Porcine Reproductive And Respiratory Syndrome Comprehensive Prevention And Control Program In Large-scale Farm

Porcine reproductive and respiratory syndrome,caused by porcine reproductive and respiratory syndrome virus,was a disease of pigs which had caused great economic losses since its discovery,and its effective prevention and control had always been a worldwide problem.From 2008 to the end of 2015,the production performance of a large-scale production field had been stable,although the production performance had fluctuated in some time,but it was within the controllable range.In December 2015,the nursery pigs showed clinical signs of redness,dyspnea and cyanosis at the end.The rate of deaths was increased to 10%.In January 2016,one-yard sows were also infected with PRRSV and the rate of sow abortion rose to 12%,the rate of death of nursery pigs rising to about 10%.According to clinical symptoms,general changes and PCR test results showed that PRRSV infection.At the same time,blood samples were collected from aborted pigs and sows,and ORF5 sequences were amplified by PCR.Multiple gene sequences were found to be identical,and the strain was named as YDBJ2016.This strain was compared with the epidemic strains from all over the country.It was found that the similarity was 92.9% and 93.5% with Guangdong GM2 and QYYZ strains,and 95.2% with GXLA12 strain,respectively.But the similarity was lower than that of other strains.The sequences of YDBJ2016 and YDBJ201312 were quite different.The similarity of ORF5 was only 83.6%.The evolutionary tree showed that the two strains were not related;that is,the variation was not in the non-field.The reasoning might be the outbreak of epidemic strain from outside in the swine herd.Nsp2 deletion of amino acid mainly occured in the 481 amino acid and 533-561 amino acids,that is,29+1 deletion.After diagnosis,the following measures showed be taken,including the isolation of infected pigs,using antibiotics to reduce secondary infection,sows infection by themselves,Nursery pigs and delivery room pigs planning partly cleaning group.At the same time,the reserve pigs used the new epidemic strain for artificial domestication of serum,so that the PRRS antibody of the reserve sows reached a certain level before all the reserve sows entered the first field.Through artificial domestication of serum,the reproductive performance of sows can be maintained at a relatively high level.At the same time,the feeding mode of "point feeding" and "all in and out" can further improve the biological safety,and maintain the high survival rate of the delivery room and the nursery.The results of the first half of 2016-2017 showed that the number of aborted fetuses in the first month of birth was 58,the miscarriage rate was 11.86%,and then the abortion was reduced to about 2% of the normal level.The mortality rate of suckling piglets increased to 10%,the survival rate was 89.33%,but slowly recovered more than 96%,the average survival rate was 97.87%,and the other two lines were very stable,the average survival rate was 98.4%.The first-line piglets were affected by PRRS for more than 3 months,the mortality rate was about 10%,and the survival rate of three months was 89.33%-92.23%.Then the first-line of nursing home to return to normal,the survival rate was 97.41%-99.33%.In addition,the average survival rate of the other nursery was 98.03% without the influence of the disease.The survival rate of medium and large pigs was between 94.77%-98.54%,and the average survival rate was 96%.The improvement of production performance indicated that this study can effectively control PRRSV by using artificial domestication of serum and improving the biological safety at the same time with the combination of partial feeding,point feeding and all-in-and-out prevention and control measures.