This study estimated the long-term exposure of fumonisin B1 (FB1) in nursery swine diets and associated toxicological adverse effects on negative productivity potential using quantitative exposure assessment. Fumonisin B1 is a mycotoxin produced by Fusarium verticillioides and Fusarium proliferatum and is a common biological contaminant of corn (Zea mays L.) and other grains. Acute effects from FB1 exposures are well recognized and managed in the swine industry, but practices to limit prolonged low-dose exposures to FB1 have been less fully considered and may negatively affect production efficiency. Deterministic (single-point estimates) and stochastic (probabilistic) modeling were performed for comparative analyses of FB1 exposures originating from genetically engineered Bacillus thuringiensis (Bt)-corn, conventional non-Bt corn, and distillers dried grains with solubles (DDGS). Six feeding scenarios differing in the source of corn in diets were modeled to assess variation in FB1 exposure representing a mixture of Bt and non-Bt grain and DDGS (blended); Bt grain and Bt DDGS; non- Bt grain and non-Bt DDGS; Bt and non-Bt grain; Bt grain; and non-Bt grain. Long-term exposure estimates (49-d duration) were compared with chronic levels of concern (LOC). The first LOC (LOC1; 1 mg of FB1/kg of diet, least observed adverse effects concentration) represents a decrease in ADG. Concentrations of 5 mg of FB1/kg of diet represent the second LOC (LOC2), which showed pulmonary pathological alterations and a significant dose-dependent increase in pulmonary weight. Estimates indicated LOC1 was frequently exceeded regardless of feeding scenario, but LOC2 was not attained. Diets where the corn fraction was entirely from Bt-corn showed the least FB1 exposure (exceeding LOC1 in 35% of occasions), whereas a blended diet or diets using non-Bt grain and DDGS sources more commonly exceeded this threshold (95% of occasions). Based on these estimates, under blended corn source feeding conditions, swine populations in nursery facilities may frequently exhibit incipient effects (i.e., LOC1) of FB1 toxicity; however, impacts on production efficiency remain uncertain.

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