International Journal of Marine Science 2016, Vol.6, No.35, 1-8
3
Results
Growth of shrimps
The growth of shrimp in terms of length was higher (1.38 cm) in the shrimp fed with unicellular cyanobacterium
Synechocystis salina
than that in the control shrimp (1.18 cm) for 15 days experiment (Fig. 1). The
physicochemical characters of all the experimental tank waters were well within the normal limit even after
addition of marine cyanobacterial diets. Survival of the shrimp was recorded at 90 % in both control and
cyanobacterial fed shrimps.
Fig. 1 showing the length of shrimp
Peneaus monodon
gain or loss due to cyanobacterial supplementary feed. The values are
significant between control and treatment (
p
<0.05).
Effect of cyanobacterial diets on nutritional budget in shrimps
The parameters such as consumption (39%), fecal output (20%), assimilation (44%), metabolism (74%), and
assimilation efficiency (11%) decreased due to the cyanobacterial supplementary feed to the shrimps (Fig. 2a-2e).
The feed increased Gross Conversion Efficiency (46%) and Net Conversion Efficiency (63%) in the shrimps (Fig.
2f, 2g). However, the feed decreased Conversion Efficiency by 30% and Food Conversion Ratio by 43% in the
shrimps (Fig. 2h & 2i). The feed increased gross conversion efficiency (78.91%) and decreased food conversion
ratio (44.15%) in the shrimp.
Effect of cyanobacterial diets on biochemical composition of shrimps
Proximate composition of shrimp after the experimental period is shown in Figure 3a-3c. The cyanobacterial feed
significantly increased the percentage of carbohydrate (31%) and lipid (13%), but protein level showed not much
variation in the body tissue of the shrimp.
Discussion
Attempts have been made in utilizing different types of marine cyanobacteria for a variety of aquaculture
applications. In one such study, 91 strains of nitrogen-fixing marine cyanobacteria have been tested for their
nutritional value in Tilapia fish and found that majority of the strains are acceptable as single-ingredient feeds.
Twenty-two strains of these marine cyanobacteria belonging to the genera
Nostoc
,
Anabaena
and
Calothrix
have
supported the growth equivalent to those of fish feed. Very high growth rates of Tilapia fish using cyanobacteria
with seawater, in indoor as well as outdoor cultures have been observed (Mitsui et al., 1983). The cyanobacterial
feed enhanced the gross conversion efficiency and net conversion efficiency. However, it reduced the
consumption, assimilation and metabolism. Food conversion ratio in the range from 1.48 to 1.81 is considered to
be excellent (Mitsui et al., 1982). The food conversion ratio (FCR) was 0.25 in the cyanobacterial species
Phormidium tenue
treated as against 0.276 in commercial treated shrimp (Palaniselvam and Kathiresan, 1998).
Supplemented feed with
Spirulina platensis
power improved that feed conversion ratio and growth rates in common
carp (Ibraheam et al., 2013, Abdulrahman 2014). The growth and feed utilization of
Oreochromis niloticus
were
