الفهرس 
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Abstract
SUMMARY AND CONCLUSION
The research was performed at the Department of Animal Production’s fish laboratory, National Research Center, Dokki, Egypt.
The study included two experiments:
The first experiment, were conducted to assess the impact of commercial powder probiotic (ZADO®) on growth efficiency of Nile tilapia mono-sex fish (O. niloticus), which were fed on basal experimental diet (the control group) and other 4 experimental diets, which was the basic diet augmented plus 0.25, 0.5, 0.75 and 1% of ZADO® for T1, T2, T3, T4 and T5, respectively. The Five experimental treatments were performed in three replicates each, the experimental aquaria were part of closed recirculating system, where environmental parameters were kept constant throughout the experimental period. Fifteen aquaria 60 × 40 × 30 cm, width, depth, height, respectively each was stocked with 15 fish. The mean individual initial body weight (4.04 g/fish) was registered at the start of the experiment. All fish for each aquarium throughout the entire experimental period were weighed every two weeks. The experimental fish were fed 32 % crude protein-based diet for (98 days). The daily feed allowances were calculated as 5% of fish body weight and were divided into 3 portions fed at 8 am, 12 pm and 4 pm.
The second experiment was performed to assess the impact of commercial liquid probiotics (ZAD®) on water quality of the fish aquarium. Five experimental groups (in 3 replicates) were supplemented with 0, 1.5 ,3 ,4.5 and 6 ml of ZAD® for the T0, T1, T2, T3, T4 and T5,respectively. Fifteen aquaria (60 × 40 × 30 cm, width, depth, height) were used each aquarium was stocked with 15 fish. Daily feed allowances were calculated according to 5% of the fish body weight. The experimental fish were fed 32 % crude protein-based diet for 45 days. The daily feed allowances were calculated as 5% of fish body weight and were divided into 3 portions fed at 8 am ,12 pm and 4 pm.
The results are summarized in the following:
Experiment I
1- The experiment indicated that T2 had the largest significant (P<0.05) final body weight (FBW g/fish) (31.94), average weight gain (AWG, g/fish) (28.03) specific growth rate (SGR % day) (2.14), Feed conversion ratio (FCR) (2.18), feed efficiency ratio (FER) (0.46) and protein efficiency ratio (PER) (1.59) among all the experimental groups.
2- No substantial variations (p > 0.05) were found in protein productive value (PPV) significant effects (p < 0.05) have been reported in fish body crud protein (CP) (57.66) and fat (EE) (23.33 ) in T2. By increasing ZADO® levels in experimental diets higher than 0.25% no significant effect were observed.
3- There were no significant effects of ZADO® levels on body dry matter
Experiment II:
1- Ammonia concentration in water was reduced significantly (P<0.05) by increasing ZAD® level in water This is due to the conversion of ammonia into a microbial protein that the fish benefit from and does not harm the environment of the aquarium.
2- Showed significant differences (p<0.05) in water pH, where T1 had higher value than the control and the other treatments.
3- showed that nitrate content was not effected significantly by increasing ZAD® level
In conclusion, the result of the present stady showed that ,adding probiotics as example ;ZADO and ZAD are essential to increase growth rate and feed utilization prameters of tilapia fish and to avoid the negative effect of fish wastes ,especially in the closed systems.