Page 58 - New additives and ingredients in the formulation of aquafeeds
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Results and discussion:
From the first sampling after 40 days of feeding, higher growth was obtained
in fish fed with diet 2, with maximum levels of rapeseed hydrolysate, main-
tained in all sampling periods, from the diets with medium and minimum
levels of rapeseed, we obtained the same weight as the control fish (Table 5).
Specific Growth Rate (SGR) obtained were similar in all diets and sampling
periods, on the other hand, a higher condition factor (K) was obtained in
diet 2 comparing to the control one during the entire experience (bigger
proportion of weight for the same length, which indicates higher profits in
fillet) (Table 6).
Table 6. Condition factor (K) evolution
K
Diet 1
Diet 2
Diet 3
Diet 4
Tanks
2-7-12
3-8-13
4-9-14
5-10-15
0- 40 days
2.21±0.19
a
2.28±0.20
b
2.22±0.16
ab
2.21±0.15
ab
40- 66 days
2.29±0.19
a
2.32±0.17
b
2.32±0.09
ab
2.31±0.16
ab
66- 115 days
2.34±0.18
a
2.44±0.18
b
2.44±0.20
b
2.46±0.23
ab
115- 150 days
2.32±0.16
a
2.40±0.22
b
2.37±0.15
ab
2.37±0.18
ab
Values with different letter in same row differ significantly (p<0.05)
Feed intake was the same in the different experimental diets, with normal
behaviour. There was no negative effect of palatability of the diets by the
inclusion of increasing levels of rapeseed hydrolysate and feed conversion
values were similar between diets for all sampling periods.
Table 7 shows the summary of the entire experimental period.
Table 7. Parameters after 150 days of feeding different experimental diets
Tank
Diet
Fish
Weight
Length
K
Sgr
Gain
Weight
Gain
Weight (g)
Intake (g)
Ic
(% Initial
Weight)
2-7-12
1
60 326.07±45.47
a
24.10±1.11
2.32±0.16a 0.43±0.12 93.28±5.78 3147.4±201.07 7649.03±192.27 2.44±0.14
3-8-13
2
60 349.42±52.01
b
24.38±1.19
2.40±0.22b 0.49±0.13 109.35±8.43 3652.2±311.30 8537.90±604.67 2.34±0.06
4-9-14
3
40 333.95±44.49
ab
24.12±0.94 2.37±0.15ab 0.45±0.12 97.63±5.49 3302.4±187.53 8116.50±337.43 2.46±0.04
5-10-15
4
60 341.05±50.54
ab
24.27±0.93 2.37±0.18ab 0.46±0.13 102.16±10.75 3447.4±379.55 8150.87±428.20 2.37±0.13
Values with different letter in same row differ significantly (p<0.05)
Concerning the biometric parameters and the final composition of the fish,
there were no differences between treatments, except for the percentage
of the total ash, where the higher values were found in fish fed by rapeseed
hydrolysate comparing to fish fed by control diet with soybean meal. The
figures of Ca, P and the ratio Ca/P were similar in the ended fishes in the
4 diets.
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Plant protein isolates and hydrolysates as alternative to the animal protein in aquaculture diets
