Effects of Protein, Lipid, Feeding Levels and Their Interaction ... 75Table 5. The effects of crude protein, crude lipid, feeding rate and their
interaction on biological parameters at the end of 4 monthsParameter HSI VSI IPF ILR
CP (P) (%)
L 253.08 ± 0.09 a 10.82 ± 0.24 2.53 ± 0.18 a 5.27 ± 0.13H 35 2.19 ± 0.09 b 10.26 ± 0.39 2.00 ± 0.18 b 5.31 ± 0.11
CL (L) (%)
L 8 2.42 ± 0.13a 9.98 ± 0.39 b 1.92 ± 0.15 b 5.43 ± 0.08
H 12 3.74 ± 0.14b 10.96 ± 0.27 a 2.51 ± 0.19 a 5.18 ± 0.13
FR (F) (%)
L 50 2.34 ± 0.22^ b 9.66 ± 0.49 b 1.61 ± 0.14 b 5.35 ± 0.19
M 70 2.50 ± 0.16^ ab 10.13 ± 0.31 b 2.07 ± 0.17 b 5.28 ± 0.14
H 100 2.89 ± 0.13 a 11.55 ± 0.28 a 2.89 ± 0.19 a 5.27 ± 0.12
Interaction
P x L ns ns ns ns
P x F ns ns ns ns
L x F ns ns ns ns
P x L x F ns ns ns ns
Values are means ± SE; values within the same column without a common superscript
are significantly different (p < 0.05); ns = not significant.
HIS = hepatosomatic index; VSI = viscerosomatic index; IPF = intraperitoneal fat; ILR
= intestinal length ratio.
DISCUSSIONS
With regards to the dietary crude protein level, fish fed with high dietary
protein gained significantly higher WG % and SGR while those fed with low
dietary protein got low WG % and SGR. This could be because protein intake
was high at high dietary protein level and the main component in diet which
influences growth is protein. However, the present results are different from
the results of El-Saidy and Gaber (2005) who found no significant increase on
growth performance at high dietary protein level (30%) compared to the low
one (25%). It could be due to the size of the fish they used as it is known that
the protein requirement of fish reduces as they grow (Wilson, 1989).
Basically, from the results, it was observed that higher values of WG %
and SGR were observed in high feeding rate. Similar results were obtained in
common carp (El-Saidy and Gaber, 2005; Adelghany and Ahmad, 2002; El-
Sayed, 2002).