Soy protein
concentrate as a protein source for Senegalese sole (Solea senegalensis
Kaup 1858) diets: effects on growth and amino acid metabolism of postlarvae
C. Aragão, L.E.C. Conceição, J. Dias, A.C. Marques, E. Gomes, M.T.
Dinis-2003
Aquaculture
Research, 34(15):
1443-1452
Abstract:
The objective of this work was to evaluate
the effect of a dietary amino acid imbalance, originating from the use of a
soy protein concentrate (SPC) as the major protein source, on the growth
performance and amino acid metabolism of Senegalese sole (Solea
senegalensis) postlarvae. Senegalese sole (85.6±24.6 mg wet
weight) were fed one of two experimental diets: one based on fish meal (FM)
and another based on SPC. Diets were isonitrogenous (around 56% crude
protein) and isoenergetic. Diet acceptability was very good and the growth
rate was 6.9% day-1
for sole eating the FM diet and 6.0% day-1
for sole eating the SPC diet. Mass-specific ammonia excretion and the
activities of selected amino acid metabolic enzymes (ALAT, ASAT and GDH) did
not present significant differences between treatments, although this may
have been due to the high variability found for these parameters in the SPC
treatment. This variability may suggest different capacities of individual
fish to adapt to the possible methionine dietary deficiency. The utilization
of amino acids as a substrate for lipogenesis does not seem to be affected
by the dietary protein source, since NAPDH-generating enzymes (G6PD and ME)
had similar activities in both treatments. Amino acid metabolism in
Senegalese sole postlarvae seems to be slightly affected by the dietary
protein source. Nevertheless, the changes induced by the SPC diet do not
seem to impair growth, at least at the high dietary protein level used in
this experiment.
(CCMAR, Universidade do Algarve, Campus de
Gambelas, 8000-117 Faro, Portugal. E-mail: caragao@ualg.pt)