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Optimizing amino acid metabolism is essential for improving protein utilization, minimizing nitrogen excretion, and preserving protein feed resources. Supplementation with niacinamide (NAM) has demonstrated beneficial effects by lowering nitrogen emissions and promoting growth performance in pigs.
Objective: This study aimed to investigate the effects of adding 360 mg/kg NAM to diets on nutrient metabolism, providing insights into how dietary NAM supplementation enhances nitrogen utilization and growth performance in pigs.
Methods: Forty growing-finishing pigs were randomly assigned to one of four experimental diets as follows: 1) basal diet + 30 mg/kg NAM (control); 2) basal diet + 360 mg/kg NAM; 3) low-protein diet + 30 mg/kg NAM, and 4) low-protein diet + 360 mg/kg NAM for 11 weeks. At the end of the experimental period, blood, liver, ileal digesta, and mucosa samples were collected.
Results: Supplementation of both the control and low protein diets with 360 mg/kg NAM resulted in decreased urea nitrogen concentrations and carbamyl phosphate synthetase-I activity. The pyruvate dehydrogenase activity in the serum and liver, as well as the activity of pyruvate dehydrogenase, citrate synthase, and glutamate dehydrogenase 1 in the ileum mucosa, was increased by supplementing the low protein diet with 360 mg/kg NAM. The low protein diet with 360 mg/kg NAM increased the villi length to crypt depth, mRNA expression of glucose transporters 1 and 2 and alanine-serine-cysteine transporter 1, and mRNA expression of mechanistic target of the rapamycin 1 in the ileum. Additionally, 360 mg/kg NAM supplementation in the low protein diet reduced ileal Lactobacillus abundance (LDA > 4) and increased ileal microbial nucleotide and purine metabolism.
Conclusion: The addition of 360 mg/kg NAM to the low protein diet reduced urea production in the liver, enhanced glucose and amino acid absorption and transport in the ileum, and improved glucose metabolism.
Long X, Wei H, Wang Z, Tang Z, Xu Y, Peng X, Sun Z, Wu L. Impacts of 360 mg/kg Niacinamide Supplementation in Low-Protein Diets on Energy and Nitrogen Metabolism and Intestinal Microbiota in Growing–Finishing Pigs. Animals. 2025; 15(14): 2088. https://doi.org/10.3390/ani15142088