BACKGROUND: Antibacterial drugs have long been used for prevention and treatment of poultry diseases but their misuse or overuse can make adverse effects on public health including occurrence of drug residues in poultry products. OBJECTIVES: To assess the frequency and status of antibacterial drug consumption in broiler production farms in Qum province. METHODS: In the present survey, Qum province was divided into six regions (north, west, southwest, south, southeast and east) and in total 138 broiler production units (59%) were studied by direct interview using a questionnaire. RESULTS: The present study showed that the most frequently used antimicrobial drugs in broiler farms were  sulfamethoxazole+trimethoprim (93.4%) followed by enrofloxacin (60.0%), colistin (49.7 %), furazolidone (42.0 %), oxytetracycline (17.5 %), and chloramphenicol (14.6 %). Mean antibacterial consumption rate during a 42-48 day production period was 3.0± 0.37 times per farm. A notable finding in this survey was the high percentage of banned drug usage such as furazolidone and chloramphenicol, indicating the ignorance or unawareness of poultrymen regarding the potential hazards of these drugs on public health. CONCLUSIONS: Owing to widespread and frequent usage of antibacterial drugs in broiler farms, all-out actions are needed to be taken in educational, research and administrative fields of veterinary and animal production sectors for rational and responsible use of these drugs in poultry industry.

Introduction: Despite the advancements in the field, there is a lack of data when it comes to co-infections in poultry. Therefore, this study was designed to address this issue. Material and Methods: Broiler birds were experimentally infected with E. coli (O78) and low pathogenic avian influenza (LPAI) strain, alone or in combination. The experimental groups were negative control. Results: The infected birds showed most severe clinical signs in E. coli+LPAI group along with a significant decrease in weight and enhanced macroscopic and microscopic pathological lesions. The survival rate was 60%, 84%, and 100% in birds inoculated with E. coli+LPAI, E. coli, and LPAI virus alone, respectively. The results showed that experimental co-infection with E. coli and H9N2 strain of LPAI virus increased the severity of clinical signs, mortality rate, and gross lesions. The HI titre against LPAI virus infection in the co-infected group was significantly higher than the HI titre of LPAI group, which may indicate that E. coli may promote propagation of H9N2 LPAI virus by alteration of immune response. Conclusion: The present study revealed that co-infection with E. coli and H9N2 LPAI virus caused more serious synergistic pathogenic effects and indicates the role of both pathogens as complicating factors in poultry infections.

The microbial community is known to have a key role during the rearing period of broilers. In this study, gut microbial composition and diversity were examined to evaluate the relationships between these factors and broiler growth performance. By applying 454-pyrosequencing of the V1-V3 regions of bacterial 16S rRNA genes, six fecal samples from four- and 28-day-old chickens from three broiler farms and 24 intestinal samples of broilers with heavy and light body weights were analyzed. Microbial composition assessment revealed Firmicutes to be the most prevalent phylum at farm A, while Proteobacteria were predominant at farms B and C. Fecal microbial richness and diversity indices gradually increased from four to 28 days at all three farms. Microbial diversity assessment revealed that small intestine microbial diversity was lower in heavy birds than in light birds. In light birds, the Firmicutes proportion was lower than that in heavy birds. In conclusion, each broiler farm revealed a specific microbial profile which varied with the age of the birds. The microbial communities appeared to affect growth performance; therefore, gut microbial profiles can be utilized to monitor growth performance at broiler farms.