Fumonisin B₁ and implications in nursery swine productivity: A quantitative exposure assessment

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 1) Bt and non-Bt grain and DDGS (blended); 2) Bt grain and Bt DDGS; 3) non-Bt grain and non-Bt DDGS; 4) Bt and non-Bt grain; 5) Bt grain; and 6) 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.