Deutscher Tropentag, October 9 - 11, 2002 in Kassel-Witzenhausen "Challenges to Organic Farming and Sustainable Land Use in the Tropics and Subtropics"

Assessing the Dietary Amino Acid Requirements of Tilapia, Oreochromis niloticus Fingerlings

¹Ebonyi State University, Department of Applied Biology, Nigeria
²Institute of Freshwater Ecology and Inland Fisheries, Department of Inland Fisheries, Germany

Abstract

Oreochromis niloticus fingerlings (initial weight, 4.35±0.24 g) were fed diets with dietary protein levels, ranging from 7.3% - 44.2% dry matter (dm) for eight weeks. Using growth performance and food conversion ratio, the dietary protein requirement of the fingerlings was estimated at 33.3% dietary protein (dm). Dietary protein: Energy (P:E) ratio of this diet was 16.1 mg kJ^-1. Dietary essential amino acid requirements for O. niloticus were expressed as the essential amino acid composition of the diet with a protein content of 33.3% dm. This follows the concept that protein requirement 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 the performance of fish on diets with an essential amino acid profile similar to the diet containing 33.32% dietary protein and others reflecting 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 but rather an indication of the concentration range which must be present in fish diet to allow adequate performance of fish. The relative ease of tilapia culture as well as its rapid growth-rate under tropical and semi-tropical climates have led to its widespread distribution. Further intenisfied culture methods for tilapias may be successful if perfected diets satisfying all of the nutrient requirements are formulated. This study's goal is to assist those in developing countries to determine the amino acid requirements of fish before formulating fish diets by introducing a more simple method.

Keywords: Protein and amino acid requirements, Tilapia

Contact Address: Johnny Onyema Ogunji, Ebonyi State University, Department of Applied Biology, P.O. Box 53,  Abakaliki, Nigeria, e-mail: ogunjijoyahoo.com