الفهرس 
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Abstract
summary
Two experiment trials were conducted at Fish Nutrition Laboratory-Aquaculture Division, National Institute of Oceanography and Fisheries, NIOF to evaluate the partial (50%) or totally (100%) substitution of dietary fishmeal (FM) with two sources of soybean meal (conventional or genetically modified soybean) for Nile tilapia, Oreochromis niloticus fingerlings. Two dietary organic acids supplementation were used as feed additives at level of 0 or 10 g/kg diet (citric acid, CA, Experimental I) and (formic acid, FA, Experimental II). The two experiment trials were conducted using 360 Nile tilapia fingerlings (with initial weight of 19.06±0.03 g for CA and 22.15±2.70 g for FA). Nine isonitrogenous (25%, crude protein) and isocaloric (19.28 MJ/kg gross energy) experimental diets were formulated. Results obtained are summarized in the following:
•First experiment
The average initial body weight of O. niloticus fingerlings did not differ (P > 0.05), indicating that groups fish were homogenous. Fish fed diet containing 50% fishmeal (FM) replaced by conventional soybean meal protein (C-SBM50) and supplemented with CA had improved final body weight (FBW), final body length (FBL), weight gain (WG), condition factor (K) and specific growth rate (SGR) of Nile tilapia. The same trend was observed for feed utilization efficiency including PER, PPV, FR, ER and best FCR.
Fish fed diet C-SBM50, un-supplemented with CA recorded the highest apparent digestibility coefficients (ADCs) of dry matter. Fish fed diet C-SBM50, supplemented with CA was showed the highest ADCs of dietary lipid, protein and gross energy contents.
Fish fed the diet C-SBM100, un-supplemented with CA and control diet, recorded the highest liver weight and hepatosomatic index (HSI). Fish fed control diet recorded the highest spleen weight and index. The length of intestine increased with increasing dietary level of C-SBM and GM-SBM, regardless of CA addition. The highest length of intestine was recorded in fish fed C-SBM100, un-supplemented with CA, which differs significantly than the rest diets. Nevertheless, fish fed the diet C-SBM50 supplemented with CA recorded the lowest length of intestine value.
Fish fed the diet C-SBM50, supplemented with CA recorded the highest values of hematocrit (Hct) and hemoglobin (Hb). The highest counts of white blood cell (WBCs) were observed in fish fed GM-SBM100, supplemented with CA followed by GM-SBM100, un-supplemented with CA. In differential WBCs counts, fish fed the diet C-SBM100, either un-supplemented or supplemented, the diet GM-SBM100 , un-supplemented and GM-SBM100 supplemented with CA recorded the highest lymphocyte count. Fish fed diet GM-SBM100, un-supplemented and GM-SBM100 supplemented with CA had a higher count of neutrophil than those fed the other experimental diets. Fish fed GM-SBM100 un-supplemented diet was recorded the highest monocytes count.
The highest value of serum total protein and serum albumin were observed in fish fed the diet C-SBM50, supplemented with CA. While, the highest globulin value was recorded by fish fed C-SBM100, un-supplemented. A/g ratios was decrease less than control group in all dietary FM replacement levels, which differ significant than other diets. The C-SBM groups were lower in triglycerides, blood glucose, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) than GM-SBM groups.
No differences were observed in micronuclei averages among fish fed all experimental diets. Any shapes in nucleus other than the round shape was well thought-out as nuclear abnormalities (NA). In adding up, the abnormal forms appeared as curved, binucleated, budding, and elongated. The nuclear abnormalities ranged from 2 to 4 cells / 2000 erythrocytes.
Nile tilapia fed GM-SBM diets at two inclusion levels represented a higher level of DNA fragments compared to other C-SBM diets, regardless of CA supplementation. Diets supplemented with CA had no significant effect on DNA fragments with the same level of replacement and the same source.
Nile tilapia fed diet GM-SBM100, supplemented with CA had the highest significant (P ≤ 0.05) values of whole body lipid and ash (%). Fish fed the control diet, C-SBM50 supplemented and supplemented diet either GM-SBM50 or GM-SBM100 recorded the highest values of protein.
•Second experiment
The average of initial body weight of Nile tilapia, O. niloticus fingerlings at the start of the experiment did not differ, indicating that fish in all treatments were homogenous (P > 0.05). Fish fed the diet C-SBM50 and C-SBM100, supplemented with FA obtained the highest growth performance compared to the fish fed diet C-SBM50 and C-SBM100, un- supplemented with FA. The same trend was observed for feed utilization induces.
The highest ADCs of dry matter, lipid, and protein were recorded by fish fed the control diet. The highest ADCs values of gross energy were recorded by fish fed the diet C-SBM50, un-supplemented and GM-SBM50, supplemented with FA. The present results mention that the addition of FA has enhanced the ADCs of dry matter, lipid, and protein in all diets except for fish received diet GM-SBM100 supplemented with FA.
The highest HSI (%) was recorded by the control diet and diet GM-SBM50, supplemented and diet C-SBM100, un-supplemented. Fish fed the diet C-SBM50, un-supplemented with FA, recorded the highest spleen index. Length of intestine of Nile tilapia increased as effect of higher inclusion of C-SBM and GM-SBM with regardless of FA supplementation. The length of intestine decreased with FA supplementation in all experimental diets. The highest length of intestine was observed in fish fed diet GM-SBM100, un-supplemented with FA.
Hb and Hct of Nile tilapia were slightly higher with dietary FA supplementation compared to the fish fed un-supplemented diet. The highest count of WBCs was observed in fish fed the diet GM-SBM100, supplemented with FA and diet C-SBM100, un-supplemented FA. In differential WBCs, the highest lymphocyte count was recorded by fish fed diet C-SBM50, supplemented with CA. Fish fed the diet C-SBM100, un-supplemented with FA has a higher count of neutrophil compared to fish fed the other diets. The highest monocytes count was detected in fish fed the diet C-SBM100, supplemented with FA.
The highest value of serum total protein was observed in fish fed the diet C-SBM50, supplemented with FA. Fish fed control diet recorded the highest value of serum albumin. While, fish fed diet C-SBM50, supplemented with FA, diet C-SBM100, un-supplemented and diet GM-SBM100, supplemented with FA recorded the highest globulin values. A/g ratios was decrease less than control diet in all replacement levels and differ significant than other diets. Increase the level of replacement level of SBM increase the level of triglycerides. The C-SBM groups were lower in triglycerides than GM-SBM groups. With regardless of FA, fish fed diet GM-SBM with different replacement levels recorded the highest level of serum glucose than fish fed C-SBM. Higher AST and ALT activities were observed in GM-SBM with higher dietary replacement FM level regardless organic acid effect.
No differences were observed in micronuclei averages among fish fed all experimental diets. In addition, the abnormal forms appeared as curved, binucleated, budding and elongated. The nuclear abnormalities ranged from 2 to 4 cells / 2000 erythrocytes.
With regardless of FA supplementation, the two inclusion levels of GM-SBM represented the higher level of DNA fragments than other diets. FA supplementation had no significant effect on DNA fragments with the same level of replacement and the same source.
The moisture content of fish not effected significantly with different experimental diets. Fish fed diet C-SBM100, supplemented with FA and diet GM-SBM100, un-supplemented with FA had higher ash value than the other diets. The highest lipid content was recorded by fish fed either control diet or diet C-SBM50 supplemented with FA. Moreover, fish fed diet GM-SBM100 supplemented with FA detected the highest protein content. Diets supplemented with FA increased ash, lipid and protein content.