Vol. 7, Issue 12, Part A (2025)

Broiler production relies on high-quality protein sources to support rapid growth, efficient feed utilisation and optimal carcass yield. Soybean meal and fish meal have long dominated commercial diets due to their balanced amino acid profiles and digestibility; however, rising global demand, fluctuating prices, land-use limitations and environmental concerns have accelerated the search for sustainable alternatives. This review synthesizes verified research on insect meals, fermented plant proteins, leaf meals, single-cell proteins and agro-industrial by-products as emerging protein replacements in broiler nutrition. Black Soldier Fly Larvae meal, Tenebrio molitor meal, fermented soybean meal, Spirulina, Chlorella and bacterial protein meals have demonstrated the ability to maintain or improve growth performance, feed conversion ratio, nutrient digestibility, gut morphology and meat quality in controlled feeding trials. Mechanistic insights reveal improvements in villus height, crypt depth, enzymatic activity, antioxidant markers and immune function. Sustainability assessments highlight reduced greenhouse gas emissions, lower water and land demands and valorization of organic waste streams. Despite these advantages, constraints include anti-nutritional factors, chitin content, variable nutrient profiles, processing costs, regulatory barriers and consumer acceptance issues. This comprehensive review consolidates multidisciplinary evidence to guide the strategic inclusion of alternative proteins in broiler diets and identifies future research priorities for scaling these ingredients into commercial poultry systems.