الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 72 |  |  |
| | | from | 72 | | |
Abstract
This study aimed to : Studying the effects of using dietary distillers dried grains with solubles in fish feeding Methods & Results : This field study was carried out at El-Manzala Lake to investigate the effect of substitution of fish meal (FM) by graded levels of distillers dried grains with solubles (DDGS) in fish diets on water quality, growth performance, feed utilization, condition factor, internal organs’ indices, whole body chemical composition, blood profile, and economic efficiency of Nile tilapia (Oreochromis niloticus, reared in five floating net cages representing the dietary treatments and stocked into the experimental cages at a rate of 35 fish/m3 (about 30.000 fish/cage). All the experimental groups were fed the experimental diets at a rate of 3% of the live body weight of the fish. The obtained results could be summarized in : The increase of DDGS level in the diets was correlated with lower diet’s cost. The price was gradually decreased thereafter by increasing the DDGS level from T2 till T5 which was the cheapest diet. All the tested growth performance parameters reflected significant differences among treatments in favor of the first two treatments (diets). The feed utilization parameters differed significantly among treatments in favor of the fifth treatment. There was significant effect of DDGS levels on condition factor and hepatosomatic index. It is noticed that ether extract percentage (and hence, the energy content) was higher and ash percent was lower in the aged fish than in the younger ones. Fish groups fed DDGS-containing dies reflected lower crude protein and ash but higher ether extract and energy contents than the control fish group. All chemical composition and energy content of the whole fish body were significantly affected by dietary DDGS inclusion. The 50 % DDGS containing diet caused the highest dry matter and the lowest ash percentages in the whole fish body. The control group reflected the highest crude protein and ash but the lowest ether extract and energy contents in the whole fish body. There were positive correlations among dry matter, crude protein and ash contents and a negative correlation between crude protein and ether extract contents, in the whole fish body. Blood total protein and globulin differ significantly. Blood total protein as well as globulin values in fish groups fed the control or 50, 75, and 100 % DDGS containing diets were significantly similar. Mean concentrations of blood serum creatinine and triglycerides and activity of both serum enzymes ALT and AST were significantly affected by the dietary inclusion of DDGS. Up to 100 % substitution of FM by DDGS did not negatively affect kidney nor liver functions of the tested fish. The fifth diet was the cheapest one to produce one Kg bodyweight gain of fish. Feeding the experimental fish the 100 % DDGS containing diet resulted in the highest economic efficiency (199.99 %).Conclusion: Conclusively, it is safe and economic to feed Nile tilapia fish diets containing DDGS (cheaper than fish meal, FM) to replace up to 100 % of the FM (which is locally not enough available) in fish diets. So, the results of the present field (i.e. its results are reproducible) study recommend using DDGS in Nile tilapia diets.