© 1994 Oxford University Press
research-article |
Influence of Low-Level Exposure to Fusarium Mycotoxins on Selected Immunological and Hematological Parameters in Young Swine1
*Centre for Food and Animal Research, Agriculture and Agri-Food Canada K. W. Neatby Building, CEF, Ottawa, Ontario, K1A 0C6, Canada
Toxicology Research Division, Bureau of Chemical Safety, Food Directorate, Health Canada Tunney's Pasture, Ottawa, Ontario, K1A 0L2, Canada
Received July 23, 1993; accepted February 3, 1994
The effects of low dietary concentrations of Fusarium myco toxins (deoxynivalenol (DON), 1 5-acetyl-DON, and zearalenone) on growth, immunological, and hematological parameters were determined in young pigs during a 28-day feeding experiment. Clean and naturally contaminated corn were incorporated into basal diets formulated to contain 0.00, 0.75, 1.50, and 3.00 mg DON/kg diet. A pair-fed control animal was used for comparison with each animal receiving the highest level of contamination (diet 4). Skin temperature, measured during the first week of the experiment, decreased linearly as the dietary mycotoxin concentration increased. Several other linear effects were observed: depressed feed intake throughout the experiment, reduction in thyroid size (absolute/relative), and changes in the appearance of the esophageal region of the stomach (thicker and higher degree of folding with increasing toxin concentration). Serum T4 (thyroxine) levels increased quadratically after 7 and 28 days of exposure compared to control animals. This change coincided with an increase in albumin levels, a decrease in 
-globulin levels, and an overall increase in albumin/globulin ratio as the level of contamination increased. After immunization with sheep red blood cells (SRBC), animals fed contaminated diets showed a delayed response in peak titers. At the end of the experiment an increase in the segmented neutrophil count was observed. The following observations were made for ani mals consuming diet 4 as compared to the pair-fed controls: lower skin temperature, better feed efficiency, more corrugated stomachs, reduced -globulin levels, and lower antibody titers to SRBC. The study showed a physiobiochemical adaptation response of animals exposed to mycotoxin-contaminated diets. Although most changes seem to be related to the nutritional status of the animal, others such as reduced skin temperature, altered stomach condition, and reduced -globulin levels suggest specific effects due to the Fusarium toxins. The pair-feeding treatment was important in reaching these conclusions, but it is also evident that the treatment itself introduces changes in response to a reduced feed intake.