Abstract
This study was conducted to determine an appropriate replacement of fishmeal with amino acids (AAs) and optimized protein levels in practical diets for Oreochromis niloticus with mean initial body weight 12.52±0.63g. Six experimental and a control diet (total 7 diets) divided into two groups, and a control diet (D1) containing 32% protein. The first group contained three diets that included different dietary protein levels, viz. 20 (D2), 25 (D3), and 30% (D4) with AAs when replacing fishmeal by plant protein sources. In the second group, the diets were contained 20 (D5), 25 (D6), and 30% (D7) without AAs. The best growth performance was achieved in fish fed with diet D1. Total feed intake was increased with an increase in dietary protein level with AAs. The specific growth rate showed a similar pattern with a significant difference between control, D4 and D7 compared to other groups. The feed conversion ratio decreased when protein levels in the diets increased. The protein efficiency ratio showed a similar performance, with a slight increase between the control diet and diets with AAs. However, insignificant differences (P>0.05) were observed between diets with and without AAs. An economic evaluation indicated that inclusion of low fishmeal in tilapia diets reduced the price/kg of diets compared to control.
Highlights
The increasing cost of the strategic use of fish meal for higher value fish species means that it is necessary to consider economic diets for aquaculture and this is especially important for the non-carnivorous fish, other thanBraz
Fish meal has a sufficient and balanced content of amino acids when compared with plant protein sources that are often limited in some of the essential amino acids with consequent negative effects on growth and feed utilization when substituted for fish meal in diet formulations (Wilson, 1989)
The main aim of this study were to define the effect of dietary protein level, Essential Amino Acid (EAA) supplementation as a replacement of fishmeal, and their interaction on growth, feed utilization, carcass composition, and the potential cost benefit to the aquaculture of Nile tilapia
Summary
The increasing cost of the strategic use of fish meal for higher value fish species means that it is necessary to consider economic diets for aquaculture and this is especially important for the non-carnivorous fish, other thanBraz. Fish meal has a sufficient and balanced content of amino acids when compared with plant protein sources that are often limited in some of the essential amino acids with consequent negative effects on growth and feed utilization when substituted for fish meal in diet formulations (Wilson, 1989). Economic feeds of tilapia contain about 5–10 percent of fish meal in the diet, but continuous price hike of fish meal forced the fish culturists to use certain supplementations (Naylor et al, 2000). The consideration has been given to tilapia nutrition with an attention on the partial or total substitution of fish meal by cheap vegetable protein sources in tilapia feeds (El-Sayed, 1999) such high levels of replacement plant vegetable sources, require supplementation of essential AAs in fish diets
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