Assessing the dietary amino acid requirements of tilapia, Oreochromis niloticus fingerlings

In an earlier study Oreochromis niloticus fingerlings (initial weight, 4.31±0.27 g) were fed diets with dietary protein levels, ranging from 7.30% 44.24% dry matter (dm) for eight weeks. Using growth performance and food conversion ratio, the dietary protein requirement of the fingerlings was estimated at 33.32% dietary protein (dm). In this study the dietary essential amino acid requirements for O. niloticus were expressed as the essential amino acid composition of the diet with a protein content of 33.32% dm. This follows the concept that protein requirements is the minimum amount needed to meet amino acid requirements and ensure maximum growth. The essential amino acid requirements, as %dm are: Arginine 1.68, Histidine 0.70, Isoleucine 1.15, Leucine 2.15, Lysine 1.98, Methionine 0.10, Phenylalanine 1.13, Threonine 1.11, Tryptophan, 0.84, and Valine 1.34. This result was verified by comparing fish performance on diets having essential amino acid profile similar to the diet containing 33.32% dietary protein and others mirroring the recommended amino acid requirement for tilapia by Santiago and Lovell (1988). The specific growth rate among different fish groups was not significantly different. Essential amino acid requirements are therefore not absolute values rather an indication of concentration range which must be present in fish diet to enhance adequate performance of fish.