The Israeli Journal of Aquaculture – Bamidgeh 56(2), 2004, 131-137.
TOTAL AROMATIC AMINO ACID REQUIREMENT OF THE
INDIAN MAJOR CARP, CIRRHINUS MRIGALA
S. Benakappa* and T.J. Varghese
College of Fisheries, University of Agricultural Sciences, Mangalore 575 002, India
(Received 16.1.03, Accepted 15.11.03)
Key words: aromatic amino acid requirement, carp, phenylalanine, tyrosine
Quantification of the essential amino acid requirements of a species is required for formulating
optimal diets for cultivated fish. In this study, crystalline L-phenylalanine was used to determine
the quantitative phenylalanine requirement of juvenile Cirrhinus mrigala. Test diets (40% crude
protein) contained vitamin-free casein and gelatin supplemented with crystalline L-amino acids
to provide an amino acid profile similar to C. mrigala muscle protein except for phenylalanine.
Diets containing six graded levels of L-phenylalanine (0.80, 1.10,1.40, 1.70, 2.00 and 2.30%)
and a fixed level of tyrosine (0.52%) were formulated and fed to triplicate groups of C. mrigala
juveniles twice a day at a rate of 10% of the fish body weight per day for 56 days. The optimum
dietary requirement for phenylalanine, estimated by breakpoint regression analysis, was 1.75%
of the diet (4.38% of the dietary protein) or 2.27% of the total aromatic amino acid (5.68% of the
dietary protein). Beyond the optimum level, phenylalanine significantly depressed growth. The
best feed efficiency, specific growth rate and survival were obtained with the diet containing
close to the optimum level of aromatic amino acid.
* Corresponding author: E-mail: firstname.lastname@example.org