Utilization of raw and
gelatinized starch by European sea bass (Dicentrarchus labrax)
juveniles
H. Peres, A. Oliva-Teles-2002
Aquaculture, 205(3-4): 287-299
Abstract:
Three isonitrogenous (48% protein) and isolipidic
(12% lipids) diets were formulated to contain 25% raw starch (RS), 25%
gelatinized starch (GS) or 12.5% raw+12.5% gelatinized starch (RS/GS).
Another diet was formulated with no carbohydrates (HP) containing 63%
protein and 18% lipid. Each experimental diet was fed to triplicate groups
of 25 fish (IBW=6 g) for 10 weeks.
The reduction of dietary protein level from 63% to
48%, by starch incorporation, did not affect growth rate or protein and
energy retention. For the diets containing starch, specific growth rate of
fish fed the GS diet and feed efficiency for the RS diet were significantly
lower than values obtained for the other diets. Protein digestibility was
independent of diet composition. Energy and starch digestibility
significantly increased with the increase in dietary gelatinized starch.
At the end of the growth trial there were no
significant differences in whole body composition between groups.
Hepatosomatic and visceral indices of fish fed the RS and HP diets were
significantly lower and the hepatic lipid content of fish fed the GS diet
was significantly higher than in the other groups. Muscle lipid content was
unaffected by diet composition. After 16 hours of fasting, the plasma
glucose level was identical for all dietary treatments.
Nitrogen (g kg-1 day-1) and
energy retention (kJ kg-1 day-1) were unaffected by
dietary treatment. However, a trend towards increased nitrogen and energy
retention (% N or E intake) was observed with the increase of dietary
gelatinized starch. Ammonia excretion (mg kg-1 day-1)
and heat increment (kJ kg-1 day-1) were significantly
lower for sea bass fed the GS diet.
In conclusion, the total replacement of raw starch by
gelatinized starch significantly reduced growth and feed intake, while
improving feed efficiency. Overall, the best results were achieved with the
diet RS/GS.
(Departamento de Zoologia e Antropologia e
CIIMAR-Centro Interdisciplinar de Investigação Marinha e Ambiental;
Faculdade de Ciências da Universidade do Porto, 4099-002 Porto, Portugal,
Tel.: +351-22-340-1507; fax: +351-22-340-1511, e-mail of A.
Oliva-Teles : aoteles@fc.up.pt)