الفهرس 
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Abstract
T-2 toxin is mycotoxin produced by various Fusarium species. The European Commission asked EFSA for a scientific opinion on the risk to human and animal health related to the presence of T-2 in food and feed. Sea bream is one of the most farmed species worldwide and surprisingly, little is known about the possible responses of Sea bream to T-2 toxin.
* The aim of this study was to evaluate the effects of T-2 toxin by dose of 1.0 mg/kg in the food of sea bream on the following :
• On growth performance of sea bream as Specific growth rate (SGR); Feed conversion ratio and Protein efficiency ratio.
• Changes in Leucocyte count (WBCs), erythrocyte counts (RBCs), packed cell volume (PCV) and hemoglobin content ((HB) in the blood of sea bream.
• Changes in differential leucocytic count in the blood of sea bream
• On some immune parameters of sea bream namely; Phagocytic activity and phagocytic index ; Respiratory burst activity (NBT), lysozyme activity and bactericidal activity and Pentaxins (C-reactive protein) levels
• Enzymatic activities of liver and kidney namely; total proteins, albumin, globulin; serum creatinine and urea levels.
• Stress biomarkers as Cortisol (P/mol L) levels.
• Biomarkers of antioxidant including; Catalase; Super oxide dismutase; Glutathione S-transferase; Glutathione reductase; Lipid peroxidase; Total Metallothionein; Oxidized Metallothionein and Reduced Metallothionein.
• Evaluation the ameliorative effect of two commercial mycotoxin adsorbents to alleviate T-2 toxins namely; Agresol® and CAP T2® by the dose of 1.0 mg/kg and the all previous mentioned parameters measured during the toxicity were carried out also.
• To confirm the previous results of T-2 toxicity by the challenge test by the V. parahemolyticus and antibody titration test against bacteria was determined.
• A histological picture of selected organs in the T-2 toxicity in sea bream was done.
* In our study :
1) A Total of 180, apparently healthy fingerlings of sea bream (Sparus auratus) were obtained from a commercial private fish farm at Borg-El Arab region at Alexandria governorate. The fish with an average body weight of (50 ± 5 grams).The fish were acclimatized for 14 days to allow for physiological adjustment, before which data collection started. Sea bream (Sparus auratus) consumed the food according initial body weight by 3% of body weight.
2) The sea bream were classified into six groups as follow; The (G 1) Sea bream were feed on basal diet ; (G 2) Sea bream were treated with 1 gm. /kg of food of Agresol®; (G 3) Sea bream were treated with 1 gm. /kg of food of CAP T2®; (G 4) Sea bream were treated with 1.0 mg/kg of food of T-2 toxin; (G 5) Sea bream were treated with 1 gm. /kg of food of Agresol® + 1.0 mg/kg of T-2 toxin and (G 6) Sea bream were treated with 1 gm. /kg of CAP T2® + 1.0 mg/kg of food of T-2 toxin.
3) The blood samples were collected every 2weeks to determine biochemical and haematological parameters ”Red Blood Cell; White Blood Cell; hemoglobin concentration; packed cell volume and haematocrit values, Total and differential leucocytic count and Mitogen assay also was carried out. Also, growth performance and feed utilization parameters recorded.
4) Determination of phagocytic activity and phagocytic index; serum total protein; serum albumin; aspartate aminotransferase; alanine aminotransferase; alkaline phosphatase ; concentration of urea; creatinine the serum cortisol; Respiratory burst activity; Serum lysozyme activity; Serum bactericidal activity; C-reactive protein) and enzymatic biomarkers (superoxide dismutase; catalase; glutathione reductase; glutathione S-transferase; reduced glutathione; Lipid peroxidation concentration and the total, oxidized and reduced levels of metallothioneins were measured in the liver.
5) Challenge Test and Pathological Studies. After end of the chronic experiment the survival fish were challenged by the V.parahaemolyticus previously isolated from diseased sea bream.
The results revealed that :
1) The clinical signs appear during the exposed of sea bream to 1.0 mg/kg of T-2 toxin were abdominal distension, darkness colouration associated with fin sloughing of the different fins.
2) The postmortem (PM) lesions of the experimentally sea bream exposed to 1.0 mg/kg of T-2 toxin showing whitish nodules of liver and severe damage of gill , also alternated area of congestion and blotched area of the liver and sever congestion of gills as well as highly congestion of the kidney were recorded
3) Growth performance of sea bream fed diet containing T-2 toxin and tow mycotoxin adsorbents to alleviate T2 toxin :-
4) Decrease in all blood parameters (WBCs), (RBCs), (PCV) and hemoglobin content (HB) in the groups chronically exposed to T2 toxin for 6th weeks than the other groups and control.
5) The lymphocytic count decreased and Monocytic, eosinophils and basophils counts revealed significant difference values among all experimental groups.
6) A lower percentage of phagocytic cells were observed in the blood of sea bream fed diet containing T-2 toxin and two antimycotoxins adsorbents to alleviate T2 toxin compared with the control group.
7) Hepatic marker enzymes are shown significant increases in serum liver function marker enzymes (AST, ALT and ALP) were recorded in T-2 toxin intoxicated fish as compared to negative control group. Significant decrease (P<0.05) in serum (AST, ALT and ALP) was also detected in the positive control group. Meanwhile, Agresol® and CAPT 2 ® treated groups showed significant improvement in AST, ALT and ALP comparing with positive control. Similarly, serum urea and creatinine levels showed significant increases in T-2 toxin intoxicated fish compared with the negative control and other treated groups. Significant improvement in the serum urea and creatinine levels was recorded in Agresol® and CAPT 2 ® treated groups.
8) In view of the state that T-2 toxin induces distinct decrease in total protein corresponding to a globulin decrease after a single application of T-2 toxin to fish. Significant improvement in the serum total protein, albumin and globulin level was observed in Agresol® and CAPT 2 ® treatment group.
9) The respiratory burst activity (NBT), lysozyme activity and bactericidal activity, showed significantly decreased immune response corresponding to feeding the fish with T-2 toxin supplemented diets. Meanwhile, Agresol® and CAPT 2 ® treated groups showed significant improvement in respiratory burst activity (NBT), lysozyme activity and bactericidal activity comparing with positive control.
10) Fish administered T-2 toxin supplemented diet exhibited significantly higher cortisol values compared to that of the control group.
11) C-reactive protein was significantly increased in the groups supplemented with T-2 toxin at concentrations of 0.1 gm. /Kg for 42 days than the other groups and control
12) On the other hand, there is a decrease in antioxidants enzyme assay (catalase, super oxide dismutase and glutathione S-transferase) in plasma of sea bream fed diet containing T-2 toxin at concentrations of 0.1 mg. /Kg. for 42 days than the other groups and control. We can notice that there is an increase in antioxidants enzyme catalase, super oxide dismutase and glutathione S-transferase in fish fed the Agresol® and CAPT 2 ® for 42 days than the other groups and control.
13) The level of T-2 toxin at dose of 0.1 mg. / Kg. showed the decrease the level of glutathione reductase (GSR) level in the whole blood along the periods of exposure. In addition to the possibility of using mycotoxin adsorbents Agresol® and CAPT 2 ® in presence of T-2 toxin increasing the levels of glutathione reductase.
14) The Lipid peroxidase activity at the T-2 toxin exposed group was found higher than at the Agresol® and CAPT 2®supplemented groups.
15) The Total Metallothionein, Oxidized Metallothionein and Reduced Metallothionein in whole blood results revealed that the values were decreased in the fish fed to T-2 toxin and significantly lower, in fish fed with Agresol® and T-2 toxin and CAPT 2® and T-2 toxin at the end of the experiment.
16) The challenge and immunization with V.parahaemolyticus in the presence of T-2 toxin and two antimycotoxins in the feed of sea bream in this study, has been effective in induce a benefic response, such as the increase in antibody titer, since this may protect fish against bacterial disease outbreak. V.parahaemolyticus challenge infection of the T-2 toxin supplemented groups –non vaccinated sea bream induced the highest mortality and low relative level of protection in compared with the non-vaccinated control group, followed by the vaccinated control. Lowest mortality and high relative level of protection was seen in the antimycotoxins supplemented group at the challenge period. The other groups showed variable results for the period of challenge
17) The results of histopathological changes during toxicity with T-2 toxin in sea bream revealed that the showing hepatic and pancreatic degeneration, hepatic degeneration of marked fatty accumulation within the hepatocytes and hepatic degeneration of marked fatty accumulation within the hepatocytes. Spleen showing marked lymphoid depletion represented by degeneration and loss of melanomacrophages centers. Gills showing marked gill lamellar adhesions. Liver of sea bream fish treated with T2 toxin and subjected with Cap T2 treatment showing diffuse hepatic vacuolation. Kidney showing focal renal tubular degeneration. Spleen showing congestion and lymphoid depletion. Gills showing diffuse telangiectasis of gill lamellae. Liver showing normal hepatocytes and pancreatic portion. Kidney showing renal tubules within normal.
VIII. REF