Exploring the possibility of quantifying the effects of plant protein ingredients in fish feeds using meta-analysis and nutritional model simulation-based approaches

Numerous studies have been carried out to test the effect of incorporating various protein sources in salmonid fish feeds at the expense of fish meal. Comparison and interpretation of the results from these studies are difficult given the wide differences in ingredients, feed formulations, experimental designs and achieved performance. The objective of this study was to contrast two approaches for analyzing and comparing the results of such studies: meta-analysis and nutritional model simulation. The meta-analysis indicated that compared to fish meal-based diets, low or moderate dietary incorporation of plant protein ingredients in general did not affect growth of salmonids, whereas fish growth was depressed at high dietary inclusion levels of plant protein ingredients even when the diets were apparently nutritionally adequate. Feed intake was not negatively affected as long as the diets were nutritionally adequate. Sources of plant protein ingredients also appear to have divergent effects on fish growth. The scope of the meta-analysis was limited due to measures to ensure the meaningfulness of the meta-analysis. Therefore a novel integrated growth and nutrient utilization model was developed and used as a simulation tool to achieve a broader and more rational comparison of studies. Overall the model adequately predicted growth of salmonids fed diets containing different levels of plant protein ingredients. The model simulation-based approach allowed a proper quantification of the effect of plant protein sources in salmonid fish feeds.

► We studied approaches to analyzing the effect of plant ingredients in fish feeds.
► Meta-analysis and nutritional model simulation were investigated.
► Meta-analysis was only meaningful when dietary compositions are comparable.
► Simulations using a nutritional model allowed a proper quantification.