International Journal of Aquaculture 2015, Vol.5, No. 41, 1-20
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2.2 Experimental fish
Before the commencement of the feeding trial, a total
of 1092
Clarias gariepinus
fish of average weight
(4.5+0.2g), were procured from a reliable fish farm
with healthy fish stocks, and acclimated under
laboratory conditions for 3 weeks during which time
they were fed commercial diet in 10 fish holding tanks
supplied with clean water with temperature, pH and
oxygen maintained at optimum range between 25°C-
32°C, 7.40-7.45, 4.80- 5.0mg/l. Water was sourced
from a borehole through an overhead tank with a pipe,
which supplied clean water to the Aquaculture and
Fisheries Management Laboratory, University of
Ibadan, Oyo State, Nigeria. All fish were left unfed for
2-3 days prior to start of experiment until they attained
the juvenile status of average weight of 11.55+ 0.2g and
length of 11.79 + 1.03 cm before experimental feeding
with phytase-treated diets. All fish were randomly
allocated to all 21 treatment combination groups of
diets, including control diet in a 4x5 design, and fed to
duplicate groups of fish stocked at 26 fish per tank.
Each of the feed rations were shared so that
experimental fish were fed twice daily (morning at
08:00 hrs) and evening (evening at 16:00 hrs) to obtain
optimum growth with faeces removed at each feeding
period. Experimental fish were weighed biweekly
throughout the experiments using an electronic compact
balance S. Mettler scale with accuracy of 0.01g (Model:
K-BH). Water was changed once every two (2) days
using static water renewal method and water quality
monitored and measured for all treatment tanks at the
beginning end of the experiment.
Table 5 Gross and chemical composition of roasted, full-fat soyabean-basal diets for juvenile
Clarias gariepinus
Ingredient (dry matter)
S
0
(0%)
S
1
(25%)
S
2
(50%)
S
3
(75%)
S
4
(100%)
Fish meal
54.29
45.38
34.16
19.62
-
Soyabean meal (full fat)
-
15.13
34.16
58.85
92.15
Maize
42.21
35.99
28.18
18.03
4.35
Vit Min Mix
#
0.50
0.50
0.50
0.50
0.50
Fish oil
1.00
1.00
1.00
1.00
1.00
CaCO
3
0.50
0.50
0.50
0.50
0.50
Salt
0.50
0.50
0.50
0.50
0.50
Cellulose*
0.20
0.20
0.20
0.20
0.20
Starch
0.80
0.80
0.80
0.80
0.80
Chemical composition (%)
Phosphorus
1.31
1.15
1.01
0.75
0.43
Available phosphorus
0.91
0.63
0.44
0.33
0.03
Calcium
1.85
1.64
1.28
0.99
0.68
Magnesium
0.25
0.24
0.28
0.27
0.27
Potassium
0.87
1.10
1.35
1.60
1.90
Sodium
54.78
51.18
43.39
31.41
20.84
Manganese
63.12
77.37
113.66
101.03
97.40
Iron (ppm)
45.02
40.77
47.59
51.14
65.53
Copper (ppm)
3.53
5.04
8.33
11.15
14.71
Zinc (ppm)
15.82
14.22
12.59
12.12
12.40
Intrinsic phytase (FTU/g)
<100
<100
<100
<100
<100
Note: # Micro mineral mix contains per kilogram: Vit A (20, 000 IU), Vit. D3 (5, 000 IU), Vit. E (300 mg), Vit K3 (10mg), Vit B1 (20
mg), Vit. B2 (25 mg), Vit. C (300 mg), Niacin (120 mg), Ca. Pantothenate (60 mg), Vit B6 (10 mg), Vit B12 (0.05), Folic acid (5 mg),
Biotin (1 mg), Choline chloride (5 mg), Inositol (50 mg), Manganese (30 mg), Iron (35 mg), Zinc (45 mg), Copper (3 mg), Iodine (5
mg), Cobalt (2 mg), Lysine (85 mg), Selenium (0.15mg), Antooxidant (80 mg), Methionine (100mg). * as carboxymethyl cellulose
2.3 Proximate and Mineral composition
Proximate composition of raw and processed
soyabean was determined by method of AOAC (2006).
For moisture, sample was mixed the sample
thoroughly and water content determined by weighing
out 2.5g into silica dish, which has been previously
dried and weighed. The dish including the sample
inside it was placed in hot air oven for 24 hours at
60°C-70°C (drying at high temperature may result in
losses of heat labile or volatile component). Finally,
