ABSTRACT
The present study was designed to study the effect of the partial
or complete substitution of fish meal by rice protein concentrate (RPC) in
the diets of Nile tilapia (O. niloticus) and their effect on the growth
performance parameters, body composition and intestinal histology. A
total of 320 O. niloticus with an average body weight of 40.50±0.250 g
were used. The fish were randomly divided into four equal replicate
groups (each replicate contains 20 fish). A basal control diet was
formulated with zero replacement of fish meal (G1) and the other
experimental groups (G2, G3 and G4) received a basal diet contained fish
meal substituted with 25%, 50%, and 100% of RPC, respectively. The
fish were fed isonitrogenous and isocaloric diets; three times daily at a
rate of 3% of the body weight for 90 days. Body weight was not affected
by substituting fish meal by 100% of RPC compared to control, while at
this level of replacement, feed intakes, and feed conversion ratios were
higher than in the control group. Protein efficiency ratio and the protein
retention efficiency were reduced by replacing fish meal with RPC at the
level of 25%, 50%, and 100% than control group. The results showed
that substitution of 50% and 100% of fish meal with RPC had recorded
significant lower protein, calcium and phosphorus and higher fat content
than control group. All experimental groups fed RPC -based diet had a
significant lowered cysteine, methionine, lysine, threonine and serine
than the control group. On the other hand, the experimental groups fed
RPC -based diet showed a significant higher intestinal villus height, crypt
depth and muscle thickness.