| At present,classic swine fever,foot-and-mouth disease and porcine reproductive and respiratory syndrome are still the main epidemic diseases in swine farms in China,which are classified as mandatory diseases by the Ministry of Agriculture of China.Although swine fever and porcine reproductive and respiratory syndrome withdrew from the compulsory immunization program after 2017,the importance of immunization still cannot be ignored.In recent years,three diseases have continued to spread and become epidemic in Henan.According to the epidemiological data in China from 2016 to 2017,classic swine fever,swine foot-and-mouth disease and highly pathogenic porcine reproductive and respiratory syndrome in Henan Province are all serious epidemic areas.In order to find out the antibody level and the law of growth and decline of three kinds of swine mandatory immunization epidemic disease vaccine in some large-scale pig farms in Shangcai County,and provide some scientific basis for the farms to improve the immunization methods,improve the level of vaccine protection,and effectively control the epidemic of the three diseases.In this study,part of the large-scale pig farms in Shangcai county(Breeding sows ? 100)as the object of the study,the serum of pigs after different seasons of vaccination was collected,and indirect ELISA and other detection methods were used to detect and analyze the vaccine antibodies.Focusing on Foot and Mouth Disease type O,supplemented by Classical Swine Fever and Highly Pathogenic Porcine Reproductive and Respiratory Syndrome,the following aspects of research have been carried out:1.The average positive rate of antibody in 15 large-scale swine farms immunized with classic swine fever attenuatedvaccine in Shangcai County was 62.89%(283/450).The average OD value was 0.69,the standard deviation was 0.566,the coefficient of variation was 81.87%,the average antibody titer was 1:128,and the proportion of 7 pig farms with antibody positive rate over 70% was 46.67%(7/15).The antibody positive rate was proportional to the mean OD value and inversely proportional to the antibody coefficient of variation.2.The average positive rate of antibody in 31 large-scale pig farms immunized with inactivated FMD O vaccine in Shangcai County was 59.25%(551/930),the mean OD value of antibody was 0.7122,the standard deviation was 0.4809,and the antibody coefficient of variation was 71.47%.The positive rate of antibody was over 70% in 5 farms,accounting for 16.13%(5/31).The antibody positive rate was proportional to the mean OD value and inversely proportional to the antibody coefficient of variation.The positive rate of hog cholera antibody was proportional to the positive rate of foot-andmouth disease antibody of type O.The positive rate of hog cholera antibody was higher in the pig farms with high positive rate of hog cholera antibody,while the other was lower.The positive rate of antibody to FMD of type O and highly pathogenic porcine reproductive and respiratory syndrome was lower in pig farms with higher antibody to FMD of type O than in pig farms with higher antibody to FMD of type O.3.The average antibody positive rate of 8 swine farms immunized with highly pathogenic porcine reproductive and respiratory syndrome attenuated vaccine in Shangcai County was 75.83%(182/240).The mean KQ value was 38.78 with a standard deviation of 26.26 and a coefficient of variation of 67.72%.The positive rate of antibody reached over 70% in 7 pig farms,accounting for 87.5%(7/8).The antibody positive rate was proportional to the mean OD value and inversely proportional to the antibody coefficient of variation.4.In combination with the results of CSF testing and the immunization program on pig farms and the actual production on pig farms,it is recommended that the pig farms appropriately adjust the immunization dose according to the requirements of the vaccine package insert and the immunization conditions,and that all sows,gilts and boars in the empty gestation period should be immunized.Piglets aged 25 – 28 days and nursing sows should be immunized once at the same time,and piglets aged about 60 days should be boosted once.Two weeks after immunization,detect the immune antibody level of the vaccine at different stages of the herd,and then modify the immunization procedure according to the test results.The focus is on adult herds being immunized not less than three times a year.It is recommended to immunize each pig once in January,May and September,and the piglets should be immunized twice before 60 days of age according to the maternal antibody level.5.Combined with the results of FMD detection and pig farm immunization program and pig farm production practice,the recommended immunization program for the 26 large-scale pig farms with the immunization qualification rate of less than 70% is(1)universal immunization for sows in the second trimester of pregnancy,sows in the empty gestation period,gilts,and boars,once at weaning for lactating sows,and twice at 70 days and 100 days after immunization for piglets at about 35 days of age.Two weeks later,the immune antibody levels were detected and the immunization program was revised according to the test results;(2)It is recommended that boars and empty pigs be immunized once in each group every year in February,June,and October,and it is more appropriate for sows to be immunized once before breeding or at weaning and once in the first month of pregnancy with fetuses;(3)and gilts and boars are immunized no less than twice before mating before testing antibodies can enter the sow herd.6.Combined with PRRS detection results and pig farm immunization program and pig farm production practice,in view of PRRSV infection and instability in pig herds,the recommended prevention and control methods are:(1)implementing broadspectrum antibiotics and immunity-enhancing drugs or drinking water for one week in adult herds and nursery and fattening herds to reduce viral hazards;(2)using RT-PCR method to detect PRRSV in boars and gilts and eliminate positive pigs;(3)blocking sow herds for 4-6 months and not introducing replacement pigs from outside;(4)immunizing attenuated vaccine twice at intervals of about 3 weeks in self-bred gilts and monitoring antibody positive before entering sow herds;(5)immunizing inactivated vaccine for 4 times per year in basic sows and boars,and immunizing attenuated vaccine at about 7 days of age in piglets;(6)implementing strict biosafety measures,adhering to self-breeding,point-by-point production,combining detection with immunization,and control of immunosuppressive diseases.7.The three immunity levels of pigs in Shangcai county were better than those in large and medium scale pig farms in general,and better than those in other seasons in autumn and winter.Combined with the immunization conditions of three kinds of epidemic diseases,under the conditions of basic sows,replacement pigs,boars,general immunity and daily immunization as well as the biosafety control of the pig population,it is suggested to implement simultaneous immunization with CSF,O-FMD and HPPRRS in piglets aged 28-35 days through three-point synchronous immunization,and meanwhile perform the second booster immunization with CSF and O-FMD,so as to reduce labor intensity. |
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