Protein and Amino Acid Metabolism in Monogastric Animals: A Mini Review

Abstract

Protein and amino acid metabolism are fundamental processes that regulate growth, tissue maintenance, and metabolic homeostasis in monogastric animals such as pigs. Unlike ruminants, pigs rely primarily on enzymatic digestion to hydrolyze dietary protein into absorbable amino acids, which are subsequently utilized for protein synthesis, energy production, and the formation of biologically active compounds. The liver plays a central role in amino acid metabolism through transamination, deamination, and urea cycle regulation, ensuring nitrogen balance and preventing toxic ammonia accumulation. Recent advances have highlighted the importance of amino acid signaling pathways, including mTOR and AMPK, in regulating protein synthesis, muscle accretion, and metabolic efficiency. Furthermore, emerging research demonstrates that amino acids function not only as structural components but also as signaling molecules that influence gene expression, immune function, and oxidative metabolism. Nutritional strategies that optimize amino acid availability can significantly improve growth performance, nitrogen utilization efficiency, and metabolic health in pigs. This review synthesizes current knowledge on protein digestion, amino acid metabolism, nitrogen balance, and metabolic regulation in monogastric animals, emphasizing recent advances in molecular nutrition and their implications for improving livestock productivity and metabolic efficiency.

Keywords: Protein metabolism; Amino acid metabolism; Nitrogen balance; Monogastric animals; Swine nutrition; Urea cycle; Molecular nutrition; Protein turnover