Soybean replacement value of canola meal as measured by growth performance and feed efficiency in broiler chickens: Insights from a meta-analysis: CANOLA MEAL HAS POOR REPLACEMENT POTENTIAL FOR SOYBEAN IN BROILER DIETS

Abstract

While the use of canola meal (CM) as an alternative to soybean meal in broiler diets is well documented, the results are still conflicting. Therefore, this meta-analysis combines results from multiple studies to provide a more precise estimate of the effect size or relationship between dietary CM and feed intake (FI), average daily gain (ADG), and feed conversion ratio (FCR) in broiler chickens. This approach explores the inconsistencies, identifies knowledge gaps, and creates new insights using published data. Search were conducted in Google scholar, Scopus, Web of Sciences, and PubMed, yielding a total of nineteen (19) relevant articles for this study. The data generated analysed using OpenMEE software. Heterogeneity was explored by subgroup and meta-regression analyses using moderator variables (i.e., publication year, strain, gender, inclusion levels, treatment methods, and study periods). The results showed that dietary CM significantly reduced FI [standard mean difference (SMD) = −0.33; 95% confidence interval (CI) = -0.41 to -0.25] and ADG [SMD = −0.68; 95% CI -0.85 to -0.50] while increasing FCR [SMD = − 0.37; 95% CI = 0.24 to 0.51] compared to the control group. Restricted subset analysis showed that studied moderators influenced the outcomes of this meta-analysis. Meta-regression revealed that the stage of development of the birds and treatment methods on CM were the significant predictors of FI while gender and treatment methods significantly predicted both ADG and FCR. In conclusion, the inclusion of CM in broiler diets resulted in poor growth performances, possibly due to anti-nutritional compounds such as glucosinolates, erucic acid, sinapine, and tannins. Thus, innovative research on processing methods to enhance the soybean replacement value of CM in broil