Vitamin B12 (cobalamin) is the only water-soluble vitamin containing the metallic element cobalt found in animal feed. As a coenzyme, it participates in multiple key metabolic processes, primarily including promoting protein and nucleic acid synthesis, maintaining normal nervous system function, and assisting folic acid in hematopoiesis (preventing pernicious anemia). In livestock production, it is essential for normal growth, feed conversion efficiency, reproductive performance, and overall animal health. Monogastric animals (such as pigs and poultry) and fish cannot synthesize vitamin B12 themselves, and plant-based feed ingredients contain almost no vitamin B12, so they must rely on exogenous supplementation. Ruminants can synthesize it through rumen microorganisms, but additional supplementation may also be required under high production loads or during early growth stages. Vitamin B12 deficiency can lead to growth stunting, anemia, rough coat, incoordination, and reproductive disorders (e.g., reduced litter size, low hatchability), among other problems. Therefore, in complete compound feeds for modern intensive farming—especially for fast-growing, high-performance animals—appropriate supplementation of vitamin B12 is a necessary measure to ensure nutritional balance and production efficiency.