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International Journal of Aquaculture, 2014, Vol.4, No.15 89
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95
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91
Table 3 Mineral composition of Nile tilapia fed phytase diets (mg/L)
Ca
Mg
P
Zn
Fe
Mn
Control
48.02
8.36
c
56.91
11.32
c
59.00
9.98
b
27.70
1.06
ab
5.61
0.08
c
4.81±0.42
a
Treatment 2
46.04
7.08
b
46.05
2.65
a
52.23
4.38
a
27.33
1.04
a
3.51
0.06
a
4.94
0.66
a
Treatment 3
57.61
0.74
f
62.84
2.58
e
66.39
3.57
f
33.20
1.07
d
6.07
0.54
d
6.03
0.60
b
Treatment 4
48.87
5.28
d
57.37
3.71
d
59.92
5.41
c
33.24
0.03
d
7.74
0.38
f
11.38
4.91
d
Treatment 5
41.92
2.68
a
49.22
2.25
b
64.93
3.03
e
27.81
1.08
b
5.05
1.15
b
5.80
0.88
b
Treatment 6
52.49
6.44
e
63.81
3.82
f
61.29
1.89
d
31.68
1.47
c
6.45
1.29
e
9.79
0.01
c
Note: Key: Mean followed by the same letter vertically are not significant different (p > 0.05). Ca= Calcium, Mg= Magnesium, P=
Phosphorus, Zn= Zinc, Fe= Iron, Mn= Manganese
Table 4 Mineral composition of the faeces after the experiment
Ca
Mg
P
Zn
Fe
Mn
Control
63.14
2.2
e
67.46
2.71
e
52.44
0.75
f
76.68
1.49
f
15.49±0.9
f
23.59
0.16
f
Treatment 2
72.45
6.8
f
67.80
4.70
f
46.05
10.4
d
76.39
6.40
e
13.63±2.6
e
19.58
1.69
e
Treatment 3
58.04
3.5
d
58.64
1.68
e
41.08
11.7
c
71.79
3.42
d
12.81±0.7
d
18.41
0.80
d
Treatment 4
44.17
6.1
c
59.78
0.06
d
47.28
9.49
e
66.12
5.02
c
11.03±2.7
c
14.28
0.98
c
Treatment 5
29.66
5.6
a
54.98
12.3
a
30.69
1.78
a
60.05
15.6
a
10.11±0.24
b
13.25
0.01
b
Treatment 6
39.96
2.1
b
57.64
0.41
b
38.25
6.23
b
61.06
4.25
b
9.07±0.60
a
11.53
2.41
a
Note: Key: Mean followed by the same letter vertically are not significant different (P>0.05). Ca= Calcium, Mg= Magnesium, P=
Phosphorus, Zn= Zinc, Fe= Iron, Mn= Manganese
2 Discussion
The effect of toasting and incubation of soybean meal
supplemented with phytase on the nutrient
digestibility and minerals deposition in Nile tilapia
,
Oreochromis niloticus
was investigated. These results
indicated that phytase supplementation to the
experimental diets had improved the Apparent
Digestibility Coefficient (ADC) of protein, gross
energy and lipid. The improvement in the ADC of
protein and gross energy agreed with the findings of
Portz and Liebert (2004) who reported similar
improvement in
O. niloticus
fed diets with 1000 and
2000 FTU kg
-1
phytase supplementation. Also, this
results support the report of Goda, 2007 who reported
higher ADC (p < 0.05) values for crude protein, ether
extracts (lipid) and gross energy were observed in
O.
niloticus
fed diet supplemented with 1000 FTU kg
-1
phytase. The inclusion rate of phytase in present study
may play an important role in releasing
phytate-phosphorus in soybean meal-based diets. Lie
et al., (1999) reported improve digestibility of crude
protein by 6.6% in Crucian carp, fed phytase
supplementation of 500 FTU/kg diet.
Also, inclusion of soybean phytase in diet of Atlantic
salmon improved protein utilisation parameters, ADC,
and body levels of Ca, Mg and Zn and retention of
Phosphorus (P) (Storebakken et al., 1998; Vielma et
al., 1998, 2000). Protein digestibility in rainbow trout
was significantly increased when fed a practical diet
supplemented with 2000 FTU/kg phytase and also
when reared with soybean meal-based diets sprayed
with phytase (Vielma et al., 2001, 2004). Biswas
et al
.,
(2007) reported that protein digestibility was
significantly influenced by phytase supplementation in
red sea bream fed soybean meal based diets
supplemented with graded doses of phytase, this report
support this present study. Phytase supplemented diet in
pangus increased apparent protein digestibility and
were significantly (p < 0.01) higher at a minimum
supplement of 500 FTU/kg or higher in contrast to
diet without phytase. Baruah et al. (2007a) reported
that maximum apparent digestibility of P and crude
protein was recorded when phytase-supplemented
diets contained 750 FTU phytase/ kg diets in feed of
rohu, agastic fish.
From the result of the mineral composition of the
fishes after the experiment, it could be observed that
the minerals increased with addition of phytase in the
diets. Phosphorus (P) is a critical element for fish and
other livestocks. It plays a major role in the structure
and function of living cells. It is an integral
component of adenosine triphosphate (ATP), nucleic