Sustainable Protein Transitions: A Comprehensive Review of Insect Meal in Broiler Diets—Nutritional Value, Immunomodulatory Effects, Gut Health Interactions, and Future Perspectives

Abstract

Simple Summary Broiler diets primarily rely on soybean meal and fishmeal, both of which carry significant environmental costs. Insect meal, principally from black soldier fly larvae (Hermetia illucens), is one of the few alternatives that can reasonably close that gap. Beyond supplying a strong amino acid profile, insect-derived ingredients bring lauric acid and chitin to the table, compounds that plant and marine proteins simply do not have, and both appear to support gut health and immune function in ways that go beyond ordinary protein replacement. Feeding trials replacing 5–15% of dietary soybean or fishmeal with insect meal consistently maintain body weight gain and feed conversion ratio within approximately 5% of conventional diet controls; at 10% BSF larval meal inclusion, several trials report numerically superior performance relative to SBM-based diets. At the environmental level, insect production systems can reduce greenhouse gas emissions by more than 80% relative to fishmeal under circular economy conditions. What remains unresolved is consensus on processing standards, dosing, and the applicability of laboratory findings to commercial settings. Insect meal currently remains more expensive than soybean meal, but cost trajectories point toward narrowing competitiveness at industrial scale. In summary, the evidence supports insect meal as a scientifically credible and ecologically coherent component of a more sustainable broiler sector.