Effect of Experimental Infection with Two Serotypes of Salmonella on Immune Response Against Newcastle Disease Vaccine in Broilers

This study was designed to show the effect of experimental infection with two serotypes of salmonella on immune response in chickens. Four groups of broilers were used. First group infected by S.typhimurium orally with 2 x 106 cfu/ml at 5 day age, and the second group infected orally by S.enteritidis with 1 x 108 cfu/ml at the same age. While the third group don't exposed to salmonella and considered as positive control . the forth group was considered as negative control .Then the first three groups vaccinated with Newcastle disease vaccine at 7 day of age. After that all the groups exposed to challenging with virulent Newcastle disease virus at 22 days post vaccination. The results showed significantly high level of antibodies in the 3rd group when compared with 1st and 2nd groups, and the protection ratio in the 3rd group is 85% while it is 70%, 60% only in the 1st and 2nd groups respectively.