A meta-analysis of the effects of dietary marine oil replacement with vegetable oils on growth, feed conversion and muscle fatty acid composition of fish species

The effects of the replacement of marine oils (MO) with canola oil (CO), linseed oil (LO) and soybean oil (SO) on growth, feed conversion and major muscle fatty acid (FA) classes were quantified using a meta-analysis of published results. There was an absence of relationships between levels of MO replaced and effect sizes for all outcomes. High heterogeneity when combining effects sizes according to fixed effects models imposed the stratification of values in MO replacement categories and the use of random effect models to calculate the summary statistics. Limited values at 50% and 60% hampered clear tendencies when compared to 100% MO replacement. A medium mean effect size (-0.3773, 95% confidence intervals -0.7325 to -0.0222, n = 22) for growth was obtained when replacing all MO with CO, whereas LO (-1.5609, 95% confidence intervals -2.3584 to -0.7633, n = 19) and SO (-1.0589, 95% confidence intervals -1.7197 to -0.3980, n = 22) resulted in high negative effect sizes. This study quantified the extent of differences in production parameters caused by dietary MO replacement with VO and could serve as reference for future experimental studies.