Antibody Level Monitoring Of CSF And PRRS For Three Years In Large-scale Pig Farms

At present,the impact of the epidemic diseases on the economic efficiency in large-scale pig farms is still huge.In our country,the two major epidemic diseases,Classical Swine Fever(CSF)and Porcine Reproductive and Respiratory Syndrome(PRRS),have plagued the veterinary workers for a long time.So,it is imminent to enhance the purification of CSF and effectively control of PRRS.To develop more efficient scheme for disease prevention and control,we must understand the changes of maternal antibody and vaccine immunization effect of CSF,and keep abreast of the epidemiological trend and development of PRRS.In this study,1009 serum samples were collected in 6 batches to monitor the antibody level of CSF and PRRS,which were gathered from a pig farm for every spring and autumn in three years(September 2014-May 2017).The Enzyme-linked immunosorbent assay(ELISA)was used to test the antibody level of CSFV and PRRS.The results are reported below.The positive rate of the antibody level of CSF was respectively 73 %,87 %,84 %,78 %,86% and 88% in the six batches.Among them,the antibody positive rate of the breeding herd was over 90%,and the positive rate of antibody in all stages of growing pig was between 14% and 100%.Antibody positive rate in 4-week-old pigs ranged from 71% to 100%,decreased to between 43% and 100% at 6 weeks,ranged from 43% to 86% at 8 weeks,increased from 71% to 100% at 10 weeks and from 57% to 86% respectively antibodies 12 weeks of age.The positive rates of pigs ranged from 14% to 86% at 15 weeks of age and ranged from 43% to 100% at 20 weeks of age.The dispersion of breeding pigs is higher.The dispersion of grower pigs is 10%-80%,and relatively higher at 15 weeks and 20 weeks.The positive rate of PRRS antibody was 64%-95% in the farm,of which 90%-100% in sow herd,t 50%-100% in boar and 29% to 100% in grower pigs.The dispersal of herds in all stages was 14%-155%,and 155% to 12-week-old herds in the spring of 2015.The ratio of S/P?2.5 for PRRS in the whole batch is between 6% and 27%,of which the highest is 27% in September 2014 and the lowest in May 2016,only 6%.And The ratio of S/P?2.5 for PRRS is 0% ~ 29% in sows,0% in boar group except 20% of the proportion in September 2014.The ratio of S/P?2.5 is 0% ~ 71% in grower pigs,among which the highest appeared in 15 ~ 20 weeks old pigs,and the lowest pigs were 4 weeks old pigs.This study indicated that the immune effect of classical swine fever virus(CSFV)and porcine reproductive and respiratory syndrome virus(PRRSV)is good in this pig farm.The effective immunization program of CSFV should be optimized according to the rise and decline of of the level of maternal antibodies,and the immune effect should be monitored continuously.For the pig group immunized PRRSV vaccine,the changes of antibody level,positive rate and coefficient of variation should be mainly concerned after immunization;for the unimmunized boar and fattening pig,in addition to this,the proportionality of which had a S/P ratio ?2.5 should be focused,and the early warning mechanism should be established by antibody monitoring.This study combined with the actual production of the pig farm,supplemented by testing of the pathogen of PRRSV,strengthening the feeding management,adjusting of the structure of the herd,improving the production process and a series of measures,so that the PRRS can be controlled in the farm.