Exploratory Assessment of N-Carbamylglutamate Supplementation on Feed Efficiency and Protein Utilization in Early Growing Pigs Fed Low Crude Protein Diet

So Dam Choi¹, Jun Young Mun¹, Abdolreza Hosseindoust¹, Habeeb Tajudeen¹, Seon Ah Park¹, Priscilla Neves Silvestre¹, Sang Sik Lee¹, Jin Soo Kim¹^,^*

¹Department of Animal Industry Convergence, Kangwon National University, Chuncheon 24341, Korea.

^*Corresponding Author: Jin Soo Kim, Department of Animal Industry Convergence, Kangwon National University, Chuncheon 24341, Korea, Republic of. E-mail: kjs896@kangwon.ac.kr.

© Copyright 2025 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: May 13, 2025; Revised: Jul 01, 2025; Accepted: Jul 12, 2025

Published Online: Aug 19, 2025

Abstract

Reducing dietary crude protein (CP) levels while supplementing with essential amino acids (AA) has been widely studied as a strategy to maintain nutrient balance while lowering nitrogen excretion. Among feed additives, N-carbamylglutamate (NCG), an arginine precursor with superior stability and mitochondrial permeability, has emerged as a promising feed additive for improving intestinal development and overall pig performance. A total of 240 crossbred grower pigs were allotted to four dietary treatments based on initial body weight. Treatments were arranged in a 2 × 2 factorial design with two levels of dietary CP (MCP, 16% moderate CP; LCP, 14% low CP) and two levels of NCG supplementation (WN, without NCG; NS, 0.1% NCG supplementation). Each treatment had 10 replicates, with six (3 male and 3 female) pigs per pen, and the feeding trial lasted for 4 weeks. Pigs fed the MCP diet tended to have higher final BW (<italic>p</italic> = 0.088) compared with the LCP diet. Feed efficiency was greater in MCP than LCP (<italic>p</italic> < 0.05) and also tended to be enhanced in the NS (<italic>p</italic> = 0.089). CP digestibility tended to increase in the NS group compared with the WN (<italic>p</italic> = 0.093). The digestibility of arginine and tyrosine was increased in the NS group compared with the WN group (<italic>p</italic> < 0.05). Furthermore, lysine (<italic>p </italic>= 0.067), glycine (<italic>p </italic>= 0.058), and the average of essential AA (<italic>p </italic>= 0.091) digestibility tended to be increased in the NS. The NS group showed higher concentrations of arginine, lysine, essential AA, non-essential AA, and total AA in the blood (<italic>p </italic>< 0.05). Trypsin activity showed a tendency to increase in the NS group compared with the WN group (<italic>p</italic> = 0.087). In conclusion, dietary NCG supplementation in a low-protein diet showed potential to improve feed efficiency, AA digestibility, and serum AA profiles in early growing pigs.

Keywords: Growth performance; arginine; nitric oxide; digestibility; amino acid