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The cost of the conversion of L-methionine precursors in mammals and birds
To fulfil the requirements for methionine, animal diets are widely supplemented with synthetic methionine sources such as L-methionine (L-Met), DL-methionine (DL-Met), and DL-2-hydroxy-4-(methylthio)-butanoic acid (DL-OH-Met). The objective of this study is to calculate the energy cost of the different conversion steps leading to L-Met and to propose energy equivalence values for DL-Met and DL-OH-Met, relative to that of L-Met. The conversion of DL-OH-Met to L-Met involves a nitrogen-sparing effect, because excess nitrogen can be used for the transformation of DL-OH-Met to L-Met, rather than being excreted as urea or uric acid Consequently, the ME-to-GE ratio of DL-OH-Met is 109% in mammals and 114% in birds, compared to the value of DL-Met. Because of differences in metabolism and the formation of hydrogen peroxide in the conversion to L-Met, the NE-to-ME ratios are 96% for DL-Met and 100% for DL-OH-Met in both mammals and birds. The conversion of DL-OH-Met to L-Met is therefore energetically less costly than the conversion of DL-Met. The stoichiometric approach presented here only considers the biochemical conversion steps, without considering the cost of transport and further transformation steps.
The cost of the conversion of L-methionine precursors in mammals and birds
To fulfil the requirements for methionine, animal diets are widely supplemented with synthetic methionine sources such as L-methionine (L-Met), DL-methionine (DL-Met), and DL-2-hydroxy-4-(methylthio)-butanoic acid (DL-OH-Met). The objective of this study is to calculate the energy cost of the different conversion steps leading to L-Met and to propose energy equivalence values for DL-Met and DL-OH-Met, relative to that of L-Met. The conversion of DL-OH-Met to L-Met involves a nitrogen-sparing effect, because excess nitrogen can be used for the transformation of DL-OH-Met to L-Met, rather than being excreted as urea or uric acid Consequently, the ME-to-GE ratio of DL-OH-Met is 109% in mammals and 114% in birds, compared to the value of DL-Met. Because of differences in metabolism and the formation of hydrogen peroxide in the conversion to L-Met, the NE-to-ME ratios are 96% for DL-Met and 100% for DL-OH-Met in both mammals and birds. The conversion of DL-OH-Met to L-Met is therefore energetically less costly than the conversion of DL-Met. The stoichiometric approach presented here only considers the biochemical conversion steps, without considering the cost of transport and further transformation steps.
The cost of the conversion of L-methionine precursors in mammals and birds
van Milgen, Jacob (author) / Batonon-Alavo, Dolores I. (author) / Mercier, Yves (author) / Ferrer, Ruth (author) / Toscan, Adriana (author) / Martin-Venegas, Raquel (author)
2019-01-01
Energy and protein metabolism and nutrition. (138)2019; 6. International Symposium on Energy and Protein Metabolism (Isep), Belo Horizonte, BRA, 2019-09-09-2019-09-12, 365-366
Conference paper
Electronic Resource
English
DDC:
690
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