Meta-analysis of the influence of the substitution of maize with cassava on performance indices of broiler chickens

Abstract There are growing numbers of publications on the effect of substitution of maize with cassava (Manihot esculenta Crantz) on growth indices of broiler chickens with variable results. The purpose of this meta-analysis was to explore the influence of substitution of maize with dietary cassava on growth traits (i.e., average daily feed intake [ADFI], body weight gain [BWG] and feed conversion efficiency [FCE]) of broilers. Search done in PubMed, Google scholar and Scopus databases yielded 303 studies of which 27 were suitable for the analysis. Heterogeneity was explored by subgroup and meta-regression analyses using the following moderator variables: publication year, study continent, processing methods, cassava form, substitution level, broiler strain, number of birds per groups and treatment durations. Results show that dietary cassava reduced ADFI (mean difference [MD] = −5.19 g/day; 95% confidence interval [CI]: −8.60, −1.79; I 2 = 99%) and BWG (MD = −8.49 g/day; 95% CI: −9.65, −7.33; I 2 = 98%) and increased FCE (MD = 0.29; 95% CI: 0.24, 0.35; I 2 = 99%) in broilers compared to controls. Publication year, broiler strain, treatment durations and substitution level) influenced the outcomes of the study and explained some of the sources of heterogeneity. In conclusion, our results suggested that dietary cassava inclusion at 5% (minimum) and 62% (maximum) reduced growth performance in broiler chickens. However, more effective methods for increasing the nutrient value of cassava roots for broiler chicken feeding as well as the cassava inclusion levels for optimal productivity are required.