GUANIDINOACETIC ACID is a feed additive containing guanidinoacetic acid (GAA), which is a metabolic precursor of creatine. Methionine forms creatine through methyl, stored in muscles, and serves as an energy source for muscles, brain, or reproductive glands. It can optimize animal energy metabolism, reduce feed costs whilst maintain growth performance and meat quality. In muscles, creatine rapidly replenishes ATP in the form of creatine phosphate, improving energy supply and efficiency. The supplementation of GUANIDINOACETIC ACID can both reduce feed energy levels and maintain growth performance. In high-producing pigs, it can significantly improve the number of piglets born and weaning weight of sows, increase piglet survival rate and growth speed, improve feed efficiency and daily weight gain, and lean meat percentage in growing-finishing pigs.