الفهرس 
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Abstract
Moldy and mycotoxin contaminated feed constitute a significant problem for the animal feed industry and an ongoing risk to feed supply security. Removing mycotoxins from contaminated feed and feedstuffs remains a major problem and there is a great demand for effective decontamination technology.
The present study aimed to investigate the protective effect of yeast or vitamin E and selenium against mycosis and mycotoxicosis induced by fungal materials of Aspergillus parasiticus and Fusarium tricinctum as common fungal contaminants on albino rats. In which, One hundred male and female albino rats were randomly divided into five experimental groups: (A, B, C, D and E) each contain 20 animals. In group A: rats were kept as a control group and received only uncontaminated feed and drinking water without any treatments. In group B: animals were received contaminated diet with fungal materials which contain aflatoxins in level of 0.5 mg/kg ration and diacetoxyscirpenol in level of 10mg/kg ration. In group C: animals were received contaminated diet as in group B. mixed with Saccharomyces cerevisiae (2g/kg of feed) during the whole time of the experiment. In group D: animals were received contaminated diet as in group B. In addition; rats were received vitamin E & Se in drinking water at the rate of 0.5 g /liter of water for 3 days/week during the experiment. In group E: animals were received contaminated diet as in group B. mixed with Saccharomyces cerevisiae (2g/kg of feed). In addition to vitamin E & Se in drinking water at the rate of 0.5 g /liter of water. At the end of 1st, 2nd, 3rd, and 4th month, respectively, five animals of each group were weighted and dissected. Tissue samples were obtained from liver, kidneys, intestine and lungs for histopathological examination by light and electron microscope.
Clinical signs
Clinical signs were more obvious in rats of group B which appeared lethargic and show loss of appetite compared to controls. Loose stools were observed on some animals of this group at 3rd and 4th month of the experiment. But in the other groups characteristic clinical signs during the study can not be detected.
Body weight and weight gain
The body weight of group B at the end of 1st, 2nd, 3rd and 4th months of experimental period were 166.6 ± 13.3, 193.3 ± 18.7, 186.6 ± 12 and 260 ± 20 (g) respectively, Significant reduction (p < 0.05) of body weight in group B start from 2nd month till 4th month when compared to that of control group. Addition of yeast to contaminated diet in the group C and group E show increase in body weight nearly similar to control when compared with group B. But addition of vit E & Se did not increase the body weights as in groups C & E when compared to the control group.
In case of weight gain significant decrease (**p < 0.01) were observed in rats of group B compared to that of control. The decrease in weight gain was highest in 2nd month till 4th month. While, no significant reduction could be recorded in weight gain of the group C and group E compared to the control. But, group D showed significance decrease of weigh gain occurred at 3rd month compared to control.
Histopathology
Histopathological changes were obvious in the liver, kidneys, intestine and lungs. The intensity of the lesions was more pronounced by increase of experimental period. Examination of liver revealed degeneration of hepatocytes, focal areas of necrosis, activation of Kupffer’s cells, apoptotic changes, increase the mitotic figures and start early steps for preneoplastic changes of hepatic cells inform of megalocytosis, nuclear pleomorphism, multinucleated hepatocytes and increased number of binucleated hepatocytes in the hepatic lobules, ultrastructurally showed presence of numerous fat globules in the hepatic cell and presence of bundle of collagen fiber in between hepatic cells. Kidneys had glomerular cellular reaction, periglomerular fibrosis and degeneration of the tubular epithelial lining, ultrastructurally showed presence of electron dense bodies in tubular epithelium and fine collagen fiber in between tubules. Intestinal lesions consisted of degeneration of intestinal epithelial cells, congestion, hemorrhage in the villous core associated with lymphocytic cell infiltration ended by villous atrophy. There were mild lymphocytic activation and at the end of experiment turned to lymphocytic depletion. Lungs revealed alveolar emphysema, exfoliation of bronchiolar epithelial cells and thickening of alveolar septa. There was also perivascular and peribronchoular mononuclear infiltration.
Treatment with yeast or vitamin E and selenium or all of them for four months markedly improved the intensity and prevalence of the lesions in different organs compared to that in group B animals. Addition of live yeast to contaminated diet positively enhances growth performance and enhances the immune defensive mechanisms of the body against mycotoxicosis (Lymphocytes and plasma cells).