Abstract

Bovine respiratory disease (BRD) is the most important cause of clinical disease and death in feedlot cattle. Respiratory viral infections are key components in predisposing cattle to the development of this disease, which allow secondary bacterial infection and disease development. This study was designed to investigate the prevalence of bovine respiratory disease complex in beef farms at Alexandria and Elbehera Governorates.
Six beef farms have 3230 fattening calves 6-12 months age were clinically examined for respiratory disease complex. 971 animals were having respiratory signs at a percentage of 30% with variable prevalence in the 6 farms.
Deep nasal swabs were collected from diseased animals and investigated for Bovine herpesvirus type one (BHV-1) by conventional polymerase chain reaction (PCR) and for bacteriological examination. PCR could detect BHV-1 infection in 3 samples out of 40 samples examined and the main bacteria isolated from diseased animals were Pasteurella multocida and Pseudomonas aerugeinosa.
In conclusion, Bovine herpesvirus type one is one of the major pathogens causing respiratory signs in beef cattle and predispose cattle to bovine respiratory disease complex. And pastuerella multocida is secondary bacterial invader which cause the disease. The role of pseudomonas aeruginosa as a causes of respiratory diseases needs further studies.

Key words: BRDC, BHV-1, P. multocida, P. aeruginosa