Four groups of seven-week-old pigs weighing about 9 kg were fed for three weeks a prestarter that contained 0.5, 1.0, 2.0 or 3.0 mg/kg of highly purified T-2 toxin. The average daily intakes of toxin by the pigs were 0.38, 0.81, 1.24 and 1.43 mg, respectively. The experimental and control pigs were immunised with 5 ml aluminum hydroxide gel-absorbed purified horse globulin on the first and fourth days of the treatment period. Blood samples were withdrawn on days 7, 14 and 21 and used for the determination of the titre of anti-horse globulin antibody, for an in vitro lymphocyte proliferation test, using purified horse globulin, phytohaemagglutinin and concanavalin-A and for determinations of the immune complex, the cytotoxic reaction and the phagocytic activity and phagocytic index of circulating granulocytes. The samples taken on day 21 were also used to determine the erythrocyte count, the mean cell volume of the erythrocytes, the haematocrit, the blood haemoglobin concentration, the leucocyte count and the proportion of T lymphocytes. At the end of the experiment samples were taken from the thymus, spleen and mesenteric lymph nodes for histological examination. The diets that contained 2 and 3 mg T-2 toxin/kg caused a significant decrease in the red blood cell count, the mean corpuscular volume and the haemoglobin concentration. A significant decrease in the leucocyte count and the proportion of T lymphocytes was observed in all the treatment groups. There were also dose-dependent, significant decreases in antibody formation and in the blastogenic transformation of lymphocytes, and mild to moderate reactive processes were observed histologically in the lymphoid organs.
The effects of different dietary levels of T-2 toxin on production, biological, immunological, and pathological parameters of growing white Pekin ducks were studied to establish the "no effect" dietary concentration of, and "no effect" exposure time to, pure T-2 toxin. Day-old white Pekin ducks were randomly allotted to nine groups of 10 ducks each. One group served as a control, and no mycotoxin was added to its feed. The feeds of the experimental groups were supplemented with 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 3.0, and 4.0 mg purified T-2 toxin/kg, respectively, from Day 1 until Day 49 of the experiment. Dermatotoxic oral lesions developed in most experimental ducks within 2 d after the start of feeding T-2 toxin-contaminated feeds. The gradual disappearance of macroscopic signs indicated the development of tolerance in groups treated with the lower T-2 toxin content. No repair was found in the 3 and 4 mg/kg groups. Dietary concentrations of T-2 toxin below 0.4 mg/kg had no effect on the average weekly weight gain in the first 6 wk, but a severe decrease was found in the last week of the experiment. The 0.6 mg/kg dietary T-2 toxin had no effect on weight gain in the first 3 wk. At Week 4 and later, the weekly weight gain was significantly reduced, and the final live weight of this group was also significantly lower than that of the control. Dietary T-2 concentrations of 1 mg/kg and greater uniformly depressed growth rate. Only the 3 and 4 mg/kg groups refused feed during the first week. From Week 3 on, the feed intakes of the 0.6 to 4 mg/kg groups were usually less than that of the control group, indicating feed refusal. Serum and plasma chemical values and hematological parameters failed to show dose-dependent effects. The blastogenic response of lymphocytes to nonspecific and specific mitogens was distinctly impaired by the T-2 toxin at all levels in the feed. In the 3 and 4 mg/kg groups, the histological examination revealed lymphocyte depletion in the spleen and bursa of Fabricius.
In two sets of experiments eight groups of seven-week-old pigs weighing about 9 kg were fed for three weeks a prestarter that contained 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 10.0 or 15.0 mg/kg of highly purified T-2 toxin. The feed of the two control groups was free from T-2 toxin. Average daily intakes of toxin by the pigs were 0.38, 0.81, 1.24, 1.43, 0.93, 0.81, 0.99 and 2.5 mg, respectively. The weight gains, the feed intakes, the extent of feed refusal, the parameters of energy and protein metabolism and the serum concentrations of calcium, inorganic phosphorus and magnesium were affected to different extents by the different doses of T-2 toxin, but the data indicated that feed consumption was reduced and the activity of aspartate aminotransferase was increased by the smallest amount of T-2 toxin tested.
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