College of Veterinary Sciences
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Item Biosecurity Practices and Molecular Epidemiology of Salmonella Species in Small and Medium-Scale Commercial Layer Farms in Mekelle City, Northern Ethiopia(Mekelle University, 2025-01-25) Aregawi GerekidanSalmonellosis infections in chicken farms pose significant risks to public health and the poultry industry. In the Tigray region, there is a notable lack of molecular-based identification methods for Salmonella species in poultry and limited understanding of existing biosecurity practices. This study aimed to isolate and molecularly characterize Salmonella species while evaluating the biosecurity measures practiced on the farms. A cross-sectional study was conducted between December 2023 and December 2024, involving the collection of 250 cloacal swabs from laying hens and identifying biosecurity practices across 28 purposively selected poultry farms. Salmonella species were isolated following the International Organization for Standardization's (ISO 6579- 1:2017/Amd.1:2020(E)). Out of 28 poultry farms tested using standard bacteriological culture methods, 16 (57.1%) were positive for Salmonella isolates. The overall isolation rate of Salmonella species was 34.8% (87/250). Among the analyzed risk factors, on farm waste disposal practice, sources of chicken, presence of other animals, age and flock size demonstrated a statistically significant association (p < 0.05) with bacteriological rate of isolation Salmonella species. The molecular detection rate of Salmonella genus was 82.4% (42 out of 51) successfully amplified with the INVA1/2 primers. Notably, 45% of these isolates were identified as Salmonella gallinarum using MS-GA-F/R primers, while 35% were identified as Salmonella typhimurium with TYPHF/R primers. The poultry farm biosecurity parameters and practices were evaluated by a scientific risk-based scoring system based on the Biocheck. UGent™ tool (Merelbeke, Ghent University, Belgium) (https://biocheck.ugent.be/en ). The overall biosecurity score for layer farms in Mekelle is 57.86%, with the scores of 48.54% for external biosecurity and 67.11% for internal biosecurity. Adapting to evolving biosecurity challenges requires the adoption of new toolkits and strategies. It showed the biosecurity measures of these farms, especially at the external levels need to be improved. The investigation revealed a higher isolation and identification rate of Salmonella species at both the farm and sample levels. Therefore, routine flock testing, farm surveillance, implementation of Salmonella prevention and control strategies, and improvements in biosecurity practices is needed