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International Journal of Aquaculture 2012, Vol.2, No.7, 40
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47
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41
comparative data are not available on the growth
performance and feed utilization efficiency on
different
Oreochromis niloticus
strains in Ethiopia.
The general objective of this study was therefore to
compare the growth performance of different
Oreochromis niloticus
strains collected from various
Ethiopian freshwater lakes (such as Lake Hawassa,
Lake Ziway, Lake Koka and Lake Hora) in pond
culture to enhance the production of tilapia
aquaculture in the country.
2 Results
The mean value of some water quality parameters of
the ponds were calculated and summarized in Table 1.
The results revealed that all the ponds have similar
water quality parameters and were not significantly
(p > 0.05) different among triplicate. Moreover, variations
in growth performance among triplicate for all strains
were insignificant. Similarly, the initial body size of
all the strains were no significantly (p > 0.05)
different (Table 2). This implies, the initial body size
of all the strains were homogeneous.
The different growth parameters for all the strains
were calculated after 60 days of the experiment and
were summarized in Table 2. The results revealed that
the different growth parameters were significantly
(P < 0.05) affected by strain difference. The highest and
the lowest final mean body weight were observed in
the Koka strain (64.04 g) and the Ziway strain
(53.13 g), respectively. The Koka strain had
significantly (p < 0.05) higher final mean body weight
Table 1 The mean value of some water quality parameters measured during the experiment
Water quality parameters
Ponds
Temperature (
℃
)
pH
DO (%)
Conductivity (uS/cm)
TDS (PPT)
Salinity (PPT)
Pond 1
20.38a
8.36b
86.40c
173.02d
99.25e
0.1
Pond 2
20.42a
8.29b
88.10c
188.66d
97.9e
0.1
Pond 3
20.38a
8.27b
87.22c
176.46d
92.62e
0.1
Note: Mean values in the same column having the same letters are not significantly different (P > 0.05)
Table 2 Growth parameters, feed conversion ratio, Fulton condition factor, gross fish yield and survival rate of four
Oreochromis niloticus
stains during experimental period
Oreochromis niloticus
strains
Growth parameters
Hawassa
Ziway
Hora
Koka
Initial mean body length(cm/fish)
9.14a
9.15a
9.18a
9.25a
Initial mean body weight (g/fish)
12.60a
12.49a
12.44a
12.40a
Final mean body length(cm/fish)
15.10a
14.30b
14.58b
15.30a
Final mean body weight (g/fish)
59.63ab
53.13a
55.83a
64.04b
Mean body weight gain (g/fish)
47.03ac
40.63b
43.40bc
51.64a
Specific growth rate (%/day)
2.59ac
2.41b
2.50bc
2.73a
Feed conversion ratio
1.76a
1.73a
1.73a
1.72a
Fulton condition factor
1.73a
1.82a
1.80a
1.79a
Gross fish yield (g/m
3
)
149.08b
131.04a
139.58a
160.09b
Survival rate (%)
100
96
100
100
Note: Mean values in the same row having the same letters are not significantly different (P > 0.05)