Interactions among the branched-chain amino acids and their effects on methionine utilization in growing pigs: effects on nitrogen retention and amino acid utilization

• Published in: British journal of nutrition Vol. 83; no. 1; pp. 43 - 48
• Main Authors: Langer, Stefan, Fuller, Malcolm F.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.01.2000
• Subjects: Amino acid utilization; Amino Acids - metabolism; Amino Acids, Branched-Chain - physiology; Animal productions; Animals; Biological and medical sciences; Branched-chain amino acids; Diet - standards; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Intestinal Absorption - physiology; Methionine; Methionine - metabolism; Nitrogen - metabolism; Swine - growth & development; Swine - physiology; Terrestrial animal productions; Vertebrates; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Branched-chain amino acids; Methionine; Amino acid utilization; Assimilation; Growth; Molecular interaction; Nitrogen; Retention; Young animal; Feeding; Pig; Branched chain; Vertebrata; Mammalia; Diet; Aminoacid; Artiodactyla; Animal production; Ungulata
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1017/S0007114500000076

An experiment was conducted to investigate the effects of branched-chain amino acid (BCAA) interactions on their utilization by growing pigs and the effects of excessive amounts of BCAA (leucine, isoleucine, valine) on the utilization of methionine. A semipurified diet containing 100 g crude protein/kg with a balanced amino acid pattern was prepared using casein supplemented with free amino acids. Three further diets were made by reducing the concentration of methionine + cyst(e)ine, valine or isoleucine by 20 %. Each of these four diets was then supplemented with leucine (50 % excess) or a mixture of BCAA (50 % excess of each but excluding the limiting amino acid). All diets were isoenergetic and were made isonitrogenous by replacement of glutamic and aspartic acids. The twelve diets were given to twenty-four growing pigs (30–40 kg) in three periods according to a randomized block design. Each period lasted 8 d and N retention was measured during the last 5 d of each period. Reducing dietary methionine, valine or isoleucine reduced the utilization of N (N retained/N digested) by approximately 20 % (P < 0·05). Adding leucine to the isoleucine-limiting diet decreased the utilization of N by 9 % (P < 0·05). This was reversed by simultaneous addition of valine. Excess leucine in a valine-deficient diet did not significantly reduce N utilization. In methionine-limiting diets an excess of either leucine alone or of all three BCAA increased the utilization of N by 8 % (P < 0·05).