Feed preparation
Six experimental diets were used in this feeding
trial. A basal or control diet was formulated without
FS and SP substitutes. Three diets were formulated
with dry fairy shrimp meal (FS)
concentrations at 10% (FS10), 20% (FS20) and
30% (FS30), two diets were formulated with dry
Spirulina meal (SP) at 6% (SP6) and 12% (SP12)
inclusion levels into the basal diet. Feed ingredients
and chemical composition of the experimental
diets are given in Table 1. The dried ingredients of
each diet were mixed in a Hobart mixer (Tong Hor
Machine Lex Product model L.N.K. 532, Taipei,
Taiwan) for 10 min. The whole food was mixed
thoroughly for another 5 min to ensure homogeneity.
Water was added to this mixture to form a
dough, which was then pressed through a 2-mmdiameter
die press. The pellet feeds were dried in
a hot air oven at 60°C for 12 h. The feed was
then crushed, sieved to obtain a particle size of
0.9–1.2 mm and kept in an aluminium foil bag,
which was stored at 20°C to avoid oxidation of
the carotenoids.