and slow growth rates,and explore its important roles in pig growth and development.【Method】 Six Saba pigs (three males and three females) with the largest and smallest body weight at 322 days were selected and divided into fast-growth group (FG) and slow-growth group (SG),and the longissimus dorsi muscle samples were collected for RNA-Seq,respectively.After quality control,alignment and splicing of the sequencing data,the DESeq2 software package was used to identify the differentially expressed lncRNA in FG and SG.Target genes were further predicted and analyzed for GO function and KEGG pathway enrichment.Six differentially expressed lncRNAs were randomly selected for Real-time quantitative PCR verification.【Result】 A total of 165 differentially expressed lncRNAs were identified,of which 71 were up-regulated and 94 were down-regulated,and 65 target genes were predicted.The results of GO function and KEGG pathway enrichment analysis showed that the target genes were significantly enriched in functional terms such as lipid metabolism process,canonical Wnt signaling pathway,as well as in pathways including Wnt signaling pathway,arginine and proline metabolism,histidine metabolism,etc.Real-time quantitative PCR results showed that the expression trends of six differentially expressed lncRNAs (ENSSSCT00000085548,MSTRG.8918.1,MSTRG.20943.30,MSTRG.7048.7,MSTRG.11735.9 and MSTRG.20943.40) were consistent with RNA-Seq results,there were significant difference in longissimus dorsi muscle between FG and SG in Saba pigs (P＜0.05).【Conclusion】 lncRNAs identified in this study were related to the process of muscle growth and development,and these lncRNAs could affect growth traits such as average daily weight gain by regulating the expression of genes such as WNT10B,SFRP4,LEP,MAOB,ARG1,PRICKLE1 and DUSP1,which might lead to the differences in growth rate within the population of Saba pigs.The results provided a theoretical basis for further revealing the molecular mechanism of growth and development and the genetic improvement of growth traits such as average daily gain in pigs.

【Objective】 The aim of this experiment was to clone the CDS region of bovine transforming growth factor beta 1 (TGFB1) gene and explore its expression in different tissues and adipocytes during differentiation of Guyuan cattle,laying a foundation for the subsequent research on the function of TGFB1 gene.【Method】 The CDS region of bovine TGFB1 gene was amplified by PCR using adipose tissue cDNA as template.The physicochemical properties,subcellular localization,protein structure and functional domain of TGFB1 protein were predicted by bioinformatics online softwares.Real-time quantitative PCR was used to detect the expression of TGFB1 gene in bovine adipocyte during differentiation and different tissues.【Result】 The CDS region of bovine TGFB1 gene was successfully cloned with a total length of 1 173 bp.The protein encoded by TGFB1 gene was mainly composed of 390 amino acids and its chemical formula was C₁₉₈₁H₃₁₃₄N₅₅₄O₅₆₄S₂₁.The total average hydrophilic (GRAVY) value was ―0.328.TGFB1 protein had 37 phosphorylation sites,49 O-glycosylation sites and 3 N-glycosylation sites.The secondary structure of TGFB1 protein was mainly composed of alpha helix and random coil,and it interacted with SMAD2,SMAD3,ITGAV and other proteins.Real-time quantitative PCR results showed that compared with 0 d after induction differentiation，TGFB1 gene expression was significantly decreased at 2 d (P＜0.05),and significantly increased at 4-10 d (P＜0.05).Tissue expression profile showed that the expression of TGFB1 gene was the highest in spleen of calves and subcutaneous fat of adult cows,respectively,and was significantly higher than that in other tissues (P＜0.05). 【Conclusion】 The expression level of the bovine TGFB1 gene was relatively high at 4 d of bovine precursor adipocytes, and it was highly expressed in spleen of calves and subcutaneous fat of adult calves. It played an important role in regulating the proliferation and differentiation of adipocytes and the physiological processes of the calf immune system. This results provided a theoretical basis for further exploring the molecular mechanism of the TGFB1 gene involved in fat deposition in Guyuan cattle.

【Objective】 The purpose of this study was to isolate and culture pancreatic mesenchymal stem cells (PMSCs) in Simmental cattle,establish PMSCs line in Simmental cattle,study its biological characteristics,and provide reference for the preservation of germplasm resources in Simmental cattle.【Method】 PMSCs were isolated and cultured from pancreas tissue in Simmental cattle by enzyme digestion and tissue block adhesion method,and the biological characteristics of PMSCs were identified.The expressions of cell surface markers (CD34,CD73,CD90 and CD166) were measured by immunofluorescence and semi-quantitative PCR.The cell proliferation ability was determined by drawing cell growth curves of P4,P10 and P16 generations and calculating population doubling time.The cell cloning rate was determined by cell cloning test,and the cell migration rate was calculated through scratch test.The purified cells were induced into osteoblasts,adipocytes and chondrocytes respectively to detect the multipotent differentiation ability of PMSCs,and the cell genetic stability was detected by chromosome karyotype analysis test.【Result】 PMSCs could be cultured using tissue block adhesion method and passaged to the third generation for basic purification.Semi-quantitative PCR results showed that the surface markers (CD73,CD90 and CD166) were positive,but CD34,a surface antigen related to hematopoietic cells,was negative.The growth curve of PMSCs in Simmental cattle showed a typical S curve,the doubling time of P4,P10 and P16 generation cells were 40.22,43.09 and 44.50 h,and the colony formation rate were 26.25%,19.00% and 13.50%,respectively.The migration rate of the third passage cells was 44.44% by scratch test.The clear lipid droplets,cartilage masses and calcium nodules were observed after differentiation of PMSCs in vitro.Karyotype analysis results showed that PMSCs in Simmental cattle were normal diploid karyotype (2n=60,XY),and the chromosome set did not change.【Conclusion】 PMSCs isolated and cultured from pancreas tissue in Simmental cattle could stably inherit and strongly proliferate,and had the potential to differentiate into osteoblasts,adipocytes and chondrocytes.The results could provide new method for tissue repair and seed cells for the protection and preservation of germplasm resources in Simmental cattle.

【Objective】 The experiment aimed to explore the effects of compound plant extracts (Cuscuta chinensis and Arctium lappa extract) on urine physicochemical indicators,antioxidant ability and immune indicators in adult cats,in order to provide a theoretical basis for the application of the compound plant extracts in pet feed.【Method】 Twenty adult British shorthair cats with similar body condition and age were randomly divided into two groups.The cats in control group were fed a basal diet,while in the experimental group received the same basal diet supplemented with 3 g/kg compound plant extracts (a mixture of Cuscuta chinensis extract and Arctium lappa extract in a 1∶2 ratio),primarily consisting of gallic acid esters,quercetin,and arctiin.Each group consisted of 10 replicates,with one cat per replicate and an equal distribution of males and females.The pre-feeding period lasted for 7 days,followed by a formal trial period of 42 days.At the end of the trial,blood samples were collected and fresh urine was obtained to evaluate routine blood test,biochemical parameters,immune indicators,antioxidant status,and urine physicochemical indicators.【Result】 Compared with control group,the experimental diet increased the serum total protein and albumin of adult cats (P＜0.05).In the experimental group,serum interleukin-1β level was significantly lower than that in control group,while serum interleukin-10 level was significantly higher than that in control group (P＜0.05).Additionally,compared with control group,serum malondialdehyde level in experimental group was significantly decreased,whereas total antioxidant capacity was significantly increased (P＜0.05).Compared with control group,the experimental diet had no effect on urinary pH (P＞0.05),but significantly increased total urine output as well as markedly decreased the concentrations of calcium,sodium,potassium,chloride,phosphate and citrate ions in the urine (P＜0.05).【Conclusion】 Dietary compound plant extracts (Cuscuta chinensis and Arctium lappa extract) could enhance the antioxidant capacity,improve immune status and urine physicochemical indexes,and help maintain the body health of adult cats.

【Objective】 This study aimed to investigate the effects of Sophora alopecuroides and alkaloids from Sophora alopecuroides on the growth performance and rumen microbial community of Tan sheep.【Method】 Sixty healthy Tan sheep in the fattening period with similar body weight (28.38 kg±1.49 kg) were randomly divided into five groups with 12 replicates each.The sheep in control group was fed a basal diet,and the sheep in trial groups 1，2 and 3 were fed the basal diet supplemented with 2%,3% and 4% Sophora alopecuroides respectively,the sheep in trial group 4 was fed the basal diet supplemented with 0.2% alkaloids from Sophora alopecuroides.The pre-feeding period was 7 days,and the feeding period was 60 days.The sheep were weighed during the trial,and their feed intake was recorded to assess growth performance.The rumen fluid samples were collected for the rumen microbial community dynamics in Tan sheep based on 16S rRNA high-throughput sequencing technology at the ending of the experiment.【Result】 ① Compared with the control group,the average daily feed intake of Tan sheep in trial group 3 was extremely significantly reduced (P＜0.01),and the feed gain ratio of the four trial groups were extremely significantly lower (P＜0.01).②There were no significant difference in the Ace,Chao1,Shannon,Simpson,and Sobs indexes of rumen microbiota among the groups (P＞0.05).③At the phylum level of the rumen microbiota in Tan sheep,Firmicutes and Bacteroidetes were the dominant bacterial phyla.Compared with the control group,the relative abundance of Firmicutes was extremely significantly decreased in trial groups 2 and 4 (P＜0.01),while the relative abundance of Firmicutes was extremely significantly increased in trial group 3 (P＜0.01).The relative abundance of Bacteroidetes and Fibrobacterota was both significantly increased (P＜0.05) in trial group 2.④At the genus level of the rumen microbiota in Tan sheep,the dominant rumen bacteria were Prevotella,Ruminococcus,Christensenellaceae R-7 group,Rikenellaceae RC9 gut group,and the norank_f_F082 group.Compared with the control group,the relative abundance of Prevotella in trial groups 1 and 2,the relative abundance of norank_f_F082 in trial group 4,and the relative abundance of Ruminococcus_gauvreauii_group in trial group 3 were all increased extremely significantly (P＜0.01).Meanwhile,the relative abundance of Olsenella in all four trial groups were decreased significantly (P＜0.05),and the relative abundance of unclassified Ruminococcaceae in trial group 3 were increased significantly (P＜0.05).【Conclusion】 Under the conditions of this experiment,the inclusion of 2%,3% Sophora alopecuroides and 0.2% alkaloids from Sophora alopecuroides in the diet effectively enhanced the growth performance of Tan sheep,regulated their rumen microbial community composition,and improved nutrient utilization.These findings provided a foundation for further exploration of the potential mechanisms of Sophora alopecuroides and alkaloids from Sophora alopecuroides as feed additives.

【Objective】 The aim of this experiment was to investigate the effects of different concentrations of tea extract in drinking water on digestive enzyme activities,nutrient apparent metabolism rate and serum biochemical indices of Cyan-shank Partridge chickens,so as to open up a new feasible way for the potential application of waste tea as a novel feed additive in poultry production.【Method】 A total of 400 one-day-old Cyan-shank Partridge chickens were randomly distributed into four groups,with 5 replicates in each group and 20 chickens in each replicate.Chickens in each group were fed the same basal diet.The chickens in control group drank water freely，and the chickens in experimental groups Ⅰ,Ⅱ and Ⅲ drank water with 0.3%,0.6% and 1.2% green tea aqueous extract,respectively.The experiment lasted for 21 days.At the end of the experiment,two chickens were randomly selected from each replicate for blood sampling,slaughtering,and collecting pancreas and duodenum to determine serum biochemical indices and intestinal digestive enzyme activities.At 19,20 and 21 days,the fresh feces of chickens were collected in the unit of repetition to determine the apparent metabolism rate of feed nutrients.【Result】 Compared with control group,the activities of pancreatic lipase of chickens in each experimental group was significantly lower (P＜0.05),the activity of duodenal trypsin in experimental groups Ⅱ and Ⅲ were significantly higher (P＜0.05),and the activity of duodenal lipase in experimental group Ⅲ was significantly lower (P＜0.05).The apparent metabolism rate of crude protein in experimental groups Ⅱ and Ⅲ were significantly higher (P＜0.05).Compared with control group,the serum triglyceride (TG) content of chickens was significantly lower in all experimental groups (P＜0.05),the serum urea nitrogen(BUN),low density lipoprotein cholesterol (LDLC) content and the activity of alanine aminotransferase (ALT) were significantly lower in experimental groups Ⅱ and Ⅲ(P＜0.05).The serum BUN content in experimental groups Ⅱ and Ⅲ was lower than that of the experimental group Ⅰ(P＜0.05),the serum LDLC content and the activity of ALT in experimental group Ⅲ were significantly lower than that of experimental groupⅠ(P＜0.05).【Conclusion】 The consumption of tea extract could increase the apparent metabolism rate of crude protein and the activity of intestinal trypsin of Cyan-shank Partridge chickens.Additionally,it had a favourable effect on serum protein and lipid metabolism indexes,and it was recommended to drink 0.6% green tea extract for Cyan-shank partridge chickens.

Calcium and phosphorus are two of the most abundant mineral elements in the animal body and play an important role in various life activities such as growth and development,metabolism,and immune function.Abnormal metabolism of calcium and phosphorus affects animals significantly,and they often cause symptoms of malnutrition and poor performance.Klotho proteins are encoded by the anti-aging gene Klotho and are expressed in kidney,brain,and bone.Klotho proteins have many important functions in biology.It was found that Klotho protein can act as a cofactor binding to fibroblast growth factor receptor (FGFR) to affect ion channel expression and regulate the secretion of hormones related to calcium and phosphorus metabolism to participate in the maintenance of calcium-phosphorus homeostasis in the animal organism.The author reviewed the expression and localization of Klotho protein, its biological functions, as well as the basic processes of calcium and phosphorus metabolism and the possible mechanisms of Klotho protein in regulating calcium and phosphorus metabolism. The paper aimed to provide theoretical references for further in-depth research on the role of Klotho protein in maintaining calcium and phosphorus homeostasis in the body, and for the development and utilization of Klotho protein as a potential target for the treatment of calcium and phosphorus metabolism diseases.

【Objective】 This study was aimed to investigate the effect of different Pseudomonas additions on the artificial rumen internal environment,and screen the appropriate Pseudomonas additions.【Method】 Four high-yielding dairy cows were selected as the donors of rumen fluid,and the total mixed ration (TMR) of donor cows was used as the fermentation substrate.A one-way four-level experimental design was used,the fermentation substrate in control group (CON) was supplemented with 0.5 g TMR,and fermentation substrate in experimental groups (A-D) were supplemented with 1×10⁹,2×10⁹,4×10⁹ and 8×10⁹ CFU/mL Pseudomonas,respectively,three replicates were set up for each level.pH and gas production were recorded at 2,4,6,8,10,12 and 24 h of fermentation,and the contents of ammoniacal nitrogen (NH₃-N),microbial protein (MCP) and volatile fatty acid (VFA) were measured at the end of fermentation.16S rRNA and internal transcribed spacer (ITS) were used for macro-genome sequencing to analyze the changes in the microbiota of rumen fluid.【Result】 ①At 10 h of fermentation,the pH of rumen fermentation broth in groups C and D was significantly lower than that in CON group (P＜0.05),and there were no significant changes in gas production,NH₃-N and MCP contents among all treatment groups at each time point (P＞0.05).②At 10 h of fermentation,the contents of butyric acid and total VFA in rumen fermentation broth of group B were significantly or extremely significantly higher than those of CON group (P＜0.05 or P＜0.01).At 12 h of fermentation,the isobutyric acid content of rumen fermentation broth in groups A and B were significantly higher than that in group D (P＜0.05).At 24 h of fermentation,the contents of propionic acid,butyric acid,isovaleric acid,acetic acid/propionic acid and total VFA in rumen fermentation broth of each experimental group were significantly or extremely significantly higher than those of CON group (P＜0.05 or P＜0.01).③The Chao1 index and Ace index of 16S rRNA and ITS in rumen fermentation broth of groups C and D were significantly or extremely significantly lower than those of CON group (P＜0.05 or P＜0.01).④At the level of phylum and genus of 16S rRNA,compared with CON group,the relative abundance of Proteobacteria and Klebsiella in rumen fermentation broth of group D was significantly increased (P＜0.05),and the relative abundance of Succinivibrionaceae_UCG-001 and Rikenellaceae_RC9_gut_group in groups C and D were significantly or extremely significantly decreased (P＜0.05 or P＜0.01).The relative abundance of Succiniclasticum in rumen fermentation broth in group B was significantly higher than that in groups C and D (P＜0.05),the relative abundance of norank_F082 was significantly higher than that in group D (P＜0.05).⑤At the level of phylum and genus of ITS,compared with CON group,the relative abundance of Kodamaea in rumen fermentation broth of groups B,C and D was significantly increased (P＜0.05),and the relative abundance of Anaeromyces in group B was significantly increased (P＜0.05).【Conclusion】 Under the condition of this experiment,2×10⁹ CFU/mL Pseudomonas had no side effects on rumen fermentation parameters in dairy cows,which increased the production of VFA,and also promoted the proliferation of fiber-degrading bacteria.Therefore,the appropriate amount of Pseudomonas to be added was 2×10⁹ CFU/mL.

【Objective】 This study aimed to investigate the optimal overfeeding time for Pekin ducks and investigate the effects of different overfeeding times on the growth performance,slaughter performance,nutritional quality and intestinal morphology.【Method】 150 1-day-old Pekin ducks with similar body weights were randomly divided into five groups using a single factor randomized experimental design.Each group consisted of 6 replicates,with 5 Pekin ducks in each replicate.The latter 7,5,3 and 1 d of the fattening period (36-42 days old) were overfed four times per one day,being force-fed for 1 (OF1 group),3 (OF3 group),5 (OF5 group)and 7 days(OF7 group),respectively and the OF0 group was the control group without overfeeding.The experimental period was 42 days.After the experiment,the Pekin ducks were weighed and their production performance was calculated.Two Pekin ducks were selected from each replicate group for slaughter and their slaughter performance was measured.The sebum and pectoral muscle tissues of Pekin ducks were collected for the detection of fatty acid and amino acid content,respectively.Duodenal,jejunal,and ileal tissues of Pekin ducks were collected for histopathological sectioning.【Result】 ①Compared with OF0 group,the final weight and average daily gain of Pekin ducks in OF3,OF5 and OF7 groups were significantly higher (P＜0.05),and the feed-to-weight ratio in OF7 group was significantly higher (P<0.05).②Compared with OF0 group,the slaughter rate,percentage of eviscerated yield,leg muscle weight (rate) and breast muscle weight (rate) of Pekin ducks in the four overfeeding groups were all not significant (P＞0.05),but the live weight,dressing weight and sebum weight (rate) of Pekin ducks in OF3,OF5,and OF7 groups were all significantly higher (P＜0.05).③ Compared with OF0 group,the contents of total fatty acids (TFA),saturated fatty acids (SFA),monounsaturated fatty acids (MUFA),polyunsaturated fatty acids (PUFA),n-3 polyunsaturated fatty acids (n-3 PUFA),and n-6 polyunsaturated fatty acids (n-6 PUFA) in the skin fat of Pekin ducks in OF1 group were significantly reduced (P＜0.05),while the contents of TFA and MUFA in the skin fat of Pekin ducks in OF3 and OF5 groups were significantly increased (P＜0.05),and the content of SFA in the skin fat of Pekin ducks in OF5 and OF7 groups was significantly increased (P＜0.05),the contents of PUFA,n-3 PUFA,and n-6 PUFA in the skin fat of Pekin ducks in OF3 group were significantly increased (P＜0.05),and the n-6/n-3 ratio showed no significant difference (P>0.05).There was no significant difference in the content of total amino acids (TAA) in the pectoral muscle tissue of Pekin ducks (P＞0.05),but the content of essential amino acids (EAA) in the pectoral muscle tissue of Pekin ducks in OF7 group was significantly reduced (P＜0.05).④ Compared with OF0 group,overfeeding could lead to different degrees of shedding,inflammatory cell infiltration and even necrosis of the villous structure in small intestine of Pekin duck.【Conclusion】 Overfeeding could significantly improve growth performance,slaughter performance and sebum nutrient content of Pekin ducks,but it would damage the intestinal morphology and structure.Thus the optimal overfeeding time was recommended to be 3 days for comprehensive consideration.

【Objective】 This study was aimed to explore the physical and chemical properties of cow manure during aerobic composting and the evolution of microbial communities,and analyze their interrelationships,so as to provide a theoretical basis for the resource utilization of manure.【Method】 Solid liquid separation of cow manure was performed through spiral extrusion.The separated solids were subjected to aerobic composting for 28 d.Samples were collected at 0 d(C0d),7 d (C7d),14 d (C14d),and 28 d (C28d),respectively.The physical and chemical indicators including moisture content (MC),organic matter (OM),carbon/nitrogen (C/N),nitrate nitrogen (NO₃-N) and total nitrogen (TN) contents were measured.The microbial community structure of samples were analyzed using high-throughput sequencing of 16S rRNA.【Result】 After composting,compared with C0d,C7d and C14d samples,the content of MC,OM and C/N in C28d sample were extremely significantly decreased (P＜0.01),while pH change was not significant.The contents of NO₃-N and TN in C28d sample were extremely significantly increased (P＜0.01).Alpha diversity analysis of microbial communities showed that the abundance and diversity of microbial communities gradually decreased during the composting process.There were significant differences in Chao1 index,Faith_pd index,and Observed species between C14d and C0d samples (P＜0.05).At the phylum level,the dominant phylum were Firmicutes,Actinobacteria and Proteobacteria during the composting.At the genus level,the conditional pathogenic bacteria such as Psychobacter and Corynebacterium were effectively killed during the composting.Correlation analysis results showed that the relative abundance of SBR1031 was positive correlated with NO₃-N content and negative correlated with OM content.The relative abundance of Limnochordaceae,Thermobiospora and Bacillus were positive correlated with TN content and negative correlated with pH.The relative abundance of Corynebacterium and Psychobacter were positive correlated with pH and negative correlated with TN content.【Conclusion】 At the end of composting,compared with C0d sample,the MC and OM content decreased by 53.14% and 19.20%,respectively,the C/N ratio decreased from 57.21 to 21.69,while the TN content increased from 8.65 g/kg to 17.29 g/kg.The diversity and abundance of microbial communities were closely related to different stages of composting,the relative abundance of Limnochordaceae,Bifidobacterium,Bacillus,Fusarium and Thermopolyspora were positively correlated with the contents of TN and NO₃-N,and negatively correlated with pH,MC and OM.

The adipose tissue can be categorized into white adipose tissue,which stores energy,and brown adipose tissue,which regulates body temperature and energy balance.Adipose tissue is primarily distributed in four forms in vivo:Subcutaneous fat,visceral fat,intermuscular fat and intramuscular fat.Intramuscular fat,also known as marbling,refers to fat deposited within the muscle and between muscle fibers,it directly influences the juiciness,tenderness and meat flavor,and is an important indicator of meat quality.The intramuscular fat content depends on the size and number of adipocytes,and its development and deposition are regulated by multiple mechanisms.In this complex biological process,the synergistic action of various transcription factors and enzymes is also critical.Increasing the content of intramuscular fat can significantly improve the taste and flavor of meat from livestock and poultry,and enhance the overall quality of meat products,it is one of the key objectives in animal breeding.Therefore,a deeper understanding of the mechanisms and signaling pathways involved in intramuscular fat development and deposition is essential.The authors synthesize relevant literature to describe the process of intramuscular fat deposition,focusing on the structural features and mechanisms of six key genes related to intramuscular fat deposition,and provide recommendations for addressing the existing gaps in current research,offering scientific insights for breeders.

【Objective】 In order to understand the germplasm characteristics and provide theoretical basis for scientific feeding,meat quality control and rational utilization of Guangyi Black pigs,the effects of gender and different slaughter weight on carcass performance and meat quality in Guangyi Black pigs were investigated in this study.【Method】 The carcass performance,meat quality and nutrient components in 30 Guangyi Black pigs (half male and half female) were measured,and the data were statistically analyzed according to different genders and slaughter weight stages (80-90,91-100 and 101-110 kg).【Result】 The weight of stomach,heart and liver of 80-90 kg Guangyi Black pigs were significantly lower than that of 101-110 kg pigs (P＜0.05).The slaughter rate and lean meat rate of Guangyi Black pigs were 74.02% and 56.93%,respectively.Compared with 91-100 and 101-110 kg pigs,80-90 kg pigs had the smallest carcass length (P＜0.05).The meat color score (45 min) and intramuscular fat content in Guangyi Black pigs were 3.77 and 4.52%,respectively.Compared with 91-100 and 101-110 kg pigs,the pH_{24 h} (P＜0.01) and inosinic acid content (P＜0.05) of meat in 80-90 kg pigs were the lowest.The contents of total amino acid (TAA),flavor amino acid (FAA) and essential amino acid (EAA) of meat in Guangyi Black pigs were 20.26%,15.48% and 9.04%,respectively.There was significant difference between 80-90 and 101-110 kg pigs (P＜0.05).The contents of calcium,copper,magnesium,sodium and zinc of meat in Guangyi Black pigs were 35.25,0.36,275.47,433.43 and 14.82 mg/kg,respectively,and the potassium content of meat was 0.41%.The sodium content of meat in 80-90 kg pigs was significantly higher than that in 90-100 kg pigs (P＜0.05),and the magnesium content was significantly lower than that in 101-110 kg pigs (P＜0.05).Meanwhile,the contents of monounsaturated fatty acids (MUFA),polyunsaturated fatty acids (PUFA),total unsaturated fatty acids (UFA) and saturated fatty acids (SFA) of meat in Guangyi Black pigs were 45.25%,9.25%,54.50% and 45.25%,respectively.Gender had no effect on carcass and meat quality traits in Guangyi Black pigs.The average backfat thickness of Guangyi Black pigs was extremely significantly positively correlated with loin-eye area,leg hip ratio and fat percentage (P＜0.01),and was extremely significantly negatively correlated with lean meat rate (P＜0.01).The marble score in Guangyi Black pigs was extremely significantly positively correlated with intramuscular fat content (P＜0.01).【Conclusion】 Guangyi Black pigs had good meat quality,the contents of meat amino acids,fatty acids and minerals were abundant,and the proportion of EAA and FAA,SFA and UFA was ideal.The carcass and meat quality traits in Guangyi Black pigs were related to slaughter weight,but not to gender,and the most suitable slaughter weight was 91-100 kg.

Plant polysaccharides,a class of natural bioactive components extracted from plants,have garnered significant attention due to their distinctive physicochemical properties and diverse biological functions.Predominantly distributed in plant cell walls and mucilage layers,these compounds are recognized for their safety,high efficacy,low residue accumulation,and absence of drug resistance,demonstrating substantial potential in ruminant production systems.This article systematically examines the biological functions of plant polysaccharides,including antiviral activity,immunomodulatory effects,antioxidant capacity,gut microbiota regulation,and antitumor (anticancer) properties.Furthermore,it reviews recent advancements in their application to ruminant production,with particular emphasis on their demonstrated efficacy and mechanistic roles in enhancing growth performance,immune competence,gastrointestinal health,and product quality/safety.Regarding growth performance,dietary supplementation with plant polysaccharides has been shown to significantly increase daily weight gain,feed intake,and feed conversion ratio in ruminants,thereby improving production efficiency.In immune system modulation,these compounds promote immune organ development,stimulate immunoglobulin synthesis,and enhance anti-inflammatory cytokine secretion,collectively strengthening immunological defenses.For gastrointestinal health optimization,plant polysaccharides improve intestinal barrier integrity,modulate microbial community composition,and enhance cellular immune responses within the gastrointestinal tract,effectively reducing digestive disorder incidence.In terms of production performance,the addition of plant polysaccharides improve the physicochemical characteristics of meat products,enhances nutritional composition,and elevates the meat quality of ruminants. In the future,the research is needed on the biological functions and mechanisms of action of plant polysaccharides,providing useful references for the development and utilization of new feed additives,and laying the foundation for further research and application of plant polysaccharides in ruminant production.

【Objective】 The purpose of this experiment was to study the effects of adding different levels of extract of Lycium ruthenicum Murr to the diet on the growth performance,slaughter performance,antioxidant function and meat quality of Bamei Ternary pigs (Landrace×Yorkshire×Bamei).【Method】 48 healthy male pigs aged (50±2) days and weighing (7.82±0.59) kg were selected and randomly divided into four groups,including a control group (CON group) and three experimental groups (LE,ME and HE).The pigs in CON group were fed a basal diet,while in the experimental groups LE,ME and HE were supplemented with 5,10 and 15 g/kg extract of Lycium ruthenicum Murr in basal diet,respectively.The experimental period lasted for 42 days,including a pre-feeding period of 7 days and a formal test period of 35 days.After the trial,the growth performance of pigs was measured,and two individuals were randomly selected for each replicate,a total of 6 pigs were selected from each group to measure slaughter performance and the antioxidant index,meat quality index,conventional nutrition composition,amino acid,fatty acid content in longissimus dorsi muscle.中 国 畜 牧 兽 医52卷 6期刘嘉逸等：黑果枸杞提取物对八眉三元猪生长性能、屠宰性能、抗氧化功能及肉品质的影响 【Result】 ①Compared with CON group,the final body weight and average daily weight gain of pigs in the three experimental groups were significantly increased,while the feed to weight ratio was significantly reduced;The average daily feed intake of pigs in LE and HE groups were significantly increased,and the carcass weight of pigs in ME and HE groups were significantly increased (P＜0.05).Comparing the three experimental groups,the final body weight of pigs in ME group was significantly higher than that in LE group,and the feed to weight ratio of LE group was significantly lower than that of HE group (P＜0.05).②Compared with CON group,the malondialdehyde contents in longissimus dorsi muscle of pigs in LE,ME and HE groups were significantly reduced (P＜0.05),while the activities of catalase,superoxide dismutase,and total antioxidant capacity were significantly increased (P＜0.05).The activity of glutathione peroxidase was only significantly increased in ME and HE groups (P＜0.05).Among the three experimental groups,in ME group,the malondialdehyde content in the longissimus dorsi muscle of pigs was the lowest,while the activities of catalase,superoxide dismutase,glutathione peroxidase,and total antioxidant capacity were the highest,and significantly higher than those in the other two experimental groups (P＜0.05).③Compared with CON group,the pH_{45 min} of the longissimus dorsi muscle in LE and ME groups were significantly increased (P＜0.05),and there was no significant difference among the three experimental groups (P＞0.05);The shear force of the longissimus dorsi muscle in ME group was significantly lower than that in CON and LE groups (P＜0.05).④There were no significant differences in the content of dry matter,crude protein,crude fat,and ash in the longissimus dorsi muscle of pigs among the four groups (P＞0.05).Compared with CON group,multiple amino acids in longissimus dorsi muscle of pigs in the three experimental groups were significantly increased,especially essential amino acids and flavor amino acids (P＜0.05).At the same time,the content of saturated and unsaturated fatty acids such as methyl laurate and methyl linoleate was significantly increased (P＜0.05).The contents of arginine,threonine,glutamine,hydroxyproline,tyrosine,non essential amino acids,total amino acids,and polyunsaturated fatty acids in longissimus dorsi muscle of pigs in ME group were significantly higher than those in LE and HE groups.The contents of glycine,flavor amino acids,as well as methyl arachidate,methyl eicosaenoic acid,monounsaturated fatty acids,and unsaturated fatty acids were significantly higher in ME group than LE group.The contents of phenylalanine,serine,and monounsaturated fatty acids were significantly higher in ME group than HE group (P＜0.05).【Conclusion】 Adding different levels of extract of Lycium ruthenicum Murr to the diet of Bamei Ternary pigs could improve growth performance,slaughter performance and meat quality,while also enhancing the antioxidant capacity of the pork.When the addition level of extract of Lycium ruthenicum Murr was 10 g/kg,the ratio of muscle amino acids to fatty acids was optimal,and the meat quality was the best.

In recent years,the development of intensive animal husbandry has led to odor pollution caused by livestock breeding,which has become a significant bottleneck problem hindering the green and sustainable development of animal industry.Skatole is an indole substance produced from tryptophan through anaerobic microorganisms in the posterior intestine.It has a low olfactory threshold concentration and emits a strong fecal odor,making it one of the primary odor compounds released from livestock and poultry feces.Research indicated that skatole production exhibited temporal-spatial effects and was closely associated with intestinal microbial composition.Skatole not only negatively impacts the health of livestock and poultry but also affects meat quality,posing potential threats to human health.Non-biological degradation methods such as photocatalytic degradation,ozonation,and the Fenton reaction have demonstrated certain efficiency in vitro.However,their application scope is limited compared to microbial degradation due to environmental concerns and lower efficacy rates.Currently,various strains capable of degrading skatole have been screened including Pseudomonas,Rhodococcus,Acinetobacter,etc.,which convert skatole into less toxic or non-toxic substances through different biochemical pathways.Nevertheless,the complete understanding of microbial degradation mechanisms for skatole remains elusive while practical applications still encounter challenges.Future research should focus on screening more efficient skatole-degrading strains along with analyzing the mechanism employed by degrading microorganisms.Furthermore,studying the types of gut microbiota responsible for producing skatole,as well as their influencing factors,will contribute to the promotion of environmentally friendly practices within the livestock and poultry industry.

Broussonetia papyrifera (stems and leaves) contains abundant protein,which can serve as a plant-based protein source to replace part of the soybean meal in livestock and poultry diets,feeding a variety of animals with high nutritional value.In 2018,the stems and leaves of Broussonetia papyrifera were included in the Catalogue of Feed Raw Materials, drawing widespread attention to its feeding value.Additionally,Broussonetia papyrifera is also a traditional Chinese medicinal herb,with its fruits (Fructus Broussonetiae),leaves,and root bark all having medicinal properties.Broussonetia papyrifera possess medicinal effects such as enhancing the immunity of animals,regulating fat metabolism,and resisting chicken coccidiosis,gradually attracting the attention of researchers for its medicinal value.Previous studies on the active ingredients of Broussonetia papyrifera have mainly focused on flavonoids,alkaloids,lignans,etc.,with less attention paid to the activity of polysaccharides.The polysaccharides from Broussonetia papyrifera have rich biological activities such as antioxidant,antimicrobial,hepatoprotective,and immune enhancing properties.Under the regulations prohibiting the addition of antibiotics in animal feed and reducing the use of antibiotics during feeding,polysaccharides from Broussonetia papyrifera may be developed into a functional feed with broad application prospects in the livestock industry.The author comprehensively reviews the extraction processes,structural characterization and biological activities of polysaccharides from Broussonetia papyrifera,analyzes and summarizes the current research hotspots and deficiencies in this field,aiming to provide theoretical references for further development and utilization of polysaccharides from Broussonetia papyrifera in livestock and poultry production.

【Objective】 This experiment aimed to investigate the effects of a 405 nm spectrally light-emitting diode (LED) light source combined with titanium dioxide (TiO₂) applied in hen houses on the production performance,health,and microbial content in the housing environment of laying hens.【Method】 A total of 480 39-week-old Jinghong No.1 laying hens with similar egg production rates were randomly divided into 2 groups,each with 6 replicates (40 hens per replicate).The control group used conventional LED lighting,while the experimental group used a 405 nm spectrally synergistic TiO₂-based LED light sources.The trial included a 1-week pre-trial period and a 12-week formal trial period.Daily production performance data were recorded.On day 72 of the trial,egg quality,tonic immobility (TI) duration,serum antioxidant and immune indices,antibody titers against Avian influenza virus H9,H7 and H5 subtypes,Newcastle disease virus (NDV),and Egg drop syndrome virus (EDSV),as well as microbial content in the housing environment,were measured.【Result】 ①The hen-housed egg production,hen-day egg production,and egg production rate of experimental group were significantly higher than those of control group (P＜0.05),while there was no significant differences in egg quality between the two groups (P＞0.05).②There was no significant difference in TI duration,serum antioxidant indices and immune indices between experimental and control groups (P＞0.05).The antibody titers against Avian influenza virus H5 subtype of hens in experimental group were significantly higher than those in control group (P＜0.05),while there was no significant difference in Avian influenza virus H7 and H9 subtypes,NDV,or EDSV antibody titers (P＞0.05).③ Compared to control group，the microbial content in the air and on surfaces in experimental group decreased by 41.43% and 34.49%,respectively (P＜0.05).Before and after chemical spray disinfection,the total number of microorganisms in the air of experimental group was significantly lower than that of control group at each time point (P＜0.05).The killing rate of spray disinfection in experimental group increased by 8.41 percentage points compared with control group at 12 hours after disinfection,and the recovery rate of microorganisms in the air in the house at 48 hours after disinfection decreased by 5.34 percentage points compared with control group.【Conclusion】 The application of a 405 nm spectrally synergistic TiO₂-based LED light sources in laying hen houses improved egg production performance without compromising flock health.Compared to conventional LED lighting,the use of the 405 nm spectrally synergistic TiO₂-based LED light sources reduced airborne microbial content by 41.43% and surface microbial content by 34.49% in the housing environment.Additionally,it enhanced the efficacy of routine spray disinfection and suppressed microbial regrowth.

【Objective】 The objective of this study was to investigate the effects of dietary supplementation of N-carbamyl glutamate (NCG) on placental morphology,newborn litter weight and body size of lambs,plasma antioxidant indexes,and vascular endothelial growth factor (VEGF) in blood and placenta，in order to understand the role of NCG in placental development of cashmere goats.【Method】 60 ewe of Liaoning cashmere goat,weighing (45.0±2.3) kg and in good condition,aged 8 months,were selected,and artificially inseminated after estrus at the same time,and the ewes conceived at the same time were recorded by B-ultrasound examination technology.They were randomly divided into control group (CON，total mixed diet) and NCG group (total mixed diet containing 0.09% NCG).The pre-trial period was 1 week and the formal period was 22 weeks.At the end of the 18th week of the experiment,blood samples were collected from the jugular vein of pregnant ewes,and plasma antioxidant indexes were determined by the kit.The placenta was collected after the end of pregnancy,the weight of placenta,the weight and number of villous leaves were calculated,the uniformity and density of villous leaves were calculated,the newborn litter weight and newborn weight of lambs were recorded,and the body height,body length and chest circumference of lambs were measured.【Result】 Compared with CON group,the placenta weight,newborn litter weight and newborn weight and chest circumference of lambs in NCG group were significantly increased (P＜0.05).The contents of nitric oxide (NO),VEGF and vascular endothelial growth factor A (VEGFA) and the activity of glutathione peroxidase (GSH-Px) in plasma of ewe in NCG group were significantly increased (P＜0.05).The contents of VEGF and VEGFA in placenta of ewe in NCG group were significantly lower than those in CON group (P＜0.05).【Conclusion】 NCG could affect the antioxidant capacity of pregnant cashmere goats and increase the level of VEGF through NO pathway,thus promoting the development of placenta and fetus.The results provided a theoretical basis for the application of NCG in the diet of cashmere goat ewes.

【Objective】 This study was aimed to explore the expression differences of miRNA in uterine flushing exosomes of cattle with different embryo numbers obtained after superovulation,so as to clarify the regulatory mechanism of miRNA in uterine flushing exosomes during embryo development and implantation in cattle.【Method】 Fifteen Xianan cattle aged 3-6 years with 480-600 kg were selected for superovulation,synchronized estrus and artificial insemination.On the 7th day after artificial insemination,the uterus in Xianan cattle was washed to obtain blastocysts.According to the international average embryo production level of 5.5 embryos as the standard,three Xianan cattle (experimental group) with the highest number of blastocysts obtained and two Xianan cattle (control group) with the lowest number of blastocysts obtained were selected.Uterine flush embryo fluid was collected for isolation and identification of exosomes,and exosomal miRNA was extracted for sequencing analysis.Target genes of differentially expressed miRNA were predicted,and GO function and KEGG pathway enrichment analysis on the target genes were performed.Four miRNAs (bta-miR-2888,bta-miR-11987,bta-miR-2484 and bta-miR-27a-3p) were randomly selected for Real-time quantitative PCR validation.【Result】 The vesicle diameters of 5 samples was 30-150 nm,which was consistent with the characteristics of exosomes.A total of 14 differentially expressed miRNAs were screened,with 9 miRNAs upregulated and 5 miRNAs downregulated.A total of 8 703 target genes were predicted from differently expressed miRNAs.GO function enrichment analysis indicated that the target genes were primarily enriched in terms related to functions such as the regulation of developmental process,regulation of multicellular organismal development,regulation of transport,positive regulation of developmental process,cell junction,and others.KEGG pathway enrichment analysis indicated that the significantly enriched signaling pathways such as MAPK and Hedgehog,which were related to embryonic development and implantation,suggesting that exosomes in uterine flush embryo fluid might be involved in the regulation of embryonic development and implantation.Real-time quantification PCR results of 4 miRNAs were consistent with RNA-Seq results.【Conclusion】 This study isolated exosomes from the uterine fluid flush in Xianan cattle,enriching the species investigated in exosome research,and providing valuable experience for future exosome research in Xianan cattle.There were 14 differentially expressed miRNAs were identified in this study,of which 8 miRNAs were associated with embryonic development and implantation.The results suggested that the change of exosome miRNA in uterus might influence embryonic development and implantation in cattle.

【Objective】 This study was aimed to investigate the effects of photoperiod regulation on fleece-related hormones in different color cashmere goats,so as to optimize breeding strategies for various types of cashmere goats and improve the production efficiency and quality of cashmere.【Method】 A total of 64 adult female cashmere goats,aged 2 years and of different coat colors (red goats (n=24),white goats (n=30) and black goats (n=10)),were randomly divided into two groups:Experimental group (short photoperiod,09:00-17:00) and control group (natural photoperiod).Blood samples were collected during different growth phases of the secondary hair follicles (telogen,early anagen,anagen and catagen phases).The concentrations of seven hormones in serum,triiodothyronine (T₃),thyroxine (T₄),prolactin (PRL),estradiol (E₂),growth hormone (GH),testosterone (T) and melatonin (MELT),were measured using ELISA kits.SAS 9.0 software was used to perform significance tests on hormone concentrations between experimental and control groups at different growth phases.CORR method was employed to explore the correlation of different hormones under short photoperiod conditions.【Result】 ①Under natural photoperiod,there were differences in hormone concentrations among different color cashmere goats,such as E₂ concentration in serum of red goats was extremely significantly higher than that of white goats during the telogen phase (P＜0.01),and T concentration in serum of red goats was extremely significantly higher than that of white and black goats during the catagen phase (P＜0.01).②Under short photoperiod,compared with control group,E₂ concentration in serum of red goats was extremely significantly or significantly decreased during the early anagen and anagen phases (P＜0.01 or P＜0.05),T concentration was significantly increased during the anagen phase (P＜0.05),and T₃ concentration was significantly increased during the early anagen phase (P＜0.05).E₂ concentration in serum of white goats was significantly decreased during the early anagen, anagen and catagen phases (P＜0.05),T concentration was significantly increased during the early anagen and anagen phases (P＜0.05),T₄ concentration was significantly or extremely significantly increased during the early anagen and catagen phases (P＜0.05 or P＜0.01),T₃ and GH concentrations were significantly or extremely significantly decreased during the anagen phase (P＜0.05 or P＜0.01),and were extremely significantly increased during the catagen phase (P＜0.01).E₂ concentration in serum of black goats was extremely significantly decreased during the early anagen and catagen phases (P＜0.01),and T concentration was significantly increased during the early anagen,anagen and catagen phases (P＜0.05).All three types of goats showed a significant increase in MELT concentration and a significant decrease in PRL concentration of serum during the early anagen and anagen phases (P＜0.05 or P＜0.01).③Under short photoperiod,the correlation results showed that there was a significant negative correlation between E₂ and PRL or T and GH concentrations in red goats (P＜0.05).T concentration was positively significantly correlated with E₂ and MELT concentrations (P＜0.05),and PRL concentration was negatively correlated with T,T₄,GH and MELT concentrations in white goats (P＜0.05).T concentration was positively significantly correlated with E₂ and T₄ concentrations in black goats (P＜0.05),and T₄ concentration was negatively correlated with GH concentration (P＜0.05).There were also non-significant negative correlation and antagonistic relationships among different hormones.【Conclusion】 There were differences in the response of different colored cashmere goats to photoperiod changes.Under short photoperiod, red goats primarily regulated T₃ and GH concentrations,white goats exhibited increased T₄,GH,and MELT concentrations and decreased T₃ concentration,while black goats mainly showed the changes in E₂,T and MELT concentrations.The negative correlations between hormones suggested antagonistic interactions.The results provided a scientific basis for optimizing cashmere goat breeding through photoperiod regulation.

【Objective】 The osteogenic differentiation-specific transcription factor 2b (Runx2b) gene played an important role in regulating fish bone development.This study aimed to explore the characteristics and expression of Runx2b gene in Qihe crucian carp (Carassius auratus).【Method】 Primers were designed by referring to the Runx2b gene sequence of Carassius gibelio (GeneBank accession No.:NC_068415.1) and conducting BLAST alignment with local genomic data.The Runx2b gene was segmented and cloned using PCR technology,and sequence similarity alignment and phylogenetic tree construction were carried out using DNAStar and Mega 11.0 software, respectively.Online websites such as ORF finder and ProtParam were used for bioinformatics analysis.At the same time, Real-time quantitative PCR was used to detect the expression of Runx2b gene in different developmental stages and different tissues of Qihe crucian carp.【Result】 After sequencing and alignment,Runx2b-A and Runx2b-B genes were obtained,with CDS regions of 1 392 bp each,encoding 463 amino acids.The similarity of the CDS sequences of the two genes was 95.33%.The amino acid sequence of Runx2b-A had the highest similarity with that of Carassius gibelio, at 98.0% and 99.1%,respectively. Phylogenetic tree analysis showed that Qihe crucian carp was most closely related to Carassius gibelio.Bioinformatics analysis showed that the molecular formulas of the two Runx2b proteins were C₂₂₀₆H₃₄₀₉N₆₃₇O₆₈₅S₁₈ and C₂₁₉₆H₃₃₉₅N₆₃₃O₆₉₅S₁₆,respectively.Both belong to hydrophilic and unstable proteins,and the protein structure was mainly composed of random coils.The characteristic Runt-dom and RunxⅠ conserved domains of Runx family proteins exist in both protein sequences.The results of Real-time quantitative PCR showed that the overall expression trends of Runx2b-A and Runx2b-B genes were relatively consistent during the whole development stage of intermuscular bones in Qihe crucian carp.The expression were relatively high in the early stage of intermuscular bone development (1-5 dph).After the intermuscular bones started to develop (5-13 dph),the expression of Runx2b genes were gradually decrease,and then showed an upward trend in the later stage,especially in the late stage of intermuscular bone development (25-45 dph),where the expression were still relatively high.The Runx2b-A and Runx2b-B genes were expressed in 9 tissues such as the brain,liver,back muscle,and tail muscle of Qihe crucian carp.Both genes had relatively high expression levels in brain and liver,which were significantly higher than those in other tissues (P＜0.05).The relative expression of both genes in tail muscle were significantly higher than those in back muscle (P＜0.05),but they showed differential expression in different tissues with different expression.【Conclusion】 In this study,the CDS sequences of two homologous genes,Runx2b-A and Runx2b-B,of Qihe crucian carp were successfully cloned.The amino acid sequences of the two genes had relatively high similarity with those of fish in Cyprinidae.The characteristic Runt-dom and RunxⅠ conserved domains of Runx family proteins existed in the protein sequences.The two Runx2b genes in Qihe crucian carp were widely distributed in tissues but show differential expression in different tissues with different expression patterns.The overall expression trends were relatively consistent in different developmental stages,and the expression were still relatively high in the late stage of intermuscular bone development.This study coould lay a foundation for further research on the development mechanism of intermuscular bones and the creation of Qihe crucian carp without intermuscular bones.

Oocyte cryopreservation by vitrification,as a technique for long-term preservation of oocytes at ultra-low temperatures,is of great significance in the preservation of excellent germplasm resources.However,the key difficulty of cryopreservation is the activation of apoptotic signals,which leads to an increase in the proportion of apoptotic cells and affects cell function,viability and developmental potential.Apoptosis refers to a programmed cell death process,often referred to as "cell suicide",and this mechanism plays a key role in living organisms,helping to maintain cell balance and tissue homeostasis.However,abnormal apoptosis can lead to adverse effects such as cell death.Therefore,effectively inhibiting or slowing down the apoptotic process becomes the key to improve the survival and developmental potential of frozen oocytes.The application of apoptosis inhibitors and antioxidants can reduce the apoptosis of vitrification oocytes,improve their survival rate and development ability,and thus improve the cell quality after thawing.The authors briefly describe the effects of vitrification cryopreservation technology on oocytes,and the endogenous and exogenous apoptosis mechanisms induced by freezing,and analyzed the application of related apoptosis inhibitors and antioxidants.In the future,the mechanism of action of new inhibitors and antioxidants in vitrification cryopreservation technology can be further explored.And explore the interaction between apoptosis and necrotic apoptosis and other cell death pathways,to provide a new idea and method for oocyte vitrification cryopreservation technology.

【Objective】 This study was aimed to evaluate the preventive effects of Vitex negundo L.var.cannabifolia (Sieb.et Zucc.) Hand.-Mazz.extract (VNE) on the growth performance,serum immunoglobulin content,immune organ index,intestinal tissue structure,and inflammatory factors of broilers with necrotic enteritis (NE) induced by Clostridium perfringen (CP). 【Method】 150 male Lingnan Yellow-feather broilers with 7-day-old were randomly divided into control group (CON),infection group (INF),and low (L-VNE),medium (M-VNE),and high (H-VNE) VNE groups,with 3 replicates in each group and 10 broilers in each replicate.Broilers in CON group were fed with basal diet,and broilers in INF,L-VNE,M-VNE,and H-VNE groups were fed with high fishmeal diet.During 7-13 days of age,broilers in L-VNE,M-VNE,and H-VNE groups were orally administered with VNE at a dose of 4,8,and 12 g/(kg·d),respectively.Continuous gavage of 5×10⁹ CFU/d CP was administered to broilers in INF,L-VNE,M-VNE,and H-VNE groups during 10-13 days of age.Broilers were weighed at 14 and 21 days of age,and the average daily feed intake (ADFI),average daily gain (ADG),feed/gain (F/G) were calculated.After weighing,3 broilers were randomly selected for blood collection in each replicate,and the contents of IgA and IgG in serum were detected.After euthanized,the spleen,thymus,and bursa of Fabricius in broilers were separated and weighed,and the immune organ indexes were calculated.The pathological and morphological changes of duodenum,jejunum,and ileum in broilers were detected.Small intestine mucosa was scraped to analyze the expression of tumor necrosis factor-α (TNF-α),interleukin-8 (IL-8),IL-17A,and IL-1β.【Result】 ①At 14 days of age,compared with INF group,the ADFI and ADG of broilers in L-VNE and H-VNE groups were extremely significantly or significantly increased (P＜0.01 or P＜0.05),the content of serum IgG in H-VNE group was extremely significantly increased (P＜0.01).②At 21 days of age,the spleen index of broilers in M-VNE and H-VNE groups were extremely significantly higher than that in INF group (P＜0.01).③At 14 days of age,compared with INF group,the duodenum villus height (VH) of broilers in M-VNE and H-VNE groups was extremely significantly increased (P＜0.01),the VH of jejunum and ileum,and the VH to crypt depth (CD) ratio (VH/CD) of duodenum in L-VNE,M-VNE,and H-VNE groups were extremely significantly or significantly increased (P＜0.01 or P＜0.05),and the CD of duodenum was extremely significantly decreased (P＜0.01).The jejunum VH/CD of broilers in M-VNE and H-VNE groups significantly or extremely significantly increased (P＜0.05 or P＜0.01),and the ileum VH/CD in L-VNE and H-VNE groups was extremely significantly increased (P＜0.01).At 21 days of age,compared with INF group,the VH of duodenum,jejunum,and ileum of broilers in L-VNE,M-VNE,and H-VNE groups were extremely significantly or significantly increased (P＜0.01 or P＜0.05).④At 14 days of age,compared with CON group,the expression of intestinal IL-8 gene of broilers in L-VNE,M-VNE,and H-VNE groups were extremely significantly decreased (P＜0.01),and the expression of IL-1β gene in M-VNE group was significantly decreased (P＜0.05).【Conclusion】 Adding VNE to the feed of Lingnan Yellow-feather broilers infected with CP could improve the growth performance,increase the immunoglobulin content of serum,promote spleen development,alleviate intestinal lesions and inflammatory reactions.The results indicated that VNE could prevent necrotic enteritis induced by CP in broilers.Under the condition of this experiment,continuous gavage of 8 g/(kg·d) VNE to broilers for 7 days could achieve good prevention effects.

【Objective】 The aim of this experiment was to prepare monoclonal antibody against Porcine rotavirus (PoRV) VP6 protein,and provide reference for the development of PoRV detection method.【Method】 VP6 gene was amplified with Vaccinia virus promoter P28 as the promoter of VP6 and G3 type PoRV nucleic acid as the template.VP6 gene fragment was cloned into pSWE178 plasmid by In-Fusion cloning method,and the recombinant plasmid pSWE178-P28-VP6 was constructed.Recombinant Suipoxvirus rSWE178-P28-VP6 expressing VP6 protein was obtained by homologous recombination and plaque purification techniques.The expression of VP6 protein was identified by SDS-PAGE.BALB/c mice were immunized with G9 PoRV as the immunogener.Spleen cells of immunized mice were fused with SP2/0 myeloma cells.VP6 protein expressed by recombinant virus was used as the detection antigen,and hybridoma cells secreting anti-VP6 monoclonal antibody were screened by indirect ELISA.Indirect immunofluorescence assay (IFA) was used to detect the reactivity of monoclonal antibody with G3,G4,G5 and G9 PoRV.One of the monoclonal antibody strains was selected for immunohistochemical (IHC) detection of porcine intestinal tissue artificially infected with PoRV.【Result】 On the basis of constructing the recombinant plasmid pSWE178-P28-VP6 expressing the PoRV VP6 protein,a recombinant Swinepox virus expressing the PoRV VP6 protein was successfully generated.The molecular weight of the expressed protein was 45 ku and which was soluble protein.Monoclonal antibody was prepared by hybridoma technique,and 29 hybridoma cell lines secreting anti-VP6 monoclonal antibody were screened.IFA results showed that 26 monoclonal antibodies could react with G3,G4,G5 and G9 PoRV,but the fluorescence brightness was different.IHC results showed that monoclonal antibody could produce specific immune response with PoRV-infected clinical samples.【Conclusion】 In this study,PoRV VP6 protein was successfully expressed by eukaryotic expression system.The hybridoma technique was used to select 29 strains of anti-VP6 monoclonal antibodies,of which 26 strains could react with G3,G4,G5 and G9 PoRV.This results laid a foundation for the establishment of PoRV immunological detection method.

【Objective】 The absence of secure and stable RNA reference materials for the nucleic acid assays of West Nile virus (WNV) at home and abroad was compromising the precision and credibility of the testing outcomes.This study was conducted to develop a safe and stable WNV nucleic acid testing quality control product to provide technical support for the monitoring of West Nile fever.【Method】 The WNV nucleic acid detection target gene,the MS2 bacteriophage coat protein CP,and the maturation enzyme protein A gene sequences were inserted into an expression vector to obtain the recombinant plasmid pET-CPA-WN.After transformation,expression and purification,a WNV armored RNA quality control material was prepared and subjected to Real-time quantitative PCR and digital PCR quantification,homogeneity and stability to assess its potential as a reference material.【Result】 PCR detection,double enzyme digestion and gene sequencing results all confirmed the successful construction of the recombinant plasmid pET-CPA-WN.After expression and purification,uniform virus-like particles with a diameter of 23-28 nm were obtained.Following nuclease digestion and Real-time quantitative PCR detection,the particle solution showed almost no residual nucleic acid and encapsulated the target gene in the form of armored RNA.The determined value was 8.80×10⁹ copies/mL.Stability experiments demonstrated that this armored RNA could remain stable for up to 20 days at 37 ℃.Random sampling of 10 samples for homogeneity testing confirmed good uniformity.【Conclusion】 The armored RNA prepared based on MS2 bacteriophage had high copy number,good uniformity and stability,which could provide a safe and stable reference sample for WNV molecular detection.

【Objective】 The interaction between complement receptor 2 (CR2) interacted with its physiological ligand C3d could bridge innate immune response and adaptive immune response,amplify the signal transduction downstream,significantly decrease the threshold for B cell activation by antigen stimulation,and increase the sensitivity of B cells to antigen by 1 000-10 000 times,which was crucial for activating B cells and initiating the immune response.This study aimed to prepare rabbit polyclonal antibody against chicken CR2 (chCR2),provide a tool for detecting the expression of chCR2 protein,and lay a foundation for further exploring the function and role of chCR2 protein.【Method】 The pTT5-His-chCR2-ΔTM recombinant plasmid was transfected into HEK293F cells to express the recombinant chCR2 protein (His-chCR2-ΔTM) in the eukaryotic expression system of HEK293F cells.The protein expression was analyzed by Western blotting.The chCR2 protein was then purified using a nickel column affinity chromatography purification system,followed by SDS-PAGE identification.The purified chCR2 protein was used to immunize New Zealand White rabbits to prepare polyclonal antibodies against chCR2.The titer of these polyclonal antibodies against chCR2 was quantified through an enzyme-linked immunosorbent assay (ELISA).The specificity and sensitivity of the chCR2 polyclonal antibody were determined through Western blotting and indirect immunofluorescence assay (IFA).【Result】 The results showed that recombinant His-chCR2-ΔTM protein could be expressed in HEK293F cell line.The concentration of recombinant His-chCR2-ΔTM protein purified by nickel affinity chromatography was 4.439 mg/mL,and the molecular weight between 45 ku.ELISA results showed that the highest titer of chCR2 polyclonal antibody was 1∶32 768 000.The Western blotting and IFA results demonstrated that the chCR2 protein could be specifically recognized by the chCR2 polyclonal antibody.The optimal dilution ratio of chCR2 polyclonal antibody for Western blotting detection was 1∶5 000,and the maximum dilution ratio for IFA detection was 1∶1 600.【Conclusion】 In this study,a rabbit polyclonal antibody against chCR2 protein was successfully prepared.The antibody had high titer and good specificity,which provided an experimental basis for the subsequent detection of chCR2 protein and the study of the function of chCR2 protein.

【Objective】 This study was conducted to determine whether the morbid pigs in a pig farm in Guangdong were infected with Porcine circovirus type 2 (PCV2).It also evaluated the genetic characteristics of the virus and its prevalence in swine herds,so as to provide scientific data to support the prevention and control of epidemics.【Method】 Real-time quantitative PCR and ELISA were used to detect and analyze the visceral tissues such as kidneys,lymph nodes and spleens,as well as serum samples of sick pigs in the farm.This study further amplified and sequenced the ORF2 gene of PCV2-positive samples by PCR.Using the MegAlign module in the DNAStar software package,the resulting ORF2 gene sequences were comparatively analyzed for similarity with the 23 PCV2 reference strains in GenBank database.In addition,a genetic evolution tree based on the ORF2 gene sequences was constructed using Mega 7.0 software to clarify the genetic relationship between the identified and reference strains.【Result】 According to the epidemiological investigation,clinical symptoms and pathological autopsy results,the sick pigs in this farm were consistent with the characteristics of PCV2 infection.Real-time quantitative PCR test revealed that the Ct values of three samples were 14.42,15.13 and 16.08,respectively,indicating a high viral load and a positive PCV2 test result.ELISA results showed that the Cap protein antibody positivity rate ranged from 60% to 100% and that of Rep protein ranged from 0 to 100% in different age groups of pigs,especially in 150-day-old pigs,the antibody positivity rate of both proteins reached 100%,indicating a high intensity of PCV2 infection.Sequencing of the ORF2 gene yielded three sequences named LZC-2305-1,LZC-2305-2 and LZC-2305-3,respectively.Similarity analysis showed that these three sequences shared 99.9% to 100% similarity with each other and ranged from 82.3% to 99.7% similarity to the sequences of the 23 PCV2 reference strains in GenBank,with the highest similarity of 99.6% to 99.7% to CZ246 sequence.Genetic evolutionary tree analysis further confirmed that these sequences had the closest affinity to CZ246 sequences attributed to the 2d branch of PCV2.【Conclusion】 This study confirmed that the infection of PCV2d branch occurred in pigs of this farm.This study not only provided a scientific basis for the prevention and control of PCV2 in this farm,but also provided a reference for disease monitoring and control in other large-scale pig farms.

【Objective】 The objective of this study was to investigate the etiological characteristics of bovine Lumpy skin disease virus (LSDV) in Shandong.【Method】 Skin nodules of suspected lumpy skin disease (LSD) cattle were collected from a cattle farm in Shandong province,and primary lamb testicular cells (PLT) were used for virus isolation.The LSDV G-protein-coupled chemokine receptor (GPCR) gene was amplified by PCR and sequenced,and the virus specificity was identified by indirect immunofluorescence assay (IFA) using anti-LSDV specific serum.The genome of the isolated strain was sequenced and its genetic variation was analyzed.The isolated strain was passed continuously in different cells,the virus titers were measured,and the growth curve was drawn.The proliferation ability in different cells was further determined.The neutralization index of the isolated strain against the antibodies of goat pox vaccine was determined by antibody neutralization test.【Result】 The nodular tissue samples of diseased cattle were cultured by PLT cells,and after blind transmission for 3 generations,the cytopathic effect (CPE) characterized by cell roundness,aggregation and shedding occurred.PCR amplification obtained 1 010 bp specific band of GPCR gene of the isolated strain，and the similarity of this gene sequence with LSDV strains at home and abroad was 99.3%-100%.The isolated strain could bind to the specific serum against LSDV,and the specific green fluorescent spot appears after immunofluorescence staining.The results of genome sequencing showed that the isolated strain was genetically close to the 7 domestic strains in 2019-2022 and Thailand strain in 2022.The virus titer was stable at 10^-6.08 to 10^-6.17 TCID₅₀/mL when the isolates were passed through 20-30 generations.The growth curve showed that the titer of the isolated strain peaked at 96 h (10^-6.16 TCID₅₀/mL) and decreased to 10^-5.60 TCID₅₀/mL at 144 h.The isolated strain could prolifate continuously on MBDK and BHK-21 cell lines for 3 generations,and the virus titers could reach 10^-4.85 and 10^-4.63 TCID₅₀/mL,respectively.The neutralization index of goat pox vaccine antibody against this strain (276) was significantly lower than that of goat pox vaccine strain (1 833) (P＜ 0.05).【Conclusion】 A strain of LSDV was successfully isolated from the skin nodular tissue of infected cattle.This strain was genetically close to other strains in China except Tibet,and could be stably cultured in MBDK and BHK-21 cells.Moreover,the neutralization ability of goat pox vaccine antibody against this strain was poor.

【Objective】 The purpose of this study was to explore the bacteriophage biological control method for Staphylococcus aureus induced bovine mastitis.【Method】 A strain of bacteriophage specific for Staphylococcus aureus Sau2703 was isolated and purified from cow feces and wastewater using a double-layer agar plate culture method.The titer,ultrastructure and optimal multiplicity of infection were studied.The one-step growth curve of bacterio phage was drawn,and its thermal stability,pH stability,UV sensitivity and fission spectrum were studied.【Result】 A specific bacteriophage of Staphylococcus aureus Sau2703 from bovine mastitis was successfully isolated and named as PhageSau2703.The titer of bacteriophage PhageSau2703 was as high as 4.62×10¹⁵ PFU/mL.Under transmission electron microscopy,the head of PhageSau2703 was icosahedral with a diameter of approximately 71 nm and an non contracting long tail,measuring 106 nm in length and 11 nm in diameter.The optimal multiplicity of infection of PhageSau2703 was 0.001,PhageSau2703 had high thermal stability and still exhibited low activity after being treated at 90 ℃ for 90 min.PhageSau2703 was stable at pH 3.0-8.0,and the tolerance to acidic environments was higher than that to alkaline environments.Ultraviolet radiation had little effect on the activity of PhageSau2703.The incubation period of PhageSau2703 was about 20 min,the outbreak period was about 50 min,and the cleavage volume was about 112 PFU/cell.The cleavage rate of bovine mastitis associated Staphylococcus aureus was 48.5%.The host spectrum of PhageSau2703 was wide.【Conclusion】 Bacteriophage PhageSau2703 had high titer,wide spectrum of fission bacteria,and strong tolerance to temperature,pH and UV light.It had the potential to be developed as a Staphylococcus aureus bacterio phage biological agent for the prevention and treatment of bovine mastitis.

The detection of animal parasitic diseases has mainly relied on the combination of traditional microscopy and PCR technology for many years.It has indeed played a significant role in clinical practice,and has also controlled the prevalence of some parasitic diseases.However,parasitic diseases are mostly chronic consumptive diseases,and the significance of early diagnosis is particularly important.The sensitivity and simplicity of traditional methods cannot meet the needs of complete control of parasitic diseases.Therefore,the promotion of the use of more sensitive and more convenient detection methods are urgently needed.In recent years,the CRISPR/Cas system has been continuously developed,and a variety of Cas protein functions have been discovered and widely used in nucleic acid detection techniques for parasitic pathogens.The researchers screened the specific target sequence and designed crRNA for the combination of Cas13 protein and Cas12 proteins with recombinase polymerase amplification (RPA) or PCR in the type 2 CRISPR/Cas system,and then combined with Cas12,Cas13 proteins and fluorescent reporter group to form a CRISPR/Cas nucleic acid detection system,which can be used for the detection of various parasitic diseases.It has the characteristics of fast,accurate,convenient and cheap,and is suitable for on-site detection,and has great market application potential.In this paper,the mechanism and classification of CRISPR/Cas system and its research progress in the field of nucleic acid diagnosis of parasitic diseases in recent years are reviewed,so as to provide reference for the early diagnosis of parasitic diseases.

【Objective】 The aim of the experiment was to optimize the extraction process of crude polysaccharide from Nymphaea candida and explore its application effect in the treatment of mastitis in mice infected with Staphylococcus aureus.【Method】 The experiment used Nymphaea candida as the test material,and the extraction rate of Nymphaea candida crude polysaccharide as the evaluation index,and the one-way factor combined with response surface method was used to optimize its extraction process.At the same time,60 SPF healthy Kunming mice were randomly divided into four groups:Blank control group (BC),model control group (MC),positive control group (PC),and crude polysaccharides from Nymphaea candida (CPNA) group,15 mice in each group.50 μL Staphylococcus aureus with 1×10⁴ CFU/mL was injected into mice in each group except for blank control group to construct a mouse mastitis model.After successful modelling,saline,0.13 g/kg ciprofloxacin,and 0.5 g/kg crude polysaccharides from Nymphaea candida were administered by gavage to mice in each group twice a day for 7 d,respectively.Mice in blank control group were not treated.The number of Staphylococcus aureus colonies,the content of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in mammary tissues of mice in each test group were measured at 3,5 and 7 d of administration,respectively,and the pathological histological changes in mammary glands of the mice were also observed to evaluate the therapeutic effect.【Result】 Under the conditions of material-liquid ratio was 1∶14,ultrasonic power was 70%,extraction temperature was 57 ℃,extraction time was 30 min,and the number of extraction times was 2,the yield of Nymphaea candida crude polysaccharide was 51.78%.On the 5th and 7th days,the number of colonies in mammary tissue,TNF-α and IL-6 contents of mice in CPNA group showed significantly or extremely significantly lower than that in model control group (P＜0.05 or P＜0.01),and the inflammatory cells and erythrocytes in mammary tissues of mice were significantly reduced.【Conclusion】 After optimizing the extraction method using one-factor combined response surface method,the yield of crude polysaccharide from Nymphaea candida was 51.78%.It had a good therapeutic effect on the animal model of mouse mastitis induced by Staphylococcus aureus.The results of this study could provide a scientific basis for the prevention and treatment of clinical mastitis and the development and utilization of Nymphaea candida.

【Objective】 Duck hepatitis A virus genotype 3 (DHAV-3) was one of the primary pathogens causing acute lethal hepatitis in ducklings,with pathogenicity exhibiting significant age-dependent characteristics.This study aimed to elucidate the regulatory mechanisms of bile secretion pathway in ducklings of different ages infected with DHAV-3 and reveal the impact of host age factors on the viral pathogenic process.【Method】 Z2 strain Pekin ducks were used as the experimental subjects,divided into three experimental groups of 7,14 and 21 days of age (50/group),along with corresponding control groups (15/group).The ducklings in infected groups were administered 0.2 mL DHAV-3 (10^-8.83 ELD₅₀/0.2 mL) via intramuscular injection,while the ducklings in control groups were injected with an equivalent volume of PBS.The ducks were raised separately until 18 hours post-infection,at which point blood,liver and ileum samples were collected.The following parameters were analyzed:Plasma biochemical indices,viral load,total bile acid (TBA) content,and the expression of bile secretion pathway-related genes.【Result】 The viral load in liver of ducklings in all age groups was significantly higher than that in ileum (P＜0.05),and the viral load in the liver of 7-day-old ducklings was significantly higher than that of 14- and 21-day-old ducklings (P＜0.05).The activity of aspartate aminotransferase (AST) and the level of total cholesterol (CHOL) in the plasma of ducklings showed a significantly decrease with increasing age in control group (P＜0.05).After DHAV-3 infection,the CHOL levels in the plasma of 7-day-old ducklings in infected group were significantly reduced compared to control group (P＜0.05),while they were significantly increased at 14 and 21 days of age (P＜0.05),accompanied by a significant increase in immunoglobulin Y (IgY) levels (P＜0.05).Bile acid metabolism displayed tissue-specific regulation.In control group,TBA level in liver decreased with advancing age,while in ileum,it increased with increasing age.Following DHAV-3 infection,the TBA in liver and ileum of ducklings in the 7-day-old infected group were significantly decreased (P＜0.05).In the 14-day-old group,a reverse regulation pattern was observed,with liver TBA level increasing and ileal TBA level decreasing (P＜0.05).In the 21-day-old group,both liver and ileum TBA levels significantly increased (P＜0.05).The bile secretion pathway-related genes cholesterol-7α-hydroxylase (CYP7A1),ATP binding cassette transporter G5 (ABCG5) and ABCG8 were significantly upregulated with advancing age in liver of ducklings in control group (P＜0.05).After DHAV-3 infection,CYP7A1 gene transcription levels in the 14- and 21-day-old ducks were significantly decreased (P＜0.05),while ABCG5 and ABCG8 genes were significantly upregulated in ileum of the 7- and 14-day-old ducks (P＜0.05) and downregulated in liver at 14-day-old (P＜0.05).Farnesoid X receptor (FXR) gene expression in liver of ducklings in control group was significantly increased with advancing age (P＜0.05),while in ileum,it significantly decreased (P＜0.05).After infection,FXR gene expression in liver of 21-day-old ducklings and FXR gene expression in ileum of 14-day-old ducklings were significantly downregulated compared to control group (P＜0.05).【Conclusion】 This study described the age-dependent characteristics of host metabolism and immune response in Pekin ducks infected with DHAV-3,and for the first time,elucidated that DHAV-3 infection induced age-dependent pathological damage by interfering with the bile secretion pathway.These findings provided new insights into the metabolic-immune cross-regulation of age susceptibility in duck viral hepatitis and suggest that the bile acid negative feedback pathway mediated by nuclear receptors might be a key clue in exploring the age-dependent mechanisms of DHAV-3 infection.

【Objective】 This study was conducted to isolate high-temperature protease-producing strains from the fermentation reactor of rendering by-product of animal carcass meat and bone residue,and study their protease activity,with the aim of providing a theoretical basis and research strategy for the degradation and utilization of proteins in meat and bone residues.【Method】 High-temperature culture conditions were established,and high-temperature tolerant protease-producing strain was assessed using casein plate hydrolysis and the Folin phenol method.Strains were identified through 16S rRNA sequencing.Thermal acclimation and UV mutation were employed to enhance the strain’s heat resistance and protease activity.Optimal enzyme production conditions were explored using single-factor and response surface methodology.【Result】 A high-temperature protease-producing strain,Bacillus thermoamylovorans R4.1,was isolated from rendering-processed meat and bone residues.UV mutation increased the protease activity by 40.92%.Thermal acclimation raised the optimal growth and enzyme production temperature of the strain from 50 to 65 ℃.Single-factor experiments indicated that the strain’s protease activity was significantly influenced by fermentation time,pH,NaCl concentration and Ca²⁺ concentration.Response surface optimization determined the optimal enzyme production conditions to be fermentation at 65 ℃ for 96.36 h,pH 8.02,NaCl concentration of 0.59%,Ca²⁺ concentration of 1.11%,and an inoculum size of 1%,under which the protease activity reached 55.08 U/mL.Compared to the original strain,the enzyme activity increased by 1.96 times.Additionally,the strain demonstrated a weight reduction rate of 12.30% in meat and bone meal after 120 h,with a crude protein content decrease of 11.06%.【Conclusion】 Bacillus thermoamylovorans R4.1 exhibited high protease activity at elevated temperatures and could effectively degrade proteins in meat and bone meal,indicating promising application potential.

【Objective】 This study aimed to analyze the main chemical components of Clematidis Radix decoction by ultra performance liquid chromatography with time-of-flight mass spectrometry (UPLC-Q-TOF-MS),and verify its anti-inflammatory mechanism by combining network pharmacology and cellular experiments.【Method】 The chemical composition of Clematidis Radix decoction was analyzed and identified by UPLC-Q-TOF-MS,the main components and corresponding targets were predicted by network pharmacology method,and the "component-target-pathway" network was constructed.The molecular docking between the main active ingredients and the core targets was carried out by AutoDock software to verify the binding ability between the core components and the key targets.The inflammation model of RAW264.7 cells was constructed by lipopolysaccharide (LPS) induction,and the core target and pathway were verified.【Result】 A total of 19 components were identified from Clematidis Radix decoction,including 8 phenolic acids and 11 saponins.Network pharmacological analysis screened 5 main active ingredients mainly modulating the PI3K/Akt/STAT3 signaling pathway mediated by core targets including phosphatidylinositol 3-kinase catalytic subunit α (PIK3CA),signal transduction and transcriptional activator 3 (STAT3),phosphatidylinositol 3-kinase catalytic subunit β (PIK3CB),and tumor necrosis factor (TNF) to exert anti-inflammatory effects.ELISA test results showed that compared with control group,the contents of inflammatory cytokines TNF-α,interleukin-6 (IL-6) and IL-1β in model group were significantly increased (P＜0.05).Compared with model group,the contents of TNF-α,IL-6 and IL-1β in each dose group of Clematidis Radix decoction were significantly decreased (P＜0.05). Western blotting results showed that compared with control group,the protein expressions of PI3K,p-PI3K,Akt and p-Akt in model group were significantly up-regulated (P＜0.05).Compared with model group,the expression levels of p-PI3K and p-Akt were significantly decreased in each dose group of Clematidis Radix decoction (P＜0.05). 【Conclusion】 Clematidis Radix could exert anti-inflammatory effects through multi-component,multi-target and multi-pathway,and the target was related to PI3K/Akt signaling pathway.The results of this study provided a reference for further study of the pharmacological material basis and pharmacological activity of Clematidis Radix.

【Objective】 The objective of this study was to investigate the alleviating effect of isorhapontigenin (ISO) on oxidative damage in porcine intestinal epithelial cells (IPEC-J2),so as to provide a theoretical reference for the application of ISO as an antioxidant in animal production.【Method】 IPEC-J2 cells were stimulated with hydrogen peroxide (H₂O₂) to establish the oxidative stress model,and the optimal working concentration of ISO was determined by the cell viability.The contents of malondialdehyde (MDA),reactive oxygen species (ROS) and 8-hydroxy-deoxyguanosine (8-OHDG),the activities of catalase (CAT),total superoxide dismutase (T-SOD),and total antioxidant capacity (T-AOC) in the cells were determined by the corresponding commercial kit.Real-time quantitative PCR was used to detect the relative expression levels of antioxidase genes (SOD-1, CAT, GSH-Px, HO-1 and NQO-1),inflammatory genes (IL-1β, IL-12 and TNF-α),and host defense peptide genes (pBD1， pBD2 and pBD3) in IPEC-J2 cells.【Result】 Pretreatment of cells with 5,20 and 40 μmol/L ISO for 24 h could alleviate the decrease of cell survival caused by H₂O₂(P＜0.05 or P＜0.01),particularly,the 20 μmol/L ISO group had the best effect among the all groups.ISO pretreatment could reduce the elevation of the levels of MDA,ROS and 8-OHDG in IPEC-J2 cells induced by H₂O₂ (P＜0.05 or P＜0.01) and increase the relative expression levels of GSH-Px, SOD1,CAT and NQO-1 genes and CAT activity (P＜0.01).In addition,compared with H₂O₂ group,ISO pretreatment could decrease the relative expression levels of IL-1β and IL-12 genes,and increase the relative expression levels of pBD1,pBD and pBD3 genes (P＜0.05).【Conclusion】 ISO could reduce the pruduction of stress products in cells,improve the expression of antioxidant enzyme genes and activity of antioxidant enzymes,and regulate the expression of inflammation-related genes,thus alleviating the oxidative damage of IPEC-J2 cells caused by H₂O₂.Under the conditions of this experiment,the recommended ISO concentration was 20 μmol/L.

【Objective】 This study was conducted to isolate Leuconostoc from dairy farm environment and bovine body samples and further explore its biological characteristics,so as to provide probiotic strains for the future prevention and treatment of dairy mastitis.【Method】 The isolates were identified by means of morphological observation and molecular biology,and the antibacterial activity of the isolates against common pathogens of dairy cow mastitis was analyzed by double-layer plate method,the main bacteriostatic substances were analyzed.Growth and acid production curves were established.The digestive tract environmental tolerance characteristics were investigated,and the safety of the strain was evaluated by drug sensitivity test and hemolysis test.【Result】 Three strains of probiotics were isolated.The three isolated probiotics showed milky white single colonies on MRS agar medium,and were identified as Gram-positive cocci by microscopy.They were named as strains 11,14 and 18,respectively.16S rDNA sequencing revealed that the strains 11 and 14 shared over 99% similarity with Leuconostoc mesenteroides identified by NCBI,while strain 18 exhibited over 99% similarity with Leuconostoc lactis.Consequently,the three isolates were classified as Leuconostoc.The inhibitory zone diameter of the three strains against Escherichia coli and Klebsiella pneumoniae was greater than 19 mm,which showed good inhibitory activity.The antibacterial substances produced by the three Leuconostoc strains against Escherichia coli mainly consist of organic acids,bacteriocins and hydrogen peroxide.For Klebsiella pneumoniae,the primary antibacterial substances of strains 11 and 14 included organic acids and hydrogen peroxide,while strain 18 mainly produced organic acids.The growth curve showed that the growth patterns of the three Leuconostoc strains were basically consistent,with 0 to 2 h being the delayed phase,2 to 12 h being the logarithmic phase,and after 12 h being the stable phase.The pH of the bacterial solution was stable at about 4.0,showing good acid production ability.The survival rate of the three Leuconostoc strains was above 56% after 4 h culture in artificial gastric juice and artificial intestinal juice.When the bile salt concentration was 0.3%,the survival rates of three Leuconostoc strains were all more than 26%,indicating that the strains had good tolerance.The results of the drug sensitivity test showed that three strains of Leuconostoc were highly sensitive to erythromycin,minomycin and tobramycin,resistant to penicillin,ampicillin and vancomycin,and moderately sensitive to cefuroxime,ceftriaxone and levofloxacin.And all of the three strains of Leuconostoc did not exhibit hemolytic activity.【Conclusion】 The three isolated Leuconostoc strains exhibited favorable antibacterial properties and safety profiles,laying a solid foundation for future research on probiotics for the prevention and treatment of bacterial bovine mastitis.

【Objective】 The purpose of this experiment was to elucidate the location of bla_CTX-M-123 gene in porcine Escherichia coli,and to explore the transmission capacity and fitness cost of the mobile genetic elements carried by bla_CTX-M-123 gene.【Method】 The intraspecific transfer ability of bla_CTX-M-123 gene was evaluated by chemical transformation test,the location of bla_CTX-M-123 gene was determined by whole genome sequencing,and the genetic environment of bla_CTX-M-123 gene in Escherichia coli was analyzed.The minimum inhibitory concentration (MIC) of Escherichia coli 911 strain,Escherichia coli DH5α competent cells and inverters was determined by broth microdilution method.In addition,competition experiments were conducted to assess the fitness cost of the plasmid carrying bla_CTX-M-123 gene,and the Galleria mellonella infection model was used for pathogenicity evaluation. 【Result】 One transformant,DH5α-pL1,was obtained through the transformation experiment,and its MIC value against ceftiofur was 256 mg/mL.The growth rate of DH5α-pL1 was higher than that of the recipient Escherichia coli DH5α competent cells,but lower than that of the wild-type strain 911.After 7 days of culture,the plasmid retention rate of DH5α-pL1 gradually declined,and after 24 h,the plasmid retention rate showed a certain fitness cost,with the relative competition index less than 1.The results of pathogenicity test showed that the survival rate of larval of Galleria mellonella was 100% in control and Escherichia coli DH5α competent cells groups.After 120 h injection of strains 911 and DH5α-pL1,the survival rate was 50% and 70%,respectively.【Conclusion】 The plasmid carrying bla_CTX-M-123gene could be transferred intra-specifically and mediate drug resistance of the transformer,and the plasmid had weak stability and a certain fitness cost.In addition,the plasmid carrying bla_CTX-M-123 gene had the effect of enhancing the virulence of the recipient bacteria,increasing the probability of infection and the difficulty of treatment.The results provided a theoretical basis for the study of drug resistance mechanism and prevention and control of bacteria.

【Objective】 The aim of this experiment was to understand the epidemic regularity and drug resistance characteristics of Streptococcus agalactiae in Guangxi,and provide scientific basis for healthy tilapia breeding.【Method】 The diseased fish from tilapia farm in Yulin,Beihai,Guigang in Guangxi were collected for bacterial isolation and culture.The isolated strains were identified by morphological observation and 16S rRNA sequencing analysis.The serotypes and main virulence genes of the isolates were identified by PCR,and their drug resistance was determined by K-B method.【Result】 A total of 38 Streptococcus strains were isolated,and the isolated strains formed milky white round small colonies with hemolytic rings on the blood plate.Gram staining was positive with typical short chain,and all were identified as Ⅰa Streptococcus agalactiae.Virulence genes sodA,cylE,gapC,bac and bca could be detected in all isolates,but virulence gene scpB could not be detected.The sensitivity of 38 isolates to aminoglycosides was low,and the resistance rate to amikacin was more than 85%.The isolates were highly sensitive to β-lactam drugs,among which penicillin G and cefoperazone were 100% sensitive.Among 38 strains of isolates,23 isolates showed multiple drug resistance,the number of drug resistance was 3-10,and 13 isolates were more than 4,accounting for 34.21% of the total isolates.【Conclusion】 The main serotype of Streptococcus agalactis derived from tilapia in Guangxi was type Ⅰa.The main virulence genes were sodA, cylE,gapC, bac and bca.The isolates were resistant to aminoglycosides,suggesting that the use of these drugs should be avoided.

【Objective】 The aim of the experiment was to study the therapeutic effect of Sihuangsan on infectious bronchitis (IB) and its effect on intestinal flora.【Method】 A total of 100 10-day-old SPF chicks were randomly divided into 5 groups:Control group,virus group and Sihuangsan low,medium and high dose groups,with 20 chicks in each group.Except for control group,the chicks in the other groups were inoculated with 10^-4.67/100 μL of IBV-QX virus solution (0.25 mL per chick) by nasal drop and eye spot.24 h after the challenge,chicks in Sihuangsan low-,medium- and high-dose groups were given 2,4,and 6 mL Sihuangsan liquid with a concentration of 1 g/mL,respectively,by drinking water,and administered twice a day in the morning and evening,and chicks in control and the virus groups drank ultrapure water,clinical symptoms were observed daily.After 24 days of continuous administration,all chicks were autopsied,trachea,lung and kidney samples were collected,the pathological changes were analyzed,and the contents of the chicken cecum were aseptically collected to measure the structure and diversity intestinal flora.【Result】 On the third day of administration, the chicks in virus group showed symptoms such as loss of appetite, dyspnea and diarrhea.On the 7th day of administration,the clinical symptoms of chicks in each dose group of Sihuangsan gradually decreased,and on the 8th day of administration,the symptoms of dyspnea of chicks in the medium- and high-dose groups disappeared and their appetite was restored.The results of histopathological observation showed that,compared with virus group,chicks in Sihuangsan groups did not have large-scale exfoliation of the respiratory epithelium of the tracheal mucosal layer,alveolar collapse and inflammatory cell infiltration of the alveolar wall,and no pathological changes such as glomerular endothelial cell proliferation,inflammatory exudation and necrosis were found.The tracheal mucosal layer of chicks in Sihuangsan medium-dose group was intact,ciliated cells and goblet cells were visible,alveolar structure was intact,glomerular structure was intact,and inflammatory cells were occasionally aggregated.The results of cecal microbiota changes showed that compared with control group,the Shannon index of the virus group was significantly decreased,and the Simpson index was significantly increased (P＜0.05). Compare with virus group,the Shannon index of Sihuangsan groups was significantly increased,and the Simpson index was significantly decreased (P＜0.05).The results of Beta diversity analysis of cecal microbiota showed that the composition of the microflora between Sihuansan groups and control group was highly similar,and there was no obvious difference.The microbial communities between virus group and Sihuangsan and control groups were significantly separated,and the differences were obvious.At the phylum level,the relative abundance of Proteobacteria in virus group was higher than that in control group and Sihuangsan groups,and the relative abundance of Firmicutes was lower than that in control group and Sihuangsan groups.At the genus level,the relative abundance of Lactobacillus in virus group was significantly lower than that in control group,and Lactococcus and Inconstantimicrobium in Sihuangsan medium dose group were significantly higher than those in virus group.【Conclusion】 Sihuangsan could effectively change the clinical symptoms,pathological changes,cecal microbiota structure and diversity of infectious bronchitis chickens,and the middle dose (0.4 g per chick) group had the best effect.

【Objective】 This study was conducted to comprehensively evaluate the safety of Polygonum hydropiper powder and provide a scientific basis for its safe application in clinical practice.【Method】 Acute toxicity tests and sub-chronic toxicity tests were designed for the study.In the acute toxicity test,20 Kunming mice were firstly selected for the preliminary test and randomly divided into 5 groups,with 4 mice in each group and an equal number of males and females.Five different dose groups (1.875,3.75,7.5,15 and 30 g/kg BW) were set.After a single oral gavage administration,the mice were continuously observed for 7 days,and their behavioral changes,weight gain or loss,and abnormal conditions of organs were recorded.If no mice died in the preliminary test,the number of mice in each group was increased to 10 in the formal test,with the same grouping,administration method and observation indicators.If no mice died still in the formal test,the maximum tolerance test was carried out.Another 20 mice were given the maximum tolerated dose of 30 g/kg BW and then observed for 7 days.In the sub-chronic toxicity test,80 SD rats were randomly divided into 4 groups,namely the high-dose (20 g/kg BW),medium-dose (10 g/kg BW) and low-dose (5 g/kg BW) groups of Polygonum hydropiper powder and the blank control group (given an equal volume of purified water),with 20 rats in each group.The drug was continuously administered for 30 days.The behavioral manifestations,poisoning and death status of the rats were observed,their body weights,food intakes and water intakes were recorded,the blood physiological and biochemical indexes were detected,the organs were collected and weighed and the organ coefficients were calculated,and pathological sections were made.【Result】 In the acute toxicity test of mice,no poisoning symptoms or death occurred in the preliminary test,formal test and maximum tolerated dose test.There were no abnormal changes in the internal organs during autopsy,and the median lethal dose (LD₅₀) was greater than 30 g/kg BW.In the sub-chronic toxicity test of rats,there were no poisoning symptoms or death in each dose group.The trend of body weight gain was similar to that of control group,and the body weight gain of male rats was higher than that of female rats.The thymus index of female rats in the high-dose group was significantly lower than that of control group (P＜0.05),while there were no significant differences in the other organ coefficients compared with control group (P＞0.05).Except for certain changes in the percentage of neutrophils (Neu),alanine aminotransferase (ALT) and aspartate aminotransferase (AST) among the blood physiological and biochemical indexes,there were no significant differences in the other indexes (P＞0.05),and all indexes were within the normal range.There were also no obvious pathological changes in the pathological sections of various internal organs.【Conclusion】 Within the dose range set in this study,Polygonum hydropiper powder had no toxic or side effects on Kunming mice and SD rats and had good safety.In the acute toxicity test of mice,the LD₅₀ of Polygonum hydropiper powder was greater than 30 g/kg BW.In the sub-chronic toxicity test of rats,the high-dose of Polygonum hydropiper powder was administered at 20 g/kg BW for 30 consecutive days,and no obvious toxic reactions were observed.

Inflammasome are an important component of innate immunity and participate in various pathophysiological processes.NOD like recepter heat protein domain associated protein 3 (NLRP3) is one of the most extensively studied inflammasome in recent years,plays an important role in the body’s response to pathogenic microorganisms and maintenance of tissue homeostasis.NLRP3 inflammasome is composed of proteins such as NLRP3,apoptosis related spotted protein (ASC),and cysteine aspartate enzyme 1 (Caspase-1),and its activation involves multi-step signal transduction,including initiation and activation signals.The activation of NLRP3 inflammasome can promote the cleavage and activation of Caspase-1,thereby mediating the maturation and release of pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18,as well as the process of cell apoptosis,thus playing a key role in the body’s inflammatory response.In veterinary field,research on NLRP3 inflammasome mainly focuses on its relationship with the occurrence and development of animal diseases and its potential as a therapeutic target.Research has shown that excessive activation of NLRP3 inflammasomes is associated with various animal diseases,including bacterial,viral,parasitic,and mycoplasma infections.Therefore,the regulation of NLRP3 inflammasome has become an important strategy for the treatment of related diseases and has shown potential as a diagnostic marker for diseases.Currently,research on NLRP3 inflammasome is being comprehensively conducted in veterinary clinical practice.In recent years,researchers have developed a series of inhibitors targeting NLRP3 inflammasome,such as UK5099 and MCC950.Although these inhibitors have shown significant anti-inflammatory effects in animal models,the development of NLRP3 inflammasome inhibitors is still in its infancy，and no target drugs have been successfully marketed.Therefore,the development of novel NLRP3 inflammasome inhibitors that are closer to clinical application remains a challenge.In this paper,the NLRP3 inflammasome and its research progress in veterinary field were reviewed in order to provide reference for the application of NLRP3 inflammasome as an important target in the treatment of animal inflammatory diseases.

【Objective】 In November 2023,an acute outbreak of yolk peritonitis in laying ducks emerged in a duck farm in Henan province.In order to provide scientific basis for the prevention and control of yolk peritonitis in the duck farm,laboratory diagnosis and pathogen analysis were carried out to determine the cause of disease.【Method】 After pathological anatomical observation,liver,spleen,kidney and blood samples were collected aseptically,and bacterial isolation culture and Gram staining microscopy were performed.The partical genome of the predominant bacterial was amplified by PCR with specific primers and sequenced.The sensitivity of the isolates to common antibiotics were then detected.The pathogens of common viral infectious diseases in laying ducks were detected by PCR/RT-PCR,and the main structural protein genes of positive pathogens were sequenced and analyzed to determine the viral pathogens and molecular epidemiology of infection in laying ducks.【Result】 Bacteriological test results showed that two dominant bacteria with different colony morphology were isolated.One colony showed translucent round protrusive,neat edges,smooth surface,Gram-negative,most of which existed in single or pair,which was consistent with the growth characteristics and bacterial characteristics of Riemerella anatipestifer (RA).The other colony showed a grayish white round protrusion on the blood plate,neat edges,smooth surface,no hemolytic ring,Gram-negative,most of which existed in a single form,in two short blunt circles,which was consistent with the growth characteristics and bacterial characteristics of Escherichia coli (E.coli).The ompA and 16S rRNA genes of the predominant bacterial was amplified and sequenced,respectively.BLAST analysis revealed that the two dominant strains were RA and E.coli. The results of drug susceptibility test showed that the RA isolate was sensitive to ciprofloxacin,amoxicillin-clavulanate potassium and flufenicol.E.coli isolate was sensitive to cefotaxime,ciprofloxacin,ceftriaxone and fosfomycin sodium.PCR/RT-PCR test results showed that the specific primer of Duck circovirus (DuCV) amplified a specific band at 915 bp,which was positive for nucleic acid,while the nucleic acid test results of other pathogens were negative.The isolated strain was named DuCV/HN-2023.Sequencing comparison results showed that the Cap gene of DuCV/HN-2023 had the highest similarity with the nucleotide sequence of duck derived Circovirus ZQ-XYF1010-1 and GZ-GXG0905-X4,which were 99.7% and 99.4%,respectively.The nucleotide sequence similarity with Muscovy circovirus FJFQ315 and FJFQ312 strains was 98.6% and 98.5%,respectively.Phylogenetic tree analysis showed that DuCV/HN-2023 was closely related to ZQ-XYF1010-1 and GZ-GXG0905-X4.【Conclusion】 Through comprehensive diagnosis,it was confirmed that the disease of laying ducks in the duck farm was caused by the mixed infection of RA,E.coli and DuCV.The drug resistance of the isolated strains was analyzed,and the genetic evolution of the isolated strain was performed at the molecular level,and the biological characteristics of the pathogen were further analyzed,which provided a reference for the prevention and control of the disease in clinic.

Mycoplasma synoviae infection is an infectious disease caused by Mycoplasma synoviae,which mainly leads infectious synovitis,eggshell apex abnormality,airsacculitis and mild upper respiratory tract diseases in chickens.Mycoplasma synoviae infection is widespread in poultry industry,mainly manifested as chronic infection and recessive infection,and often co-induced mixed infection with other respiratory pathogens,causing huge economic losses to domestic poultry industry.Mycoplasma synoviae involves a variety of intricate pathogenic mechanisms,including the adhesion to host cells,competition for nutrients,and the secretion of metabolites.Currently,a variety of detection methods,including pathogen isolation and culture,molecular biology techniques,and serological testing,are available for the laboratory diagnosis of Mycoplasma synoviae.However,only a limited number of vaccines are available in China for the prevention of Mycoplasma synoviae infection.When Mycoplasma synoviae infection occurs in poultry,it is mainly treated with antibacterial drugs.The author summarized the research progress on the epidemiology,clinical symptoms,pathogenic mechanism,diagnostic methods and prevention measures of Mycoplasma synoviae infection in recent years,which provided new insights for the prevention and control of Mycoplasma synoviae infection.

Klebsiella pneumoniae (KP) is a significant zoonotic pathogen that can cause various infections,impacting the health of both humans and animals.The widespread spread of multidrug-resistant KP and the spread of highly virulent KP (hvKP) have aroused great concern for KP infection.Antibiotics are a crucial means to combat KP infection,but the emergence of antimicrobial resistance (AMR) and the exacerbation of multidrug resistance have rendered antibiotic treatment insufficient to meet clinical needs.Phage therapy has attracted much attention due to its unique antibacterial mechanism.Studies have shown that phage can effectively fight KP infection.However,relevant reports mainly focus on pre-clinical in vivo and in vitro trials and a few clinical cases,and lack systematic safety evaluation and application guidance.The author summarized the existing research data from domestic and international studies,systematically reviewed the preclinical studies and clinical case reports of phage against KP infection,aiming to provide reference for the development of phage therapy against KP infection.