Effect of Feed Quality on Growth Performance and Water Quality in Cage Culture System for Production of Nile Tilapia [Oreochromis Niloticus, (Linnaeus, 1758)] in Lake Hora-Arsedi, Ethiopia
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Date
2011-05
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Addis Ababa University
Abstract
Six months (Jun 7 to November 22/ 2010) feeding trial was conducted to investigate the effects of
feed quality on growth performance and water quality in cage culture system of mixed-sex Nile
tilapia (Oreochromis niloticus) in Lake Hora-Arsedi using fifteen suspended 1 m3 net cages. The
initial length and weight of the fish ranged from 119.32 ± 1.44 to 125.00 ± 1.50 mm and 42.80 ±
2.53 to 43.51 ± 2.36 gm, (mean ± SD), respectively. Fish diets were prepared from three kinds of
locally available plant protein source feeds, i.e. oil seed cake (O), mill sweeping (M), and rice
bran (R). In all the combination 20% of blood and bone meal (B) was added to increase the
crude protein level and supplement growth limiting mineral, phosphorus. Therefore, four
combination of feeds were prepared as diet-1 (ROM+B), 22.87% crude protein (CP); diet-2 (RM
+ B), 22.22% CP; diet-3 (MO+B), 22.00% CP, and diet-4 (RO+B), 24.28% CP). About 26.67%
each of plant protein source ingredient was in diet-1, whereas 40% of it in the other
combinations. There was a triplicate of control cages in which fishes were provided with only the
natural feeds. Each treatment was assigned to triplicates of 100 fish in a completely randomized
design along the U-shaped jetty (walkway). The fish were fed sinking extruded feeds, 3% of their
body weight, twice a day manually using feeding tray. The results showed significant differences
among the test diets. Diet-1 gave the best mean weight gain (MWGs) of 197.38 ± 5.57 followed
by diet-3 with MWGs of 182.16 ± 4.12, diet-2 with MWGs of 169.27 ± 6.31. Diet-4 and the
control gave MWGs of 146.27 ± 6.82 and 80.62 ± 3.34 gm, respectively. MWGs in treatment fed
with diet-1 were significantly higher (P < 0.05) than MWGs of other treatments. Mean DGR
ranged from 0.28 for the control treatment to 0.92 for the fish fed with diet-1. Specific growth
rate was also highest in the treatment fed diet-1 (0.9%/ fish) and lowest in the control (0.38%/
fish). Food conversion ratio and efficiency were best with diet-1, followed by diet-3 and least
with diet-4. Visceral to body weight ratio for the treatment fed with diet-1 was significantly
better (P < 0.05) than the values for other treatments. Percentage survival ranged from 80% in
the control to 94% in cages fed with diet-1. The study showed that diet-1 can be effectively used
in the diet of O. niloticus and also in terms of cost it sees more efficient than other followed by
diet-3. This study also showed that the feeds did not bring any effect on water quality at least in
experimental level.
Key words: Economic analysis; feed conversion;mill sweeping, rice bran; oil seed cake
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Keywords
: Economic analysis; feed conversion;mill sweeping, rice bran; oil seed cake