During phase 2, the best results were obtained by supplementing the
control feed throughout the production cycle with 3 kg/MT of the feed
additive (treatment AG3); resulting in a significantly better final weight
and reduced amount of feed consumption at the end of the cycle (Table 2).
Relatively compared to the control group, treatment AG3 showed improved
survival (+2.8%), daily weight gain (+5%), feed conversion (-6.4%), fileting
yield (+1.5%), visceral fat deposition (-9.9%), hepatosomatic index (-22%),
and viscerosomatic index (-10.7%). Reducing the additive inclusion from 3
to 1.5 kg/MT during phase 2, still resulted in interesting benefits on growth,
feed conversion and visceral fat but did not affect fileting yield.
Table 2: Fish performance and processing parameters (fileting yield, visceral fat,
hepatosomatic index HSI, viscerosomatic index VSI) of Nile tilapia (from approx.
170 g to commercial size) fed different diets during phase 2
Control
Control +
aquagest OMF
3 kg
Control +
aquagest OMF
3-1.5 kg
lc Feed +
aquagest OMF
2 kg
Fish performance
Survival (%)
92.1
ab 94.7
a
93.0 a
85.6
b
Initial weight (g)
166.9
177.4
166.7
160.8 n.s.
Final weight (g)
714.2 b
751.1
a
730.1
ab
739.2
ab
Growth (g/day)
4.93
5.17
5.08
5.21
n.s.
Feed Intake (kg/cage)
676.6 b
644.5 a 655.25 ab
662
ab
FI as (%ABW/d)
3.09 ab 2.91
a
2.93 a
3.18
b
FCR
1.72
ab
1.61
a
1.63 a
1.77
b
Processing parameters
Fileting yield (%)
33.4 a
33.9 a
33.3 a
31.5
b
Visceral Fat (%)
4.76
4.29
4.17
5.00 n.s.
HSI (%)
1.07
0.83
0.96
0.84
n.s.
VSI (%)
8.84
7.89
8.18
8.67
n.s.
Different letters indicate significant differences (p<0.05, Sampaio-Gonçalves et al., 2012)
Figure 4: Daily weight
gain and feed conver-
sion of juvenile Nile
tilapia during phase
1 (from 28 to approx.
170 g) fed the control
diet with or without
the supplementa-
tion of a digestibility
enhancing additive.
* indicate significant
differences (p<0.05)
and deviations from
control are shown as
percentages in red
(Sampaio-Gonçalves et
al., 2012)
digestibility enhancing additive. * indicate significant differences (P<0.05) and
deviations from control are shown as percentages in red (Sampaio Gonçalves et al.,
2012
).
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