Control And Eradication Of Pseudorabies In A Pig Farm In Jiangsu Province

Porcine pseudorabies(PR)is caused by porcine pseudorabies virus(PRV).It can result in abortion and stillbirth of pregnant sows,infertility of boars,death of newborn piglets,dyspnea and growth stagnation of growing and fattening pigs.Recessive infected pigs and convalescent pigs can carry the virus for life.They can infect the same group of pigs through respiratory tract or digestive tract when the pigs suffers from stress or low immunity.PR is widespread in China,and it is difficult to eradicate it,which causes huge economic losses to the pig industry.Some countries in the Europe and United States have implemented PR eradication programs relying on gene deficient vaccine and corresponding diagnosis methods.In China,PRV in some pig farms also turned from positive to negative by drawing on the successful eradication scheme abroad.From 2015 to 2018,the PR eradication was achieved by implementing the eradication scheme of vaccine immunization and eliminating PRV infected pigs in a pig farm in Jiangsu Province.Firstly,reserve pigs were immunized with Boehringer’s Bartha K-61 live vaccine with gE gene deletion three times before mating.The breeding boars and production sows were immunized four times a year.The gE antibody were detected four times a year by Pseudorabies Virus gpI Antibody Test Kit(IDEXX PRV/ADV gI),and the breeding boars with positive gE antibody were eliminated.Furthermore,the positive rate of PRV gE antibody and PRV gB antibody,and production performance were detected and evaluated.From 2015 to 2018,a total of 3255 samples(416 boars and 2839 sows)were detected One hundred and seventy samples(30 boars and 140 sows)were PRV gE antibody positive,and all breeding pigs with PRV gE antibody positive were eliminated.The number of PRV gE antibody positive samples showed a downward trend year by year.The PRV gE antibody positive rate decreased from 18.5%to 10.29%in 2015.In 2016,the gE antibody positive rate dropped to 3%.In 2017,the positive rate of PRV decreased to 0%.No positive sample was detected in 2018.The experimental pig farm reached the PR eradication.The PRV gE antibody positive rate of boars decreased from 21.88%to 16.67%in 2015;the PRV gE positive rate in 2016 decreased to 7.41%.The positive rate was 0 in the second quarter of 2017.The PRV gE antibody positive rate of sows decreased from 17.86%to 9.44%in 2015.In 2016,the positive rate of PRV gE antibody decreased to 2.31%.And no PRV gE positive sample was detected in sows since the third quarter of 2017.In order to evaluate the immune effect of PRV vaccine,PRV gB antibody was detected from 2017.Our results showed that the gB antibody qualified rate was more than 95%,which indicated that the vaccination had a good immune protection for breeding pigs.In order to evaluate the impact of eradication and pseudorabies on the production level of pig farms,the production data from 2015 to 2018 were further analyzed.The incidence of parturition increased by 7.73%.The rate of born alive of sows increased by 6.66%from 89.59%in 2015 to 95.56%in 2018.The survival rate of piglets before weaning increased by 7.23%from 88.40%in 2015 to 94.79%in 2018.This study showed that the sows performance and piglet survival rate were significantly improved by PR eradication.