International Journal of Aquaculture 2015, Vol.5, No. 41, 1-20
8
Table 8 Effect of soya bean (full fat) and phytase on
antinutrients (phytate and soyabean) in the diet of juvenile
Clarias gariepinus
Sources of
variation, P
value
Phytate (%)
Oxalate (%)
Phytase
0.000
0.000
Soya bean
0.000
0.000
Phytase* Soya
bean
0.000
0.000
Pooled SE
0.002
0.015
Tukey HSD
(means,
P values)
Phytase
P0 vs P1
0.18*, 0.000
0.55*, 0.000
P0 vs P2
0.02, 0.107
0.88*, 0.000
P0 vs P3
-0.01, 0.469
0.89*, 0.000
P0 vs P4
0.20*, 0.000
0.89, 0.000
P1 vs P2
-0.16*, 0.000
0.32*, 0.000
P1 vs P3
-0.19*, 0.000
0.33*, 0.000
P1 vs P4
0.02*, 0.288
0.34*, 0.000
P2 vs P3
-0.03*, 0.005
0.01*, 1.000
P2 vs P4
0.18*, 0.000
0.02*, 0.997
P3 vs P4
0.21*, 0.000
0.01*, 1.000
Soya bean
S0 vs S1
0.004, 0.997
-0.98*, 0.000
S0 vs S2
-0.002,1.000
-1.72*, 0.000
S0 vs S3
-0.06*, 0.002
-2.18*, 0.000
S0 vs S4
0.08*, 0.000
-1.48*, 0.000
S1 vs S2
-0.01, 0.916
-0.74*, 0.000
S1 vs S3
-0.06*, 0.000
-1.20*, 0.000
S1 vs S4
0.08*, 0.000
-0.50*, 0.000
S2 vs S3
-0.05*, 0.000
-0.46*, 0.000
S2 vs S4
0.08*, 0.000
0.24*, 0.000
S3 vs S4
0.14*, 0.000
0.70*, 0.000
Note: *Mean differences are significant at P<0.05
2.6 Growth and nutrient utilization
Growth performance was monitored biweekly with
the following parameters measured:
Mean final weight= Mean total weight after 84 days
Mean weight gain= Mean final weight –mean initial
weight
Daily weight gain= mean weight gain/ experimental
period (84 days)
Daily Feed Intake, DFI (%) = Feed intake (dry matter)
x 100/[initial fish weight + final fish weight) x days
fed/2]
Feed Conversion Ratio (FCR): Feed Intake (g)/Fish
weight gain (g)
Specific Growth Rate, SGR (%): In (W2-W1)/ (t2-t1),
where W2 and W1 are weights on day t2 and t1,
respectively.
Where, W2= final weight, W1= initial weight, t2=
time at the end of experiment, t1= time at end of
experiment
Protein efficiency ratio (PER)= Weight gain/ protein
fed
Survival rate (%) = Initial number of fish –mortality/
initial number of fish X 100
2.7 Water quality
Water quality was regularly monitored throughout the
experiment. Parameters were analyzed in two
replicates per treatment at the beginning and end of
the experiment. Dissolved oxygen was measured
using digital dissolved oxygen meter (Model Lab tech
DO meter); pH and temperature (pen type) correct to
±0.1 and 0.01°C, respectively, were measured using a
hand held portable dual function pH meter (pen type);
ammonia and nitrate were measured using the
automated phenate method and UV spectrophotometer
screening method, respectively (Technical Instrument
Corporation, 1973; Searle, 1984; Greenberg et al.,
1992).
2.8 Economic analysis
Economic evaluation of producing catfish by phytase
supplementation in all diets used in the experiments
were carried out by determining profit index and
incidence of cost.
2.8.1 Profit index (PI)
Profit index was determined from the relationship
between value of fish produced and cost of feed
consumed by fish as described by Miller (1976).
Profit Incidence = Value of fish produced (N/kg)/ Cost
of feed used in production (N/kg)
2.8.2 Incidence of cost (IC)
Incidence of cost was also determined as described by
Vincke (1969) according to the formula:
Incidence of Cost = cost of feed used in production
(N/kg)/ total weight of fish produced (kg)
