The chemical compositions of the diets used in the present
study are shown in Table 2. The chemical composition was similar
for the three samples with exception of the fiber content in the test
diet. The higher fiber content in the test diet indicates an important
soluble fiber fraction in the composition of the microorganism.
According to Sgarbieri and Silva (1996) the soluble fiber fraction
in a diet causes an increase in the volume and weight of the
excretas.
The nutritional parameters of the bioassay are shown in Table 3.
Rats fed the test diet (Aphanothece) had the lowest body weight
gain (6.64 g/rat for 10 days of the experimental period), significantly
different (p < 0.05) from that of rats fed of the control diet
(17.06 g/rat). The body weight gain may be compensated by the
partial substitution of protein source. According to Chow and
Woo (1990) and Olvera-Novoa et al. (1999) the replacement of
20–40% of a commercial diet with Spirulina maxima did not affect
the body weight gain of tilapia (Oreochromis mossambicus). They
found that the growth and feed efficiency of fish fed with Spirulina
(levels between 20% and 40%) were similar to that of those fed the
control diet. However, fish performance was reduced when SCP totally
replaced in the commercial diets