Dexamethasone Decreases Mortality Rate in Broiler Infected with Infectious Bronchitis Disease

Abstract

To investigate the impact of dexamethazone (Dx) with or without spiramycin (Sp.) in controlling the mortality
rate of broiler farms infected with infectious bronchitis (IB), two experiments were conducted. In the first
pilot experiment, 750 broiler chicks (Ross) were divided into control (C) and two treated groups received
Dx and Sp (G1) or only Sp (G2), respectively. Second experiment was conducted on five selected broiler
farms (6000 chicks each), two farms were kept without treatment as a control, whereas other farms were
treated with a combination of Dx and Sp. All birds were vaccinated against Newcastle disease (ND), avian
influenza (AI), infectious bronchitis (IB) and infectious bursa disease (IBD), and monitored throughout
the experiment to detect any respiratory sings. The treatment protocol was started when respiratory sings
appear. Blood samples were collected at day 5 of treatment from jugular vein and serum was to assess
aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) and
to detect the antibody titer for the deferent vaccines by ELISA. The result showed significant decrease of
mortality rate in G1 group among experimental groups and insignificant differences of liver function tests
and immune response to the vaccination against ND and AI. It can be concluded that using a combination of
dexamethasone and spiramycin has an efficient effect to protect broiler chicks against infectious bronchitis
by decreasing the mortality rate with no immune suppression.