Background and Aim: Biosecurity practices are a must in broiler farms to reduce the risk of infectious agents. This study aimed to evaluate biosecurity measures in nine broiler farms in the Suez Canal area – Egypt with measuring the seasonal prevalence of salmonellosis.

Materials and Methods: A cross-sectional study was conducted on randomly selected nine broiler farms of different housing systems based on the ventilation methods from March 2018 to April 2019. A total of 12,600 samples (6480 environmental, 4320 non-environmental, 1080 sera, and 720 live birds) were collected during four successive seasons.

Results: Highly significant increases (p<0.01) were recorded in body weight gains in opened and closed-houses during summer; in food conversion ratios in opened-houses during winter and in closed-houses during winter and fall; in performance indices in opened-houses during summer and closed-houses during winter; and in live body weights, carcasses weights, liver, spleen, and bursa's weights in opened-houses during spring and in closed-houses during fall. Highly significant increases (p<0.01) were recorded in total bacterial, Enterobacteriaceae, and Salmonella counts in opened-houses during spring and in closed-houses during summer, in Salmonella Typhi O and H, and Salmonella Paratyphi A and B sera titer in opened-houses during summer and closed-houses during fall. Biosecurity measures scored 34 out of 43 with an average salmonellosis prevalence of 6.0% in closed-house and 24 out of 43 with an average salmonellosis prevalence of 24.67% in opened-house broiler farms.

Conclusion: Weak biosecurity measures in broiler houses (opened and closed) were not sufficient to prevent the entrance and multiplication of Salmonella spp. Disciplines, commitment, and regulations of biosecurity need to be enforced in broiler houses to prevent the introduction and spread of diseases.

Keywords: biosecurity, broiler, Egypt, housing systems, Salmonella, seasons.