الفهرس 
Cover Page Title in EnglishOnly 14 pages are availabe for public view
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Abstract
The success of modern aquaculture has been the direct result of good management, good nutrition and good disease control., there is a growing need to control, prevent or minimize the devastating effects of disease in fish culture resource to toxic chemicals or antibiotics. In keeping with approaches to disease control in fish and higher mammals, interest is developing in compounds that confer protection and / or enhance immune reactivity to likely pathogens of aquatic species.
The aim of this study : To prove and study the effect of immunostimulants (Feed additives Salikal) on the immunity of the fish through their effects on total WBCs, RBCs, the differential leucocytic counts, Hb%, PCV, Phagocytic activity, Phagocytic index, serum enzymes, Glucoe cholesterol and serum proteins (Total protein, albumin, globulin and Albumin/globulin ratio) . Also, serum lysozomal activity and serum bactericidal activity and the effect of vaccine in the immune response at the end this lead to increase body weight gain and economic importance .
A total number of 400 healthy fish Oreochromis niloticus, average body weight of fish about (50 ± 5 g) were obtained from private fish farm (30 fish were only used each group) and were transported alive to the laboratory in plastic bags containing water enriched by air (2/3).
Immunostimulants were used in this study, they include Salkil® (propionic acid) (Put in the ration by about 2 L/ ton ration).
The most important results of this study include :
1. Good immunostimulant must be characterized by, particularly suitable for boostering immature immune systems, effective against a number of opportunistic pathogens, useful at times of known stress such as transportation and vaccination, enhances immune response to conventional vaccine, safe and non-toxic- no risk of overdose, no resistance problems and environmentally friendly & fully biodegradable.
2. The addition of Salkil® (propionic acid) improve the immunity of the fish especially toward the end of the experiment than the control group. And Salkil® (propionic acid) is potent in improving immunity and improve the different leucocytic counts.
3. The level of T. WBCs and T. RBCs increased graduially from the 1st to the last week of the experiment. And the feed additives especially Salkil® (propionic acid) improve the level of T. WBCs and T. RBCs than control group.
4. This result indicated that the level of Hb% and PCV% increased gradually from the 1st to the last week of the experiment. And the feed additives especially Salkil® (propionic acid) improve the level of Hb % and PCV % than control group.
5. This results indicated that the level of PA and PI increased gradually from the 1st to the last week of the experiment. And the feed additives especially Salkil® (propionic acid) improve the level of PA and PI than the control group.
6. Our results indicated that, the total serum protein and serum albumin level decreased gradually from the 1st week to the 3rd week of the experiment and increased in the 4th week of the experiment and the level of total protein increased in salikal treated group followed by infected and control group allover the period of the experiment. And also, the albumin/globulin ratio increased gradually from the 1st week to the 4th week of the experiment and the level of total protein increased in Salkil® (propionic acid) treated group and both of them higher than that of the control group all over the period of the experiment.
7. The serum globulin level decreased gradually from the 1st week to the 2rd week of the experiment and increased in the 3rd and 4th of the experiment and the level of serum globulin increased in Salkil® (propionic acid) treated group all over the period of the experiment. The α- globulin level increased in Salkil® (propionic acid) treated group but lower than that of the control group. While, the β-globulin level in groups treated with Salkil® (propionic acid) and control group. The level of γ- globulinincreased in Salkil® (propionic acid) treated group than control group. In general our results cleared that, Salkil® (propionic acid) treated group of higher serum globulin level than control group.
8. Our results concluded that the feed additives decreased the level of serum glucose and cholesterol and its level in Salkil® (propionic acid) decreased and was lower than the control in its content in glucose and cholesterol.
9. Our results concluded that the feed additives Salkil® (propionic acid) increased bactericidal activity than the control.