N-Carbamylglutamate supplementation as an effective strategy for low-protein-based diets in pigs

The efficient utilization of dietary protein is a critical factor in modern pig production. This study aimed to evaluate the dose-response effects of dietary N-carbamylglutamate (NCG) supplementation on growth performance, nutrient digestibility, and blood profiles in crossbred grower-finisher pigs fed low-protein diets. One hundred and fifty pigs with an average initial body weight of 50.85 ± 3.11 kg were assigned to five feeding strategies. The treatments consisted of a control diet (NP), and low protein diets (LP) with NCG supplementation (0, 0.4, 0.7, and 1.0 g/kg) 0 over three phases (phase 1, d 1-21; phase 2, d 22-42; phase 3, d 43-63). The data were analyzed using the GLM procedure of SAS. The NCG supplementation linearly improved gain to feed ratio in phases 1 and 2, and overall. The NP group showed a greater gain-to-feed ratio in phases 1 and 3 and a greater overall average daily gain compared to LP treatment. Digestibility of crude protein was linearly increased with supplementation of NCG. Digestibility of Arg, His, Leu, Lys, Phe, Thr, Val, Ala, Glu, Gly, Ser Pro, Cys, Cit, and Orn was linearly improved with NCG supplementation. Digestibility of Arg, His, Ile, Val, Glu, Pro, and Cit was higher in the NC treatment compared with the LP. The gene expression of solute carrier transporter (SLC)6A19, SLC7A5, SLC7A7, SLC7A9, SLC38A2, and mechanistic target of rapamycin in the jejunum was linearly increased with supplementation of NCG. The marketing age and backfat thickness were linearly reduced with supplementation of NCG, and the slaughter weight, carcass weight, and loin muscle area were linearly increased. The NP treatment showed a lower marketing age, and a higher slaughter weight, carcass weight, and dressing percentage compared to the LP. The 0.10% dietary NCG supplementation is recommended for pigs due to linear increase in growth performance, feed efficiency, amino acid utilization, and carcass quality.