Benakappa S., Varghese T.J., 2003. Isoleucine, leucine, and valine requirement of juvenile Indian major carp, Cirrhinus cirrhosus (Bloch, 1795). Acta Ichthyol. Piscat. 33 (2): 161-172.
Background. Mrigal, Cirrhinus cirrhosus (Bloch, 1795) (junior synonym C. mrigala ), is one of the most widely cultured Indian major carps.The main aim of this study was to quantify the dietary isoleucine, leucine, and valine requirements of mrigal juveniles.
Materials and methods. Growth studies were conducted with juvenile mrigal to determine the minimal requirements for the branched-chain amino acids: isoleucine, leucine, and valine.The experimental diets were formulated from purified ingredients to contain 40% crude protein. Casein and gelatin served as protein sources and were supplemented with crystalline L -amino acids to provide an amino acid pattern found in mrigal muscle protein. The amino acids for which the requirements were being determined was were supplemented at varying levels. Dietary inclusion levels for isoleucine ranged from 0.88 to 1.45%, for leucine from 1.36 to 2.05%, and for valine from 1.23 to 1.75%.
Results. The optimum dietary requirements for isoleucine, leucine, and valine for mrigal, estimated using break point analysis were 1.25%, 1.73%, and 1.55% of dry diet, respectively. These values correspond to 3.12% isoleucine, 4.33% leucine, and 3.87% valine when expressed as a percentage of dietary protein. Food conversion rate, specific growth rate, and survival were better in treatments with diets containing 1.25%for isoleucine, 1.73%for leucine, and 1.55%for valine.
Conclusion. Results of this study clearly demonstrated that Cirrhinus cirrhosus could utilize free amino acids for growth. Further, the findings would be useful in formulating isoleucine, leucine, and valine balanced diets in controlled production of mrigal.
Keywords: isoleucine, leucine, valine, requirement, fish, mrigal, Cirrhinus cirrhosus, C. mrigala