Abstract:
Two legume seeds Vigna catianq and F’haseolus munqo
were tested for the possibility of using as a partial
replacement of fishmeal in practical diets for young
Oreochromis niloticus (L.) diets. 20 diets were evaluated
*
in this study each for 70 days using a closed recirculating
system.
Control diets were prepared using fishmeal as the
main protein supplement of 20% (C4), 2 5'/. (C3) and 28% (C2
and Cl) protein levels.The highest protein level was
further evaluated at 14% and 22% lipid levels. Control diets
were served as reference to evaluate the test diets, which
had fishmeal substitution levels of 25% (VI, V3, F'l and F’2 )
and 50% (V2 and V4) in 28% protein diets, 33% (V5, and F'3)
66% (V6 and F'4) in 25% protein diets and 20% (V7 and F'5,
60% (V8 and F’6 ) and 100% (V9 and F’7) in 20% protein
diets.All the diets were tested with 2-3 g size fish while
28% protein diets were also evaluated for fish of 4-5 g
size.
All fish were fed ad_ 1 ibiturn twice a day except
22% lipid diets which were also tested for a feeding
frequency of thrice a day.
Daily variability of food consumption showed a
rythmic pattern. Absolute consumption gradually increased
with fish growth. % ADG decreased as the plant inclusion
level increased. Poor performance were observed for SGR,
FCR and PER as the substitution level of fishmeal increased
except at 20% substitution of F .munqo.
IX
C2 gave the best %ADG, SGR and F'2 produced the
best FCR of 1.81. PER tends to increase as the protein
level in the diet goes down. Best NPU was recorded for P5
diet.
Digestibility was estimated using Cr203 and
crude fibre. Crude fibre estimation was higher than the
Cr203 estimations. As the dietary protein level
decreases the dry matter digestibility tends to increase.
However, protein digestibility increased with increasing
plant inclusion level in the diets.
Carcass composition indicated that the initial
moisture content was reduced, significantly, in all the
diets at the end of the trial while protein and lipid
contents increased. As the dietary protein level decreased
carcass lipid increased from 8.84% to 11.19%.
Economic evaluation revealed that diet V9 is the
best from an economical stand point but poor in the growth
performance. Fish maintained on F'6 and F'7 diets were the
costliest to produce 1 Kg of fish.
