Feed and pet food systems stand at a decisive crossroads. Climate pressure, resource constraints, regulatory evolution, and shifting market expectations are reshaping how protein and lipid sources are evaluated and implemented. This volume delivers a structured and interdisciplinary assessment of novel ingredients—including insects, algae, agricultural by-products, microbial- and plant-derived sources —across livestock, aquaculture, and companion animal nutrition. It addresses nutritional performance, oxidative stability, functional properties, regulatory pathways, sustainability trade-offs, and market dynamics. By integrating scientific evidence, decision-modelling approaches, and industry case studies, the book enables readers to translate innovation into robust, economically viable, and environmentally responsible solutions.