TEMPORAL AND DOSE-RESPONSE FEATURES IN SWINE FED CORN SCREENINGS CONTAMINATED WITH FUMONISIN MYCOTOXINS

Fumonisin B-1 (FB1), a mycotoxin produced by Fusarium moniliforme and F. proliferatum, induces liver damage and pulmonary edema in swine. We examined the temporal and dose-response features of FB1 toxicosis in male weanling crossbred pigs fed nutritionally balanced diets, contain ing corn screenings naturally contaminated with fumonisins, for 14 day s. Total fumonisins (FB1 and FB2) in diets 1 through 6 were assayed at 175, 101, 39, 23, 5, and <1 ppm (below detectable concentrations), re spectively. Clinical signs, serum biochemical alterations, and morphol ogic changes were evaluated. Pigs were weighed, and bled for hematolog ic and clinical chemistry evaluation on days 5 and 14. They were eutha nized on day 14, or earlier if respiratory distress was observed. Resp iratory distress developed in 3/5 pigs fed diet 1 between days 4 and 6 due to severe pulmonary edema and pleural effusion. Histologic eviden ce of hepatic injury was present in all pigs fed diets 1 and 2, 3/5 on diet 3, and 1/5 on diet 4. Serum bilirubin and cholesterol concentrat ions, gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), al anine aminotransferase (ALT), aspartate aminotransferase (AST), and ar ginase (ARG) activities were elevated in pigs fed diets 1 and 2. Based on liver histopathology, the no observed adverse effect level (NOAEL) for fumonisin toxicity in swine was <23 ppm total fumosins for the 14 -day period. Based on regression analyses of the clinical chemistry pr ofiles at 14 days, the NOAEL was <12 ppm, with ALP being the most sens itive parameter. In conclusion, pulmonary edema occurred only at the h ighest fumonisin concentration (175 ppm), while liver damage occurred at much lower concentrations with a NOAEL of <12 ppm.