الفهرس 
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Abstract
The present study was carried out at the experimental fish farm, faculty of
agriculture (Saba-Basha), Alexandria university, alexandria, Egypt from July to
November. The main objective of this work was conducted to study the effects of two
commercial diets and two sex ratio on the productive performance of Nile Tilapia,
Oreochromis niloticus broodstock and their offspring produced. The first experiment
aimed to study the effect of two dietary protein levels and two sex ratio on the
productive performance and fry production of Nile Tilapia, O. niloticus broodstock.
The results of the first experiment were summarized in the following points: 1-
Insignificant differences in IBW and FBW were detected between O. niloticus
broodstock fed on two commercial diets (20% and 25% protein). While these
differences were highly significant (P≤0.01) and (P≤0.001) in WG and DG,
respectively, and were only significant (P≤0.05) in SGR% and %BWI. 2-
Insignificant differences were detected between two sex ratio examined of all growth
performance parameters measured. Moreover, the interaction between two dietary
protein levels and two sex ratio showed that there were insignificant differences. 3-
The crude protein, lipid and moisture contents of Nile Tilapia, O. niloticus broodstock
bodies were not affected significantly (P≤0.05) by two dietary protein levels or two
sex ratio or their interaction. 4- Insignificant differences in dry feed intake were
detected between Nile Tilapia, O. niloticus broodstock fed on two dietary protein
levels. Also, the results showed that there were significant differences (P≤0.05) in
FCR, PER and PR%, but these differences were highly significant (P≤0.01) in ER%.
The higher or best were recorded by 25% protein diet. 5- The results of two sex ratio
examined showed that insignificant differences were detected in all feed utilization
parameters studied. While, PR% of interaction between dietary protein levels and sex
ratio showed significantly differences (P≤0.05). 6- Insignificant differences between
two dietary protein levels and the interaction were detected in all fry production
parameters measured. While, the results of two sex ratio examined showed that there
were significant differences (P≤0.05) in the third batch only, since the 1:1 sex ratio
showed higher mean of fry per female compared with the 1:3 sex ratio. While the
objective of the second experiment was evaluation the offspring produced as affected
by two dietary protein levels and two sex ratio of Nile Tilapia, O. niloticus
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broodstock. The results of second experiment were summarized in the following
points: 1-Insignificant differences in IBW, FBW, WG, DG, SGR%/day and %BWI
were detected by dietary protein levels or sex ratio or their interaction. 2- Insignificant
differences in initial and final analysis of fry bodies of crude protein, lipid and
moisture contents were detected by dietary protein levels or sex ratio or their
interaction. 3- Insignificant differences in dry feed intake, FCR, PER, PR% and ER%
were detected between two dietary protein levels and two sex ratio examined and their
interaction. 4- The results of this experiment recommended that no effect of the
broodstock nutritional history and sex ratio on growth performance, body composition
and feed utilization of the Nile Tilapia, O. niloticus progeny produced up to fry stage