Some considerations for sow back feeding
Vaccines are generally treated physically or chemically, so that the virulence of the virus or bacteria contained in the vaccine is reduced or inactivated before being used in pigs.
Return feeding is a pig disease that is suspected to be caused by certain pathogenic microorganisms known or unknown. In the absence of an effective commercial vaccine, the disease materials presumed to contain these pathogens, such as placenta and intestinal contents, are given to pigs. It produces antibodies to these pathogens to achieve a simple "vaccination" process that protects itself and its offspring. Since most of the disease comes from piglets or their accompanying products such as the placenta, which is fed back to the sow, this method is called return feeding. In addition to returning to empty or pregnant sows in production, the gilts are also fed back to produce antibodies to prevent sows from becoming pregnant and during childbirth. In this regard, the United States Minnesota pig farm senior consulting veterinarian Tim Loula introduced some of their practices, combined with our experience, the following points should be noted when doing back feeding:
1 More than 1 return to pregnant sows
It is usually carried out at 6, 5, and 4 weeks before birth, so that each sow can be exposed to the pathogen every week, so that it can produce strong immunity without being poisoned in the farrowing house. According to the ninth edition of the domestic translation of "Pig Disease": "The transmission mode of PEDV is not much different from TGEV, but it is more likely to persist after an acute outbreak on the farm." "The fecal test can be performed within 3-11 days after the experimental infection. The PEDV antigen was detected by the child, and the peak of detoxification was 4-5 days after inoculation. The above description reminds us that the cause of diarrhea in the farm may be related to persistent infection of PEDV. In addition, some domestic data suggest that the return of feeding should be more than two weeks before the delivery of the pregnant sow, which may be related to the fact that the sow is close to the delivery time and cannot produce sufficient antibodies.
2 must use fresh disease materials
The reason for the use of fresh disease materials is that the bacteria can produce toxins within a few hours and increase the toxicity to the sows. Second, some pathogens will die soon after they leave the animal, and their antigenicity changes to weaken the effect of returning. According to "Pig Diseases": "TGEV freeze storage is very stable, but unstable at room temperature or above. The virus is very sensitive to light, and the virus in the intestinal excretion containing 105 infection titers is exposed to sunlight for 6 hours. All are inactivated." Although inactivation does not necessarily affect the antigenicity of the virus, it cannot be proliferated because the virus is inactivated, and the total amount of antigen is reduced. Therefore, TimLoula recommends mixing the disease and use within 1 day.
3 Detecting the pathogen contained in the returned feed material
"Pig Diseases" introduces: "After rotavirus is highly toxic, the body will have protective power without being reinfected by the same type (usually P or G type) rotavirus." TimLoula said: "Rotavirus type C is difficult to produce immunity to the virus if it is not in the material to be returned." In addition, we believe that if the piglets are infected with the pseudorabies virus, the symptoms of diarrhea are also very obvious, but they cannot take the form of returning to prevent the pregnant sow from being infected. Therefore, it is best to do a virus separation to confirm the cause of diarrhea.
4 Returning feed during the isolation of imported pigs
If a negative reserve pig is introduced into the blue ear disease-positive field, the pig should be allowed to adapt for 60 days during isolation to produce antibodies against blue ear disease, and then returned. Because if the disease is fed at this time, the virus in the field of blue ear disease will infect the new backup pig, so that it can not produce enough anti-diarrhea virus antibodies. Pigs that are positive for blue ear disease also need time to recover, so give the reserve pigs time to produce antibodies. If a 6-month-old gilt is introduced, the antibody may not be high at 7 months of age and can only be bred at 8 months of age.
Back feeding is characterized by rapid, simple and low cost. However, since the general pig farm does not separate and identify the pathogen, the nature and content of the pathogen contained in the disease material are uncertain, and the return feeding effect is sometimes difficult to guarantee. For beginners, it is necessary to choose the target for returning. For example, if diarrhea occurs in a suckling piglet, the feeding material of the suckling piglet cannot be used for conservation or finishing pigs for "back feeding" because the same pathogen may cause these pigs. Group disease. Therefore, it is best to make an accurate diagnosis when the disease occurs on the farm, and then take comprehensive and effective prevention and control measures in time.
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