N-carbamylglutamate, a promising functional feed additive in swine production: A review

N-carbamylglutamate is structurally similar to N-acetylglutamate, a necessary co-factor for carbamyl phosphate synthetase I, the enzyme that catalyzes the first step of the urea cycle. N-carbamylglutamate was first used to relieve acute hyperammonemia and to restore neurological development by replacing absent or deficient N-acetylglutamate caused by N-acetyl glutamate synthetase deficiency and activating the enzyme carbamyl phosphate synthetase I. Recent studies suggest that supplementation of exogenous N-carbamylglutamate to animals can decrease ammonia and enhance the synthesis and metabolism of endogenous arginine, thereby producing nitric oxide and polyamines. Arginine is a conditionally essential amino acid, especially during gestation, lactation, the early stage of life, severe stress, and injury. Dietary supplementation with arginine can enhance the reproductive performance of multiparous animals, improve intestinal health and development, and promote the growth of young animals. Arginine is useful, but not very practical due to its shorter half-life, higher degradation by arginase, higher cost, more susceptible to impair the absorption of dietary basic and/or structurally related amino acids such as tryptophan, histidine, or lysine, and higher microbial degradation rate as compared to N-carbamylglutamate. As a precursor of arginine, N-carbamylglutamate is a more viable and cost-effective functional feed additive by increasing the synthesis and metabolism of endogenous arginine to improve swine production. This review article summarizes the multifunctional roles of N-carbamylglutamate as a feed additive in pig production and its underlying mechanism and provides reference for future N-carbamylglutamate related research.