| FMD is is a contact,febrile and acute infectious disease that mainly occurs in artiodactyl and is caused by foot-and-mouth disease virus.The clinical characteristics of the disease are that adult animals produce blisters and putrefication in the mouth mucosa,hooves and breasts,etc.and the young animals often suffer from myocarditis,making it more likely to die.OIE classifies the disease as an animal infectious disease that must be reported,which is classified as Class A animal epidemic disease in China.Foot-and-mouth disease(FMD)is a fulminating infectious disease that seriously harms the health of cows.The disease has many transmission routes,fast transmission speed and wide epidemic range,and meanwhile,it will also cause severe economic losses to dairy cow-farming breeding industry.In this study,the detection and analysis of antibody levels of foot-and-mouth disease for three consecutive years from 2015 to 2017 in 20 large-scale dairy farms of a dairy company are selected,and at the same time,the immune procedure suitable for the company is screened,to provide a basis for the immunization of foot-and-mouth disease in large-scale dairy farms.Test one: Detection of foot-and-mouth disease antibody level in large-scale dairy farms from 2015 to 2017Select a company 20 large-scale dairy farm,among which 2 are calf farms(under 6 months of age cows),4 are dairy farms(6 months to 24 months of age cows)and 14 are adult dairy farms(more than 24 months cows).The total number of dairy cows in each farm is about 2000,which are modern ranches with regular management and qualified safety index;For three consecutive years(2015-2017),40 dairy cows were random Ly sampled from each pasture every month every year by liquid-phase blocking ELISA method for detection of antibody levels of foot-and-mouth disease type A,type O and Asia-I.That is,800 cows were detected every month;2400 cows were detected every quarter;9600 cows were detected every year.The qualified rate of three kinds of antibodies against FMD in different seasons,different ages,different months and different pastures was carried on the statistics.The results show that:From 2015 to 2017,the annual average qualified rate of three types of foot-and-mouth disease antibodies in 20 farms was higher than the minimum level required by the state(70%),and the protection rate of antibodies in 20 large-scale farms was relatively stable.The average qualified rates of type A samples from 2015 to 2017 was 86.36%,83.3% and 85.17% respectively.The average qualified rates of O-type samples were 87.7%,87.13% and 88.81%,respectively;The average qualified rates of Asia-I samples were 87.71 %,85.58% and 88.06% respectively.The average qualification rate of type A antibody in three years was higher in the fourth quarter,and lower in the third quarter.The average qualification rate of type O antibody was higher in the second quarter and lower in the third quarter.The average pass rate of Asia-I antibody was higher in the second quarter and lower in the fourth quarter respectively.The qualified rate of three kinds of FMD antibodies was the highest in adult cows and the lowest in calves.Test two: Screening of immunization procedures for foot-and-mouth disease in dairy cattleFirstly,serum was collected from 40 calves of different ages that had not been immunized in two pastures,and the qualified rate of maternal antibody level was detected,and the law of growth and decline of maternal antibody was analyzed to determine the first immunity time.Serum samples were collected at 15 d,30d,45 d,60d,90 d and 105 d after the first immunity of calves for FMD antibody detection,and then the time of booster immunity after the first immunity was determined;Then 40 adult cows from two different pastures were selected to test the qualified rate of three types of FMD antibodies.Cows in 1 pasture were immunized by subcutaneous injection of the neck,and cows in the other pasture were immunized by intramuscular injection of the buttocks.Serum samples were collected 21 days later to test the qualified rate of antibody level.At the same time,the 80 cows were conducted booster immunization,and the qualified rate of FMD antibody level was detected on 21 d,60d and 100 d after immunization.Another 40 pregnant cows with average pregnancy days of around 120 d in two pastures were selected for foot-and-mouth disease vaccination.Injection methods: 2m L intramuscular injection once and 1m L intramuscular injection twice(one week apart)were adopted to compare the number of side effects of different injection methods in pregnant cows in two pastures.At last,two different pastures were selected,one of which was immunized for 2 times and 3 times in the whole year,respectively.The antibody levels were detected on 30 d,60d,90 d and 120 d after immunization,and then compared with the antibody levels of different immunization times in the whole year.Through the above experiments,a more appropriate immune procedure was selected out.The results show that: It was found that the optimal time for the first immunization was 90 days old,and the second immunization was strengthened 30 days after the first immunization;it was found that the immunological results of intramuscular injection in buttocks were better than that of subcutaneous injection in neck;it was found that the side effects of two different intramuscular injection methods were less frequently;the antibody qualification rate of 3 immunization times in the whole year was higher than that of 2 immunization times in the whole year.Through the above experiments,the selected immunization procedures for FMD are: intramuscular injection was used to immunize calves at 90 days of age for the first time,30 days after the first immunization,the second booster immunization was performed.Adult cows were immunized by intramuscular injection of buttocks three times in the whole year,respectively in March,August and November,and pregnant cows were immunized by intramuscular injection at two different points. |
PDF Full Text Request