الفهرس 
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Abstract
5. SUMMARY
The present study was carried out at the wet lab of Central Laboratory for Aquaculture Research (CLAR), Abbassa, Abou-Hammad, Sharkia, Egypt, during the year 2010 in order to determine the response of all male Nile tilapia fry to biogen, megalo, yeast, garlic oil and fennel oil as dietary probiotics and feed additives.
In the present study 8 diets were prepared, the 1st one as control and the others was supplemented by 0.2% Biogen (D2), 0.3% yeast (D3), local probiotic 0.2% Megalo (D4), 0.1% Garilc oil (D5), 0.1% Fennel oil (D6), 0.1% Garlic oil+0.2% megalo (D7) and 0.1% fennel oil+0.2% megalo (D8). The feeding trial lasted after 12 weeks and the most important results obtained could be summarized as follows:
- Average values of water temperature ranged from 27.20 to 29.25°C, the averages values of DO ranged between 3.32 and 3.81 mg/l and pH values were ranged between 8.04-8.30 with significant differences between the different treatments in DO values only.
- The initial body weight for fish received the different treatments ranged between 1.78 and 1.93 g and the differences between these means were insignificant. At the experiment termination, T1(control diet) released the lower BW (12.15 g) while the other treatments released the highest body weights (20.80, 21.45, 21.40, 20.50, 20.72, 21.95 and 19.56 g for the different experimental diets T2, T3, T4, T5, T6, T7 and T8, respectively, and the differences between BW for the control group and each of the other treatments (the different feed additives) were significant (P<0.05) while the differences between these treatments (T2, T3, T4, T5, T6, T7 and T8) were not significant indicating that the different feed additives and probiotics used in the present experiment released relatively the same BW which significantly higher than showed for the control diet (without feed additive or probiotics).
- After 2 weeks of the experimental start, the averages of weight gain ranged between 0.63 and 1.11g and the differences were significant. During whole experimental period (0-12 weeks) the average body weight gain ranged between 10.37 and 20.02 g and the differences between these means were significant.
- Average values of SGR ranged between 1.96 to 2.93 and from 2.12 to 5.68 for the first two experimental periods (0 - 2 and 2 - 4 weeks from the experimental start), respectively and the differences in SGR values between the different experimental treatments during the first two periods were significant. During the entire experimental period (0-12 weeks) SGR of Nile tilapia fish groups fed the diets supplemented with the different feed additives showed the significant values SGR compared to fish fed the basal diet (T1).
- Feed intake during the period of 0-2 weeks from the experimental start ranged between 1.07-1.16 g/fish/day for fish groups fed the different experimental diets with insignificant differences between feed intake values for the different experimental diets. During the period of 2-4 weeks after the experimental start feed intake values ranged from 1.42 to 1.76 g and the differences between these means were significant and the same trend was observed during the subsequent experimental periods (4-6, 6-8, 8-10 and 10-12 weeks). During whole experimental period (0-12 weeks) results indicated that fish fed relatively the same amount of feed when the different feed additives and probiotics were added to the basal diet and the differences in feed intake between the different feed additives (T2, T3, T4, T5, T6, T7 and T8) were not significant while the differences between each of these treatments and control group was significant.
- Feed conversion ratio values had no clear trend for the experimental periods, 0-2, 2-4, 4-6, 6-8, 8-10, 10-12 weeks of the experimental start. During the whole experimental period (0 – 12 weeks) the FCR for the control group showed the highest (worst) values compared to the other experimental diets supplemented with the different feed additives and probiotics and some of their combinations. FCR for the whole experimental period (0-12 weeks) significantly improved compared to the control group.
- PER during the whole experimental periods are significantly improved compared to that recorded for that of control diets.
- Supplementation of the basal diet with feed additives or probiotics and spices did not significantly (P>0.05) affected hematocrite (Ht) while hemoglobin (Hb) level showed some variation and have not clear trend.
- Liver transferase enzymes (AST and ALT) values ranged between 10.95-12.00 and 8.00-10.90 u/l for AST and ALT, respectively. Analysis of variance indicated that there were insignificant differences in liver enzymes AST and ALT between control and any of the other feed additives.
- Chemical analysis of whole fish at the end of the study showed that, dry matter content of whole fish are relatively the same and ranged between 26.52-27.22% for the different diets and the same trend was also observed for protein (63.33- 63.73%), fat (25.05-26.23%), and ash (10.55-11.23%). Analysis of variance indicated that, the differences in dry matter, protein, fat and ash between the different feed additives and probiotics used in the present study were not significant.