THE EFFECT OF AMINO ACID SUPPLEMENTED DIETS ON GROWTH PERFOMANCE OF NILE TILAPIA (Oreochromis niloticus Linnaeus, 1758) FINGERLINGS REARED IN HAPAS SUSPENDED IN EARTHEN POND

Abstract

Commercial diets are produced in bulk with significant anti-nutritional factors increasing aquaculture production cost. The proximate composition of local feed ingredient is limited by unbalanced dietary amino acid contents, thereby increasing ammonia levels in pond water. This study formulated diets using local ingredients and balanced the Essential Amino Acids (EAAs) to enhance the physical quality and nutritive value for culture of Oreochromis niloticus. Three practical diets were formulated at 30% crude protein and one commercial diet with 32% CP was locally purchased and tested at the University of Eldoret fish farm. Diet 1 received both methionine + lysine, diet 2 constituted lysine supplement only while the control diet 3 did not receive any supplement. The supplementation rates were at 5.1 g kg-1 lysine and 2.7 g kg-1 methionine. The growth performance was conducted in hapas suspended in an earthen pond 150 m2 in a randomized design for 105 days. There were slight variations in temperature (24 to 260C), Dissolved oxygen (4.8 to 6.2 mg L-1) and pH (7.2-7.6) but within optimal range for tilapia during the study period. The diets provided 17.17 MJ kg-1 with 22.9% digestible CP level, 8.03% ash and 90.7% dry matter. There were significant differences at (p<0.05) in growth perfomance in all tested diets. Lysine supplemented Diet 2 induced the highest mean final weight of 156.05±1.74 g whereas the commercial Diet 4 induced the least mean weight gain of 94.08 ±3.064g. Supplemented Diet 1 indicated better Mean final weight of 125±1.681g while control diet had 114±1.917g at p<0.05. All performance indicators confirmed that lysine supplemented Diet 2 was better than other diets with SGR of 2.4, and FCR of 1.42 and Protein Efficiency Ratio of 2.68. Crude lipid content in the carcass were relatively lower in supplemented Diet 1 (10.371±0.21a) and Diet 2 (10.346±0.27a) compared to higher crude lipid contents in commercial Diet 4 (14.358±0.23c).Diet 2 exhibited a high profit index (2.286±0.07) at low incidence cost (0.437±0.05). Commercial diet low profit index (1.652±0.04) at high incidence cost (0.951±0.14) at (p<0.05).The study concluded that EAAs supplementation at 5.1 g kg-1 Lysine and 2.7 g kg-1 Methionine improved growth perfomance in FCR, PER and Weight Gain of O. niloticus. The study recommends supplementation of limiting essential amino acid at 5.1 g kg-1 Lysine and 2.7 g kg-1 Methionine in plant protein feed ingredients to improve the feed nutritive value, growth perfomance of O. niloticus at reduced production cost.