78 Safina Musa, Christopher Mulanda Aura and Rodrick Kundu
feeding rate also has no significant effects on plasma TG and CHOL either at
the end of the experiment but there was a trend which showed that TG and
CHOL increase with increasing feeding rates.
From the results, low GLU level observed at high dietary protein level
could be caused by low starch content. This is consistent with the results in
other fish species such as Arctic charr (Salvelinus alpines) (Cameron et al.,
2002) and young Japanese flounder (Paralichthys olivaceus) (Lee et al., 2002)
where low plasma GLU levels were observed at high dietary protein levels.
However, the present results differ from the findings of Chen et al. (2009) who
reported significant increase of plasma glucose content at high dietary protein
level in juvenile red tilapia (O. niloticus).
Low dietary crude protein level enhanced high plasma TP and the contrary
happened to the high crude protein. This is contrary to the findings of Cheng et
al. (2006) in grouper (Epinephelus coioides) who found no significant
difference of plasma TP between high dietary protein and the low one. It could
again be due to the difference in species. But Jauncey (1982) also reported that
protein retention is known to be high at low level of protein inputs.
Crude lipid level has no significant effects on plasma TP at the end of the
experiment. This is different from the results of Aderolu and Akinremi (2009)
where fish fed with high dietary lipid diets gained significantly higher plasma
TP and vice versa. There was a clear cut difference between high and medium
feeding levels compared to low feeding level with regards to the influence of
feeding rate on plasma TP at the end of the experiment. This could be due to
the amount of feed they ate.
The highest correlation between WG % and blood parameters was
observed between it and CHOL (57%). There was a negative correlation which
means that the higher the WG %, the lower the CHOL in plasma. The same
trend was observed between FBW and blood parameters. A positive
correlation occurred between SGR and CHOL which implies that as SGR
value increases, CHOL level also increases. The correlation between FI and
TP showed that as FI increases, plasma total protein also increases.
Low crude protein enhanced significantly higher HSI and IPF than high
crude protein. This implies that HSI and IPF tend to be inversely related to the
dietary protein level and directly related to dietary carbohydrate (cassava)
content in the diet in this study. This kind of relationship was revealed in many
studies (Papaparakeva-Papoutsoglou and Alexis, 1986; Daniels and Robinson,
1986; Hidalgo and Alliot, 1988; Brown et al., 1992; Yang et al. 2002; Peres
and Oliva-Teles, 1999) where the increase of HSI was due to high digestible
carbohydrate. From the results, it was observed that high lipid level enhanced