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Online Journal of Veterinary Research©
Volume 22 (2): 139-149, 2018.
Effects of relative humidity and commercial medicinal treatments on complex respiratory infections and pathology in broilers.
Faghihzadeh S., DVM, Asasi K., DVM, PhD, Abdi-Hachesoo B., DVM, PhD.
Poultry Diseases Research Center, Department of Clinical Studies, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
Faghihzadeh S, Asasi K, PhD, Abdi-Hachesoo B., Effects of relative humidity and commercial medicinal treatments on complex respiratory infections and pathology in broilers. Onl J Vet Res., 22 (2): 139-149, 2018. Respiratory complex infections are the most common cause of mortality in broiler chicken farms in developing countries. We report effects of 25 to 80% relative humidity (RH) on treatments with Bromhexine® and Bronchimax® in broilers inoculated with infectious bronchitis virus (IRFIBV32), avian influenza virus (H9N2) and E. coli (O2). Nine groups of 43 broiler chicks were challenged and 3 groups of 20 were used as unchallenged controls but all received treatments and were exposed to 3 levels of RH. Results showed highest mortality rates (28%) occurred at low relative humidity in broilers given Bronchimax® and lowest mortality (11.5%) in high relative humidity without treatments (P < 0.05). Oral mucosal discharges were significantly higher in groups exposed to high humidity with Bromhexine and/or high humidity with Bronchimax compared with other groups (P≤0.05). Syrinx casts, were lower in those exposed to 50-55% RH and treated with Bromhexine (P≤0.05). In dead birds, aggregation of fibrinous exudate occluded the syrinx leading to asphyxiation. We report clinical signs, necropsy findings, tracheal histopathology, ciliary stasis scores, serology and RT-PCR results for all poultry affected by complex respiratory disease. High relative humidity may decrease mortality but mucolytic and/or herbal treatments, increase mortality in chickens infected with respiratory complex agents.
Key Words: Respiratory Complex, Relative Humidity, Mucolytic drugs, IBV, H9N2, E. coli.