Eradication Technology Of Porcine Circovirus Virus Disease In Breeding Swine Herds

Porcine circovirus disease is a kind of infectious disease caused by porcine circovirus type 2, with the main symptoms of postweaning multisystemic wasting syndrome and porcine dermatis and nephropathy syndrome. It is spreaded by two ways of horizontal and vertical, its main source of infection may be the infection breeding herds. Pigs infected with PCV-2 can cause the immune inhibition, immune failure, seriously respiratory system-, digestive system diseases and reproductive disorders, low feed remuneration, increase mortality, have cause great economic losses to the pigs industry. With the commercialization of PCV-2 vaccines widely used, the vaccine has become the most economic and effective ways to control PCVD. But single vaccination doesn’t control the PCV-2 infection completely, therefore, it’s important to carry out comprehensive prevention and control measures to PCVD. This study though immunity of the breeding herds, comprehensive measures such as detection and elimination, and observe the breeding herds PCV-2 changes of nucleic acid and antibody, swine fever antibody, and comparative analysis of differences in sow reproductive performance before and after purification, in order to explore purification PCVD area control procedures and methods, provide a scientific basis for effective prevention and control of PCVD for large-scale pig farms.In order to explore purge control measures of porcine circovirus disease(PCVD) for breeding swine herds, in this study, breeding swine were vaccinated with PCV-2 inactivated vaccine(after fundamental immunity twice, breeding swine were given an intensive vaccination once every four months), detection(before fundamental immunity,20 d after second vaccination, three months after second vaccination, three months after intensive vaccination, breeding swine were got the blood from anterior vena cava and separate blood serum, detect PCV-2 and classical swine fever antibody by ELISA and PCV-2 nucleic acid by PCR), the breeding swine which PCV-2 nucleic acid was still positive were eliminated after intensive vaccination, at the same time, we collect production data of sows purification around 1 years,including litter size,number born alive,number born death, nest mummy tire in number,nest produced a weak litter size.birth weight and estrus returning rate.After one year’s purification work, the results showed that PCV-2 nucleic acid positive rate of breeding swine herd had decreased significantly from 33.33% to 2.27%, of which the positive rate of reserve pig had decreased from 39.02% to 5.88%, the rate of breeding boars had decreased from 33.33% to 0, the rate of sows had decreased from 15.38% to 1.25%.Analysis of different ages, PCV-2 nucleic acid positive rate was highest of 2～3 months and 4-5 months of age group pigs,which was 8.33%,≥10 months of age was low, which was1.06%,but PCV-2 nucleic acid were all negative of 6-9 months of age pigs. PCV-2 antibody of the breeding herds’s was fall before, than rising after. The litter size of vaccinated sows increased significantly by 0.52 than that before vaccination, the alive litter size increased by 0.78, the mummy litter size decreased significantly by 0.3.Antibody qualified rate of classical swine fever of breeding swine herd had increased from 53.73% to 83.49%,and the average blocking rate had increased from 43.31% to 63.46%.The results show that application of immunization detection^ elimination measures for PCVD purification effect in breeding swine herds were obvious. The program which were popularization and had application value could be used to provide a scientific basis for PCVD purification in large scale pig farms.In order to know the poisoned rate and situation of vertical transmission of PCV-2 among stillbirth in large-scale pig farms, in this study, we collected and investigated clinical samples from 3 immune farms and 2 unimmunized farms, we collected a total of 89 stillbirth and got 67 sows’ blod from anterior vena cava, separated blood serum, used PCR to detect PCV-2 nucleic acid of stillbirth and the sows serum, used ELISA to detect PCV-2 antibody without vaccine of the sows serum. The results showed that average positive rate of PCV-2 nucleic acid of stillbirth was 35.96%, in which immunized farms of the average positive rate was 27.27%, the average positive rate of unimmunized farms was 50%, The detection rate of PCV-2 of immunized farms was significantly lower than unimmunized farms. We detected 32 positive patients of stillbirth, and 4 corresponding to the sows serum which were positive. This study showed that pigs immune PCV-2 vaccine can reduce porcine reproductive barrier which caused by PCV-2, to a certain extent, showed that PCV-2 has the possibility of vertical transmission.