Combination of non-protein nitrogen and N‑carbamylglutamate supplementation improves growth performance, nutrient digestibility and carcass characteristics in finishing pigs fed low protein diets

•N-Carbamylglutamate (NCG) or non-protein nitrogen (NPN) was used in low protein diet.•We tested the performance of finishing pigs fed low protein diet with NPN and/or NCG.•Supplementation of NPN did not alter growth performance of pigs fed low protein diet.•NPN in combination with NCG improved the performance of pigs fed low protein diet. This study was conducted to determine whether supplemental non-protein nitrogen (NPN) and/or N-carbamylglutamate (NCG) in the low protein diet enhance the growth performance, nutrient digestibility and carcass characteristics of finishing pigs. A total of 150 (Duroc boar× (Landrace boar × Yorkshire) sow) finishing pigs (initially body weight 74.3 ± 3.8 kg) were blocked by weight and sex, and allotted to one 5 treatments with 6 replicate pens (3 barrows and 2 gilts per pen). Diets were normal protein diet (NP, crude protein (CP) 136.4 g/kg), low protein diet (LP, CP 111.4 g/kg), LP supplemented with 0.8 g/kg NCG (LNCG, CP 111.8 g/kg), LP supplemented with 7.1 g/kg NPN (LNPN, CP 119.8 g/kg), and LP supplemented with 7.1 g/kg NPN and 0.8 g/kg NCG (LNN, CP 120.3 g/kg) and fed to pigs for 40 days. At the end of the experiment, 30 pigs (one barrow per pen) were slaughtered to evaluate carcass traits and meat quality. Compared to the LP group, the combination of NPN and NCG supplementation significantly increased (P