A systematic review and meta-analysis of the efficacy of alternatives to antibiotic growth promoters as strategies to reduce Salmonella in meat-type poultry (pre-harvest).

Recent estimates indicate chicken meat products as the prominent contributing sources of foodborne salmonellosis, accounting for 18.6 % of the Salmonella-related illnesses. Salmonella in poultry processing originates at production, with the fecal-oral route being a major route of spread. The efficacy of pre-harvest interventions (probiotics, prebiotics, organic acids, essential oils, bacteriophages, vaccines, and intervention combinations) is highly variable. A systematic review and meta-analysis were conducted to evaluate the relative efficacy of pre-harvest interventions to reduce the Salmonella population in meat type birds. A total of 7,041 studies were identified from Web of Science, PubMed, and Google Scholar databases. After applying exclusion criteria, a total of 97 studies from 60 relevant articles were included in the meta-analysis. Due to the variability in the age and genetics of birds, rearing conditions and sample type, a standardized mean difference (SMD) based on Hedge's G was used for the comparison and reported as the effect size. Data were analyzed using a random effect model of meta package in R version 5.1-1. Results from the random effect model were reported as A high heterogeneity (I2 = 80 %) was observed from the meta-analysis model. The meta-analysis revealed that most of the interventions were effective in reducing Salmonella population at pre-harvest with an overall SMD of -1.58 (P≤ 0.01). Combinations of interventions showed greater reduction in Salmonella population in birds (SMD=-2.34, P≤ 0.01), followed by vaccination (SMD=-2.21, P≤ 0.01) and organic acids (SMD=-2.11, P≤ 0.01). Probiotics showed a moderate effect in reducing Salmonella population in birds with SMD of -1.69 (P≤ 0.01). Prebiotics (SMD= -0.96, P≤ 0.01), bacteriophages (SMD= -0.81, P≤ 0.01), and essential oils (SMD= -0.72, P = 0.02) were less effective compared to other interventions. The meta-analysis suggests that interventions at pre-harvest can reduce Salmonella populations in broilers, with combination treatments, vaccination, and organic acids being the most effective strategies. However, caution must be exercised in adopting a specific intervention, and its efficacy and safety should be evaluated prior to implementation.