【Objective】 This study was aimed to investigate the sequence characteristics of coding region and promoter region of the proteasome 20S subunit beta 9 (PSMB9) gene in Hu sheep,and analyze its potential transcriptional regulation mechanism and its impact on myoblast cell proliferation. 【Method】 The CDS region of PSMB9 gene in Hu sheep was obtained by cloning and sequencing,the promoter region was determined by genome position in sheep,and the characteristics of CDS and promoter region were analyzed by bioinformatics method.The phylogenetic tree based on the amino acid sequence of PSMB9 was constructed using Neighbor-Joining (NJ) method of Mega 5.0 software.The tissue expression profile of PSMB9 gene in Hu sheep was detected by Real-time quantitative PCR.The overexpression vector of PSMB9 gene in Hu sheep was constructed by double enzyme digestion.CCK-8 kit were determined to detect the proliferative capacity,Real-time quantitative PCR was used to detect the overexpression effect of PSMB9 gene in C2C12 cells and the expression of proliferation gene PCNA. 【Result】 The results showed that the CDS region of PSMB9 gene in Hu sheep was 660 bp,encoding 219 amino acid residues,and the similarity of nucleotide and amino acid sequences with mammals including Homo sapiens,Bos taurus,Sus scrofa and Mus musculus were high.The active sites and beta subunit interaction sites of PSMB9 were highly conserved.Phylogenetic tree analysis found that Hu sheep first clustered with Bos taurus,and then clustered with Sus scrofa,Homo sapiens and Mus musculus,indicating that PSMB9 was relatively conserved in mammals.PSMB9 gene promoter contained one CpG island,two GC-boxes (CCGCCC) and two E-boxes (CANNTG),as well as potential binding sites for various transcription factors such as SP1,KLF4,STAT3,YY1 and CREB1.Tissue expression pattern showed PSMB9 gene was widely expressed in various tissues of Hu sheep,especially highly expressed in spleen and followed by muscle.Compared with control group,overexpression of PSMB9 gene in C2C12 cell lines could extremely significantly improve the proliferation ability of cells (P＜0.01),the expression of proliferation gene PCNA was extremely significantly upregulated (P＜0.01). 【Conclusion】 The sequence of PSMB9 gene in Hu sheep was successfully cloned in this study,PSMB9 gene was highly conserved in mammals,the promoter region of PSMB9 gene contained important regulatory elements,CpG island and potential binding sites of transcription factors.PSMB9 gene was highly expressed in spleen and muscle of Hu sheep,and overexpression of PSMB9 gene could promote the proliferation of myoblasts.The results provided a basis for further elucidating the molecular mechanism of PSMB9 gene regulation of muscle development in Hu sheep.

【Objective】 The coat color phenotype of Jianhe White Xiang pigs is mostly two-end black,but the candidate genes affecting its coat color phenotype have not been reported.This study was aimed to screen the candidate genes affecting the two-end black coat color of Jianhe White Xiang pigs. 【Method】 Based on the transcriptome data of black and white skin tissues of Jianhe White Xiang pigs,differentially expressed gene screening was performed,and at the same time,the selective signals were analyzed using the data from 138 Jianhe White Xiang pigs and 50K chip of 130 Beijing Black pigs (Porcine SNP50 BeadChip),and the candidate genes affecting coat color were screened by GO function and KEGG pathway analysis. 【Result】 The results showed that 554 genes were differentially expressed in black and white coat color skin tissues in the transcriptome analysis,of which 295 were up-regulated and 259 were down-regulated.A total of 6 GO terms and 2 KEGG pathways,and a total of 12 candidate genes,such as TYR,TYRP1,DCT and PLCB4,related to the formation of hair color were screened.Based on the genome data,Fst analysis was performed,and a total of 3 GO terms and 4 KEGG pathways were screened,32 other candidate genes,such as PLCB4,FZD8 and WNT2,might be involved in the process of hair color formation in Jianhe White Xiang pigs. 【Conclusion】 Through comprehensive selection signal and transcriptome differential analysis,PLCB4 gene was identified as an important candidate gene that affected the phenotype of two-end black coat color in Jianhe White Xiang pigs.The results provided a reference for future molecular regulatory mechanisms related to coat color formation in Jianhe White Xiang pigs.

【Objective】 The aim of this study was to sequence the whole genome and analyze the bioinformatics of Ligilactobacillus animalis S7,a strain isolated from pig with good acid tolerance and bile salt tolerance. 【Method】 The sequencing technology combining the third generation PacBio RS Ⅱ sequencing platform and the second generation Illumina HiSeq 2000 sequencing platform was used to sequence the genome of S7,and then the functional genes of the genome were annotated in the databases of GO,EggNOG,KEGG,CAZy,VFDB and CARD.The phylogenetic tree was constructed used TYGS and collinearity analysis was performed with two nearest type strains. 【Result】 The genome size of Ligilactobacillus animalis S7 was 2.03 Mb,and the GC content was 44.14%.A total of 1 993 encoding genes were predicted,including 65 tRNA,19 rRNA,35 sRNA,29 housekeeping genes,11 gene isolands,6 prophages,4 CRISPR-Cas,8 insertion sequences and 10 transposons.1 521,1 567,1 185,and 60 genes were annotated in the databases of GO,EggNOG,KEGG and CAZy,respectively.181 virulence genes and 110 drug resistance genes were annotated in VFDB and CARD databases.In addition,14 acid tolerance-related genes,2 bile salt tolerance-related gene,22 cell adhesion and aggregation-related genes were found in S7.A variety of genes related to heat stress,oxidative stress resistance,and bacteriocin synthesis that are associated with probiotic functions were also found in the genome of S7.The phylogenetic tree and collinearity analysis results indicated that the strain had the nearest evolutionary relationship to type strain Ligilactobacillus animalis P38. 【Conclusion】 The genome of Ligilactobacillus animalis S7 had functional genes related to acid tolerance,bile salt tolerance,adhesion and aggregation,temperature stress,oxidative stress,and bacteriocin,which provided theoretical basis for the scientific application of the strain in feed additives.

【Objective】 The aim of this study was to investigate the biological characteristics of heat shock protein family A member 8 (HSPA8) in chickens and its expression patterns in thymus under stress. 【Method】 In this study,the thymus of Gushi chickens was used as the material,and the CDS region of HSPA8 gene was amplified using PCR and cloned,and its biological and structural characteristics were analyzed by bioinformatics method.The relative expression of HSPA8 gene in different tissues were detected. The models of beak trimming stress and heat stress were constructed,and Real-time quantitative PCR was used to detect the expression of inflammatory factor and HSPA8 gene in thymus of chickens with different stress models. 【Result】 The length of CDS region of chicken HSPA8 gene was 1 941 bp,encoding 646 amino acids,which was 98.92% similar to the gene sequence of Gallus gallus.Phylogenetic tree results of HSPA8 gene sequence showed that Gushi chickens was the closest related to Meleagris gallopavo,followed by mammals,and most distantly related to lower fish.HSPA8 protein was acidic protein with strong stability and hydrophilicity.It didn’t belong to secreted protein and had no transmembrane domain,with multiple phosphorylation and glycosylation modification sites.It mainly functions in the nucleus and had two conserved domains.It interacted with DNAJC5,HSPB1,DNAJA1 and GAK proteins,et al.HSAP8 gene was widely expressed in various tissues and organs of chicks,with the highest expression in pancreas and the lowest expression in pectoral muscle.The results of stress model evaluation showed that beak trimming stress and heat stress resulted in the significant increase of the contents of serum corticosterone,interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) (P＜0.05),and decrease of the contents of T cell subsets (CD3⁺) and immunoglobulin G (IgG).The expressions of IL-1β,IL-6,TNF-α and IL-8 genes in thymus were significantly increased on day 1 (P＜0.05) and significantly decreased on day 5 (P＜0.05),while the expressions of IL-1β,IL-6,TNF-α and IL-8 genes were significantly increased in thymus under heat stress (P＜0.05).The expression of HSPA8 gene in thymus were increased significantly on day 1 and day 3 after beak trimming (P＜0.05),decreased significantly on day 5 (P＜0.05),and decreased significantly in the continuous heat stress group (P＜0.05). 【Conclusion】 HSPA8 gene was involved in the stress immune response of chicken thymus,which could be used as a reliable indicator of whether poultry was in the state of stress immunosuppression.The above results provided a reference for further studying the immune regulatory function of HSPA8 gene.

The growing problem of drug resistance caused by the abuse of antibiotics has led to the urgent need for the development and utilization of new antimicrobial drugs.Traditional Chinese medicine (TCM) offers several advantages,including multi-targeting,low side-effects,anti-drug resistance,and broad-spectrum applications,which have led to its use in a wide range of antimicrobial contexts.The development of sequencing technology and high-resolution mass spectrometry has facilitated the widespread use of transcriptomics,proteomics and metabolomics technologies in the study of antimicrobial mechanisms of TCM.Transcriptomics technology can be employed to screen and validate differentially expressed genes,thereby enabling the understanding of the interaction pathways between TCM and bacteria.Proteomics can assist in the identification of the active ingredients present in herbal medicines,as well as in the resolution of their interactions with pathogenic bacterial proteins.Metabolomics techniques can be utilized to detect changes in metabolites,thus facilitating the identification of differences in relevant metabolites between TCM and bacteria.However,single-omics studies have inherent limitations,and joint multi-omics analyses can provide a more comprehensive understanding of bacterial-host interactions and the mechanisms by which herbal medicines regulate bacterial infections.The authors present a systematic review of the literature on the antibacterial activity of TCM and the antibacterial mechanism of TCM affecting group sensing,biofilm formation,substance metabolism,and oxidative stress response based on studies using transcriptomics,proteomics,metabolomics,and multi-omics combined techniques,so as to provide a theoretical basis for the analysis of the antibacterial mechanism of TCM and the screening and development of antibacterial drugs.

【Objective】 The aim of this study was to investigate the effects of cannabidiol (CBD) on lipopolysaccharide (LPS)-induced inflammatory response and apoptosis of mouse mammary epithelial cells (HC11). 【Method】 HC11 cells were divided into control group,LPS group and different concentrations of CBD＋LPS groups (CBD concentration was 2,4 and 6 μmol/L,respectively).The cells in control group were only treated with culture medium,and the cells in LPS group were treated with LPS.CBD＋LPS groups were pretreated with different concentrations of CBD for 1 h and then LPS was added.Cell samples were collected after 24 h of culture.The contents of inflammatory factors in the cells were detected by ELISA.Real-time quantitative PCR and Western blotting were used to detect the mRNA and protein expression levels of inflammatory cytokines,and genes related to nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways,respectively.Apoptosis rate and mitochondrial membrane potential were detected by AnnexinV-FITC/PI and JC-1 staining,respectively. 【Result】 Compared with control group,the contents and mRNA expression levels of tumor necrosis factor-α (TNF-α),interleukin-1β (IL-1β) and IL-6 in LPS group were extremely significantly or significantly increased (P＜0.01 or P＜0.05),the mRNA expression and protein phosphorylation levels of NF-κB p65,nuclear factor-κB inhibitory protein α (IκBα),extracellular signal-regulated kinase (ERK),mitogen-activated protein kinase (p38),and stress-activated protein kinase (JNK) were extremely significantly or significantly increased (P＜0.01 or P＜0.05).Compared with LPS group,the contents and mRNA expression of TNF-α,IL-1β and IL-6 in cells treated with different concentrations of CBD and LPS were extremely significantly or significantly decreased (P＜0.01 or P＜0.05). The mRNA expression and protein phosphorylation levels of NF-κB p65,IκBα,ERK,p38 and JNK were extremely significantly or significantly decreased (P＜0.01 or P＜0.05).The results of apoptosis rate and mitochondrial membrane potential detection showed that,compared with control group,the apoptosis rate of HC11 cells in LPS group was significantly increased (P＜0.05),and the mitochondrial membrane potential was significantly decreased (P＜0.05). Compared with LPS group,the apoptosis rate of HC11 cells was significantly decreased after 4 μmol/L CBD and LPS co-treatment (P＜0.05),and the mitochondrial membrane potential was significantly increased (P＜0.05). 【Conclusion】 In the LPS-induced inflammation and apoptosis model of HC11 cells,the appropriate concentration of CBD could inhibit the activation of NF-κB and MAPK signaling pathways,thereby inhibiting the release of inflammatory factors to alleviate inflammation.Furthermore,it could reduce the apoptosis rate and up-regulate the mitochondrial membrane potential of HC11 cells induced by LPS,thus inhibiting the cell apoptosis.

【Objective】 To investigate the effect of artificial light supplementation on the growth of Ashan wapiti antlers and fecal hormone levels. 【Method】 Thirty-six healthy adult Ashan wapiti were selected and randomly divided into supplemental light group and natural light group,with 18 wapiti in each group. The supplemental light test started on February 1 according to the sunrise and sunset schedules of the experimental site,and spotlights was used to simulate the March light in February,and so on,untill the end of May.Fresh fecal samples were collected from five different sites in each pen every 7 d during the test period by partial fecal collection method,and antler length was measured,and fresh antler weight was weighed at the time of antler cutting,testosterone,estradiol and melatonin content of feces were measured by ELISA.Sampling and monitoring continued untill the end of August. 【Result】 Compared with natural light group,the wapiti in supplemental light group shed their antlers 10 d earlier,and there was no significant difference in the weight of the first antler crop between the two groups (P＞0.05),but the growing time of antler in the light-supplemented group was extended by 11.18 d, and the weight of the second antler crop was increased by 28.30% (P＜0.05). Compared with natural light group, the fecal testosterone content in February and April was significantly or extremely significantly lower (P＜0.05 or P<0.01),the fecal estradiol content in February,March and May was significantly or extremely significantly higher (P＜0.05 or P<0.01),and the fecal melatonin content in February,March,April and May was extremely significantly lower (P＜0.01) of the supplemental light group.After the light supplementation,the levels and changes of fecal hormones between the two groups were basically consistent. 【Conclusion】 Artificial light supplementation could promote early disk shedding,prolong antler growth,and increase antler yield,and to some extent reduce testosterone and melatonin levels and increase estradiol levels in feces.

【Objective】 This study was aimed to investigate the effect of adding Rosa roxburghii Tratt. residue to the diet on the intestinal histomorphology,antioxidant capacity,immunity and metabolomics of common carp,so as to provide a scientific basis for the popularization and application of Rosa roxburghii Tratt. residue feed for paddy-fish farming in rural mountainous areas of Guizhou province. 【Method】 One hundred and eighty healthy and disease-free common carp with an initial body weight of 25 g±1 g were selected and randomly divided into normal group (no Rosa roxburghii Tratt. residue was added to basal feed) and Rosa roxburghii Tratt. residue feeding group (0.4% Rosa roxburghii Tratt. residue was added to basal feed),with three replicates of 30 fish in each group,the experiment period was 60 d.The mid-portion of the intestine of common carp was collected after the experiment,and the intestinal histomorphology,antioxidant capacity,immunity and metabolomics of common carp were analyzed by microscopic observation,ELISA and metabolomics technology based on liquid chromatography. 【Result】 Compared with normal group,the feeding of Rosa roxburghii Tratt. residue had no adverse effect on the normal structure of intestine in common carp,the length of intestinal villi and thickness of muscularis propria were both extremely significantly increased (P＜0.01),the activity of glutathione peroxidase (GSH-Px) in intestinal tract of common carp in Rosa roxburghii Tratt. residue feeding group was significantly increased (P＜0.05),and the content of tumor necrosis factor-α (TNF-α) was significantly decreased (P＜0.05).A total of 85 differential metabolites were significantly enriched in Rosa roxburghii Tratt. residue feeding group,including 2-ketobutyric acid,L-(+)-lactic acid,propionic acid,succinic acid,D-aspartic acid,D-glutamine,xanthine nucleoside,hypoxanthine,thymine,uracil,D-pyroglutamic acid,etc.,which were mainly enriched in the metabolic pathways of propionate metabolism,alanine,aspartate and glutamate metabolism,purine metabolism,pyrimidine metabolism,etc. 【Conclusion】 The addition of Rosa roxburghii Tratt. residue in diet could improve the antioxidant property and immune indexes of intestinal tissue in common carp,which might improve intestinal health and enhance immunity of common carp by affecting the purine and pyrimidine metabolism of common carp as well as the related metabolites,such as D-glutamine,xanthine nucleoside,hypoxanthine,thymine,2'-deoxyuridine-5'-monophosphate and uracil.

【Objective】 This experiment was aimed to analyze the differences in microbial colonization patterns on the back,neck and rectal chyme of Dezhou male donkeys. 【Method】 A total of 3 000 Dezhou male donkeys with uniform skin thickness were fed with the same basal diet.The skin thickness on the back and neck of donkeys was continuously monitored.Seven donkeys with high and low skin thickness increments in both areas were selected,respectively.The composition and function of microbial communities on the back and neck surfaces,as well as in the rectal chyme,were analyzed by determining the sequences of 16S rRNA amplification. 【Result】 There were significant differences in the thickness increment of donkey skin between the high and low groups (P＜0.05).There was no significant difference of microbiota in Alpha diversity of skin on the back,neck and rectal chyme between the two groups (P＞0.05).However,the results of principal co-ordinates analysis (PCoA) showed that there were varying degrees of differences in microbial community clustering between the two groups (P＜0.05).Venn diagram revealed that there was common amplicon sequence variant (ASV) or unique ASV of microbiota in skin on the back,neck and rectal chyme between the two groups.At the phylum level,the dominant bacteria in different parts of the two groups included Firmicutes,Actinobacteriota,Chloroflexi,Proteobacteria,Bacteroidota,etc.At the genus level,the dominant bacteria included Clostridium_sensu_stricto_1,Corynebacterium,Streptococcus,Ornithinimicrobium,etc.Among these,Streptococcus was the dominant bacteria in the rectal chyme microbiota,and Ornithinimicrobium was the dominant bacteria in skin on the back and neck.Differential species analysis results showed that compared with the neck skin of low thickness increment group,23 genera were enriched in the neck skin of high thickness increment group.Compared with the back skin of low thickness increment group,7 genera were enriched in the back skin of high group.Compared with the rectal chyme of low thickness increment group,13 genera were enriched in the rectal chyme of high thickness increment group. 【Conclusion】 Dezhou donkeys with varying skin thickness had different microbial community structures and functions.Moreover,compared with rectal chyme,the microbial diversity of skin showed a higher trend.The results provided a theoretical basis for analyzing the microbial colonization pattern and potential regulatory mechanisms of donkey skin transformation efficiency in Dezhou donkeys.

【Objective】 The objective of this experiment was to investigate the effects of dietary protein level on growth,slaughter performance,intestinal microflora and structure of squabs under the "2+2" production mode (1 pair of parent pigeons feeding 2 squabs in 1 breeding cycle). 【Method】 60 pairs of healthy Tarim breeding pigeons aged 12-18 months,with similar reproductive performance,were randomly divided into 5 groups,with 12 pairs in each group,and each pair bred 2 squabs. The breeder pigenons were fed diets with energy level of 12.64 MJ/kg and different crude protein (CP) levels (12%,13%,14%,15% and 16%),respectively.The experiment had a 3-day pre-experimental period and a 28-day experimental period.The body weight of squabs was measured every 3 days,and 8 squabs in each group were slaughtered at 28 days of age,and their slaughter performance and jejunal microbial community structure were measured. 【Result】 ① Dietary protein level had significant effects on body weight and average daily gain of squabs (P＜0.05).The body weight of squabs increased linearly with the increase of day age,and the average daily gain of squabs first decreased and then increased,showing a quadratic curve change (P＜0.05).The average daily gain of squabs in CP13% group was the largest.② Dietary protein level had significant effects on the slaughter rate,abdominal fat rate,breast muscle rate and wing rate of squabs (P＜0.05),and the slaughter rate of CP16% group was significantly higher than that of CP13% and CP14% groups (P<0.05).③ At the phylum level,the top ten in each group were Actinomyces,Firmicutes,TM7,Cyanobacteria,Proteobacteria,Bacteroidetes,Parasicutes,OP11,Chloromyces and Blastomonas.The relative abundance of Proteobacteria in CP16% group was significantly higher than that in CP14% and CP15% groups (P＜0.05).At the family level,the top ten species in each group were Corynebacteriaceae,Lactobacillaceae,Rhodiaceae,Clostridiaceae,Erysipelothriaceae,Enterococcaceae,Veillonaceae,actinomyceaceae,Bifidobacteriaceae and Rs-045.The relative abundance of Rhodiaceae in CP14%,CP15% and CP16% groups was significantly higher than that in CP12% group (P＜0.05).The relative abundance of Bifidobacteriaceae in CP14% and CP16% groups was significantly higher than that in CP12% and CP13% groups (P＜0.05).At the genus level,the top ten in each group were Corynebacterium,Lactobacillus,Strangella,Segmental filamentous bacterium,Enterococcus,Veyronella,Bifidobacterium,Breidella,Actinomyces and Kinetocampylobacter,and the relative abundance of Bifidobacterium in CP14% and CP16% groups was significantly higher than that in CP12% and CP13% groups (P＜0.05).The relative abundance of Strangella in CP15% and CP16% groups was significantly higher than that in CP12% group (P＜0.05).The relative abundance of Veillonella in CP16% group was significantly higher than that in CP12% group (P＜0.05). 【Conclusion】 Under the conditions of this experiment,the average daily weight gain of squabs was the highest when the crude protein level in the diet for breeder pigeons in the "2+2" production mode was 13%,and the slaughter performance was better.Different crude protein levels in the diet for breeder pigeons had a certain effect on the jejunal microbiota structure of squabs at 28 days old.A crude protein level of 13% in the diet for breeder pigeons was more suitable for the growth performance of squabs.

【Objective】 In this experiment,the bioavailability of three types of rumen-protected methionines (A,B and C) was measured using the selenomethionine method and the modified in vitro three-step procedure,respectively,and the results obtained from the two methods were subjected to correlation and regression analyses aiming at exploring the relationship between the two methods. 【Method】 ① Selenomethionine method:Thirty-three healthy lactating dairy cows were used in the experiment,divided into three groups according to a randomised block trial design,with a total of 32 days divided into three phases,of which the first 7 days were pre-feeding (phase 0),the days 8 to 22 were phase 1,and the following 10 days were phase 2.In phase 0,cows were fed only the basal diet,and starting from phase 1,all cows were supplemented with selenium yeast at a dose of 0.3 mg Se/kg DM,in Phase 2,continued with the same dose of selenium yeast supplementation,all cows were supplemented with rumen-protected methionine supplementation A (33.3 g/d,group A),B (29.4 g/d,group B) and C (56.82 g/d,group C) based on the same amount of effective methionine (25 g/d).Milk samples were collected on days 22 and 32 for the determination of selenium,methionine and nitrogen concentrations,and the bioavailability of the three rumen-protected methionines was measured as the change in the ratio of selenium concentration/methionine concentration (selenium concentration/nitrogen concentration) in phases 1 and 2.② Modified in vitro three-step procedure:Three lactating dairy cows fitted with rumen fistulas were used in the experiment,and each of the three rumen-protected methionines (rumen-protected methionine A,B,and C) was set up in two parallels and three replicates,and the bioavailability of rumen-protected methionines were assessed by rumen incubation and in vitro simulation of gastric-small intestinal digestion of DM and CP.The correlation between the two methods was analysed and regression equations were established. 【Result】 The results of the selenomethionine method showed that the bioavailability of rumen-protected methionine A based on changes in the ratio of milk selenium concentration/methionine concentration and milk selenium concentration/nitrogen concentration were 83.02％ and 81.42％,respectively,while for rumen-protected methionine B,72.94％ and 72.47％,respectively,and for rumen-protected methionine C,51.77％ and 50.98％,respectively.② The results of the modified in vitro three-step procedure showed that the bioavailability of rumen-protected methionine A,B and C were 86.87％,75.47％ and 59.56％,respectively.The analysis of the results of the two methods showed that there was no significant difference (P＞0.05),and there was a highly significant positive correlation (r＝0.867-0.964,P＜0.01) between the results of the two methods. 【Conclusion】 Under the conditions of this test,both the selenomethionine method and the modified in vitro three-step procedure could be used for the determination of the bioavailability of the three types of rumen-protected methionines,and a strong positive correlation existed between the two methods.

【Objective】 This experiment was conducted to analyze the effects of grazing on chicory grassland under forest and traditional cage system on caecum microflora and metabolites of Beijing-You chickens. 【Method】 10-week-old Beijing-You chickens with similar weight were randomly divided into three groups and raised for 95 days:Grazing on chicory grassland under forest groups,with grazing densities of 100 hens/677 m² (T1) and 120 hens/677 m² (T2),and the traditional cage system was used as the control group (CK),the grazing groups adopted a combination of grassland grazing and basal diet supplementation,and the CK group adopted basal diet only.At the end of the experiment,caecum contents were collected,the richness,diversity and structure of microbial community were analyzed by 16S rRNA high-throughput sequencing,and the differential metabolites and KEGG enrichment pathways were analyzed by liquid chromatography-mass spectrometry (LC-MS). 【Result】 Compared with CK group,the Sobs index,Chao1 index,Ace index and Shannon index of T1 group were increased,and the Simpson index was decreased to a certain extent (P＞0.05),the Sobs index,Chao1 index and Ace index of T2 group were obviously increased by 41.3%,33.6% and 34.7% (P＜0.05).Compared with CK group,the relative abundance of Ruminococcus_torques_group,Rikenellaceae_RC9_gut_group,Olsenella,unclassified_f__Lachnospiraceae and UCG-005 in caecum of T1 and T2 groups were increased to a certain extent (P＞0.05).The difference metabolites of T1 and T2 groups were mainly concentrated in the metabolism of terpenoids and polyketides,biosynthesis of plant secondary metabolites,lipid metabolism and amino acid metabolism. 【Conclusion】 The relative abundance of beneficial bacteria in caecum and the lipid metabolism pathway and amino acid metabolism pathway of Beijing-You chickens were positively affected by grazing on chicory grassland under forest,and it played a series of benign effects such as controlling body fat,increasing essential amino acid and improving immune performance.

【Objective】 This experiment was aimed to study the effect of melatonin (MT) on the antioxidant capacity and quality of mutton,and investigate whether or not MT could improve the quality of mutton and extend shelf life in vitro. 【Method】 Five-month-old Hu sheep with similar body weight (36.23 kg±0.31 kg) were selected,and the longissimus dorsi muscle was collected and randomly divided into four groups.The mutton in control group was soaked in distilled water,and the mutton in experiment groups Ⅰ,Ⅱ and Ⅲ were soaked in the solution containing 3,6 and 9 ng/mL MT,respectively.After 30 min,it was drained and stored in a self-sealing bag at 4 ℃.The MT content was measured on the first day of the experiment.The antioxidant capacity and meat quality were measured on the 1st,4th,7th,10th and 13th days of the experiment.The total volatile base nitrogen (TVB-N) content in mutton was measured at 12,36,84,132,180 and 228 h of the experiment. 【Result】 Compared with control group,the MT contents of mutton in groups Ⅰ,Ⅱ and Ⅲ were extremely significantly increased (P＜0.01).On the 1st,4th and 7th days of the experiment,the total antioxidant capacity (T-AOC) of mutton in group Ⅲ was significantly increased (P＜0.05),the malondialdehyde (MDA) contents of mutton in groups Ⅱ and Ⅲ were extremely significantly decreased (P＜0.01).On the 7th,10th and 13th days of the experiment,pH of mutton in groups Ⅱ and Ⅲ was significantly decreased (P＜0.05),the drip loss of mutton in group Ⅰ was extremely significantly decreased (P＜0.01),the shelf life of mutton in groups Ⅰ,Ⅱ and Ⅲ was extended by 9.11,12.89 and 14.91 h,respectively. 【Conclusion】 MT could improve the antioxidant capacity and quality of mutton in vitro to a certain degree,and extend the shelf life of mutton.In summary,this study recommended 3 ng/mL as the optimal concentration of MT.

【Objective】 This study was aimed to investigate the effects of substituting soybean meal with Zanthoxylum bungeanum seed meal on the growth performance,slaughter performance,serum biochemical indicators,antioxidant capacity,and immune function of broilers,so as to provide a potential strategy to reduce the reliance of soybean meal in broilers. 【Method】 A total of 180 AA broilers at 1 day of age,with a uniform body weight of 48.87 g±0.15 g,were selected and randomly assigned to 3 treatment groups,each consisting of 6 replicates with 10 chickens per replicate.The broilers in control group (CON) were fed a basic diet,while the experimental group received diets containing 2.5% (ZBM-1) and 7.5% (ZBM-2) Zanthoxylum bungeanum seed meal as a substitute for soybean meal in basic diet.The experimental period lasted for 42 d.The effects of replacing soybean meal with Zanthoxylum bungeanum seed meal on the growth performance,slaughter performance,serum biochemical indicators,antioxidant capacity,and immune function of broilers were analyzed. 【Result】 ① Compared with CON group,the average daily weight gain,average daily feed intake,and feed to gain ratio of broilers in ZBM-2 group were significantly increased at 1-21,22-42,and 1-42 days of age (P＜0.05).② The eviscerated carcass weight rate of broilers in ZBM-2 group was significantly higher than CON and ZBM-1 groups (P＜0.05).③ Compared with CON group,the drip loss and cooking loss of muscle of broilers in ZBM-1 and ZBM-2 groups were significantly decreased (P＜0.05).④ Compared with CON group,the albumin and globulin levels in serum of broilers at 21 days of age in ZBM-2 group were significantly increased (P＜0.05),but the alanine aminotransferase activity was significantly decreased (P＜0.05).The albumin and globulin levels,and the alkaline phosphatase activity in serum of broilers at 42 days of age in ZBM-2 group were significantly increased (P＜0.05),but the total cholesterol content was significantly decreased (P＜0.05).⑤ Compared with CON group,the total antioxidant capacity,immunoglobulin A and immunoglobulin M levels,and the activities of superoxide dismutase and glutathione peroxidase in serum of broilers at 21 and 42 days of age in ZBM-2 group were significantly increased (P＜0.05),but the malondialdehyde content was significantly decreased (P＜0.05). 【Conclusion】 Under the conditions of this experiment,substituting Zanthoxylum bungeanum seed meal for soybean meal in diet could enhance the meat quality,antioxidant capacity,and immune function of broilers.The recommended usage rate of Zanthoxylum bungeanum seed meal in broilers was 2.5%.

【Objective】 This study was conducted to investigate the effect of fermented mulberry leaf powder (FML) on growth performance,antioxidant and immune capacity,and gut microbiota structure of Yellow-feathered broilers. 【Method】 540 1-day-old Yellow-feathered broilers with an initial weight of (40.07±0.05) g were selected and randomly divided into 3 groups,each with 6 replicates and 30 broilers per replicate.Three types of equal nitrogen and equal energy experimental feed were fed with 0(control group),4.5% FML(group FML45),and 9.0% FML(group FML90) during the brooding,growth,and adult stages,respectively.The experimental period was 50 days.At 21,42 and 50 days of age,the broilers were weighed with fasting and feed intake was analyzed to calculate growth performance.At 50 days of age,3 broilers with average body weight from each replicate were selected for blood collection and slaughter,and serum antioxidant indicators were determined.The ileal mucosa was taken to determine antioxidant and immune functions,and the ileal content was taken to determine the gut microbiota structure. 【Result】 Compared with control group,① The broilers in group FML90 showed a significant decrease in body weight(BW) and average daily gain (ADG)(P＜0.05),as well as a significant increase in feed to weight ratio (F/G)(P＜0.05),and an increasing trend in average daily feed intake (ADFI)(P=0.084).There was no significant difference in mortality among groups(P＞0.05).② The activity of superoxide dismutase(SOD) in serum of broilers in groups FML45 and FML90 was significantly increased (P＜0.05),and there were no significant differences in the content of malondialdehyde(MDA) and the activities of glutathione peroxidase(GSH-Px) and total antioxidant capacity(T-AOC) among groups (P＞0.05). T-AOC in ileum of broilers in group FML45 was significantly higher than that in control group and group FML90.There were no significant differences in the contents of MDA,the activities of GSH-Px and SOD in ileum among groups (P＞0.05).③ The broilers in group FML90 showed a significant increase in the content of secreted immunoglobulin A(SIgA) (P＜0.05),and there were no significant differences in the contents of interleukin-1β (IL-1β),IL-10,tumor necrosis factor α (TNF-α),transforming growth factor β (TGF-β) and complement 3 (C3) among groups (P＞0.05).④ There was no significant differences in the relative abundance at phylum level in ileum among groups (P＞0.05).The relative abundance of Faecalibacterium were significantly increased (P＜0.05),while the relative abundances of unclassified_o_Eubacteriales and unclassified_o_Oscillospiraceae were significantly decreased (P＜0.05),the relative abundance of Phascolarctobacterium showed an increasing trend (P=0.067),and the Ace index and Chao1 index were significantly decreased (P＜0.05) in groups FML45 and FML90. 【Conclusion】 Diets supplemented with FML could enhance the immunity and antioxidant capacity,improve the relative abundance of beneficial bacteria in intestine,but excessive addition could reduce the growth performance of broilers.It was recommended to add 4.5% FML to the diet for broilers.

【Objective】 The aim of this experiment was to investigate the effects of adding fermented shiitake residues to diets on the growth performance,meat quality and flavor substances of finishing pigs. 【Method】 A total of 100 Duroc×Landrace×Yorkshire crossbred finishing pigs with similar body weight (68.00 kg±0.50 kg) and health status were randomly divided into 2 groups (10 replicates per group and 5 pigs per repetition).Finishing pigs in control group was fed with a basal diet,and finishing pigs in experimental group was fed with a basal diet with the addition of 3% fermented shiitake residues.The pretrial period was 3 days,and the experiment period lasted for 59 days.After the average weight of the two groups of pigs reached 120 kg,one pig approaching to the average weight was randomly selected from each replicate for slaughter for a total of 20 pigs.After the experiment,the pigs were weighed to calculate growth performance.Blood was collected intravenously to detected serum biochemical indexes,carcasses were split to determine carcass traits,and the longissimus dorsi muscles were collected to determine the mRNA expression of myofiber type genes,meat quality and flavor substances. 【Result】 Compared with control group:① The growth performance,carcass traits and serum biochemical indexes of finishing pigs had no significant effects in experimental group (P＞0.05),but the 24 h redness value of the longissimus dorsi muscle of finishing pigs was significantly increased (P＜0.05),the dry matter,crude protein and ether extract content of the longissimus dorsi muscle of finishing pigs in experimental group were significantly increased (P＜0.05).② The longissimus dorsi muscle of finishing pigs in experimental group,the proportion of oleic acid and total monounsaturated fatty acids were significantly increased (P＜0.05),the content of leucine in the bitter amino acids was significantly decreased (P＜0.05),and the content of glutamic acid in the flavor amino acids and the equivalent umami concentration were significantly increased (P＜0.05).③ In the longissimus dorsi muscle of finishing pigs in experimental group,the taste and chewiness were significantly enhanced (P＜0.05),and the juiciness was significantly improved (P＜0.05).Based on headspace solid phase microextraction gas chromatography mass spectrometry,a total of 12 volatile flavor compounds were both identified in the two groups,and among them,the relative contents of N-heptanol,3-methylbutanol,phenylethanol,benzaldehyde,hexanal, decanal, longifolene and 1-octen-3-ol in the longissimus dorsi muscle of finishing pigs in experimental group were significantly increased (P＜0.05).④ The mRNA expression of oxidized myofibril type genes myosin heavy chain type Ⅰ and type Ⅱa were significantly increased in the longissimus dorsi muscle of finishing pigs in experimental group (P＜0.05). 【Conclusion】 The addition of 3% fermented shiitake residues to the diet did not have a significant effect on the growth performance and carcass traits of finishing pigs.But it was able to improve the color of the longissimus dorsi muscle post slaughter,enhance synergistic effects of flavor-presenting amino acids and flavor-presenting nucleotides and promote the deposition of volatile flavor substances and the proportion of oxidized myofibrillar types to improve meat quality.

【Objective】 Feed in the storage process due to moisture content,environmental temperature,humidity and other factors,feed is prone to mildew and produce mycotoxins,how to reduce the mycotoxins contamination of feed is an urgent problem to be solved currently.The aim of this experiment was to study the effects of three aluminosilicate adsorbents,namely attapulgite,permutite and montmorillonite,and mannooligosaccharides on five toxins,namely,aflatoxin B₁ (AFB₁),deoxynivalenol (DON),zearalenone (ZEN),ochratoxins A (OTA) and T-2 toxin in vitro. 【Method】 The adsorption rates of attapulgite,permutite,montmorillonite and mannooligosaccharides at the addition of 0.25%,0.5%,1% and 2%,respectively,as well as the adsorption and desorption rate of each adsorbent at different pH were determined by enzyme-linked immunosorbent assay (ELISA). 【Result】 ① The addition amount,adsorbent and interaction between the two had extremely significant effect on the adsorption rates of five toxins (P<0.01).Among them,compared with the other three additions,the adsorption rate of five toxins was extremely significantly higher at 2% addition (P＜0.01),the adsorption rate of montmorillonite on five toxins was extremely significantly higher than that of attapulgite,permutite and mannooligosaccharides (P＜0.01).② Under the condition of the same additive amount,the adsorption rates of AFB₁ by mannooligosaccharide,attapulgite and montmorillonite at pH 10.0 were extremely significantly higher than those at pH 4.0 (P＜0.01),the adsorption rate of four adsorbents on DON were extremely significantly higher at pH 10.0 than those at pH 4.0 (P＜0.01).Permutite adsorption of OTA at pH 10.0 was extremely significant higher than that at pH 4.0 (P＜0.01),and the OTA adsorption rate of attapulgite at pH 4.0 was extremely significantly higher than that of pH 10.0 (P＜0.01).At 1% addition,four adsorbents adsorbed ZEN and T-2 toxins at pH 10.0 were extremely significantly higher than those at pH 4.0 (P＜0.01).At the addition of 0.5%,mannooligosaccharides and permutite adsorbed ZEN at pH 10.0 were extremely significantly higher than those at pH 4.0 (P＜0.01), and attapulgite,permutite and montmorillonite adsorbed T-2 toxin at pH 4.0 were extremely significantly higher than those at pH 10.0 (P＜0.01).③ After adding PBS with pH 7.0 to the centrifugal precipitation at pH 4.0,the desorption rate of montmorillonite was extremely significantly lower than that of attapulgite and permutite (P＜0.01).After adding methanol to the centrifugal precipitation at pH 7.0 again,the desorption rates of montmorillonite and permutite were extremely significantly lower than those of attapulgite (P＜0.01). 【Conclusion】 The adsorption rates of four adsorbents on AFB₁,DON,ZEN,OTA and T-2 toxins at 2% addition were montmorillonite ＞ permutite ＞ attapulgite ＞ mannooligosaccharides in descending order.Four adsorbents adsorbed higher on AFB₁,DON and ZEN at pH 10.0 and 1% addition,and after the adsorption environment at pH 4.0 was changed to pH 7.0 or methanol,the adsorption rate of three adsorbents on DON,ZEN,OTA and T-2 toxins were montmorillonite ＞ permutite ＞ attapulgite in desorption rate from low to high.

【Objective】 The experiment aimed to investigate the effects of adding Polygonum hydropiper L.to high-concentrate diet on rumen fermentation parameters,microbial populations,lactic acid metabolism,and enzyme activity in sheep. 【Method】 Forty 3-month-old Duhan hybrid male sheeps with an average weight of (23.26±0.33) kg were selected and randomly divided into four groups with 10 sheeps per group.Lambs were fed individually with a crude-to-processed diet ratio of 75∶25.The levels of Polygonum hydropiper L.supplementation were 0 (control),5 (L1),10 (L2),and 15 g/d (L3).After a 15-day adaptation period,a 60-day experimental period was conducted,lasting 75 days.Rumen fluid samples were collected from all lambs 3 hours after morning feeding at the end of the experimental period for subsequent analysis of rumen fermentation parameters,microbial enzyme activities,lactic acid metabolism,and microbial populations. 【Result】 ① The total volatile fatty acid (TVFA) content in rumen fluid of sheep in group L3 was significantly higher than that in control group and L1 group (P＜0.05),the propionic acid content was significantly higher than that in the other three groups (P＜0.05),the ratio of ethylene to propylene was significantly lower than that in control group,and the ammonia nitrogen (NH₃-N) content was significantly lower than that in L1 group and control group (P＜0.05).The content of microbial protein (MCP) was significantly higher than that in L1 group and control group (P＜0.05).The contents of propionic acid and MCP in rumen fluid of sheep in L2 group were significantly higher than those in control group (P＜0.05),the ratio of ethylene to propylene and the content of NH₃-N in L2 group were significantly lower than those in control group (P＜0.05),the content of NH₃-N in rumen fluid of sheep in L1 group was significantly lower than that in control group (P＜0.05).② The activity of cellobiase in rumen fluid of sheep in L2 and L3 groups was significantly higher than that in control group (P＜0.05),and the activity of protease was significantly lower than that in control group (P＜0.05),the protease activity in rumen fluid of sheep in L3 group was also significantly lower than that in L1 group (P＜0.05),and the α-amylase activity was significantly higher than that in L1 group and control group (P＜0.05).③ Lactic acid content in rumen fluid of sheep in L3 group was significantly lower than that in control group and L1 group (P＜0.05),and lactate dehydrogenase activity was significantly lower than that in other three groups (P＜0.05).Pyruvate content and pyruvate kinase activity in rumen fluid of sheep in 3 experimental groups were significantly higher than those of control group,and L3 group was significantly higher than L2 and L1 groups (P＜0.05).④ The number of total methanogens in rumen fluid of sheep in group L3 was significantly lower than that in control group (P＜0.05),the number of total protozoa and Prevotella ruminalis was significantly lower than that in L1 group and control group (P＜0.05),and the number of Ruminococcus albus was significantly higher than that in control group (P＜0.05).The number of Ruminbacter amylophilus was significantly higher than that in L1 and control groups (P＜0.05).The number of total protozoa and Prevotella ruminalis in rumen fluid of sheep in L2 group was significantly lower than that in control group (P＜0.05),and the number of Ruminbacter amylophilus was significantly higher than that in control group (P＜0.05). 【Conclusion】 The addition of Polygonum hydropiper L. to a high-concentrate diet influenced rumen microbiota,improved fermentation,reduced A/P ratio,enhanced pyruvate-related protein synthesis,decreased NH₃-N concentrations,and regulated lactic acid metabolism by altering enzyme activities,thereby reducing lactic acid accumulation.Under these conditions,the optimal supplementation level was determined to be 15 g/d.

【Objective】 This experiment aimed to investigate the effects of Acremonium terricola culture (ATC) on the growth performance,slaughter performance,hematological parameters,serum biochemistry,and antioxidant capacity of Pekin ducks. 【Method】 A total of 216 one-day-old healthy male Pekin ducks (51.36 g±0.15 g) were randomly divided into three groups,each with eight replicates and twelve ducks per replicate.The ducks were fed a corn-soybean meal-based basal diet supplemented with 0 (control group),0.1% and 0.2% ATC.The feeding trial lasted for 42 days.Growth performance and slaughter performance were recorded,and whole blood and serum samples were collected to measure hematological parameters,serum biochemical indexes,and antioxidant indicators. 【Result】 ① There was no significant effect of dietary 0.1% and 0.2% ATC supplementation on the growth performance of Pekin ducks (P＞0.05).② The breast muscle yield of Pekin ducks in 0.1% ATC group was significantly higher than that in control and 0.2% addition groups (P＜0.05),and the liver index of Beijing ducks in 0.2% ATC group was significantly lower than that in control group (P＜0.05).③ Compared to control group,in 0.2% ATC group,lymphocyte (LYM) and monocyte (MID) counts,and red cell distribution width standard deviation (RDW-SD) of Pekin ducks were significantly increased,while white blood cell (WBC) and granulocyte (GRA) counts of Pekin ducks were significantly decreased (P＜0.05).④ Compared to control group,the serum glucose level of 0.1% and 0.2% ATC groups were significantly decreased,and serum triglyceride level of 0.1% ATC group were significantly decreased (P＜0.05).⑤ Compared to control group,the serum activities of T-SOD,CAT,and GR of 42-day-old Pekin ducks in 0.1% and 0.2% ATC groups were increased (P＜0.05).Additionally,compared to control and 0.1% ATC groups,the serum activities of GSH-Px and T-AOC of 42-day-old Pekin ducks in 0.2% ATC group were significantly increased (P＜0.05). 【Conclusion】 Dietary supplementation with 0.1% and 0.2% ATC did not improve the growth performance or organ development of Pekin ducks,but it significantly increased breast muscle percentage,enhanced immune and antioxidant capacities,and promoted glucose and lipid metabolism.

【Objective】 This study was aimed to investigate the genetic diversity,population genetic structure and genetic differentiations of Jinnan cattle,Pinglu Mountain cattle and "Taihang Yun cattle",so as to provide data bases for the protection of local cattle in Shanxi province. 【Method】 12 microsatellite (SSR) markers were selected to perform PCR amplification,sequencing and genotyping in the 3 populations(including 230 individuals).At the same time,the allele numbers,genetic heterozygosity,polymorphic information content (PIC) and genetic distance between populations were detected and calculated. 【Result】 The allele numbers of 12 SSR markers were 2 to 15.Besides,the average of effective number of alleles (Ne),observation of heterozygosity (Ho),expected heterozygosity (He) and polymorphism information content (PIC) of 3 populations were from 3.025 to 4.611,0.680 to 0.735,0.646 to 0.750 and 0.601 to 0.716,respectively.Hardy-Weinberg equilibrium (HWE) results showed that except for HAUT27 was deviated from HWE (P＜0.05) in Jinnan population,the other SSR markers were all in HWE (P＞0.05).F statistics analysis showed that the within population inbreeding coefficient (F_IS),population average inbreeding coefficient (F_IT) and population differentiation coefficient (F_ST) were ―0.012, 0.043 and 0.054,respectively.The UPGMA phylogenetic tree indicated that Jinnan cattle and Pinglu Mountain cattle were clustered firstly,then clustered with "Taihang Yun cattle".The principal coordinate analysis (PCoA) results showed that there was closer relationship between Jinnan cattle and Pinglu Mountain cattle,with genetic exchanges existing between the two populations.The STRUCUTRE analysis results found that there were population admixture among 3 populations. 【Conclusion】 The genetic polymorphisms of 3 local cattle populations in Shanxi province were higher,and they all had relatively independent phylogenetic relationships.There was more genetic exchanges between Jinnan cattle and Pinglu Mountain cattle.The results contributed to a deeper understanding of the genetic structure of 3 local cattle breeds in Shanxi province,and provided data basis for the formulation of variety protection plans.

【Objective】 This study was aimed to construct specific genetic markers for Tibetan horses based on the analysis of the population structure and genetic diversity of domestic horses,so as to provide a theoretical basis for identification of Tibetan horses. 【Method】 This study conducted population structure and genetic diversity analysis of global domestic horses and construct specific genetic markers for Tibetan horses utilizing genome sequences data of 404 horses from 47 breeds. 【Result】 The whole-genome resequencing yielded a total of 8 917 800 high-quality single nucleotide polymorphism (SNP).The results of the global domestic horse population structure analysis revealed significant ancestral genetic differences between Shetland ponies and other groups.The population genetic diversity analysis indicated that compared with Middle Eastern,European and American horses,as well as other Asian horse breeds,which had experienced strong selective breeding pressure and consequently a decrease in genetic diversity,Chinese domestic horses had maintained good genetic diversity.A set of 110 SNPs specific markers for Tibetan horses was constructed,which could effectively distinguish Tibetan horses from other domestic horses worldwide,with an identification accuracy rate of 100%. 【Conclusion】 In summary,the global domestic horse population structure was complex.Western horse populations had more similar genetic backgrounds and lower genetic diversity,whereas Chinese domestic horses possessed higher genetic diversity,offering greater breeding potential.The specific genetic markers for Tibetan horses developed in this study provided a theoretical basis for the identification of Tibetan horse breeds worldwide and offered new technical support for the conservation and development of local Chinese horse breeds.

【Objective】 Testicular Sertoli cells (SCs) are located in the epithelium of seminiferous tubules,which provide physical framework and energy material support for the development of male germ cells at different stages of differentiation,and are very important for spermatogenesis.The purpose of this experiment was to study the technical method of separating SCs from frozen testicular tissue in Pengbo Semi-fine wool sheep under the condition that it was inconvenient to obtain fresh testicular tissue samples in sheep. 【Method】 The cryopreserved testicular tissue of Pengbo Semi-fine wool sheep was resuscitated by cryopreservation solution.The morphology of the recovered testicular tissue was detected by hematoxylin-eosin (HE) staining.The testicular SCs were isolated,purified and cultured by combined enzyme digestion and differential adherence method,the growth pattern was observed,and the growth curve was drawn.The specific genes in testicular SCs were identified by RT-PCR and immunofluorescence staining (IF). 【Result】 The spermatic cord and leydig of frozen-thawed testis were well preserved.Spermatogenic epithelial cell suspension meeting the experimental requirements could be obtained after digestion with combined enzymes.After 2-4 h of separation and culture,the cells adhered to the wall,and the shape was spindle or irregular polygon.After 3-4 d of culture,they converged,and the growth rate was slow after 1-2 d of culture.The proliferation rate was accelerated after 3-4 d of culture,and,the proliferation rate was reduced after 7-8 d of culture.RT-PCR detection showed that GNDF,WT1,ABP and SOX9 genes were specifically expressed in testicular SCs of Pengbo Semi-fine wool sheep,and IF results showed that the specific antibodies GATA4 and Vimentin were immune positive. 【Conclusion】 The primary SCs that met the experimental conditions could be isolated and applied to scientific experimental research after the cryopreservation of testicular tissue pretreated with antifreeze was revived.

【Objective】 The large-scale farming of Tibetan Holstein cattle had great economic meaning in this region,but the population characteristics of growth and milk production traits of Holstein cattle were generally significantly reduced after the introduction of Holstein cattle into plateau areas.This study aimed to explore the potential influencing factors of conformation traits and milk production traits of Tibetan Holstein cattle and their correlation with milk production traits. 【Method】 The linear classification records of 20 conformation traits of 237 Holstein cattle and 895 DHI records on a large-scale ranch in Lhasa,Tibet were collected,and the scores of 5 parts (body capacity,rump,feet and leg,mammary system and dairy character) and final score were calculated.The GLM procedure of SAS 9.2 software was used to analyze the influencing factors of parts scores of conformation traits of Holstein cattle,such as source pasture,parity,identifier and so on.The correlation coefficients of five parts scores,final score and daily milk yield were calculated by Pearson correlation analysis program of IBM SPSS Statistics 21 software. 【Result】 The absolute values of the deviation between the mean and ideal score of conformation traits of Holstein cattle in Tibet ranged from 0.30 (stature) to 3.70 (rear udder height),and the mean of 5 parts scores and final score ranged from 78.97 (rump) to 87.72 (body capacity).The average daily milk yield was 21.23 kg,the average percentage of milk fat and milk protein were 4.45% and 3.75%,and the somatic cell count ranged from 0.30×10⁴ to 28.60×10⁴/mL.The results of ANOVA analysis showed that the source pasture and identifier had a significant effect on final score (P<0.05),while days in Tibet and lactation days had no significant effects on the 5 parts scores and final score (P>0.05).The parity effect only had a significant effect on the feet and leg score (P<0.05).There was a medium to high significant correlation between the 5 parts scores and the final score (0.395-0.857),but the correlation between conformation traits and the daily milk yield was low,ranging from ―0.021 (body capacity and daily milk yield) to 0.117 (rump and daily milk yield). 【Conclusion】 The conformation traits of Tibetan Holstein cattle were significantly affected by a variety of feeding and management factors,and were related to milk production traits.This study laid the data foundation for the future development of large-scale breeding and regional characteristic breeding of Holstein cattle in high-altitude climate areas.

Correct meiotic spindle assembly in mammalian oocytes is crucial for ensuring accurate chromosome separation during meiosis.Transferring a complete set of chromosomes to daughter cells during cell division is essential for development and tissue homeostasis.Abnormal assembly of bipolar spindles often cause chromosomal missegregation,which in turn can easily lead to natural miscarriage and chromosomal birth defects.Therefore,exploring the mechanism of spindle assembly is necessary for understanding the process of meiosis.In somatic cells,mitotic spindle assembly is mediated by the centrosome acting as the microtubule organizing center.However,mammalian oocytes lack typical centrosomes and rely on other pathways such as microtubule organizing centers (MTOC) to assemble spindle.Although many components and pathways contributing to spindle assembly have been described,the assembly and functional mechanisms of acentriolar spindle still need to be improved.This review introduces the process of acentriolar spindle assembly in mammalian oocytes,and focus on the molecular mechanisms involved in microtubule nucleation,spindle polarization and elongation,chromosome arrangement and separation,as well as the role of spindle checkpoint (SAC) in spindle assembly.In addition,the mechanism by which chromosomes and actin filaments participate in spindle assembly during meiosis is also discussed in this review,aiming to provide reference for the study of bipolar spindle assembly and chromosome separation mechanisms in mammalian oocytes.

【Objective】 The purpose of this study was to explore the polymorphisms of phospholipid phosphatase 3 (PLPP3) gene and its correlation with back fat thickness and fatty acid content of Beijing Black pigs,in order to provide reference for genetic improvement of back fat thickness and fatty acid content of Beijing Black pigs. 【Method】 In this study,the ear tissue samples of 239 Beijing Black pigs were collected to obtain genomic resequencing data.The thickness of back fat in different parts of 239 Beijing Black pigs (the thickest of the shoulder,junction of the 6-7 thoracic vertebrae,thoracolumbar junction,the joint of the lumbar sacral) and the contents of 5 fatty acids (palmitic acid,stearic acid,oleic acid,linoleic acid,α-linolenic acid) in the back fat of junction of the 6-7 thoracic vertebrae of the left carcass were determined.The sequencing results were utilized to study the population genetic characteristics and haplotype linkage of single nucleotide polymorphism (SNP) sites in the PLPP3 gene,and conduct association analysis between SNPs and back fat thickness and fatty acid content in various parts.The transcription factor of SNP in promoter region were predicted,and the differential gene expression in back fat of individuals with different genotypes of PLPP3 functional SNPs were detected by Real-time quantitative PCR. 【Result】 A total of 8 SNPs of PLPP3 gene were detected in the Beijing Black pig population,of which 5 were moderate polymorphisms (0.25＜PIC＜0.5) and 3 were low polymorphisms (PIC＜0.25),g.155894136 C＞T was in Hardy-Weinberg equilibrium (P＞0.05).Haplotype linkage analysis showed that there was a strong linkage between g.155800228 G＞A and g.155800259 A＞C (D’=91%).There was a certain linkage between g.155891807 G＞A and g.155891715 A＞G(D’＞80%).The association analysis between gene polymorphism and backfat thickness showed that there were significant differences in back fat thickness among individuals with different genotypes,including g.155800222 C＞A,g.155891715 A＞G,g.155891807 G＞A,g.155894136 C＞T (P＜0.05).The association analysis between gene polymorphism and fatty acid content showed that there were significant differences in the content of palmitic acid and the ratio of linoleic acid/α-linolenic acid in back fat among individuals with different genotypes,including g.155800222 C＞A,g.155800228 G＞A (P＜0.05).TFs prediction of SNPs in promoter region found that the mutation of g.155800228 G＞A caused the binding transcription factor to change from SPI1 to MYB.Further analysis of PLPP3 gene expression differences among different genotypes at g.155800228 G＞A showed that PLPP3 gene mRNA level in AA individuals was significantly higher than that in GG individuals (P＜0.05). 【Conclusion】 In summary,the different genotypes of PLPP3 gene were significantly differences with the thickness of back fat and the content of some fatty acids in different parts of Beijing Black pigs.It could be used as a potential molecular marker of back fat thickness and fatty acids content of Beijing Black pigs,and provided theoretical support for breeding of Beijing Black pigs.

【Objective】 The aim of this study was to investigate the effect of SOX12 gene on the replication of Porcine epidemic diarrhea virus (PEDV),so as to provide the effective molecular marker for anti-PEDV breeding. 【Method】 Three SOX12 gene interference sequences (siRNA1,siRNA2 and siRNA3) and a negative control sequence (siNC) were synthesized and transfected into African green monkey kidney cells (Vero cells) in this study.At 48 h after transfection,the cells were collected,and the interference efficiency was detected by Real-time quantitative PCR.Effective interference fragments and siNC were transfected into Vero cells for 24 h,respectively.Then,the cells were infected with PEDV at a multiplicity of infection of 0.05,and divided into four groups:PEDV-infected assay group at 12 h (12 hpi-siRNA),PEDV-infected control group at 12 h (12 hpi-siNC),PEDV-infected assay group at 24 h (24 hpi-siRNA),and PEDV-infected control group at 24 h (24 hpi-siNC).Cell samples from each group were collected and their RNA was extracted.The expression of PEDV N and SOX12 genes was detected by Real-time quantitative PCR,and the expression of PEDV N protein was analyzed by Western blotting.The viral titer of PEDV was determined through 50% tissue culture infective dose (TCID₅₀) assay,and the replication of PEDV of cells in each group was detected using indirect immunofluorescence (IFA) method.The SOX12 interaction genes were predicted using GeneMANIA website,and the expression changes of these interaction genes were detected by Real-time quantitative PCR after inhibiting SOX12 gene expression. 【Result】 The interference efficiency of the three SOX12 interfering fragments was 30% to 60%,with siRNA3 showing the highest efficiency of 60%.Compared with 12 hpi-siNC and 24 hpi-siNC groups,the transcription and protein expression of PEDV N gene in 12 hpi-siRNA and 24 hpi-siRNA groups was significantly decreased,respectively (P＜0.05).The results of the viral titer phenotype determination indicated that the viral titers of PEDV in 12 hpi-siRNA and 24 hpi-siRNA groups were significantly lower than that in their control groups,respectively (P＜0.05).IFA results also showed that PEDV replication in 12 hpi-siRNA and 24 hpi-siRNA groups was significantly less than that in control group.The gene interaction prediction and Real-time quantitative PCR detection results revealed that compared with siNC group,the expression of interacting genes (SOX17,DDX51,ZMIZ2,SSRP1,TAF6 and ABCB8) were significantly decreased after interfering with SOX12 gene expression (P＜0.05). 【Conclusion】 This study revealed that the regulatory role of SOX12 gene in the process of PEDV infection in Vero cells,and found that the downregulation of SOX12 gene expression significantly inhibited PEDV replication and the expression of its interacting genes SOX17, DDX51,ZMIZ2,SSRP1,TAF6 and ABCB8.

【Objective】 This study was aimed to establish a rapid and accurate method for targeted insertion of exogenous genes into the Duck enteritis virus (DEV) genome using the HDR-CRISPR/Cas9 gene editing technology under optimized conditions,so as to lay the foundation for the development of recombinant vaccines utilizing DEV as a vector. 【Method】 The DEV vaccine strain was isolated,propagated,and the viral titer was determined.The gRNA was designed and synthesized based on the non-coding sequence between UL26 and UL27 genes,then inserted into PX459-V2.0 to form the gRNA-Cas9 plasmid.Simultaneously,the enhanced green fluorescent protein (EGFP) reporter gene was inserted into the PVAX-1 vector via conventional gene cloning techniques to construct a recombinant expression plasmid containing the eukaryotic expression cassette P_CMV-EGFP-BGH pA.Using the DEV genome as a template,upstream and downstream homologous arm sequences of the gRNA target site were amplified,fused with P_CMV-EGFP-BGH pA,and cloned into PUC19 to obtain donor plasmid PUC19-UP-EGFP-DOWN. Recombinant virus rDEV-EGFP was constructed by transfecting plasmid and infecting parent DEV.The experimental conditions for the construction of the recombinant virus were optimized by controlling single variable method,and the optimal conditions were determined based on the number of green fluorescent plaques formed under different conditions.The plaques expressing green fluorescence were screened and purified using the limited dilution method to obtain the recombinant virus rDEV-EGFP.Subsequently,the genetic stability and in vitro replication ability of the recombinant virus rDEV-EGFP were evaluated. 【Result】 PCR amplification and sequencing results showed that the gRNA-Cas9 plasmid targeting the non-coding region between UL27 and UL26 genes of DEV genome and the donor plasmid containing EGFP eukaryotic expression box were successfully constructed.The chick embryo fibroblast (CEF) was infected with DEV after being transfected with gRNA-Cas9 and donor plasmid,and green fluorescence plaque could be observed under fluorescence microscope.The results showed that the EGFP reporter gene was successfully inserted into DEV genome using HDR-CRISPR/Cas9 gene editing technology.The optimal experimental conditions were as follows:Multiplicity of infection (MOI) of DEV was 0.2,the transfection ratio of gRNA-Cas9 plasmid to donor DNA was 1∶2,the transfection form of donor DNA was DNA fragment,the interval between transfection and infection was 6 h,and the collection time of recombinant virus was 48 h after DEV infection.After optimization,the knockin efficiency of EGFP reporter gene was significantly increased (P ＜ 0.05).Recombinant virus rDEV-EGFP was passed in CEF for 15 consecutive passages,and the EGFP eukaryotic expression box was still stably integrated in the non-coding region between UL26 and UL27 genes,showing good genetic stability.The results of growth curve showed that the replication ability of recombinant virus rDEV-EGFP in CEF was not significantly different from that of the DEV vaccine strain,and the growth trend was consistent,indicating good in vitro replication ability. 【Conclusion】 In this study,a method for rapidly constructing recombinant DEV based on HDR-CRISPR/Cas9 gene editing technology was established.Recombinant virus rDEV-EGFP with good genetic stability and in vitro replication ability was successfully constructed,which provided a theoretical basis and technical platform for the development of recombinant DEV vector vaccine candidate strains.

【Objective】 The objective of this experiment was to investigate the genetic variation of epidemic strains of Tembusu virus (TMUV) from waterfowl and the molecular characteristics of membrane precursor protein (prM) and membrane protein (E). 【Method】 BHK-21 cells were used to isolate the virus from the liver tissue samples of ducks and geese suspected to be infected with TMUV,and the whole gene sequence of the isolates was obtained by whole gene cloning,sequencing and splination.ModelFinder and MrBayes were used to analyze the genetic evolution of open reading frame (ORF) and E genes.With TMUV MM1775 in GenBank database as reference,amino acid mutation sites of prM and E proteins were analyzed.The transmembrane region,B-cell epitope,secondary and tertiary structures of prM and E proteins were predicted by bioinformatics online software. 【Result】 Two strains of TMUV from waterfowl were isolated and named as FSE and ZJ2,respectively.Whole genome genetic evolution analysis showed that the isolates FSE and ZJ2 belonged to Cluster 2.1.1 and Cluster 2.2,respectively.Amino acid variation sites analysis showed that there were multiple amino acid variation sites in prM and E proteins of the isolates FSE and ZJ2.The results of bioinformatics analysis showed that E protein of the isolates FSE and ZJ2 had 2 transmembrane regions.There were multiple linear B cell epitopes in prM and E proteins.Compared with the amino acid sequences of prM and E epitopes of vaccine strain DF-2,prM protein of the isolate FSE had mutation at the E73H amino acid site,and the E protein had mutation at the A157V amino acid site.The secondary structure was dominated by random coil,and the prediction result of tertiary structure was consistent with those of secondary structure. 【Conclusion】 In this study,two Cluster 2 TMUV were isolated from Guangdong province,and the prM and E proteins of the two isolates had multiple amino acid mutation sites,indicating that TMUV was still mutating during the epidemic process in Guangdong province.

In recent years,the frequent emergence of antibiotic-resistant bacteria worldwide has posed a great challenge to public health,prompting the research community to explore novel antibacterial strategies other than traditional antibiotics.Phages,as natural enemies of bacteria,have attracted extensive research interest due to their unique antibacterial properties that make them potential alternatives to antibiotics.Phages exhibit diverse bacterial inhibitory mechanisms by directly disrupting bacterial cell structures,such as cell membranes and cell walls,triggering bacterial lysis,or indirectly interfering with bacterial metabolic pathways and life processes to effectively inhibit bacterial growth.In view of this,a comprehensive analysis of phage-encoded bacteriostatic proteins,their mechanisms of action and their synergistic effects is of critical scientific value to guide the development and optimisation of novel phage therapeutics and to uncover new targets for antibacterial treatment.The authors summarize and evaluate recent developments in the study of phage inhibitory proteins,with a special focus on the classification,mechanism of action and their multidimensional effects on the bacterial life cycle,so as to reveal the potential of phage proteins for innovative antibacterial applications by exploring in detail how these molecules precisely target and inhibit key physiological processes in bacteria,including the cleavage of cellular structures,interference with DNA replication,protein synthesis and cell wall synthesis.Meanwhile,several examples are included to demonstrate the effectiveness of phage proteins in different application scenarios,such as clinical therapy,food safety and environmental protection,to further emphasize their practical translational significance.The comprehensive analysis in this review will not only enhance the scientific understanding of the antimicrobial mechanism of phage proteins,but also provide innovative perspectives and strategies to address the crisis of antibiotic resistance,and facilitate the exploration of a new way for antimicrobial research.

【Objective】 This study was aimed to investigate the genetic variation of Porcine reproductive and respiratory syndrome virus (PRRSV) in pig farms in South China in 2023,and provide theoretical basis for PRRSV prevention and control in South China. 【Method】 Real-time quantitative PCR was used to detect PRRSV in 328 samples collected from different pig farms in South China.ORF5 gene of 29 representative PRRSV-positive samples from different pig farms were sequenced and analyzed for genetic evolution. 【Result】 The positive rate of PRRSV in all samples was 54.27% (178/328).The sequence analysis of ORF5 gene of 29 strains of PRRSV showed that all the obtained strains belonged to the genotype Ⅱ.The nucleotide sequence similarity between the 29 PRRSV ORF5 gene was 83.7% to 100%,and the amino acid sequence similarity was 83.0% to 100%.Among them,6 strains belonged to lineage 1 represented by the recombinant strain NADC30-like,2 strains belonged to lineage 5 represented by the classical strain VR2332,and 21 strains belonged to lineage 8 represented by the highly pathogenic strain JXA1.The amino acid mutations derived from the ORF5 gene were mainly concentrated in 2 highly variable regions,1 bait epitopes,and 3 transmembrane regions.5 strains of lineage 1 showed a V27A mutation in the bait epitope region,while 2 strains of lineage 5 showed a V29A mutation in the bait epitope region.In the neutralizing epitope region,8 strains of lineage 1 exhibited I39L mutations,and 5 strains of lineage 8 exhibited I39F mutations.In virulence-related loci,some strains had undergone mutations in R13Q,R151K,R151I and R151G.In addition,there were more variations in the N-glycation sites of lineage 1,mainly concentrated in amino acids at positions 30－32,32－34,33－35,34－36,35－37 and 57－59,while the N-glycation sites of lineage 5 and lineage 8 were relatively conserved. 【Conclusion】 At present,there was a high positive rate of PRRSV in pig farms in South China.The prevalence of PRRSV was characterized by multi-lineage genotype Ⅱ strains,with lineage 8 and lineage 1 strains accounting for a relatively high proportion and having complex and diverse variations.It was necessary to strengthen the monitoring of PRRSV,understand the genetic variation among PRRSV strains,and timely implement prevention and control measures.

Chicken infectious anemia (CIA) is one of the most common immunosuppressive infectious diseases in clinical practice.Currently,there is no specific therapy,which poses a serious threat to animal health and the economic benefits of the poultry industry.Although some areas have used live vaccines for clinical prevention of CIA,safety concerns and the low efficiency of virus cultivation and production are the main bottlenecks restricting the promotion and application of live vaccines.The authors conduct a comprehensive analysis of the etiology and epidemiological characteristics of the Chicken infectious anemia virus (CIAV) that causes CIA,as well as the immune response features and protective power of traditional vaccines and new vaccines in stimulating the host’s immune system.By dissecting the advantages and disadvantages of existing vaccines and integrating the theoretical and technological strengths of new vaccines,the authors propose a research direction for the development of efficient CIA vaccines,and provide new ideas and scientific basis for the development of CIA vaccines.

【Objective】 The aim of this experiment was to study the biological characteristics of eight potential probiotic strains isolated from the intestinal tract of geese,and provide a reference for the subsequent development and utilization of the strains in a rational way. 【Method】 The strains were characterized by morphological observation,biochemical identification,PCR identification and 16S rRNA gene sequencing.Biological characterization of the strains included acid production,optimum growth temperature,acid resistance,bile salt resistance,bacteriostatic activity and enzyme production were tested.The drug resistance of the strains was analyzed by drug sensitivity test and drug resistance gene detection. 【Result】 Eight strains of bacteria isolated from goose intestines were named A1-A5 and X1-X3,respectively.Through morphological observation and biochemical identification,it was preliminarily determined that A1-A5 were Bacillus and X1-X3 were lactic acid bacteria.PCR amplification of 16S rRNA gene obtained bands of about 1 500 bp in all isolates.The sequence similarity alignment results of 16S rRNA gene showed that A1 and A2 were Bacillus subtilis,A3-A5 were Bacillus velezensis,Bacillus amyloliquefaciens and Bacillus licheniformis respectively,X1-X3 were Lactobacillus fermentum, Lactobacillus reuteri and Lacticaseibacillus paracase,respectively.The results of acid production performance showed that X1-X3 had strong acid production performance,and the acid production performance of X1 was the best,with the pH reaching 3.84 at 36 h.The optimal growth temperature of all eight strains of bacteria was 37 ℃.The results of acid and bile salt resistance test showed that all eight strains of bacteria had good tolerance,among which A2 had the best tolerance,with a survival rate of more than 70% when the pH was 4.0 and the bile salt concentration was 0.9%.The results of the bacterial inhibition test showed that all eight strains of bacteria had good bacterial inhibition,and the inhibition zone diameters were all above 10.00 mm,among which A2 had the best bacterial inhibition effect.The results of the enzyme production performance test showed that A1-A5 had strong enzyme production performance,and the enzyme production effect of A2 was the best,with the diameter of the amylase ring reaching 15.5 mm,and the diameter of the cellulase ring reaching 14.3 mm.The results of the drug sensitivity test showed that the eight strains of bacteria were more than moderately sensitive to most antibacterials.Resistance gene analysis showed that tetracycline gene TetA (25.0%),quinolone gene GyrA (12.5%) and macrolide gene ErmF (12.5%) were the major resistance genes,among which strain A3 carried tetracycline gene TetA (480 bp),strain A4 carried quinolone gene GyrA (382 bp) and tetracycline gene TetA (480 bp),and strain X1 carried the macrolide gene ErmF (306 bp). 【Conclusion】 Among the eight strains of bacteria isolated from the intestinal tract of geese,Bacillus subtilis A2 had strong probiotic properties and had the potential to be used as a microecological agent of goose origin.

【Objective】 This study was aimed to investigate the effect of total flavonoids from Melastoma dodecandrum Lour.(TFMD) on lipid peroxidation in diabetic nephropathy (DN) mice,and explore the medicinal value of TFMD in renal function protection and anti-lipid peroxidation,so as to provide experimental basis for the clinical application of Yao medicine Melastoma dodecandrum Lour. 【Method】 Ninety SPF male C57BL/6J mice were randomly divided into blank group (n＝10) and model group (n=80).Mice in blank group were given normal diet,and mice in model group were given high-fat diet for 6 weeks,after fasting for 12 h,mice in model group were intraperitoneally injected with streptozotocin (STZ) 0.05 g/kg,and mice in blank group were injected with the same dose of sodium citrate buffer.After 5 days of continuous injection,fasting blood glucose (FBG) was measured at 72 h and 1 week after the last injection.Mice with FBG≥16.7 mmol/L for two consecutive times were randomly divided into DN model group (high-fat diet),metformin group (high-fat diet＋0.5 g/kg metformin),TFMD high-dose group (high-fat diet＋1.2 g/kg TFMD),TFMD middle-dose group (high-fat diet＋0.8 g/kg TFMD) and TFMD low-dose group (high-fat diet＋0.6 g/kg TFMD),10 mice in each group.After 10 weeks of administration,the general physiological status of mice was observed during administration,and FBG was detected weekly.After 10 weeks of administration,24 h urine was collected,FBG of mice in each group was detected by cutting tail,and the kidney index were calculated. The levels of urine protein (UP) and microalbumin (MAU),serum urea nitrogen (BUN) and serum creatinine (SCr),and activities of glutathione (GSH) and superoxide dismutase (SOD) and levels of malondialdehyde (MDA) in renal tissue were detected.The expression of Nephrin,podocin,PTGS2 and ACSL4 proteins in renal tissue of mice in each group was detected by Western blotting.HE and PAS staining sections of kidney tissues of mice in each group were made and pathological changes were observed. 【Result】 Compared with blank group,the body weight,GSH and SOD activities of mice in DN model group were extremely significantly decreased (P＜0.01),FBG,kidney index,the levels of MAU,UP,SCr,BUN and MDA were extremely significantly increased (P＜0.01),the expression of Nephrin and podocin proteins in renal tissue was extremely significantly decreased (P＜0.01),the expression of PTGS2 and ACSL4 were significantly increased (P＜0.05),and severe damage was observed in renal tissue under light microscope,indicating that the DN model was constructed successfully.TFMD could improve the weight loss of DN mice,significantly reduce the kidney index and FBG (P＜0.05 or P＜0.01),reduce the levels of UP,MAU,SCr and BUN in DN mice (P＜0.01),and increase the levels of Nephrin and podocin in renal tissue (P＜0.05).The damage of kidney tissue in TFMD group was recovered to different degrees.TFMD also increased the levels of GSH and SOD in DN kidney tissue (P＜0.05 or P＜0.01),decreased the level of MDA (P＜0.05 or P＜0.01),down-regulated the expression of lipid peroxidation-related proteins PTGS2 and ACSL4 in kidney tissue (P＜0.05 or P＜0.01),improved the body’s antioxidant capacity and slowed down the body’s lipid peroxidation and its product accumulation. 【Conclusion】 TFMD could significantly delay the occurrence and development of DN induced by high-fat diet combined with STZ,and its mechanism was related to the regulation of lipid peroxidation and oxidative stress,and the regulation of PTGS2/ACSL4 signaling pathway.

【Objective】 The purpose of this experiment was to investigate the resistance characteristics and pathogenicity of Enterobacter hormaechei in a large-scale pig farm in Yili,Xinjiang,and provide reference for the prevention and control of Enterobacter hormaechei. 【Method】 Bacteria was isolated and purified from the samples of anal and nasal swabs of pigs.The isolate was identified by Gram staining,morphological observation,colony morphological characteristics,biochemical characteristics,species-specific detection and 16S rRNA sequencing analysis.The sensitivity of the isolate to 20 commonly used antibiotics was determined by K-B method.The drug resistance genes and virulence genes were detected by PCR,and the pathogenicity was analyzed by animal test.The biofilm forming ability of the isolate was measured by glass tube method and microtitration plate method. 【Result】 A strain of bacteria was isolated and named H1.The isolate could form milky white colonies with protrusion,smooth and wet surface on the nutrient agar medium.Gram staining showed that the bacteria were red in short rod shape and scattered in arrangement.The results of biochemical identification showed that glucose,lactose,urea and other biochemical tests were positive,and hydrogen sulfide and phenylalanine were negative.PCR results showed that the target bands of Eh specific gene and 16S rRNA were 487 and 1 476 bp,respectively.Sequencing results showed that the similarity between the isolated strain and Enterobacter hormaechei reached 100%,and the isolated H1 was comprehensively determined to be Enterobacter hormaechei.The isolate was resistant to 15 antibiotics,such as enrofloxacin,flufenicol and cotrimoxazole,and sensitive to 5 antibiotics,such as polycolistin B and ciprofloxacin.It carried 8 drug resistance genes (bla_CTX-M-1,tem,sul1,sul2,sul3,tetA,tetM and qnrB genes) and 5 virulence genes (fimA,csdg,papD,ompA and cpa genes).The results of animal pathogenicity test showed that the isolte was pathogenic to mice,causing duodenum,liver,spleen and kidney damage after infection,and had strong biofilm formation ability. 【Conclusion】 In this study,a strain of Enterobacter hormaechei was isolated and obtained,which showed multiple drug resistance,carried multiple drug resistance genes and virulence genes,had certain pathogenicity to mice,and had strong biofilm formation ability.The results provided a scientific basis for the prevention and control of Enterobacter hormaechei.

【Objective】 Yeast with probiotic potential was isolated and identified from the rumen fluid of sika deer,and its probiotic functions in vitro were evaluated to provide a reference for its application in animal nutrition and feed and the development of deer derived probiotic preparations. 【Method】 The yeast strain was isolated from rumen fluid of healthy male sika deer by YPD solid medium.The isolate was identified by morphological observation,physiological,biochemical and molecular biology.The growth performance and acid production were measured,and the growth curve was drawn.The tolerance of the isolate in different pH,different concentration of bile salts,artificial gastric fluid and artificial intestinal fluid was investigated.The drug sensitivity of the strain was detected by Kirby-Bauer (K-B) method,and the safety of the strain was tested in mice. 【Result】 A dominant yeast strain was isolated from rumen fluid of sika deer and named DZ018.The morphological characteristics,physiological and biochemical characteristics and ITS rRNA sequence of the colony were consistent with those of Candida rugosa.The results of growth performance test showed that the isolate grew rapidly in YPD liquid medium,entered logarithmic growth stage after cultured for 2 h,and had a certain ability to produce acid.The results of tolerance evaluation showed that the isolate had good tolerance to low pH,and could grow normally in the range of pH 2.5-6.5,and the optimal growth pH was 4.5.The isolate had strong tolerance to bile salts,and the survival rate was ＞100% in 0.3% and 1.0% bile salts,and the survival rate reached 74.27% in 2.0% bile salt.The survival rate of artificial gastric fluid and intestinal fluid was 31.64% and 64.80%,respectively.The results of drug sensitivity test showed that the isolate was sensitive to fluorocytosine,fluconazole and ketoconazole,and resistant to amphotericin B.The results of safety test in mice showed that the isolate had no adverse effects on the growth performance and organ coefficient of mice. 【Conclusion】 In this study,a strain of Candida rugosa DZ018 with probiotic potential was isolated from rumen fluid of sika deer,with strong tolerance and good safety.The experimental results provided reference and theoretical basis for the application of deer probiotics in the production of deer animals and the development of microecological preparations.

Antibiotic resistance is a global public health issue that seriously threatens the health of animals and humans.Prevalence of antibiotic resistance in animals is particularly prominent in China,posing a serious threat to the safety of aquaculture.It is urgent to develop new natural and efficient antibacterial drugs or alternative antibiotics.Usnic acid,also known as lichen acid,is one of the main active ingredients in plant extracts such as Pineapple and Litmus.Usnic acid has been widely studied and it has been demonstrated to have various pharmacological activities,including antibacterial,anti-inflammatory,anti-tumor,antiviral,anti-tuberculosis,anti-parasitic,analgesic,and antipyretic properties.It has been reported that usnic acid has good antibacterial activity against Gram-positive bacteria.The potential mechanisms may involve the inhibition of nucleic acid and protein synthesis,interference with efflux pumps,disruption of cell membrane integrity,disruption of bacterial metabolic homeostasis,and inhibition of biofilm formation.Usnic acid is considered as a potent antibacterial adjuvant based on its synergy effect with several clinical antibiotics such as polymyxin to overcome antibiotic resistance.Usnic acid is reported to have the poor solubility and toxicity issues,which limits its application.The author reviewed the antibacterial activity,mechanism of action,potential toxicity,and research progress on nanomaterials of usnic acid,following to offer the theoretical basis for its further development and utilization.

【Objective】 The resistance and virulence genes of Klebsiella pneumoniae,which could easily cause pneumonia and other diseases of adult forest musk deer,were analyzed in a forest musk deer farm in Guangdong,so as to provide reference for effective prevention and control of diseases caused by Klebsiella pneumoniae. 【Method】 In this study,81 fresh feces of forest musk deer were collected from a forest musk deer ranch in Guangdong. Klebsiella pneumoniae was isolated and purified by isolation culture,morphological observation,biochemical analysis,and PCR amplification of 16S rRNA and hemolytic enzyme (khe) genes.The characteristics of isolates were studied by serotype identification,drug susceptibility test,drug resistance and virulence genes detection. 【Result】 The isolates formed pink,smooth and moist single colony on McConkey plate.The strain showed short red rod shape under the microscope after Gram-staining and was Gram-negative.Strains with biochemical characteristics consistent with Klebsiella pneumoniae were selected for PCR amplification.PCR amplification of 16S rRNA gene showed that a band with a size of about 1 542 bp was obtained.A total of 33 isolates showed a nucleotide similarity of over 98% with the 16S rRNA gene of Klebsiella pneumoniae in GenBank database,and the specific gene khe was detected as positive.Therefore,this study successfully isolated and identified 33 strains of Klebsiella pneumoniae from 81 samples.The serotype test results showed that the dominant serotype among the isolates was K57.The drug sensitivity results showed that the isolates exhibited varying degrees of resistance to penicillin,aminoglycosides,tetracyclines,sulfonamides,chloramphenicols,quinolones and monocyclic β-lactams.However,it was sensitive to cephalosporins and carbapenems.Among the 12 drug resistance genes detected,the detection rates of bla_SHV and oqxA genes were both 96.97%.The detection rates of aac(6')-Ⅰb-cr,rmtB,tetA,tetM,sul1,sul2,oqxB and floR genes were 57.58%,51.52%,78.79%,84.85%,72.73%,66.67%,87.88% and 51.52%,respectively.bla_KPC and bla_NDM genes were not detected.Among the 9 virulence genes detected,the detection rates of wabG,uge,mrkD,entB and ureA genes were 90.91%,96.97%,96.97%,100% and 100%,respectively.The detection rates of aerobactin and allS genes were 6.06% and 18.18%,respectively,and ybtA gene was not detected. 【Conclusion】 In this study,33 strains of Klebsiella pneumoniae were isolated and identified from forest musk deer.The dominant serotype was K57,which had multiple drug resistance and a high carrying rate of drug resistance genes and virulence genes.The results of this study could provide data support for the prevention and control of diseases caused by Klebsiella pneumoniae from forest musk deer.

【Objective】 Klebsiella pneumoniae infection is a common cause of mastitis in dairy cows,which induces acute clinical mastitis with severe clinical symptoms,resulting in reduced milk production and quality,thereby causing significant economic losses to dairy farms.The purpose of this study was to explore the virulence effects of different sequence types (ST) of Klebsiella pneumoniae originating from cow mastitis,and screen for potential key virulence genes that contribute to the infectious role of Klebsiella pneumoniae. 【Method】 The multi-locus sequence typing (MLST) method was employed to analyze the distribution of ST among 129 strains of Klebsiella pneumoniae isolated from clinical mastitis cases in two large dairy farms located in Shandong and Hubei provinces.Subsequently,3 of the most prevalent ST of Klebsiella pneumoniae were selected to establish mastitis model in mice,and the morphological damage and expression changes of inflammatory factors in mammary glands of mice were investigated.The key virulence genes associated with Klebsiella pneumoniae infection were screened by analyzing the infection characteristics and virulence gene distribution of Klebsiella pneumoniae. 【Result】 129 strains of Klebsiella pneumoniae were categorized into 79 ST types,of which ST107 accounted for the highest proportion of 19.37%,followed by ST2324 (7.75%) and ST13 (3.87%).Compared with ST107 and ST13,ST2324 induced Klebsiella pneumoniae clinical score and mammary gland bacteria load were significantly increased 24 h after infection (P ＜ 0.05).The acinar contour disappeared and a large number of inflammatory cells infiltrated,and the mRNA expressions of interleukin-1β (IL-1β),tumor necrosis factor-α (TNF-α),and cytochrome C (Cyt C) were significantly increased (P ＜ 0.05).Virulence gene detection results showed that 74 virulence genes were detected in 3 different ST isolates,among which the virulence genes manB, pla and pilW were detected in ST2324 but not in ST13 and ST107. 【Conclusion】 In this study,a total of 79 ST types were detected from 129 strains of Klebsiella pneumoniae,among which ST2324,ST107 and ST13 were detected with high rates,and ST2324 had the strongest pathogenicity to mice,and the virulence genes manB,pla and pilW were closely related to the high pathogenicity of Klebsiella pneumoniae.The results of this study provided a theoretical reference for further analysis of the mechanism of Klebsiella pneumoniae infection of dairy cow mastitis.

【Objective】 The aim of this experiment was to screen Bacillus with high enzyme activity and antibacterial properties from chicken intestines,and determine its probiotic properties,so as to provide high-quality strains for the development of poultry microecological preparations,promote the healthy development of poultry industry. 【Method】 Strains were screened from intestinal contents and mucous membrane of White-feathered broilers,and high-quality Bacillus was selected by morphological observation,enzyme-producing activity and bacteriological inhibition.The colony morphology, in vitro growth characteristics,tolerance,intestinal adhesion and drug sensitivity of the isolates were further determined to evaluate their basic probiotic properties.The species types of the isolates were identified by physiological,biochemical and molecular biological tests. 【Result】 9 strains were isolated and purified,which were named P1-P9.Morphological identification showed that 7 strains were Gram-positive and 2 strains were Gram-negative.The optimal strain P2 was selected by enzymic activity and bacteriostatic characteristics.The diameter of transparent circle of protease,cellulase,amylase and lipase of the isolate P2 were 46.86,41.52,20.70 and 14.47 mm,respectively.The inhibition zone diameter against Escherichia coli, Staphylococcus aureus and Salmonella Pullorum were 14.77,24.05 and 19.19 mm,respectively.The colony form of the isolate P2 was round,milky white,and the surface was wrinkled and convex,opaque,and had a sense of viscosity.It was a short rod-like bacterium,with a single bacterium size of (1.46±0.07) μm×(0.81±0.03) μm.The isolate P2 had good growth performance,strong tolerance to strong acids and bile salts,and certain intestinal adhesion with a adhesion capacity of 146.52 CFU/cell.The results of drug sensitivity test showed that P2 was sensitive to gentamicin,kanamycin,clindamycin,vancomycin,ampicillin,streptomycin,chloramphenicol and erythromycin.Physiological,biochemical and molecular biological identification results showed that the isolate P2 was Bacillus siamensis,and named CPU-B1. 【Conclusion】 In this study,a strain of Bacillus siamensis CPU-B1 from chicken was screened,which had strong enzyme production activity,strong antibacterial properties,excellent growth characteristics,tolerance and intestinal adhesion,and could be further developed as a microecological preparation for poultry industry.

【Objective】 The purpose of this experiment was to obtain the recombinant mutant of Clostridium perfringens alpha-toxin (CPA),evaluate its virulence and antigenicity,and then prepare monoclonal antibodies against CPA,and evaluate the characteristics of the monoclonal antibodies. 【Method】 The CPA gene fragment containing 6 amino acid mutations (aspartic acid mutation at positions 56 and 130 to glycine,tyrosine mutation at positions 275,307 and 331 to phenylalanine,aspartic acid mutation at position 336 to aspartic acid) was synthesized.The synthetic fragment was cloned into pET-30a (+) vector,and transformed into Escherichia coli BL21 (DE3) competent cells for induction expression and purification,and the recombinant protein rCPA_m6 was obtained.The toxicity and immunogenicity were detected.The indirect ELISA assay based on rCPA_m6 for the detection of CPA antibody was established.BALB/c mice were immunized with inactivated natural CPA as immunogen,and the monoclonal antibody was prepared and its function was identified. 【Result】 Recombinant protein rCPA_m6 could be expressed in both soluble and inclusion form in Escherichia coli BL21 (DE3) competent cells. The results of toxicity test showed that all mice survived after 100 μg/mice rCPA_m6 challenge.The results of immunogenicity analysis showed that after 1×minimum lethal dose (MLD) of natural CPA,all mice died in control group,and the survival rate of mice in 10 and 20 μg/mice rCPA_m6 immune groups was 100%.An indirect ELISA method for the detection of CPA antibody was successfully established using rCPA_m6,and 4 hybridoma cell lines secreting anti-CPA monoclonal antibody were screened,named 6E3,6B8,10A11 and 13D10,respectively.The titers of the 4 cell supernatants were all ≥1∶3 200,among which the monoclonal antibody 6B8 cell supernatants could neutralize the natural CPA and react with rCPA_m6. 【Conclusion】 The recombinant protein rCPA_m6 with good safety and immunogenicity was successfully obtained,and the CPA monoclonal antibody 6B8 had certain neutralizing activity as well as high specificity and sensitivity.The results provided a candidate antigen for the development of CPA subunit vaccine,as well as a material basis for the treatment of CPA intoxication and the establishment of antigen/antibody detection methods.

Antibacterial agents are the key drugs for the treatment of bacterial infections and one of the most important foundation drugs in modern medicine.However,the current problems of increasingly serious antimicrobial resistance and insufficient channels for new antimicrobial agent discovery have attracted attention and need to be solved urgently.Antibacterial activity is acted when antibacterial agents permeate across the bacterial outer membrane and accumulate to effective concentration at the target.Therefore,measuring the cellular accumulation of antibacterial agents in bacteria would be helpful to establish the relationships between properties of the intracellular accumulation of compounds and their structures.The guidance for the design of new antibacterial agents could be provided through these relationships.At present,a variety of detection methods have been developed for the determination of antimicrobial agent concentration in bacteria.This paper briefly introduced the structural differences of cell membranes between Gram-positive bacteria and Gram-negative bacteria.Subsequently,radiometric assay,fluorometric assay and new methods based on mass spectrometry,which included LC-MS/MS,SPE-MS,nanofluidics-MS,TOF-SIMS and biological probes were reviewed.Each detection method and their current applications were presented.The advantages and disadvantages of the above analysis methods were summarized,and prospects were made for future development,with the aim of providing suggestions for the application of the assays of antimicrobial agent accumulation in bacteria,and reference for the design and development of new antibacterial agents,especially new drugs against Gram-negative bacteria.

【Objective】 This study was aimed to understand the China-Russia-North Korea border area prevalence of pathogenic bacteria carried by migratory birds in Hunchun Jingxin wetland,so as to provide scientific basis for migratory bird disease prevention and control. 【Method】 This study collected 155 fresh fecal samples from the migratory bird species Anser albifrons located at the Hunchun Jingxin wetland.The collected Anser albifrons fecal samples were diluted in PBS and cultured on LB agar and blood agar media.Individual colonies were isolated and purified,and the bacteria were identified using Gram staining,biochemical tests,PCR amplification and sequencing of the 16S rRNA gene,and other methods. The drug resistance of the isolated bacteria was analyzed. 【Result】 The isolated bacteria were Gram negative bacteria,appearing as purple red short rod-shaped bacteria.Biochemical tests of the isolate strain revealed positive results for urease,lysine decarboxylase,ornithine decarboxylase,semisolid,etc.,and hydrogen sulfide,phenylalanine,gluconate,etc.were negative.A single band with a size of 1 500 bp was amplified by PCR,and the amplified sequence had the highest similarity with the sequence of Pseudomonas aeruginosa MZ836867 published in NCBI,which was 99.6%.Phylogenetic analysis revealed that the isolated strain belonged to the same branch with strain MZ836867.This indicated that the isolated strain was Pseudomonas putidis.The results of drug sensitivity test showed that the isolate was sensitive to 13 kinds of drugs,such as chloramphenicol,cotrimoxazole and norfloxacin,intermediated to 9 kinds of drugs such as polycolistin B,clindamycin and imipenem,and it was resistant to 8 drugs including vancomycin,flufenicol, lincomycin and oxacillin, etc.,among which lincomycin and oxacillin were the most resistant. 【Conclusion】 This study successfully isolated multidrug-resistant Pseudomonas putida from the fecal samples of Anser albifrons in Hunchun Jingxin wetland,providing a reference for further research on the gut microbiota of migratory birds in this wetland.

【Objective】 This study was aimed to investigate the prevalence and drug resistance of Escherichia coli in milk from diseased cows and environment of dairy farms in some regions of Xinjiang,and to provide basis for clinical drug use of Escherichia coli in this region. 【Method】 171 samples (55 milk samples from diseased cows and 116 environmental samples) from four intensive farms in some regions of Xinjiang were isolated and purified by plate scribing method,and the Escherichia coli isolates were identified by morphological observation,Gram staining microscopy, biochemical identification and molecular biology methods. The resistance phenotypes and resistance genes of 16 kinds of antibacterial drugs of Escherichia coli isolates were analyzed by broth dilution method and PCR method. 【Result】 A total of 45 strains of Escherichia coli were isolated from 171 samples,including 8 strains from milk samples from diseased cows with a separation rate of 14.55% (8/55),and 37 strains from environmental samples with a separation rate of 31.90% (37/116).All isolates were pink round colonies.Gram staining microscopy showed red,short rod Gram-negative bacteria.Biochemical identification results showed that lactose,mannitol,indigo matrix and MR were positive,while oxidase,H₂S,VP and simonium citrate were negative,which was consistent with the biochemical characteristics of Escherichia coli.The results of drug susceptibility test showed that the Escherichia coli isolates showed different degrees of resistance to cephalothin,ampicillin,streptomycin and tetracycline,with resistance rates of 82.22%,48.89%,33.33% and 33.33%,respectively,while they showed high sensitivity to meropenem,kanamycin,gentamicin,ciprofloxacin and sulfamethoxazole,with sensitivity rates of more than 85.00%,including 16 Escherichia coli strains with multiple drug resistance.The multidrug resistance rate was 35.56%.The results of drug resistance gene detection showed that,β-lactams resistance gene bla_TEM,aminoglycosides resistance genes addA1 and strA were 13.33%,6.66% and 11.11%,respectively.The positive rates of tetracycline resistance genes tetA and tetC were 13.33% and 33.33%,respectively. 【Conclusion】 Escherichia coli isolated from dairy cattle breeding sites in some regions of Xinjiang was highly resistant to β-lactam antibiotics and exhibited severe multidrug resistance.

【Objective】 The aim of this study was to investigate the preventive and therapeutic effects of the compound traditional Chinese medicine preparation Chushi Lifei Xiaodusan (XDS) on chickens artificially infected with Infectious bronchitis virus (IBV). 【Method】 Twenty-five 9-day-old SPF chicken embryos were randomly divided into five groups and inoculated via the allantoic cavity with different doses of XDS (1.33, 0.665, 0.332, 0.166, and 0 g/0.1 mL) mixed with IBV virus solution (10³ EID₅₀). The control group received sterile PBS instead of XDS. After incubation at 37 ℃ for 36 hours, allantoic fluid was collected for viral quantification. Sixty experimental chickens were randomly divided into prevention,treatment,model and control groups,with 15 chickens in each group.Chickens in the first three groups were inoculated intranasally and intraocularly with 0.1 mL of IBV (gx2021/12-z strain) at 15 days old at a dose of 10⁵ EID₅₀/0.1 mL,while chickens in control group received an equal volume of sterile PBS.Chickens in prevention group received XDS in drinking water at a dose of 2.66 g/d per chicken starting from 12 days old for 3 days.Chickens in treatment group received XDS in the same manner and dose for 5 days starting from 1 day post-infection.Chickens in control and model groups did not receive XDS.Throughout the experiment,the mortality rate,weight gain and clinical symptoms of the chickens were monitored.Trachea and kidney tissues were collected 3,7 and 14 days post-infection to stain with hematoxylin and eosin for histopathological observation, measure the expression of immune-related genes (TLR7,IRF7,IFN-α and IFN-β) and pro-inflammatory cytokine genes (TNF-α,IL-1β,IL-6 and IL-8) using Real-time quantitative PCR,and to determine the viral load in trachea and kidney. 【Result】 The viral loads in the allantoic fluid of chicken embryos in the 0.332, 0.665, and 1.33 g/0.1 mL dosage groups were significantly lower than those in the control group (P＜0.05), and the viral loads decreased with increasing dosage. All chickens in prevention and treatment groups survived,while the chickens in model group had a mortality rate of 20%.In terms of clinical symptoms,compared to model group,XDS effectively alleviated clinical symptoms such as tracheal rales and open-mouth breathing in prevention and treatment groups. 14 days post-infection,the body weight of chickens in model group was significantly lower than that in control group (P＜0.05),whereas no significant differences were observed among the other groups (P＞0.05).HE staining results showed that 7 days post-infection,tracheal ciliated epithelial cells of chickens in model group exhibited shedding and necrosis,while chickens in treatment group maintained better tracheal mucosal integrity. 14 days post-infection,chickens in model group displayed damaged renal tubule structures,whereas chickens in treatment group showed no obvious pathological changes. The extent of tracheal and renal damage in prevention group was intermediate between that of model group and treatment group. In terms of viral load,Real-time quantitative PCR results indicated that the viral load in the trachea and kidneys of chickens in prevention group was significantly lower than that of model group 3 and 14 days post-infection (P＜0.05).The viral load of chickens in treatment group was consistently lower than that of model group throughout the observation period (P＜0.05).The expression levels of immune-related genes TLR7 and IFN-α of chicken trachea were significantly higher in prevention and treatment groups than that in model group 3 days post-infection (P＜0.05). 7 days post-infection,TLR7 gene expression level of chicken trachea were significantly higher in prevention group,and TLR7,IRF7,IFN-α and IFN-β gene expression levels of chicken trachea were significantly higher in treatment group compared to model group (P＜0.05).The expression levels of pro-inflammatory cytokine genes TNF-α,IL-1β, IL-6 and IL-12 of chicken trachea were significantly lower in prevention and treatment groups than that in model group 3 and 7 days post-infection (P＜0.05). 【Conclusion】 XDS effectively alleviated clinical symptoms,enhanced weight gain,reduced viral load in the trachea and kidney,mitigated pathological damage in trachea and kidneys of chicken,and maintained immune homeostasis in chickens infected with IBV.It had good preventive and therapeutic effect on infectious bronchitis of chicken.

【Objective】 The aim of this study was to obtain the complete gene sequence of antimicrobial peptide LL-1 and study its biological characteristics and antibacterial effect,in order to lay a foundation for further research and development of antimicrobial peptide drugs. 【Methed】 In this study,an antimicrobial peptide,named LL-1,was discovered through transcriptome sequencing and sequence alignment analysis of Conogethes punctiferalis.The complete gene sequence was obtained by RACE technology,and its corresponding amino acid sequence was derived.After cleavage,the mature peptide sequence was analyzed using multiple sequence alignment and chemically synthesized.Subsequently,the antibacterial effect of antimicrobial peptide LL-1 was evaluated by establishing a model of E.coli infection in chicken meat.Finally,the salt and temperature resistance of antimicrobial peptide LL-1 were analyzed. 【Result】 The results showed that the LL-1 gene had a total length of 474 bp with an ORF length of 192 bp encoding 63 amino acids.Mature antimicrobial peptide LL-1 consisted 39 amino acid residues,and belonged to cecropin family.At the concentration of 50 mg/kg,antimicrobial peptide LL-1 could extremely significantly inhibit E.coli growth in chicken meat (P<0.01).The temperature tolerance analysis showed that the antibacterial effect of antimicrobial peptide LL-1 was not significantly affected by temperature within the range of 4-50 ℃.After being treated at 100 ℃ for 1 h,the antibacterial activity of antimicrobial peptide LL-1 was significantly lower than that of antimicrobial peptide LL-1 treated at 37 ℃ (P<0.05).The salt tolerance analysis showed that the antibacterial effect of antimicrobial peptide LL-1 did not show a significant change after being treated with NaCl solutions of 0-200 mmol/L concentration. 【Conclusion】 Antimicrobial peptide LL-1 had good stability and antibacterial activity,and had the potential to be developed into new drugs.