Nitrogen utilisation and ureogenesis as affected by dietary nucleic acid in rainbow trout (Oncorhynchus mykiss) and turbot (Psetta maxima) |
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| Authors: | V Fournier MF Gouillou-Coustans R Métailler C Vachot J Moriceau H Le Delliou C Huelvan E Desbruyeres SJ Kaushik |
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| Institution: | (1) Laboratoire de Nutrition des Poissons, Unité mixte INRA-IFREMER, IFREMER, Centre de Brest, B.P 70, 29280 Plouzané, France;(2) Station d'Hydrobiologie, INRA, B.P 3, 64310 St Pée sur Nivelle, France |
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| Abstract: | We evaluated the influence of dietary nucleic acid (NA) supplied either as an RNA extract (RNA) or as brewer's yeast (BY)
on nitrogen (N) utilisation, N excretion and ureogenesis in a freshwater teleost, the rainbow trout (Oncorhynchus mykiss) and a marine teleost, the turbot (Psetta maxima). Five diets containing two levels of NA or BY were formulated for each species, and fed to juvenile rainbow trout (initial
body weight (IBW): 21.7 g) and turbot (IBW: 11.8 g) over 8–10 weeks. Besides growth and N utilisation, we monitored total
ammonia-N and urea-N excretion rates and measured the activities of selected enzymes (glutamate dehydrogenase, ornithine carbamoyltransferase,
arginase and uricase). There was no clear N sparing effect of dietary NA or BY supplementations in either species. Feeding
diets containing the RNA extract led to an almost two-fold increase in postprandial plasma urea-N and uric acid concentrations
and in urea-N excretion rates. Glutamate dehydrogenase and arginase activities were decreased in fish fed NA supplemented
diets. Uricase activities were inversely related to dietary NA levels. Data on N excretion and enzyme activities clearly suggest
that ureogenesis is influenced by dietary NA in both species.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | dietary nucleic acid nitrogen excretion rainbow trout turbot ureogenesis |
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