This Special Issue, titled Application of Fermentation Technology in Animal Nutrition: 2nd Edition, belongs to the Industrial Fermentation Section of Fermentation-Basel. Curated by Guest Editors Drs. Siran Wang, Lin Sun, Lei Chen, and Jie Bai, it includes nine peer-reviewed original research studies, advancing the global understanding of fermentation's role in modern animal nutrition and husbandry. Fermentation technology is foundational to animal feed production, preserving feed, enhancing palatability, and optimizing under-utilized agro-industrial by-products. However, knowledge gaps exist in optimal fermentation conditions, metabolite utilization in animals, and impacts on gastrointestinal health, ruminal function, and productivity-this issue directly addresses these gaps with cutting-edge research covering silage production, fermented feed development, and biological effects on livestock and poultry. This Special Issue bridges practical application and fundamental science, driving innovation in fermentation technology and shaping efficient, eco-friendly, high-performance animal nutrition globally.