Effects of probiotic supplementation on broiler growth performance: A meta-analysis of randomised controlled trials

Abstract

Context. The effects of probiotics on broilers' growth and productivity performance have been reported in many scientific studies, and different results have been found. Aim. This study aimed to assess the effects of probiotics on broiler growth performance via meta-analysis. Methods. In this study, the PubMed database was searched with the keywords "broiler' and "probiotic' and it was determined that 60 of 605 studies were suitable. Average daily gain and feed conversion ratio were used as performance parameters. Publication bias was evaluated with Egger's and Begg's tests. The trim and fill method was applied when even one of these tests was significant. Heterogeneity among studies was assessed using the Cochran Q test. The random effect model was used to estimate effect sizes if heterogeneity was statistically significant; otherwise, the fixed-effect model was used. In addition to evaluating all studies, subgroup analyses were performed depending on study duration, probiotic strain, and the probiotic content. Key results. According to the meta-analysis results, there was a significant difference between the probiotic and control groups in studies lasting 35 days in terms of average daily gain (P = 0.005) and feed conversion ratio (P = 0.002). But only the average daily gain (P < 0.001) value was different between the groups in studies lasting 42 days. According to the probiotic strain, significant differences were found between the probiotic and control groups in terms of both growth parameters examined in studies using mono-strain and multi-strain probiotics. A significant difference was found between the probiotic and control groups in average daily gain values in studies where probiotics containing lactic acid bacteria (LAB) and clostridia were used. Conclusion. In conclusion, this study is a current research that examined the effects of probiotic use in broilers in detail according to more than one factor. Implication. In this study, articles in the PubMed database were examined. The sample size of the study can be increased by scanning other databases with the same keywords.