Dietary requirements of the Indian major carp, Labeo rohita (Hamilton), for total aromatic amino acids

The dietary aromatic amino acid (phenylalanine and tyrosine) requirement of Labeo rohita (rohu) was determined by conducting a growth study. The test diets (40% crude protein) contained casein and gelatin, supplemented with crystalline L-amino acids to provide an amino acid profile similar to rohu muscle protein, except for the tested amino acids. The experimental diets consisted of six isonitrogenous diets containing graded levels of phenylalanine (0.69, 1.0, 1.3, 1.6, 1.9 and 2.2%) and a fixed level of tyrosine (0.61%). Each diet was fed to triplicate groups of rohu fingerlings twice a day up to satiation for 60 days. The dietary requirement for phenylalanine, estimated by breakpoint analysis, was 1.6% of the dry diet (4.0% dietary protein) or 2.21% of the total aromatic amino acid in the diet (5.53% protein). The best feed efficiency, specific growth rate and survival were obtained with the diet containing the optimum level of aromatic acid.