Saliva replaces the blood, the test does not require blood drawing? Recently, many foreign scholars have proposed the use of saliva samples for the detection of antigens and antibodies so that workers and pigs can be liberated at the same time. This is a boon for large-scale breeding farms. However, experts in the industry believe that the relevant standards for saliva detection have not yet been established, and it will take time to apply it to the frontline of culture.
In recent years, many farms will assess the health status of pigs in the farm through antigen and antibody testing. The largest amount of work is blood collection, which has a higher technical requirement for workers, and second, the stress of pigs. At the just-concluded 22nd World Congress of Pig Diseases, experts from the United States pointed out through experimentation that the use of saliva samples for the detection of blue ear, swine fever antigen and antibodies can achieve the effect of using blood as a sample.
In this regard, Dr. Wu Jun, head of IDEX China, believes that if it is possible to establish an evaluation standard for saliva samples, saliva testing has certain feasibility. Dr. Fan Fuhao, director of the Laboratory of the Ministry of Agriculture's Breeding and Testing Center (Guangzhou), believes that using saliva to replace blood as a test sample is subject to too many interference factors and the test is not reproducible.
According to Dr. Fan Fuhao, the saliva collection method is very simple. Using the curiosity of pigs and the craving of cravings, gauze balls are used to collect saliva. The gauze is made into a gauze ball fixed at the front end of the wire, and the pig will actively chewing the gauze ball. Saliva will enter the gauze ball through the siphon phenomenon. The saliva in the gauze ball was squeezed out and released into the sample bag. The saliva in the sample bag was transferred to a centrifuge tube. "It's much simpler than blood collection, but there are too many unstable factors in this method and it needs experts and scholars to further study." Fan Fu thinks that although this method is convenient and concise, it has a lot of blank content, so this method is used abroad in 2009 or so. After it was proposed, it was always in the research stage and it had not yet been applied to the actual production.
In this regard, Wu Jun thinks that the biggest problem is the criteria for judging. "Can not use the blood index to determine." According to Wu Jun, saliva is also a kind of body fluids, can reflect a certain physiological and biochemical indicators, but can not be used to determine the blood of the yin and yang in the saliva samples. For example, in the blood sample, the blue ear's evaluation index is that the OD value is greater than 0.4 is negative, and less than 0.4 is positive; the antigen and antibody content in the saliva is correspondingly lower than in the blood, therefore, the demarcation point is certainly not 0.4. How much it needs to be obtained through a large number of experiments.
"In the detection of antigens can be implemented, but subject to environmental pollution," Wu Jun told the Southern Rural News reporter, this method can only determine the group and can not be informed of the individual situation, because the same nest of pigs, each have It is possible to bite the hanging cotton ball and at the same time it is easily contaminated by the surrounding environment, and non-specific reactions occur, eventually resulting in errors or instability in the results.
For the use of saliva as a testing experiment, Fan Fu thinks the error is good. According to Fan Fuhao, similar experiments were conducted two years ago to collect saliva from pigs for antibody testing. "Can detect antibody levels, but the error is relatively large." Fan Fu told the Southern Rural News reporter, the amount of saliva samples directly affect the experimental results, the same pig body, more or less collected, the experimental results are different; and collected Different times, the experimental results are also different. "So when collecting samples, it is best to unify the premise criteria: for example, it is not allowed to drink water before the collection, or just chewing for 2 hours." Fan Fu said.
According to Fan Fuhao's analysis, since the antibodies in saliva and the antibodies in blood are not the same concept, it is necessary to avoid understanding the use of serum antibodies to explain the effects of antibodies in saliva. Most of the antibodies in the serum are circulating antibodies, while the antibodies in the saliva are secreted antibodies. The effects of the two are different, and the correlation with the antigen is also different.
Although there are doubts about saliva testing in this or that way, Dr. Wu Jun believes that this will be a trend. After all, foreign countries increasingly implement welfare pig raising, and the blood collection is relatively stressful for individuals and groups. According to Harm Voets DVM, head of marketing at Boehringer Ingelheim Animal Health Products Co., Ltd., in the United States, the farms are constantly experimenting with this saliva test. Dr. Fan Fuhao also believes that saliva testing is a technique that is worth promoting and is very convenient for farms if the relevant criteria for the method are established.
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