Study On The Practical Application Of Domwstication Of Prrsv In Industrializer Pig Farm

Porcine Reproductive and Respiratory Syndrome is still a huge threat to the swine industry,which is critical to the pig industry as it causes immeasurable losses to the world's pig economy.(1)In this study,we investigated the anti-PRRSV N protein antibodies in pigs at all stages of the scale field and found that anti-PRRSV N protein antibody in 12-week-old finishing pigs turned from negative to positive.The fever,loss of appetite and other symptoms of pigs were collected serum and anatomical collection of tissues,serum and tissue samples by RT-PCR method for detection of pathogens,the results of reproductive and respiratory syndrome virus positive,swine fever,JE negative,The pig pseudorabies,ring,Haemophilus parasuis was negative.(2)The ORF5 gene was sequenced on the positive samples of PRRSV.The results showed that the nucleotide sequence of ORF5 of A-1 and A-3 was distributed on the branch of American strain,indicating that they were American type PRRSV.And the strains A-l and A-3 and VR-2332 belonged to subtype VR-2332-like.The homology of deduced amino acid sequence of A-1,A-3 and ORF5 genes were 99.8%and 100%,respectively.The homology of amino acid sequence was 56.6-99.0%with reference sequence of NCBI.The homology was 98.5%with VR-2332,90.0%homology to the corresponding CH-1a of Chinese first isolate,which was similar to that of HP-RRSV strain JXA1 and HUN4 The corresponding amino acid homology of the isolates was 86.5%and 87.0%,respectively.Based on ORF5 gene construction,the results showed that A1 and A3 were distributed on the branch of American strain,which indicated that they were American type PRRSV.And VR-2332-like subtypes of the strains A-1 and A-3 and VR-2332.Indicating that the field is only a serotype of strains,suitable for serum domestication.(3)In this study,the best way to determine PRRSV positive sera infection in pigs was as follows.The results showed that:the intramuscular infection of the nursery pigs,nursery pigs clinical symptoms were mild,almost no pathogen in the serum;muscle(muscle injection,nasal spray,intramuscular injection of nasal spray three different infection routes)The experimental pigs showed severe clinical symptoms,such as fever,loss of appetite and other clinical symptoms,but returned to normal soon after the injection of the method of infection and infection of experimental pigs,the experimental pigs showed severe clinical symptoms,high fever;,And the first day after infection can be detected PRRSV.Intramuscular injection of nasolabial infection in pigs,in 48 hours the body temperature reached 42 ?,indicating that at this time on the 3rd pig in the viremia period,PRRSV is a large number of breeding,killing 3 pigs,access to a large number of Positive serum containing PRRSV.(4)PRRSV-positive serum was obtained by RT-PCR method,the concentration of PRRSV positive serum was 1:120.PRRSV positive serum diluted according to different concentrations,the detection of PRRSV minimum dilution concentration of 1:1200,on this basis,assuming the detection of PRRSV minimum dilution concentration of 10 times the optimal concentration of serum acclimatization,namely 1:120.Pretest results of serum domestication by the gilts showed that PRRSV positive sera diluted 1:120,infected with gilts by nasal spray,could rapidly increase the anti-PRRSV N protein antibody in pigs,Phenomenon,and no large fluctuations in body temperature.Indicating that the best serum dilution of the concentration of 1:120,also shows that serum domestication for gilts.(5)By comparing the effect of serum domestication and vaccine immunization on gilts,the positive rate of PRRSV positive serum antibody and vaccine antibody against PRRSV N protein were 100%and 99.3%,respectively,and the antibody level of vaccine immunization was PRRSV positive seradomesticated to produce anti-PRRSV N protein antibody S/P value is high;PRRSV positive serum acclimation and vaccine immunization can improve sow conception rate,delivery rate,the total number of births,fetal birth weight,fetal The number of live births and the reduction of the weaning rate,the rate of stillbirth,serum domestication and vaccine immunization methods can improve the reproductive performance of gilts,and improve the effect of considerable.