Serological Supervision And Prevention Of Porcine Reproductive And Respiratory Syndrome In Large-scale Swine Farm

Recently, porcine reproductive and respiratory syndrome (PRRS), especially caused by highly pathogenic PRRS virus (PRRSV) has become one of the most important infectious diseases of swine industry in the world. The etiological agent mainly invades reproductive and respiratory systems of swine, leading to the reproductive failure of sows, the high mortality of piglets and the respiratory disease of finishing pigs. In order to find out a practical process to solve the problems lied in practice and to decrease the economic losses caused by PRRSV, serological variation, vaccine immunization, and best prevention administration to PRRSV in 7 large-scale swine farms belonged to were studied.1. In order to insight into PRRSV antibody variation in the farms, different age piglets in seven intensive swine farms of Shanghai farms were randomly selected to detect antibody against PRRSV. The results showed that antibody level was the lowest between 45 and 65 day age and then increased rapidly, which maybe indicated PRRSV infection happened at this stage. At the same time, compared antibody variation with clinical signs, we can concluded that, with the decreasing of S/P value, the appetite of piglets were decrease accordingly. It provided the theory basis for controlling prevention of PRRS.2. In order to study growth performance in piglets with different immunization procedures. Eighty pregnant sows were chose and randomly divided into four groups. The neonate piglets of three experimental groups were vaccinated at 14d,28d,35d, respectively, and other group was mock immunized. The average weight, daily weight gains, the feed conversion ratio and surviving rate were investigated. The results showed that average weight of piglets (vaccinated at 14d) was 102.19±5.46kg, daily weight gains was 642g, the feed conversion ratio was 2.82:1, surviving rate was 90.11%. The growth performance in early immune group was better than that in late immune group and control group. Implementation of integrated prevention and control techniques in 7 extensive swine farms demonstrated that growth performance was significantly improved in surviving rate (90.37%), the feed conversion ratio (2.95:1), live pig sell rate of one sow per year (21.53), birth rate(87.89%), percentage of effective estrus (92.29%). It indicated that the control of viral diseases greatly depended on a set of the optimized administration practice specifications, establishment of the immunity against specific PRRS virus strain and related pathogens and lowering the level of microbe in the environment.