Discussion
Effect of dietary carotenoid on growth performance
Growth performance, in terms of growth percentage
or specific growth rate, is an important
parameter for the estimation of fish production.
This study found that feeding fish with
200 g kg1 FS resulted in high body weight and
growth. On the other hand, the body weight and
specific growth rate of fish fed with SP decreased
when the amount of SP increased in the formula.
These results showed that fish were digesting
protein from FS better than from SP. Similar to
our previous studies, we showed that a decreased
growth rate was observed, as in common carp
exposed to Microcystis by feeding with boom scum
(Li & Chung 2004) and in planktivorous fish by
natural ingestion of M. aeruginosa (Rai 2000). In
contrast, Zhao, Xie, Zhu, Yang, Gan and Song
(2006) reported that Nile tilapia that constantly
consumed the dietary cyanobacterium Microcystis
increased their growth and it had no impact on
feed conversion efficiencies. Moreover, Dong, Zhu,
Han, Yang, Song and Xie (2009) reported that
hybrid tilapia O. niloticus 9 O. aureus fed cyanobacteria
from Lake Taihu showed a high specific
growth rate. All fish performed well with acceptable
weight increments and specific growth rates
in all treatment groups in our experiments. Results
of weight gain and specific growth rate after a
90-day growth trial indicated that the experimental
diets sustained a good growth performance, similar
to the results of Rodehutscord, Becker, Pack and
Pfeffer (1997). The average growth percentage of
fish was enhanced with DFSM supplementation