Kwon

Effects of dietary isoleucine and valine supplementation to excess or low leucine diets on nitrogen balance and metabolism of branched-chain amino acids in growing pigs

Leucine is a key regulator that stimulates catabolism of branched-chain AA (BCAA; i.e., Leu, Ile, and Val) in skeletal muscle and liver. If diets fed to pigs contain excess Leu, catabolism of all 3 BCAA may increase because of the stimulating effect of the Leu metabolite, α-keto isocaproate, on the branched-chain α-keto acid dehydrogenase enzyme complex, which is responsible for degradation of the 3 branched-chain α-keto acids that originate from metabolism of the 3 BCAA. Serum Ile and Val concentrations were reduced by excess dietary Leu in growing pigs, and high dietary Leu reduces feed intake and growth performance in pigs, which may be a result of the imbalanced supply of BCAA that result from increased metabolism of Val and Ile. Recent data confirmed that excess dietary Leu reduced growth performance and tended to reduce protein synthesis, which is likely a result of reduced availability of Val and Ile.

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Tryptophan can partially overcome negative effects of leucine in pig diets

Kwon, W. B., and H. H. Stein. 2020. Tryptophan can partially overcome negative effects of leucine in pig diets. National Hog Farmer, Online edition. Jan.

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Excess dietary leucine in diets for growing pigs reduces growth performance, biological value of protein, protein retention, and serotonin synthesis

Kwon, Woong B., Kevin J. Touchette, Aude Simongiovanni, Kostas Syriopoulos, Anna Wessels, and Hans H. Stein. 2019. Excess dietary leucine in diets for growing pigs reduces growth performance, biological value of protein, protein retention, and serotonin synthesis. Journal of Animal Science, 2019, 4282–4292. Link to full text.

Effects of dietary leucine and tryptophan supplementation on serotonin metabolism and growth performance of growing pigs

Tryptophan is an indispensable AA that is often limiting for growth in pigs fed corn-soybean meal-based diets. Tryptophan may act as a regulator of feed intake by enhancing serotonin signaling in the brain, because Trp is a precursor for serotonin. High Trp intake increases feed intake, and this is partly attributed to increased serotonin synthesis. Availability of dietary Trp in the brain is considered the rate-limiting step in hypothalamic serotonin synthesis. However, to be transported into the brain, Trp competes with other large neutral AA such as Val, Leu, Ile, Tyr, and Phe for a common transporter (L-type AA transporter 1) to cross the blood-brain barrier.

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Effects of heat treatment on digestibility of amino acids and concentration of metabolizable energy in soybean meal fed to pigs

Lee, S. A., M. S. F. Oliveira, W. B. Kwon, and H. H. Stein. 2019. Effects of heat treatment on digestibility of amino acids and concentration of metabolizable energy in soybean meal fed to pigs. Book of Abstracts. In: 1st International Feed Technology Congress, Cologne, Germany. p. 33. (Abstr.). Link to Abstract.

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Update on amino acids in high fiber diets: Threonine and branch chained amino acids

Kwon W. B., and H. H. Stein. 2019. Update on amino acids in high fiber diets: Threonine and branch chained amino acids. Midwest Swine Nutr. Conf. Indianapolis, IN, Sep. 4, 2019, p. 11-17. Link to full text

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Effects of dietary leucine and tryptophan supplementations on serotonin metabolism and growth performance of growing pigs.

Kwon, W. B., K. J. Touchette, A. Simongiovanni, K. Syriopoulos, A. Wessels, and H. H. Stein. 2019. Effects of dietary leucine and tryptophan supplementations on serotonin metabolism and growth performance of growing pigs. In: 6th EAAP International Symposium on Energy and Protein Metabolism and Nutrition, Belo Horizonte, Minas Gerais, Brazil, Sep. 9-12, 2019. Pages 303-304.

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Effects of dietary leucine concentration on branched-chain amino acid metabolism in growing pigs

Kwon Woong B., Kevin J. Touchette, Aude Simongiovanni, Kostas Syriopoulos, Anna Wessels, Hans H. Stein. 2019. Effects of dietary leucine concentration on branched-chain amino acid metabolism in growing pigs. Journal of Animal Science, Volume 97, Issue Supplement_2, July 2019, Pages 65–66. (Abstr.). Link to abstract.

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Excess leucine reduces nitrogen retention, growth performance in pigs.

Kwon, W. B., and H. H. Stein. 2019. Excess leucine reduces nitrogen retention, growth performance in pigs. July 29, 2019. Link to ful text.

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Effects of dietary leucine concentration on branched-chain amino acid metabolism in growing pigs

Leucine, Val, and Ile are categorized as the branched-chain AA (BCAA) because of the structural similarity of their side chains. All 3 BCAA share the enzymes that are involved in the first 2 steps of their catabolic pathway. The first step is a transamination step catalyzed by BCAA transaminase (BCAT) and producing branched-chain α-keto acids (BCKA). The second step is an irreversible degradation step catalyzed by branched-chain α-keto acid dehydrogenase (BCKDH). In the second step, Leu has been considered a key regulator as its BCKA metabolite (α-keto isocaproate) stimulates activation of the BCKDH complex in the liver. When excess Leu in diets is offered to pigs, degradation of all 3 BCAA may increase because of increased activity of BCAT and BCKDH. Leucine and Trp are both categorized as large neutral AA, and they share a common uptake pathway across the blood-brain barrier. Therefore, it is possible that excessive Leu may result in reduced Trp uptake into the brain due to competition for transporters, resulting in reduced serotonin synthesis.

 

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Non-antibiotic feed additives in diets for pigs: A review

Yanhong Liu, Charmaine D. Espinosa, Jerubella J. Abelilla, Gloria A. Casas, L. Vanessa Lagos, Su A. Lee, Woong B. Kwon, John K. Mathai, Diego M.D.L. Navarro, Neil W. Jaworski, Hans H. Stein. 2018. Non-antibiotic feed additives in diets for pigs: A review. Anim. Nutr. 4:113-125. Link to full text (.pdf)

Amino acid digestibility of a modified corn byproduct (Gold Pro) with and with a multi-enzyme supplement (CORE) when fed to weanling pigs

Soltwedel, K. T., F. B. Sandberg, W. B. Kwon, H. H. Stein, S. J. England, M. R. Bible, T. M. Fakler, and J. Y. Jacela. 2018. Amino acid digestibility of a modified corn byproduct (Gold Pro) with and with a multi-enzyme supplement (CORE) when fed to weanling pigs. J. Anim. Sci. 96(Suppl. 2):150 (Abstr.) Link to abstract (.pdf)

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Non-antibiotic feed additives in diets for pigs

Liu, Y., D. Espinosa, J. J. Abelilla, G. A. Casas, L. V. Lagos, S. A. Lee, W. B. Kwon, J. K. Mathai, D. M.D. L. Navarro, N. W. Jaworski, and H. H. Stein. 2016. Non-antibiotic feed additives in diets for pigs. Pages 263-281 in Proceedings of the 2016 Chinese Swine Industry Symposium, Shanghai, China, October 20-21, 2016. Link to full text (.pdf)

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