Tryptophan
requirement of juvenile Asian sea bass Lates calcarifer
R.M. Coloso, D.P. Murillo-Gurrea, I.G. Borlongan, M.R. Catacutan-2004
Journal of
Applied Ichthyology, 20(1):
43-47
Abstract:
The dietary requirement of tryptophan for
juvenile Asian sea bass (Lates calcarifer Bloch) was studied. The
juveniles (mean initial weight, 5.30 ± 0.06 g) were given
semi-purified test diets containing fish meal, gelatin, squid meal, and
crystalline amino acids, for 12 weeks. Each set of isonitrogenous and
isocaloric test diets contained graded levels of tryptophan. Fish (15 per
tank) were reared in 250-L fiberglass tanks provided with continuous
flow-through sea water at 26°C and salinity of 28 p.p.t. Fish were fed
twice daily at a feeding rate of 8% of the body weight day-1 for
the first 4 weeks and at 3.5-2.5% of the body weight day-1
from 5 to 12 weeks. The experiment was in a completely randomized
design with two replicates per treatment. Mean percentage weight gains and
feed efficiency ratios were significantly different in fish fed varying
tryptophan levels. Survival was 100% in all treatments. On the basis of
break-point analysis of the growth response, the dietary tryptophan
requirement of juvenile Asian sea bass is 0.41% of the dietary protein. This
information will be useful in further refinement of practical feed
formulations for the Asian sea bass.
(Aquaculture Department, Southeast Asian
Fisheries Development Center, Tigbauan, Iloilo 5021, Philippines. E-mail: rmcoloso@aqd.seafdec.org.ph)