Epidemiological Investigation Of Group Ⅰ Fowl Adenovirus Of Duck Embryos In Shandong Province

With the rapidly development of the duck breeding industry,the output of meat-duck in China is always at the head of the world.What’s more,as the density of feeding getting increased,the intensive production has led to great difficulty in disease controlling.The conventional infectious diseases,such as avian influenza and Newcastle disease,are prevailing,while the newly breaking diseases emerge.For example,the duck beak atrophy and dwarfish syndrome caused by novel goose parvovirus emerged in 2015 and the Hydropericardium Hepatitis Syndrome breaking in Cherry Valley Ducks in China in 2015,which caused group I fowl adenovirus.The prevalence of the fowl adenovirus has caused enormous economic loss to the industry of duck breeding.The previous report suggested that the fowl adenovirus can transform vertically via the embryos.The study collected a large amount of duck embryos and hatching ducks from several breeding duck farms in Shandong province regularly.The samples were used to perform the PCR assay and virus isolation to gain deeper understanding of the prevailing situation of group I fowl adenovirus among the duck embryos in Shandong.What’s more,the hexon gene of fowl adenovirus isolated in the study was sequenced to confirm the mutation of fowl adenovirus recently.Total of 461 embryos were collected,and the infection rate of which was 37.5%,vary from 23%to 57.4%.the fowl adenovirus can be earliest detected from the 8-day old.Total of 120 hatching ducks were collected,and the infection rate of which was 34.2%,vary from 30%to 35%.And the 120 samples of cloacal swabs were collected from a breeding duck farm in Dezhou city,the injection rate of which was 28.3%(34/120).4 virus strains were isolated in the study,among which 3 strains were clustered into the serotype 4,and one was of serotype 1.The results revealed that the fowl adenovirus serotype 4 is mainly epidemic among the duck farms.To sum up,the invisible infection situation is pretty severe in the breeding duck farms.Also the vertical transmission contribute to the embryos infected with the fowl adenovirus,which leading to the hatching ducks born with the infection.All these above have cause huge hind to the development of the duck breeding industry.