Success of fishmeal replacement through poultry by-product meal in aquaculture feed formulations: a meta-analysis

Poultry by-product meal (PBM) is a popular animal-based protein source tested in aquaculture feed formulations for replacing fishmeal (FM), mainly due to its high protein content, relatively cheap price and broad availability. However, due to the well-documented variability in success ofPBMinclusions, a meta-analysis approach was utilized to summarize the efficacy and success ofPBMinclusion in aquaculture diet formulations substitutingFM. Hedges'geffect sizes were calculated by quantitatively comparing final weight and feed conversion ratio (FCR) between animals fed control (100%FM) andPBM-supplementedFMdiets using data from 47 published articles targeting 33 different species (141 and 96 effect size calculations for final weight andFCR, respectively). In addition, several analyses were performed to determine the effect of different moderators as well as variation across species. Meta-regression was conducted to evaluate the effect of varyingPBMproportions of the diet on the response variables. Overall, a non-significant final weight but a significant higherFCRwas detected with aquaculture species fedPBMdiets. Similar trends in final weight were observed for subgroups. However,FCRfor crustaceans and marine fish fedPBMdiets was not significantly different than those fed control diets. In both freshwater and marine fish, 'species' was a significant moderator effect on responses, while the 'level ofFMreplacement' was significant only in marine fish. Higher between-study heterogeneity was detected for fish, which may be due to the influence of certain factors, such as variability in nutritional quality and palatability and digestibility ofPBMor due to variability on the fish meal used. In contrast, low between-study variation was observed in crustaceans indicating consistent success inPBM-supplemented diets for shrimp compared with fish.