Previous studies have shown that tilmicosin can inhibit porcine reproductive and respiratory disorders syndrome virus(PRRSV)replication in vitro.Here,to further study the inhibitory effect of tilmicosin on PRRSV in vivo,healthy piglets were selected as experimental animal fed with or without tilmicosin.Seven days later,these piglets were artificially infected with a highly pathogenic PRRSV strain.Then,the clinical manifestations,viral replication,mortality and growth performance of the piglets between the tilmicosin treated group and the con-trol group were compared.The results showed that tilmicosin significantly inhibited PRRSV replication in vivo,alleviated disease symptoms,reduced mortality by 20％,and increased daily weight gain of the PRRSV infected piglets.This study provided reference for clinical use of tilmicosin to prevention and control of PRRSV infection.
This study was to establish a rapid field screening method for screening African swine fever(ASF)gene-deleted mutants in or-der to identify the complex infection situation of ASF in China.Based on the epidemic trends of ASFV in China,the specific primers and exo probes were designed and synthesized by analyzing the conserved regions of the ASFV B646L and MGF-505R genes,in order to establish a double real-time RPA method for detection of the above-mentioned mutants.The sensitivity and specificity of the method were analyzed.In addition,the method was tested in clinical application using the optimized RPA.The result indicated that the double real-time RPA method could monitor the detection process within 15 min.Its minimum detection of RPA was up to 10 copies/response for both the genes.The meth-od was highly specific,without cross-reactions with classical swine fever virus,porcine respiratory and reproductive syndrome virus,pseud-orabies virus,porcine parvovirus and porcine circovirus type 2.Then,266 clinical samples were tested using the dual real-time RPA and WOAH recommended real-time PCR,with a coincidence rate of up to 100％.The double real-time RPA method for detecting ASFV MGF-505R gene-deleted mutants could be adapted to the mobile real-time RPA detector,which possessed the advantages of rapidity,high sensi-tivity and strong specificity.The method is applicable for rapid clinical detection of ASFV,and it could serve as a new screening method for prevention and control of ASF.
The aim of the trial was to explore the effect of Alisma powder in alleviating high energy and low protein diet-induced hepatic lipid deposition in laying hens.Seventy-two 260-day-old Hy-Line Variety Brown laying hens were obtained and randomly divided into three groups,namely,the control group(CON,treated with 10.9 MJ/kg metabolizable energy,16.9％crude protein),the high-energy and low-protein diet group(HF,with 13.0 MJ/kg metabolizable energy,12.1％crude protein),and the high-energy low-protein diet supplemented with Alisma powder group(HFA,with 13.0 MJ/kg metabolizable energy,12.1％crude protein,supplemented with 72 mg/kg Alisma pow-der).The hens were housed in cages and subjected to restricted feeding with 110 g/d/head.The room temperature of the chicken house was about 24 ℃,the light regime was 16L:8D,and the test period was 12 weeks.The results showed that the egg production rate,egg weight,egg quality index,plasma alanine aminotransferase activity,total cholesterol and triglyceride concentration in the HF group were not signifi-cantly different from those in the control group(P＞0.05),whereas the content of triglycerides in their liver was significantly(P＜0.05)higher than that of the control group;and adding Alisma powder to the diet significantly alleviated the hepatic lipid deposition of the laying hens,and at the same time significantly(P＜0.05)reversed the up-regulation of fatty acid synthase,acetyl-CoA carboxylase 1 and stearoyl-CoA desaturase-1 mRNA of the hepatic lipid synthetic genes.Simultaneously,the upregulation of hepatic glucocorticoid receptor(GR)mRNA and protein was also significantly alleviated in the hens.These results suggested that Alisma alleviated hepatic lipid metabolic disorder induced by high-energy and low-protein diets by regulating de novo lipogenesis in laying hens.GR might be involved in the signaling pathway of the function of alisma.
In order to investigate the anti-tumour effects of baicalin carbon dots on canine mammary tumour,the carbon dots were prepared hydrothermally using baicalin as the carbon source.The morphological structure and optical properties of the baicalin carbon dots were char-acterized by transmission electron microscopy,infrared spectroscopy,UV-vis absorption spectroscopy and fluorescence spectroscopy.CCK-8 cell test was used to study the inhibitory effect of carbon dots on the proliferation of canine mammary tumour cells CIPp and CMT-7364.The results showed that the baicalin carbon dots were round in shape,uniform and well dispersed,with particle sizes ranging from 3 nm to 6 nm,and lattice spacing of 0.253 nm.The baicalin carbon dots possessed good optical properties.There were hydrophilic groups such as hydrox-yl,amino and carboxyl groups on the surface.The IC50 of the baicalin carbon dots against CIPp and CMT-7364 were 41.65 μg/mL and 42.78 μg/mL,respectively.In summary,baicalin carbon dots with good water solubility showed significant anti-canine mammary tumour activity,which provided ideas for innovation and development of clinical therapeutics for canine mammary tumours.
The aim of this study was to construct a Marc-145 cell line with stable expression of porcine reproductive and respiratory syn-drome virus(PRRSV)N protein by a lentivirus expression system.The N gene was amplified by PCR using PRRSV SH1 strain infectious cloning plasmid as template.Then,the N gene was cloned into the Lentiviral vector,resulting in a recombinant lentivirus plasmid pSin-Ires-Puro-N.The recombinant plasmid pSin-Ires-Puro-N and auxiliary plasmids psPAS2,pMD2.G and pRSV-Rev were co-transfected into 293T cells for lentivirus packaging in order to obtain recombinant lentiviral particles expressing N protein,and the particles were used to infected Marc-145 cells.Next,positive cells were preliminarily screened with puromycin;and after several generations of screening,the Marc-145 cell line with stable expression of N protein was obtained by limited dilution and end-point dilution.PCR amplification of N gene showed that there was N protein gene sequence in the cell line,IFA and Western blot assays verified that N protein could be stably expressed in the cell line.Therefore,we successfully constructed a Marc-145 cell line with stable expression of PRRSV N protein.
This study was to evaluate the anti-obesity effect and safety of nuciferine(NUC)on high-fat diet beagles.After 2 weeks of a-daptive feeding,a total of 36 adult beagles were used and randomly divided into 6 groups fed with normal diet,normal diet with 0.1％NUC,high fat diet with 0.05％NUC,high fat diet with 0.1％NUC,and high fat diet with 0.15％NUC,respectively.After 8 weeks of feeding,the tests of corpuscle,biochemistry and electrolyte in blood samples collected from the tested dogs were performed,and the subcutaneous adi-pose tissue of the groin was stained with H & E to observe the size of adipocytes.The results showed that the final body weight,body weight gain,subcutaneous fat thickness,adipocyte area,triglycerides(TG),total cholesterol(TC),and low-density lipoprotein cholesterol(LDL-C)in the high fat diet group were higher than those in the normal diet group,while supplementing 0.1％NUC and 0.15％NUC re-versed these changes.In addition,supplementation of 0.1％NUC reduced the levels of total bilirubin(TBIL)and alanine aminotransferase(ALT)in the high-fat diet dogs.Supplementation of different doses of NUC had no effect on corpuscle and serum electrolytes in the blood of the animals.In summary,NUC in the diet improved the obesity and liver enzymes induced by a high-fat diet in beagles,with a 0.1％added dose having the best effect.
The aim of this experiment was to explore the effects of 1.5％to 8％hybrid Broussonetia papyrifera leaves on the physical prop-erty indicators and nutrition composition indexes of egg quality after replacing part of corn and soybean meal in the basic diet of Dawu Golden Phoenix laying hens at early laying stage.270 Dawu Golden Phoenix laying hens at 147 days of age were selected,and were randomly divid-ed into 6 groups(3 replicates/group,15 pieces/replicate).The groups of the laying hens were fed with basic diets containing 0,1.5％,2.5％,3.5％,4.5％,and 8％hybrid Broussonetia papyrifera leaves replacements,respectively.The pre-test period lasted for 7 days,and the formal trial lasted for 49 days.At the end of the trial(a total of 56 days),the physical property indicators and nutrition composition in-dexes of the eggs of the hens were measured with each replicate as measured unit.The results showed as follows:There was no significant(P＞0.05)difference in the physical property indicators of egg quality among the groups.The 1.5％substitution ratio extremely significantly(P＜0.01)increased the contents of C16H32O2,C18H36O2 and C18H30O2 in the eggs.In addition,it helped to increase the content of Phe and Se in the eggs.The 2.5％substitution ratio extremely significantly(P＜0.01)increased the contents of VD3,VA,VE and Fe in the eggs.The 3.5％substitution ratio extremely significantly(P＜0.01)increased the contents of C14H28O2,C18H34O2,CHOL,TAA and K in the eggs,and significantly(0.01＜P＜0.05)increased the contents of Arg and Ile in the eggs,more helpful in increasing the relative weight of egg shell and the contents of Pro,Ala,Met and Lys.The 4.5％substitution ratio extremely significantly(P＜0.01)increased the contents of C4H8O2,C42H80O6,C19H36O2,Na,Ca and Zn in the eggs,and helped to increase the egg weight,egg yolk weight,egg yolk relative weight,egg shell weight,egg shell thickness and the content of Ala in the eggs.The 8％substitution ratio extremely significantly(P＜0.01)increased the contents of total CP and Glu in the eggs,and significantly(0.01＜P＜0.05)increased the contents of C16H30O2,Asp and Leu.It also helped to increase the color of the egg yolk and the contents of Gly,Val and Tyr in the eggs.The above results indicated that the ap-propriate replacement feed ratio of hybrid Broussonetia papyrifera leaves helped to improve the physical property indicators of egg quality,and significantly or extremely significantly improved the nutrition composition indexes of egg quality.The replacement feed ratio of 3.5％to 4.5％had the best comprehensive effect,and was the most appropriate for application in egg production.
In order to establish a large-scale suspension culture technology of canine distemper virus(CDV)isolated from mink and realize its high-density cell growth and efficient virus proliferation,Cephodex was used to culture DF-1 cells by suspension to proliferate CDV3.In the whole process,shake flask culture was adopted,and optimal culture conditions were established by optimizing the key technical condi-tions such as virus culture temperature and virus harvest time.The results showed that,after being cultured at 37 ℃ for 72 hours,and the DF-1 cells were inoculated with CDV3.Then,these cells were infected by the CDV3 and continued to be cultured at 35 ℃ for 72 hours,and finally the viral titer reached 105.0 TCID50 per 0.1 mL.Therefore,a technology of CDV micro-carrier suspension culture was established here,which laid an important technical foundation for high-efficiency mink canine distemper vaccine production.
Based on the specific binding between 6-FAM and anti-(6-FAM)monoclonal antibodies,biotin and streptavidin,colloidal gold lateral immunochromatographic strips were prepared,in this study,that can be used to visualize the results of recombinase polymerase amplification(RPA)reaction product of the probes cleaved by nfo enzyme.Firstly,6-FAM monoclonal antibodies with high affinity were prepared using the hybridoma and induced ascites methods(the affinity constant was 5.38×109 L/mol).The labeling conditions of 6-FAM and colloidal gold were optimized by high concentration NaCl destruction test,the optimal labeling pH was 8.0 and the optimal labeling amount of colloidal gold was 12 μg/mL colloidal gold.Then,the optimal T-line coated buffer was determined to be 0.2 mol/L HAc-NaOAc(pH=5.0)using simulated samples.RPA nfo reaction products were used as actual samples to observe the depth of the strips.Finally,the optimal detection performance of the strips could be achieved under the conditions of 0.1 mol/L PB chromatography solution(pH=7.4),1 mg/mL SA coating,5 μL reaction solution and 10 μL gold labeled antibody dosage.The results was that the colloidal gold lateral immuno-chromatography strip we developed independently was able to show clear bands 5 min after sample loading,which was 100％(9/9)consist-ent with the results of the current commercial strips.This strip could replace the existing commercial strips,reducing the detection cost and shortening the detection time.The present result also laid a foundation for establishment of RPA nfo-GICS and RPA-CRISPR Cas12a-GICS detection methods.
In order to obtain the structural protein of the porcine deltacoronavirus(PDCoV)and to evaluate its immunogenicity,the com-plete S,E,M and N genes of the PDCoV CZ2020 strain were amplified by RT-PCR,and cloned to pCAGGS eukaryotic expression vectors;and then eucaryotic expression plasmids pCAGGS-PDCoV-S,pCAGGS-PDCoV-E,pCAGGS-PDCoV-M and pCAGGS-PDCoV-N were constructed.The plasmids were identified by sequencing and were transfected to HEK293T cells,and the expressions of PDCOV S,E,M and N proteins were detected by indirect immunofluorescence test(IFA)and Western blot(WB).BALB/c mice were prepared for subcuta-neous injection of the proteins,and recombinant proteins polyclonal antibodies were produced in immunized mice.Next,the titers of the anti-bodies were measured by WB and IFA,and their immunogenicity was evaluated.The results showed that the recombinant plasmids pCAGGS-PDCoV-S,pCAGGS-PDCoV-E,pCAGGS-PDCoV-M,pCAGGS-PDCoV-N were successfully constructed and expressed in HEK293T cells.The recombinant proteins were specifically bounded to anti-pig PDCoV serum.The polyclonal potency of pCAGGS-PDCoV-S,pCAGGS-PDCoV-E,pCAGGS-PDCoV-M,pCAGGS-PDCoV-N was as high as 1∶10 000.These results indicated that vaccines prepared by recombinant proteins would be able to induce mice to produce higher levels of antibodies.This study suggested that pCAGGS-PDCoV-S,pCAGGS-PDCoV-E,pCAGGS-PDCoV-M and pCAGGS-PDCoV-N eucaryotic expression vectors were successfully constructed.The poly-clonal antibodies prepared were highly immunogenic and could serve as a basis for development of diagnostic kits and new vaccines.
Mycobacterium bovis is an important zoonotic pathogen that seriously harms the cattle industry.Polymerase chain reaction(PCR)is one of the effective methods to detect the pathogen.In our study,the best PCR detection method was selected to provide technical reference for clinical surveillance of Mycobacterium bovis infection.Four pairs of primers were designed for four specific genes(16S rRNA,IS6110,IS1081 and Mpb64)of Mycobacterium bovis,and the optimal annealing temperature was determined by temperature gradient PCR.The nucle-ic acid of the reference strain of Mycobacterium bovis was used to determine the minimum detection limit of PCR.At the same time,the Chi-nese reference strain of Mycobacterium bovis,the international reference strains of Mycobacterium bovis,Mycobacterium avium,intracellular mycobacterium,Mycobacterium paratuberculosis,Brucella ovis and Brucella bovis were used for specific comparative tests.Finally,the detec-tion effects of different PCR methods were compared using artificial tissue samples(lungs,lymph nodes,milk samples)infected with Myco-bacterium bovis.Four pairs of primers were able to detect Mycobacterium bovis when the annealing temperature was 60 ℃,and primers 2-4 specifically detected Mycobacterium bovis.Primers 2 and 3 showed the highest sensitivity in detecting the genome of Mycobacterium bovis,reaching 10-10 ng/μL.The sensitivity of primer 2 in detecting Mycobacterium bovis in the lungs and lymph nodes of the tested cattle was high-er than 106 CFU/mL,and the sensitivity of primer 4 in detecting Mycobacterium bovis in the milk samples from the cattle was as high as 102 CFU/mL.In this study,the most appropriate PCR detection method was selected,providing reference for pathogenic detection of bovine tuberculosis and its application in clinical practice.
Keratin is the most abundant structural protein in keratin biomaterials,and it is the main component of animal fur,feathers,horns,hooves and human hair and nails.Keratin biomaterials are one of the most natural polymeric compounds in tissue engineering because of its rich resources and good biological functions,and they have been extensively studied in biocompatibility,degradability,tissue healing and regeneration.At present,methods for keratin extraction include chemical hydrolysis,hydrolysis via microbial digestion,and dissolution in ionic liquids,microwave technique,steam explosion technique,thermal hydrolysis or superheated process.Keratin materials have been widely used in drug delivery,wound healing,tissue repair engineering and other biomedical fields.This paper summarizes the structure,bio-logical characteristics,source,extraction methods and separation technologies of keratin materials,and reviews the application of keratin bio-materials in many medical fields.The aim is to provide theoretical references for future study of keratin and its related applications.
In order to analyze the structural characteristics of the promoter region sequence of the EDN3 gene in chickens and explore the transcriptional regulation mechanism of the sequence.Based on the 2 052 bp nucleotide sequence of 5'UTR and exon 1 of the chicken EDN3 gene registered in the NCBI database,the core promoter region,cis-acting elements,transcription factor binding sites and CpG island of the sequence were predicted by means of a variety of online softwares.The similarity of the EDN3 gene promoter sequence between chicken and other species was compared,and phylogenetic tree construction was carried out using DNASTAR Lasergene 17.3 and MEGA 5.0.The results showed that the 592-2 000 bp upstream of the initiaton codon of the chicken EDN3 gene was a possible candidate core promoter region,and two potential transcription initiation sites T and A were found at 633 bp and 1 547 bp of the 5'UTR.There were two CAAT-boxes,three GC-boxes,six TATA-boxes,nine E-boxes and three CpG island regions in the promoter region of the EDN3 gene.The sequence also con-tained some transcription factor binding sites,such as Sp1,C/EBPα and NF-1.The similarity of the promoter region sequence for the EDN3 gene between chickens and ring-necked pheasants,quails,rock ptarmigans,ruddy ducks,crested ducks,goats,sheep,cattle,pigs,hu-mans was 38.8％-90.3％.The phylogenetic tree revealed that chickens were the most closely related to quails,and the farthest related were pigs.In this study,bioinformatics software was used to predict and analyze the promoter sequence of the EDN3 gene in chickens,which pro-vided theoretical reference and basis for further revealing the transcriptional regulation mechanism of the EDN3 gene in pigmentation trait of chickens.
To develop a recombinant pseudorabies virus(PRV)vaccine candidate strain against highly pathogenic porcine reproductive and respiratory syndrome virus(HP-PRRSV),a pair of primers was designed and synthesized according to the GP5 gene sequence of the HP-PRRSV HuN4 strain,and BamH I restriction endonuclease site was introduced into the 5'ends of the upstream and downstream prim-ers.The GP5 gene was amplified by RT-PCR from viral RNA extracted from a HP-PRRSV strain.The target fragment was digested by BamH I and was inserted into the eukaryotic expression vector pG which had been digested by the same endonuclease and dephosphorylated,so as to construct a recombinant plasmid pG-GP5/HP-EGFP.The recombinant pseudorabies virus strain rPRV-GP5/HP-EGFP carrying the GP5 gene of the HP-PRRSV strain and the green fluorescent protein marker gene was obtained by transfecting the plasmid pG-GP5/HP-EGFP into ST cells which were inoculated with the PRV variant three gene deletion strain rPRV-gE-/gI-/TK-using liposome transfection.The recombinant virus rPRV-GP5/HP-EGFP was inoculated into ST cells which were transfected with the knockout plasmid CRISPR/Cas9 EGFP.Finally,a recombinant virus rPRV-GP5/HP strain without the green fluorescent protein was obtained after four rounds of plaque puri-fication.The sequencing results verified that the rPRV-GP5/HP strain had a 1 232 bp deletion on the EGFP gene.RT-PCR and indirect im-munofluorescence test further confirmed that the rPRV-GP5/HP was successfully constructed in this study.
The aim of this study was to identify the pathogenicity of dead pigs suffering from respiratory diseases in Liupanshui Pig Farm.Oral and nasal swabs and lung tissues of sick pigs were collected afflicted pigs for pathogen isolation,identification and pathogenicity analy-sis.The biological characteristics of the pathogenic bacteria were investigated using physiological and biochemical methods,16S rDNA gene sequence analysis,MLST typing,virulence gene and drug resistance gene detection and artificial infection test.The results showed that the isolated strain was Gram-negative bacillus,which was identified by PCR and 16S rDNA sequencing as Pasteurella multocide and it was named PM0712.It was found that the isolated strain PM0712 was swine type A Pasteurella multocida.MLST analysis showed that PM0712 belonged to the ST3 type.The isolated strain carried 17 virulence genes and 4 resistance genes,and it possessed moderate biofilm formation ability,with a median lethal dose of 1.6 × 101 CFU/mL in mice.PM0712 was sensitive to antibiotics such as ciprofloxacin and norfloxacin,and traditional Chinese medicines Coptis chinensis and Fructus Mume.The present results provided a reference for prevention and control of swine type ST3 Pasteurella multocida infection and for research on the pathogenic mechanism of the infection.
In order to establish a loop mediated isothermal amplification(LAMP)fluorescence method for detecting Toxoplasma gondii,two sets of primers were designed and synthesized using highly repetitive conservative sequences of Toxoplasma gondii as templates.The prim-er sets were compared and reaction conditions were optimized to determine specificity and sensitivity of the detection mehtod.The results showed that the sensitivity of the established method for detection of Toxoplasma gondii within 62 ℃ and 50 min was 1 copies/uL,which was higher than that of the standard method and superior to a commercially available real-time fluorescence quantitative PCR detection kit.There was no cross reaction with Schistosoma japonicum,Toxocara felis,Babesia canis,Neospora canis,and Leptospira.Then,the LAMP fluores-cence detection method was used to detect 200 clinical samples of Toxoplasma gondii with known background information,and 10 positive samples and 190 negative samples were detected.The detection results were consistent with those of the standard method and the fluorescence quantitative PCR detection.The innovative points of this method are its rapidity,high sensitivity,strong specificity,and wide application range of instruments and equipment,which are suitable for promotion and application in veterinary laboratories and animal hospitals.
In this study,the loop mediated isothermal amplification(LAMP)and fluorescence quantitative PCR(qPCR)targeting the re-petitive sequence fragments of Toxoplasma gondii(Rep-529)were compared,and the optimal DNA detection method was screened out and preliminarily applied to molecular detection of Toxoplasma gondii infection in pet cats.A plasmid containing a 529 bp repetitive sequence fragment(Rep-529)of Toxoplasma gondii was synthesized as a template,and the minimum detection limit of the reported and self-designed primer groups was compared.Next,cross-reactivity was tested using DNA extracts from other pathogens;and the selected optimal primer set was used to detect Toxoplasma gondii DNA in pet cat feces.The results showed that,when the detection limit was compared with the plasmid containing Rep-529 as a template,the detection limit was the lowest in the primer group 529-11 in LAMP.This was followed by the LAMP RE primer set and qPCR,both of which had a detection limit of 104 copies/μL.The LAMP 529-3 and 2021 primer sets had the highest de-tection limit,both at 105 copies/μL.However,none of the primer sets amplified DNA from Cryptosporidium,Giardia,Trichinella spiralis,Escherichia coli,salmonella typhimurium or feline panleukopenia viruses.Using isothermal amplification of the LAMP 529-11 primer group,11 out of 29 pet cat feces were detected positive with a total detection rate of 37.93％(11/29);and 2 out of 10 anal swabs were positive(20.00％,2/10),with a total detection rate of 33.33％(13/39).Using the Rep-529 repeat sequence of Toxoplasma gondii as the target gene,this study screened the 529-11 LAMP primer group as a rapid,sensitive,and specific isothermal amplification primer group,which effectively amplified Toxoplasma gondii DNA within 30 minutes.This method caused 33.33％of pet cats to ovulate their oocysts,which posed a huge potential risk of pollution and infection to the environment and humans.
In order to improve the nutritional value of palm kernel cake,the orthogonal experimental design and entropy weight-TOPSIS method was used to optimize the conditions for enzymatic hydrolysis of Palm meal using a complex enzyme consisting of mannanase,acid pro-tease and cellulase.The methods used in this experiment were as follows:The composition of complex enzymes and the optimal concentration of each enzyme were screened using Palm kernel cake as raw material,reducing sugar and trichloroacetic acid-soluble protein as indicators.The optimal conditions for material water ratio,complex enzyme hydrolysis time,hydrolysis pH value,and hydrolysis temperature were ob-tained through single factor experiments.On the basis of the single factor experiments,the orthogonal experimental design and entropy weight-TOPSIS method was used to obtain the optimal enzymatic hydrolysis conditions.The results were as follows:The composition and content of complex enzymes were 250 U/g of acidic protease,45 U/g of mannanase,and 160 U/g of cellulose,respectively.The optimal conditions for each factor were:material water ratio 1∶3,time 24 h,pH value 4.8,and temperature 37 ℃.The optimal enzymatic hydrol-ysis conditions were:material water ratio 1∶2,time 24 hours,pH value 4.8,and temperature 42 ℃.In conclusion,the content of reduc-ing sugar was as high as 65.29 mg/g,the content of acid soluble protein was 3.86％,and the crude fiber was as low as 8.58％after the complex enzyme hydrolyzed Palm meal under the conditions of a material water ratio of 1∶2.time of 24 hours,pH value 4.8,and tempera-ture of 42 ℃.
Infectious diarrhea is a common disease that seriously affects the growth and development of calves and the economic benefits of animal husbandry.Calves often suffere from diarrhea due to poor feeding conditions and improper sanitation management,resulting in re-duced body resistance.In recent years,the rate of infectious diarrhea in calves has been on the rise.The main pathogenic factors of infec-tious diarrhea in calves are pathogenic microorganisms such as viruses,bacteria and parasites.Current reports show that common pathogens clinically causing infectious diarrhea in calves include bovine rotavirus,bovine coronavirus,Escherichia coli,Cryptosporidium,etc.;some of these pathogens also have mixed infection,leading to the occurrence of respiratory diseases,mastitis,hoof disease and so on,which ulti-mately greatly increases the difficulty of treatment.Epidemic monitoring in various regions can help strengthen regional governance and pro-tect animal and human health from outbreaks of infectious diarrhea.In this paper,the epidemic status,pathogen characteristics,methods for detection and prevention of various pathogens causing infectious diarrhea in calves are introduced and discussed based on the authors'clinical experience,so as to provide a reference for future prevention and control of infectious diarrhea in calves.
This study was to compare the effects of different superovulation protocols on lamb supernumeraries and on their oocyte matura-tion in vitro and to screen the best superovulation protocol for the young animals.The experiment was conducted on 1-2 month old sheep lambs which were divided into three groups,two of which,the scheme Ⅰ and scheme Ⅱ groups,were injected with hormones as the experi-mental superovulation groups and one of which was the control group without hormone injection,so as to determine the effects of different su-perovulation methods on ovarian responsiveness,ovarian size and oocyte maturation in vitro in sheep lambs.The results showed that the ovu-lation protocol Ⅱ groups treated with 6x12 h intervals and a total dose of 180 U FSH was more effective than the ovulation protocol Ⅰ group with 4x12 h intervals and a total dose of 200 U FSH.The oocyte maturation rate was 45.4％in the superovulation Ⅱ group,as compared to 32.2％in the superovulation Ⅰ group.To conclude,screening of a superovulation protocol with 6x12 h intervals,a total dose of 180 U FSH and 330 U PMSG injected intramuscularly at the same time as the first FSH injection was the best superovulation protocol for the young animals,which laid a theoretical foundation for sheep lambs in expanding the source of eggs needed for in vitro fertilization,in shortening the generation interval,in producing a large number of excellent offspring and in speeding up the breeding process.
