الفهرس 
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Abstract
This study was conducted at the Fish Research Center - Suez Canal University - Ismailia in order to reduce the cost of feeding through compensatory growth of cultivated fish and applying this technique to intensive fish production systems. The study was conducted in two experiments:
The first experiment experience (2x 4) in which mono-sex Nile tilapia (Oreochromis niloticus ) was stored in two different densities (42, 84 fish / m3). Under each intensity, fish were cultured with different diet regimes in terms of number of days (1/6, 2/7, 3/11, 4/14) saturation and feeding. The first group was the control, which fed daily except for one day. The second group was two days fasting followed by re-feeding for seven days. The third group was Three days fasting and re-feeding eleven days and the fourth group was four days fasting and fourteen days re-feeding. The experiment was conducted from 25 July 2015 to 16 October 2015 in 24 fiberglass tanks (240 liter). Water was changed at a rate of one third of the total volume daily. The mean fish weight was at the beginning of the experiment (21.62 ± 0.08 g / fish). The fish were also fed on a commercial diet (Screiting Egypt - Hendrix), Protein content was 30% crude protein. The fish were fed twice daily for satiety for 84 day.
The most important results obtained at the end of the experiment were the following:
- There was no change in the water properties of dissolved oxygen, acid concentration, temperature and total ammonia.
- The best growth rate was obtained by the third group for the control, which was starved for three days and re-feeding for eleven days.
- The best conversion coefficient of feed was the third group in both intensities.
- Fish group fed for eleven days and starved three days in the density of 42 fish / m3 gave less food consumption and less food cost.
- The results of chemical analysis of fish body showed that there was no significant difference in the analysis of fish body in terms of dry matter, protein, ash and fat between treatments.
- The results showed that the histological sections of the muscles of during the period of the hypothetical contractions and shrinkage and begin the distances between the fibers of the muscles and some of them increase but the opposite occurred after the recharge directly, as the size of the muscles significantly and faster than normal.
Second Experiment in which the mono-sex Nile tilapia was stored in two different temperatures (26°C and 32°C). Under each temperature fish were cultured in different feeding regime the same as in the 1st experiment. The experiment was conducted in the period from 1 December 2015 to 22 February 2016 in 24 fiberglass tanks with (240 liters). Water was changed at a rate of one third of the total volume daily. The average fish weight at the beginning of the experiment was 25 ± 0.05 g / fish at 15 fish /tank (63 fish / m3). The fish were also fed on a commercial diet (Screiting Egypt - Hendrix), Protein content was 30% crude protein). The fish were fed twice daily for satiety for 84 day.
The most important results obtained at the end of the experiment were the following:
- The best growth rate was obtained by the third group, which was starved three days and the re-feeding eleven days under water temperature of 26oC.
- There was no change in the concentration of dissolved oxygen and total ammonia but the temperature was controlled by thermostatic heaters to change the temperature of two different degrees (26, 32 ° C) and follow-up daily.
- The results showed the best conversion ratio was obtained by the third group, which was adopted at a temperature of 26oC, which was starved three days and re-fed for a period of eleven days.
- The chemical analysis of the fish body showed no significant differences between the four parameters in terms of protein, fat and dry matter at the end of the experiment.
Conclusion:
The current study indicates that Nile tilapia feeding costs can be reduced dramatically through starvation without affecting growth performance, nutrients utilization, and survival rate. Therefore, feed restriction can be used as a management tool to reduce feeding costs, improve growth rates, and maximize nutrients utilization when properly planned.