Sustainability of Animal Production Chains: Alternative Protein Sources as an Ecological Driver in Animal Feeding: A Review

Sustainability of animal production requires reducing reliance on soybean meal by identifying viable alternative protein sources. Within the framework of the Italian Agritech National Research Center, seven Italian research groups collaborated to evaluate unconventional feed ingredients and their effects on animal performance and product quality. Alternative legume seeds (peas, chickpeas, faba bean, and lupins) can partially or completely replace soybean meal without impairing productivity, while enhancing product health value and shelf-life through bioactive compounds. Microalgae (Chlorella, Spirulina) improved carotenoid content, antioxidant activity, fatty acid profile, and cholesterol levels in poultry products, with limited effects in pigs. Insects supported optimal growth in fish at 25–30% inclusion, whereas maximum recommended levels are 15% in broilers and 24% in laying hens to sustain growth, egg production, and quality. Camelina by-products are suitable for poultry diets at up to 5–10%, beyond which performance declines. Whole-plant soybean silage, tef (Eragrostis tef), and triticale–lupin intercropping represent promising protein-rich resources for ruminants, provided diets maintain balanced protein-to-energy ratios, adequate fibre characteristics, and appropriate harvest timing under drought-prone conditions. Collectively, these findings highlight the potential of diverse protein sources to improve the sustainability of livestock systems while preserving productivity and enhancing the nutritional quality of animal-derived foods.