Abstract:
The experiments on Qreochromis nilotions {L *)
(young) of initial mean weight of 2.9+0.3g were fed 15
isocalorific diets of three isonitrogenous levels of 20%,
257. and 307. (by dry weight). At each protein level a series
of diets with increasing level of substitution from 137. to
507. of the legume green gram (Phaseolus aureus) were also
tested. Experiments were conducted for 10 weeks. 0.
ni loticus of initial mean weight of I=03+0.1g were onlymaintained
on 10 isocalorific diets of 25% and 30% dietary
protein levels
Daily food consumption was variable and was higher
during the first two weeks of the experiment. The mean
weekly consumption expressed as per unit weight of fish or
per unit fish, with relation to the body weight did not
vary significantly between P = aureus substituted diets at a
particular protein level, except in one instance. The
overall consumption was influenced by the dietary protein
content at higher levels.
" The dry matter, protein and lipid digestibility of
the plant ingredient P. aureus was found to be suitable for
incorporation into formulated diets for 0= niloticus. The
degree of incorporation of P. aureus into the diets did not
appear to influence the digestibility, significantly. The
total and protein digestibility decreased with increasing dietary protein content.
The best average daily gain (7.ADG) of 0, ni loticus
for the green gram substituted diets were at 25% level of
substitution at all three dietary protein levels. Food
conversion ratio ranged from 1.68 to 3.213 1.55 to 2.24 and
1.53 to 2.01 for diets of 207., 257. and 307. protein
contents. FCR of the plant substituted diets gave
comparable results to the reference or fishmeal diets
except in a few instances. Protein efficiency ratio ranged
from 1.51 to 2.99, 1.84 to 2.52 and 1=65 to 2.06 and net
protein utilization ranged from 22.507= to 46.12%, 30.72% to
40.917. and 28.60% to 32.05% for diets of 20%, 25% and 30%
protein content respectively. PER and NPU for 0. niloticus
young decreased with increasing dietary protein level and
did not show a uniform variation with the level of P=
aureus substitution.
There was an increase in carcass moisture and
protein and decrease in lipid with increasing dietaryprotein
level whilst changes in carcass ash and energyappeared
unclear. The carcass composition did not change
significantly with the level of P. aureus substitution.
Overall;, it is found that green gram, which is a
less expensive ingredient than fishmeal, can be
incorporated into practical diets for 0. niloticus upto 37%
with out adverse effects
