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Changes in amino acid composition in the tissues of African catfish ( Clarias gariepinus ) as a consequence of dietary L‐carnitine supplements
Author(s) -
Ozório R. O. A.,
Booms G. H. R.,
Huisman E. A.,
Verreth J. A. J.
Publication year - 2002
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1046/j.1439-0426.2002.00317.x
Subject(s) - clarias gariepinus , catfish , biology , carnitine , composition (language) , fishery , clarias , zoology , fish <actinopterygii> , biochemistry , linguistics , philosophy
A study was undertaken to examine the effect of different amounts of dietary lysine (13 and 21 g kg −1 diet), lipid (80 and 160 g kg −1 diet) and L ‐carnitine (0.2 and 1.0 g kg −1 diet) on growth performance, proximate composition and amino acid metabolism of the African catfish ( Clarias gariepinus ). Juvenile African catfish (23 ± 1.5 g/fish) were stocked into 70‐L aquaria (16 aquaria, 28 fish/aquarium) connected to a recirculation system during a maximum period of 74 days. All groups were fed at a level of 24 g kg −0.8 day −1 in an experiment run at pair feeding. Animals receiving 1.0 g carnitine accumulated up to six times more carnitine in their tissues than animals receiving 0.2 g (P < 0.05). Acyl‐carnitine and free L ‐carnitine levels increased in the whole body and in tissues. Dietary L ‐carnitine supplements increased protein‐to‐fat ratios in the body, but did not affect growth rate. Protein‐to‐fat ratios were only affected when the biosynthesis capacity of L ‐carnitine was restricted due to low lysine levels and when there was a shortage of dietary fat. When lysine was offered at 21 g kg −1 feed, dietary L ‐carnitine supplements did not affect the amino acid concentrations of body tissues. Dietary L ‐carnitine supplements raised the concentration of glutamic acid > aspartic acid > glycine > alanine > arginine > serine > threonine in skeletal muscle tissue (P < 0.05). Total amino acid concentration in muscle and liver tissues (dry‐matter basis) increased from 506 to 564 and from 138 to 166 mg g −1 , respectively, when diets were offered with high L ‐carnitine, low lysine and low fat levels. These data suggest that dietary L ‐carnitine supplementation may increase fatty acid oxidation and possibly decrease amino acid combustion for energy.