The valorization of agricultural residues into high-value feed resources is essential for sustainable livestock production. Insects have emerged as efficient bioconversion agents due to their rapid growth, high feed conversion efficiency, and ability to utilize diverse organic wastes. This chapter reviews key insect species, including Tenebrio molitor, Musca domestica, Acheta domesticus, Bombyx mori, Alphitobius diaperinus, and Hermetia illucens, highlighting their roles in converting agricultural by-products into nutrient-rich biomass. Their nutritional profiles, including protein, lipids, and bioactive compounds, and their applications in poultry, aquaculture, and livestock feeds are summarized. Special attention is given to black soldier fly larvae for their industrial potential and role in reducing antibiotic residues and antibiotic resistance genes. Overall, insect-based systems provide a sustainable strategy to recycle waste, enhance feed efficiency, and support circular agriculture.