Effects of Dietary N-Carbamylglutamate Addition with Two Different Levels of Crude Protein (Low and High) on the Growth, Nitrogen Retention, Amino Acids in the Carcass, Blood Health, Gut Bacteria, and Meat Quality of Finishing Pigs

This experiment was performed to investigate the effect of two different CP levels, with or without NCG supplementation, on finishing pigs’ performance and meat quality. A total of 200 pigs ([Yorkshire × Landrace] × Duroc) with an initial average body weight (BW) of 50.06 ± 1.34 kg were randomly assigned to one of four treatments for 70 days. There were four treatment groups with ten replicates and five pigs (three males and two females) per pen. The dietary treatment includes low-protein NCG−, 13% CP (LP NCG−); low-protein NCG +, 13% CP + NCG 0.1% (1 kgton) (LP NCG+); high-protein NCG−, 15% CP (HP NCG−); high-protein NCG+, 15% CP + NCG 0.1% (1 kg/ton) (HP NCG+). After 6 weeks of experimentation on CP effect, blood urea nitrogen, total protein, glucose, and albumin levels in pigs fed LP NCG− diets were significantly lower (p < 0.05), while in terms of the effect of NCG on creatinine level, the levels in the HP NCG+ diet were significantly lower than those in LP NCG+. Dry matter intake and nitrogen intake in HP NCG− diets were significantly higher than in LP NCG−. Loin muscle area (LMA) and cooking loss in LP NCG+ diets were significantly higher than in HP NCG+. Isoleucine, histidine, lysine, alanine, and tyrosine showed higher values in HP NCG−diets than in LP NCG−. LP NCG+ feeds improved species diversity and abundance of Firmicutes, LP NCG− of Lactobacillus, and HP NCG+ of Bacilli. Thus, low dietary protein can be beneficial for nitrogen retention, blood profile, and carcass amino acids, and NCG supplementation at 0.1% for gut health and meat quality.