The present study was conducted to investigate the effect of replacement of soybean meal with alfalfa meat at 0.25.50 and 75% levels on growth performance, feed utilization and the whole body chemical composition. The
experiment was conducted in fiberglass tanks belouging to the Faculty of Agriculture, Al-Azhar University, Cairo, Egypt. Four dietary treatments were performed, each in three replicates, where male Nile tilapia with an initial
weight of 27.50g were stocked in fiber glass tanks 50 fish / tank (1m3 total volume) and fed on diets contianing 0.25.50 and 75% alfalfameat in replacement with soybean meal. The experiment lasted 16 weeks after start. Fish were fed on
the experiment diets at a rate of 3 % of the tank biomass. Results obtained are summarized as follows:
1-Final weight decreased significantly at substitution levels 50 and 75% of
Alfalfa while the substitution level of 25% released no significant effects on
final weight compared to the control group.
2-The same trend was observed with weight gain daily gain, specific growth rate
and condition factor.
3-Final body length, protein efficiency ratio, energy efficiency ratio, protein
productive value, total feed intake; protein intake and energy intake were
significantly (P<005) decreased as the increase substitution levels of alfafa
meal in the diets.
4-Feed conversion ratio was best for control group, followed the group fed
25.0% (T2) alfalfa meal; while groups fed T3 (50%) and T4 (75%) showed the
worst feed conversion ratio.
5-Insignificant differences were observed for mortality rate of fishes fed
different levels of alfalfa meal or control group.
6-The group fed 25.0 % of alfalfa meal consumed more feed as compared with
control or other dietary treatments.
7-Insignificant differences were observed for water temperature, pH value for
groups of fishes fed different levels of alfalfa meal, while dissolved oxygen
was significantly (P<0.05) decreased by the increase of substitution levels in
the diets. 8-Ammonium, nitrite and nitrate concentrations mg/L significantly (P<0.05)
increased by the increase of alfalfa meal in diets.
9-Crude protein was increased in flesh of fish by the increase of alfalfa meal in
the diet; while the opposite trend was observed for ether extract; ash % and
gross energy (Kcal/kg) where they decrease as the substitution levels of alfalfa
meal increased in the diets.
10-The profit index was higher for group of fish fed (75.0%) substitution level
in compared with other treatments including control group.