Regarding the nutrient retention rates obtained from the composition
of whole fish and the particular nutrient intake, it was found a nitrogen
incorporation rate significantly higher in diets with maximum content in
rapeseed hydrolysate. Nitrogen excretion rates showed a significantly lower
value compared to the control diet 2 (Table 8), however, the retention/
excretion of total P and total ash did not differ between treatments.
Table 8. Excretion rates of N and P
Diets
Diet 1
Diet 2
Diet 3
Diet 4
N Excretion (%N)
79.69±0.10
b
77.12±0.33
a
79.93±1.38
b
79.00±2.24
ab
P Excretion (%P)
71.30±11.38
76.92±9.23
74.13±2.86
63.97±15.59
Values ​​with different letter in same row differ significantly (p<0.05)
At the end of the experiment, the composition of the fillets did not differ
between diets, while in the case of fatty acids, it was observed a slight
increase in some of them (w-3, DHA, EPA, for example) by the inclusion
of rapeseed hydrolysate in the diets, the only statistical differences were
found in the total w6 fatty acids (lower for all diets with rape compared
to the control one) and 18:2 w-6 (lower for the diet with higher level of
rapeseed comparing to the control one) (Table 9).
Table 9. Fatty acid composition in the fillets at the end of the experiment (% of
total fatty acids)
Diets
1
2
3
4
Fatty Acids
Total Saturates
23.96±1.22
24.41±0.78
24.43±0.42
24.61±0.30
Total Monoenoics
34.76±1.31
34.57±2.21
34.0±3.65
33.59±2.59
Total w-3
19.94±2.10
21.85±1.96
22.39±3.73
22.29±3.16
Total w-6
19.96±0.19
b
17.83±0.35
a
17.83±0.62
a
18.10±0.77
a
Total w-9
25.56±0.81
25.22±1.46
24.58±2.45
24.22±1.58
Total w-3HUFA
17.0±2.18
19.15±2.24
19.53±4.21
19.42±3.33
18:2 w-6
16.94±0.39
b
14.79±0.51
a
14.82±0.99
ab
15.03±0.99
ab
EPA
3.97±0.12
4.33±0.14
4.44±0.26
4.54±0.50
DHA
9.73±1.91
11.37±2.07
11.52±3.90
11.36±2.71
Values ​​with different letter in same row differ significantly (p<0.05)
According to the oxidative state of the fillets as a measure of its quality,
all diets with rapeseed provoked lower values comparing to the control
one when the slaughter happened. The day 4, however, these differences
disappear.
Plant protein isolates and hydrolysates as alternative to the animal protein in aquaculture diets
57
1...,49,50,51,52,53,54,55,56,57,58 60,61,62,63,64,65,66,67,68,69,...84