The Application Of The Vaccine Of Marek's Disease To Broiler

The infecting rate of MD is 10%-60% in broilers, although the typical clinical signs of MD seldom can be seen in broiler due to its short life cycle . The infection of MD will cause immumesuppression and low performance of broiler.We chose randomly 100 broilers at market age in the field ,which had never been inoculated with the vaccine of MD, and then numbered ,weighed, blooded and anatomized them, so we got the weight of body and the serum which was used to test the MD AGP liter, ND HI titer, IBD Elisa titer, at the same time, we weighed the spleen and bursa, then observed the histopathological characteristic of them. Comparing the ND HI titer, IBD ELISA titer, the weight of spleen, bursa and body, and the pathology between the positive group of MD and the negative one, we found that :1)the positive rate of MD is 23%; 2)the negative group is better evidently in ND HI titer and IBD Elisa titer than MD positive group:3)the weight of body is higher by 7%, the spleen is lighter and the bursa is heavier than that of the positive;4)MD infecting lesions were pathologically observed in the spleen and bursa of the positive. This result shows that the influence of MD infecting should be taken into account seriously.In order to make the application of the vaccine of MD to broiler in China, we have performed several field trials in some large broiler companies in the past years, including the vaccination to one-day old chickens with dried HVT and 18 days old embryos with frozen HVT. The number of the vaccinated chicken is 894,154 and the number of the control is 1,374,493. The result shows that the vaccine of MD have been able to decrease the infecting rate of MDV I , especially for the large companies of broiler, the infecting rate is almost zero; and then the performance of broiler is improved, which is shown as follow: the living rate increased by 1.16% averagely; FCR by 0.02 point; EPI by 47 point and the mass margin by 0.18 yuan in RMB per bird. As a result of the vaccination, the inoculated broilers increased the sale amount by 0.36 yuan in RMB per bird at market age. Vaccination to broiler can bring the direct economic: profit, so we should make it applied in China.