Immune Antibody Detection And Analysis Of Newcastle Disease In Cuiping District Of Yibin

Newcastle disease(ND)is a type of Class A disease of the World Organization for Animal Health(OIE),also classified as categoryⅠinfectious disease in China,it will not only cause catastrophic damage to birds(the mortality rate of chickens can be as high as high as 100%),but also trigger international trade restrictions and blockades,which will cause more serious economic losses.China has implemented comprehensive immunization strategy against the Newcastle disease,through comprehensiveprevention and control measures based on vaccine immunization,it has been effectively controlled.However,Newcastle disease costantly apperes local epidemics or dissemination in part of china.The situation of Newcastle disease prevention and control in Yibin is very serious due to various factors.Firstly,Yibin is adjacent to Yunnan Province where Newcastle disease has occurred continuously for many years,and pathogen monitoring by professional institutions also shows that the phenomenon of hidden virus is common;secondly,Yibin belongs to south Sichuan region which is located on the central asis-india migration route of the eight largest migratory routes in the world,the annual migration of migratory birds flow south brings big difficulties to the prevention and control work.Thirdly,some newly-built large-scale farms and farmers are weak to deal with epidemic prevention in awareness,knowledge and technology,introducing a lot of seeds across regions and over long distance,the construction of epidemic prevention facilities and epidemic prevention and control work are not doing well,all of these bring greater pontential dangers to epidemic prevention and control work.Fourthly,the scale of farming is still relatively low overall,free-ranging livestock and poultry are generally not immunized entirely or not immunized.Cuiping District as the main animal huabandary area of Yibin city,has developed chicken industry rapidly in recent years.In order to understand the general situation of Newcastle disease prevention and control in this region and investigate the factors affecting its immune effect,the national standard testing methods(HI test)is used to test and analyze the immune antibody titer and pass rate of Newcastle disease in 1808 chicken serum samples from 17 townships in Cuiping District from 2017 to 2019.The results show that the average immune antibody titers agaist Newcastle disease are 5.82±2.64 log2,with a pass rate of 81.89%,which meets the requirement of the Department of Agriculture on vaccine immune antibody pass rate ≥70%.Among them,the pass rate of immune antibody in 2019(95.51%)> 2018(81.66%)> 2017(75.96%),but the antibody titer in 2019 is significantly lower than the previous two years;among 17 townships,Yongxing,has the highest qualified rate of immunization(97.67%),however Gaodian town reaches the lowest qualified rate of immunization(43.66%);the immune antibody pass rate among three breeding models is that breeding enterprises(92.38%),greater than professional cooperatives(89.77%),greater than individual free-range households(65.08%),the qualification rate and antibody titer of Newcastle disease in the first two modles is significantly higher than that of the individual free-range households;the immune antibody pass rate for different types of chicken Newcastle Disease was that egg-laying hens(93.01%),greater than broiler chickens(89.13%),the antibody titer of egg-laying hens is significantly higher than the broiler chickens.In addition,based on the results of the above test,card-square analysis and bicategorical logistic stepwise regression analysis,with detection result(Y)as the dependent variable and year(X1),breeding mode(X3),and chicken type(X4)as the covariatesto enter model optimal equation of the prediciont model.The prediction model is (?).After testing the-2 logarithmic likelihood value of the model,the accuracy rate of predition model,and the ROC curve,the fitting effect of this prediction model is very general.Using the model to test the probability of passing Newcastle disease immune antibody test this year in Cuiping District,and five different combinations models are found,after comparing the set probability condition P2020>0.70,passing rate ranges from 0.723-0.785,therefore,in 2020,the prevention and control of the Newcastle disease in Cuiping District should continue to implement the strategy of comprehensive immunization,and make the epidemic prevention work be better,pay more attention on free-range farmers,make moderately inspection efforts to cooperatives,and take regular sampling inspection in breeding enterprise farming,all these efforts to ensure the effectiveness of Newcastle disease prevention and ensure the safe development of the chicken farming industry.This study providesa strong basis and support for the scientific implementation on immunization prevetion and control of Newcastle disease in Cuiping District.