ABSTRACT
 
Salmonella is the foremost cause of food-borne zoonotic disease worldwide. This study aimed to investigate the effect of amino acids (AA) on the immune status of poultry against salmonella infection. A total of 180 one-day-old chicks (Ross 308) were reared, swapped for detection of salmonella and divided into 5 groups randomly. G1 noninfected, non-treated, G2 infected with S.entertieds at the 7 ^th day old, G3 infected with S.entertieds at the 7 ^th day old and supplemented with AA 1 cm/ liter for 3 successive days per week, G4 non-infected and supplemented with AA 1 cm/liter for 3 successive days per week and G5 infected with S.entertieds. The body weight gain increased significantly in G4. The IgG level was very low in G4, especially on the 35th day, while it was high in G5. IgM level was markedly low in G4, especially on the 28^th day and very high in G2 on the 28^th day. Glutathione peroxidase enzyme level increased significantly in G4 at age 35. A total number of 58 (12.89%) Salmonella isolates were recovered from 450 samples. The sopB, bcfC, and stn genes were detected in all isolates, while the spvC gene was absent in all isolates. The (qnrA) gene was detected only in one examined isolate, while (qnrB) was detected in two isolates. Histologically the liver and intestine were improved in the AA-supplemented groups even with infection (G3), with normal hepatic parenchyma and hepatocytes and abundant goblet cells and hyperplasia of the intestinal mucosa. Besides, the immunoreactivity (CD3 and CD79) significantly increased, indicating more lymphocytes compared to other groups. In conclusion, supplementation of amino acids improved the performance and immunity of poultry and reduction of colonization of S. Enteritidis in the rearing birds.
Keywords: Essential, Amino acids, immunomodulator, Salmonella, broiler, immunohistochemistry