The effect of dietary
ribonucleic acid incorporation in performance of European sea bass (Dicentrarchus
labrax) juveniles
H.
Peres, A. Oliva-Teles-2003
Aquaculture, 215(1-4): 245-253
Abstract:
The aim of this study was to evaluate the effect of
dietary ribonucleic acid (RNA) on the performance of European sea bass
juveniles. Two diets containing fish meal as the only nitrogen source were
formulated with 39% or 50% of crude protein (LP and HP diet, respectively).
Two other diets were formulated similarly to LP diet, but included yeast-RNA
extract at 6.2% and 12.4% levels (LP6 and LP12 diets, respectively) by
replacing dextrin. Total nitrogen content of the LP12 diet was equivalent to
that of the HP diet. The four experimental diets were isoenergetic (22 kJ GE
g-1 DM). Triplicate groups of 25 fish (IBW=13 g) were fed the
test diets for 10 weeks. The reduction of dietary protein level did not
significantly affect growth rate but significantly increased feed intake and
decreased feed efficiency. However, nitrogen retention (%N intake) was
significantly improved with the decrease in dietary protein level. Dietary
RNA incorporation did not affect feed intake or feed efficiency, although it
reduced growth rate of fish fed the highest dietary RNA level. Nitrogen
retention (%N intake) significantly decreased with the dietary
supplementation of RNA. Dry matter, nitrogen and energy digestibilities were
not significantly affected by dietary treatments. Final whole-body
composition was also unaffected by dietary treatments, except for ash
content which was significantly higher in the LP12 group. Hepatosomatic
index was significantly increased by the dietary incorporation of RNA. The
dietary supplementation of RNA had no protein sparing effect and
significantly reduced energy retention. It may be concluded that dietary RNA
supplementation had no nutritive value for European sea bass.
(Departamento
de Zoologia e Antropologia e, Centro Interdisciplinar de Investigação
Marinha e Ambiental (CIIMAR), Faculdade de Ciências da Universidade do
Porto, 4099-002, Porto, Portugal ,Tel.: +351-223-401-507; fax:
+351-223-401-511; email: aoteles@fc.up.pt)