International Journal of Aquaculture 2015, Vol.5, No. 41, 1-20
9
2.8.3 Cost savings
Cost savings= (IC
fish meal
-IC
diet
) x Cost of feed
consumed
fishmeal
Where, IC
fish meal
= incidence of cost for fish meal diet
(S0P0)
IC
diet
= Incidence of cost for experimental diet
Cost of feed consumed
fishmeal
= cost of feed consumed
for fish meal diet
Assumptions:
·Cost of feeds formulated was based on the prevailing
market prices.
·Value of fish was based on the selling price of
N500/kg.
·Total weight of fish produced was got from the total
weight of fish recovered at the end of the experiment.
Table 9 Anti-nutrients in experimental diet based on soya bean
(fullfat)
Treatment
Tannin
(mg/g)
Phytate
(mg/g)
Oxalate
(mg/g)
S0P0
0.00±0.00
0.40±0.02
e
0.40±0.02
a
S1P0
0.00±0.00
0.52±0.01
hi
1.92±0.02
f
S1P1
0.00±0.00
0.14±0.01
a
1.94±0.12
f
S1P2
0.00±0.00
0.61±0.01
k
1.39±0.04
e
S1P3
0.00±0.00
0.51±0.01
hi
0.91±0.01
bc
S1P4
0.00±0.00
0.18±0.01
b
0.74±0.01
b
S2P0
0.00±0.00
0.57±0.01
j
2.26±0.11
gh
S2P1
0.00±0.00
0.44±0.01
fg
2.26±0.08
gh
S2P2
0.00±0.00
0.41±0.01
ef
1.95±0.09
f
S2P3
0.00±0.00
0.39±0.01
e
2.02±0.13
f
S2P4
0.00±0.00
0.18±0.01
b
2.09±0.12
fg
S3P0
0.00±0.00
0.43±0.02
efg
3.09±0.11
j
S3P1
0.00±0.00
0.34±0.04
d
2.28±0.03
gh
S3P2
0.00±0.00
0.51±0.02
h
2.42±0.04
hi
S3P3
0.00±0.00
0.55±0.01
ij
2.47±0.23
hi
S3P4
0.00±0.00
0.44±0.01
fg
2.61±0.11
i
S4P0
0.00±0.00
0.40±0.01
e
4.95±0.21
k
S4P1
0.00±0.00
0.21±0.01
b
1.40±0.01
e
S4P2
0.00±0.00
0.25±0.01
c
0.83±0.05
b
S4P3
0.00±0.00
0.45±0.01
g
1.14±0.12
d
S4P4
0.00±0.00
0.26±0.01
c
1.08±0.05
cd
Sig.
<0.05
<0.05
Note: Means with the same superscript in the same column are
not significant (P<0.05). n=2
2.8.4 Statistical analysis
At the end of the all experiments, all subjected to one
way analysis of variance (ANOVA) using statistical
software (SPSS 20) to detect significant differences in
all parameters. Duncan new multiple range tests
(Duncan, 1955) was used to detect individual
differences between treatment means of growth,
antinutrients, water quality and economic analysis.
Main effects and interaction of soyabean and phytase
was assessed by factorial analysis. Tukey HSD test of
comparison was used to detect significant difference
between mean pair differences for antinutrints, water
quality and growth parameters. Correlation was
employed to define the relationship between growth,
water quality, and dietary phytase supplementation in
Clarias gariepinus
fed graded levels of soya bean
meal-based diets. All data were presented as means +
S.D and a rejection level of P>0.05 was used for all
statistical analysis.
3 Result
3.1 Growth and nutrient utilization
Significant interaction of soya bean and phytase was
observed for mean weight gain, feed conversion ratio
and surivival rate (Table 6). Mean weight gain also
declined (Table 6) with increasing substitution of fish
meal by soyabean (Tukey, P<0.05), irrespective of
phytase levels (Figure 1). However, supplementation
of 250 FTU/g phytase improved mean weight gain
compared to 500 FTU/g and 1000 FTU/g (Tukey,
P<0.05). Compared to diet without phytase (Table 6,
fig 2), mean weight gain of fish fed 250 FTU/g diet
was higher, but did not differ significantly (Tukey,
P<0.05). Phytase increased significantly mean weight
gain of fish fed 25% soya bean (S1) from 39.94±0.21g
(S1P0) to 40.88±2.53g (S1P3). No significant effect of
phytase was observed for mean weight gain of fish fed
50% soyabean (Duncan, P>0.05). Phytase inclusion in
75 % soya bean (S3) resulted in highest weight gain
for S3P1 fish (Table 7), which was statistically
different from S3P2, S3P3, and S3P4 (Duncan,
P<0.05). No statistical difference in mean weight gain
and FCR for fish fed S3P1 and S0P0 (Duncan, P>0.05)
was recorded.
Mean weight gain increased
significantly with phytase addition to diet based on
100% (S4) soya bean meal (P<0.05). Fish fed S4P4
had the lowest mean weight gain compared to S4P1,
S4P2, and S4P3 (Duncan, P>0.05). Irrespective of
