| Porcine circovirus type 2(PCV-2) is an important immune suppression virus which has been caused significant economic losses in the swine industry nowadays. Vaccination is the effective method to prevent PCV-2 infection. So we select kinds of commercialize PCV-2 vaccine to evaluate of immune effects, which is practical significance. The purpose of the study include:(1) To investigate the immune status of PCV-2 vaccine from the different growing stages pigs on 4 large-scale pig farms in Guangdong province, provide guidance for following comparative studies on the immune efficacy of different PCV-2 vaccine;(2) To study different commercialize PCV-2 vaccines influence with swine production performance and immune performance after vaccination PCV-2 vaccine, expected to select out the high cost performance vaccine, and provided the immunization reference for large-scale pig farms to prevent PCV-2;(3) To realize that changes of sows production performance and their piglets maternal antibody levels after vaccination PCV-2 vaccine, provide the basis for the selecting of the best days for primary vaccination. The main results are as follows:1. Investigation of PCV-2 antibody and antigen levels in different growing stage pigs from large-scale pig farmsIn this parts, to investigate the immune effect of PCV-2 vaccine from the different growing stages pigs, we detected specific antibody and antigen levels of PCV-2 from different stages pigs in 4 large-scale pig farms via ELISA and nested-PCR respectively.From the aspect of the levels of PCV-2 antibody and positive ratio, with the age increasing, the levels of PCV-2 antibody and positive ratio was declined to a lowest level first and then increased, and the maternally derived antibody of vaccinated pig herd can long to 10 weeks. In addition, the detection rate of PCV-2 antigen between different stage pigs in the same farms or the same stage pigs in different farms have significantly difference, the rates is 62%, 25%, 47%, 46% respectively. The reasons may be due to immune effect of different vaccine, feeding management and the characteristics of PCV-2 virus itself etc. Thus, those results contribute to our understanding of the immune status of PCV-2 vaccine.2. Comparative study on the immune efficacy of four commercial PCV-2 vaccines in large scale pig farmDetect PCV-2 antidody and nucleic acids by ELISA and PCR. Collect each group pigs statistics including the average daily gain, feed conversion ratio, death and survival rate in conservation stage, growth stage and the fattening stage.The results showed that, group C average antibody level between 30 d and 120 d is higher than other groups, the level is 0.765 at 60 d, it has significant difference between other three groups, piglets day age that detected PCV-2 nucleic acids is later than other groups. Additionally, the average daily gain of C group test pigs is 0.72 kg, compared with group A, group B and group C, the average daily weights gain of 10.6%, 4.3% and 17.6%, respectively; feed conversion ratio is 1.93 and superior to others, feed conversion ratio reduce 0.35, 0.26, 0.36 than others respectively. Piglets survival rate of group C reach 100%, has no dead scouring pigs. So immune performance and production performance analysis shows that the immune vaccine C is better.3. change observation of sows production performance and their piglets maternal antibody levels after vaccination PCV-2 vaccineThe results showed that after PCV-2 vaccine inoculation, group C exhibited higher reproductive performance, compared to other groups, birth weight increased 9.5%, 5.2% and 7.3% respectively; weaning weight increased 11%, 3.8%, and 8.5% respectively. After sucking colostrum, antibody level in piglet levels at 2~3 weeks old is higher than that of the other, and rapidly decreased after 3 weeks old, then maternal antibodies decreased gradually with the increase of day age. This study showed that inoculated of PCV-2 vaccines can significantly improve sows performance and reduce piglet PCV-2 infection. |
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