Ammonia-Nitrogen Added to Low-Crude-Protein Diets Deficient in Dispensable Amino Acid-Nitrogen Increases the Net Release of Alanine, Citrulline, and Glutamate Post-Splanchnic Organ Metabolism in Growing Pigs

作者：Mansilla Wilfredo D^*; Silva Kayla E; Zhu Cuilan; Nyachoti Charles M; Htoo John K; Cant John P; de lange Cornelis F M

来源：Journal of Nutrition, 2018, 148(7): 1081-1087.

DOI：10.1093/jn/nxy076

• ammonia
• dispensable amino acids
• hepatic vein
• liver
• low-protein diet
• nitrogen requirement
• pigs
• portal vein

Background: Dietary ammonia is rapidly absorbed but poorly used for urea synthesis in pigs fed low-crude-protein (low-CP) diets deficient in dispensable amino acid (DAA)-nitrogen.
Objective: We explored the effect of dietary ammonia on net amino acid (AA) balances in portal-drained viscera (PDV) and livers of pigs fed a diet deficient in DAA-nitrogen.
Methods: Eight barrows with an initial body weight (BW) of 26.5 +/- 1.4 kg (mean +/- SD) were surgically fitted with 4 catheters each (portal, hepatic, and mesenteric veins and carotid artery). The pigs were restricted-fed (2.8 x 191 kcal/ kg BW0.60) for 7 d, and every 8 h a diet deficient in DAA-nitrogen supplemented with increasing amounts of ammonia-nitrogen (CP = 7.76%, 9.27%, and 10.77% for the control and low-and high-ammonia diets, respectively). The treatment sequence was based on a 3 x 3 Latin-square design with 3 consecutive periods. On the last day of each period, blood flows in portal and hepatic veins were determined with a continuous infusion of.-amino hippuric acid into the mesenteric vein. Consecutive blood samples were taken for measuring AA concentrations in plasma, and AA balances were calculated for PDV and the liver.
Results: Cumulative release of citrulline (Cit) and proline (Pro) increased with ammonia supplementation in PDV but decreased for glutamine (Gln) and glycine (Gly) (Gln: -19.32 +/- 3.56, -32.50 +/- 3.73, and -42.11 +/- 3.55 mmol/meal for the control and low-and high-ammonia groups, respectively; P <= 0.05). Cumulative release of alanine (Ala), glutamic acid (Glu), and Gln increased with ammonia supplementation across the liver (P <= 0.05). When combined, PDV+liver, the cumulative release of Ala, Cit, and Glu increased with ammonia-nitrogen supplementation (P <= 0.05).
Conclusion: Dietary ammonia could be used as a nitrogen supplement to increase the synthesis of Ala, Cit, and Glu across splanchnic organs in pigs fed a diet deficient in DAA-nitrogen.

• 出版日期2018-7