International Journal of Aquaculture 2015, Vol.5, No. 41, 1-20
16
rather than the effect of water quality (Lemarie et al.,
2004). An evidence of this assertion is the fact that
high dissolved oxygen and lower ammonia was
observed in S3P1 compared to S3P0, S3P2, S3P3, and
S3P4 (Table 12). Fish fed 100% soya bean also
showed the lowest feed intake, specific growth rate,
protein efficiency, and the highest feed conversion.
The low growth in soya bean fish may be due to
unbalanced amino acid profile of soya bean compared
to fish meal (Eyo, 2003; Castro et al., 2011), high
fibre (Haghbayan and Mehrgan, 2015), the presence
of antinutrients (Lei and Porres, 2011) an, including
phytate and oxalate (Table 4), high fat content (Table
1) and low phosphorus (Table 2) and zinc (Table 3)
compared to fish meal ,which limits its total
substitution of fish meal limiting its total substitution.
Zinc is essential for the growth and development in
animals (Akpoilih et al., 2016). Survival rate, however,
was improved in fish fed 100% soya bean with
phytase at 250 FTU/g (S4P1), 500 FTU/g (S4P2) and
750 FTU/g (S4P3) showed improvement compared to
value for fish fed diet without phytase, which may be
due by low phosphorus level at 100% substitution
(Table 5). Low dietary phosphorus level in fish (Cao
et al., 2007) and animal (Lim et al., 2000) has been
reported to stimulate positive response to phytase.
Table 15 Economic analysis of experimental diet with phytase based on full fat soyabean meal for
Clarias gariepinus
Treatments Cost of feed consumed (N)
* #
Value of fish (N)
Incidence of cost
Profit index Cost savings (N)
S0P0
721.86±59.31
i
626.56±49.02
f
0.46±0.01
bcd
0.87±0.00
fgh
0.00
S1P0
596.93±32.61
fgh
521.89±0.14
e
0.45±0.02
bc
0.88±0.05
fgh
7.21
S1P1
622.18±40.12
gh
541.36±55.42
ef
0.44±0.01
abc
0.87±0.03
fgh
14.44
S1P2
609.39±68.81
fgh
471.70±13.03
de
0.49±0.06
cde
0.78±0.11
ef
-21.66
S1P3
655.70±26.52
hi
541.39±60.64
ef
0.46±0.02
bcd
0.81±0.04
fg
0.00
S1P4
586.50±30.41
efgh
521.31±24.17
e
0.44±0.02
abc
0.89±0.08
fgh
14.44
S2P0
499.54±40.96
cde
492.64±8.22
de
0.39±0.02
ab
0.99±0.06
h
50.53
S2P1
435.75±41.16
bc
412.75±36.01
cd
0.40±0.01
ab
0.95±0.01
gh
43.31
S2P2
441.95±39.99
bc
424.29±42.66
cd
0.39±0.00
ab
0.96±0.01
gh
50.53
S2P3
539.84±62.94
defg
556.65±104.06
ef
0.38±0.01
ab
1.03±0.07
hi
57.75
S2P4
497.09±47.64
cde
491.80±21.81
de
0.39±0.04
ab
1.00±0.13
h
50.53
S3P0
400.45±41.72
b
363.87±64.61
c
0.39±0.01
ab
0.91±0.06
fgh
50.53
S3P1
481.45±12.09
bcd
557.44±10.41
ef
0.36±0.04
a
1.16±0.05
i
72.19
S3P2
429.05±23.41
bc
375.55±68.09
c
0.40±0.02
ab
0.87±0.11
fgh
43.31
S3P3
547.90±22.95
defg
343.80±43.39
c
0.55±0.04
e
0.63±0.05
de
-64.97
S3P4
521.00±34.51
cdef
332.21±9.72
c
0.53±0.02
de
0.64±0.06
de
-50.53
S4P0
284.31±27.39
a
31.71±5.73
a
0.76±0.01
f
0.11±0.01
a
-216.56
S4P1
284.33±43.57
a
158.35±5.47
b
0.45±0.03
bc
0.56±0.07
cd
7.22
S4P2
234.27±13.25
a
97.50±4.62
ab
0.48±0.00
cde
0.42±0.01
bc
-14.44
S4P3
260.32±26.90
a
108.89±24.49
ab
0.50±0.01
cde
0.42±0.05
bc
-28.87
S4P4
248.89±32.24
a
72.79±24.66
ab
0.55±0.11
e
0.30±0.14
b
-64.97
Sig
P<0.05
P<0.05
P<0.05
P<0.05
4.2 Water quality
Improvement in growth of fish was consistent with
improved water quality (Table 12, Table 13, Table 14).
Water quality measured in the study indicates not only
a positive effect of promotion pollution management,
but also on sustainable aquaculture production. There
was observed decrease in oxygen consumption with
concomitant increase in dissolved oxygen levels in
experimental treatment (Table 11), which may indicate
better oxidation of nutrient and less excretion of
nitrogen (Castro et al., 2011) as recorded in Table 12.
The highest dissolved oxygen recorded for 250 FTU/g
phytase compared to 500, 750, and 1000 FTU/g with
acorresponding growth improvement (Figure 2, Figure
5) may indicate better phosphorus utilization (Olukosi,
2012) from phytate (Table 8), resulting in the
reduction of pollution (Nwanna et al., 2008) in the
form of ammonia (Table 12). There was observed
increase in dissolved oxygen (decreased consumption)
in treatment 25%, 75%, and 100% soyabean diet with
phytase addition compared to fish meal, which
showed the lowest dissolved oxygen (increased
