Brucellosis of dairy cows is the second kind of zoonosis, which exists widely all over the world. It has been prevalent in some areas and caused great harm to the health of dairy cows and related workers. In the 1970s and 1980s, the epidemic situation of brucellosis in China dropped significantly, but it rose in the 1990s. In dairy cattle breeding, strict diagnosis and scientific and reasonable prevention and control of this disease should be carried out.
1. Serological diagnosis of brucellosis
(1) Experiments on Agglutination Reaction of Rose Bengal Plate
This method is suitable for field trials and wide-ranging screening. The results will be observed in four minutes by mixing the serum of the cows tested with the antigen and then placing the reaction. The antigen in the plate agglutination test of brucellosis is inoculated with Brucella strains with good antigenicity in the culture medium. After a certain period, the bacteria are harvested. After heat inactivation, the disease is stained with tiger red dye after centrifugation, and the antigen can be obtained by suspension in the lactic acid buffer.
When judging the results, it is based on the agglutination strength criteria. It is particularly important to pay attention to the further complement binding reaction test and auxiliary test for dairy cattle with positive results to further detect and determine. The method is simple to operate, easy to judge, sensitive and cheap, but it is prone to false positives. Therefore, the samples with positive results should be further analyzed by tube agglutination test and complement binding reaction test to determine whether cows are infected with brucellosis.
(2) Test tube agglutination test
After 1-2 weeks of infection with brucellosis in dairy cows, immune systems of the body will be stimulated to produce a 1gM antibody in the blood. Because the antibody can bind to the corresponding antigen and produce specific binding, under the action of electrolyte, it will gradually agglutinate to form a naked-eye visible agglutination reaction. At the same time, the turbidimetric tube and experimental tube will be deployed. To determine the results, we use the agglutination test to detect cow blood. In each test, positive serum, negative serum and antigen must be used as a control to determine the results. So this method is complicated, time-consuming and laborious, and the result is slow, but it has high specificity, strong sensitivity, and wide practicability. It can be used as both quantitative and qualitative experiments.
(3) Complement binding test
In the current serological detection of brucellosis in dairy cows, a complement binding reaction test has the best specificity. This method uses an antigen-antibody complex complement to bind, and gradually depletes the complement in the complement reaction solution, which results in the decrease of concentration, so that antigen or antibody can be detected. Three weeks after infection, the 1gG antibody will appear in the serum of infected cows, which can be detected by complement binding reaction test. At present, it is generally believed that the sensitivity and specificity of this method are better than other methods. Therefore, this method is often used to detect the positive and suspicious results of Huhong plate agglutination reaction and test tube agglutination reaction. The sick animals were further analyzed qualitatively.
2. Prevention and treatment of brucellosis in dairy cows
(1) Sterilization of aquaculture farms
Brucellosis is sensitive to light, heat and common chemical disinfectants. It can be killed by sunlight for 10-20 minutes, moist heat for 10-20 minutes at 60 degrees Celsius and 3% bleaching powder clarifier for a few minutes. Besides, 3% Lysol and 5% lactic acid disinfection can kill the virus in 1-2 seconds. Cattle farms can be disinfected with a 3% bleaching powder solution, and pens can be sprayed with 3% Larsson for disinfection.
(2) Report the epidemic situation to relevant departments in time
When purchasing dairy cows, cattle ranchers should pay attention to check the quarantine certificates and immunization certificates issued by relevant departments to prevent the purchase of diseased cows. Once breeding personnel finds suspicious brucellosis animals, they should immediately report to the local village veterinary epidemic prevention officers or township veterinary stations, and isolate suspicious disease animals until relevant department personnel arrives at the scene. Check and verify, actively cooperate with their work, and take appropriate measures.
(3) Improving the vaccination of brucellosis vaccine
Dairy cows should be vaccinated with the Brucellosis vaccine in the area where Brucellosis occurs. Live Brucellosis vaccine (I) and live Brucellosis vaccine (II) produced by regular manufacturers can be used. However, this vaccine is generally not vaccinated against pregnant animals and breeding males, and female cows should be vaccinated before vaccination. It should be noted that these two vaccines are: Vaccines have certain pathogenicity to people, so vaccinators should do a good job of corresponding safety protection to avoid infection.
(4) Mandatory culling of positive dairy cows
Strictly implement relevant regulations and policies, send samples of suspected diseased animals to the testing department for detection. Once confirmed to be positive for brucellosis, diseased cattle must be killed and harmlessly treated. At the same time, milk and dairy products of diseased dairy cattle, aborted fetuses, fetal clothes, excrements, and other non-polluting treatment should also be carried out to prevent and control the disease. Human and animal infections are common.
This passage introduced the causes of brucellosis in dairy cows and related prevention and control measures from two aspects of serological diagnosis and control measures, to reduce the incidence of brucellosis and improve the output and economic benefits of dairy cows. With the continuous development of science and technology, it is believed that the dairy farming industry will develop more healthily and steadily, and the quality of dairy products in China will also be greatly improved.