Effects of feeding varying levels of mycotoxin-containing corn fines on diet choice and growth performance of nursery pigs

Mycotoxins in feed are known to negatively affect growth and other physiological processes in pigs. Two experiments were conducted to investigate the effects of feeding diets with varying levels of mycotoxins and boron (a nutrient reported to mitigate some aspects of mycotoxicosis). Screenings from the 2020 crop year corn contained mycotoxin levels of 23,038 ppb total fumonisins (FUM), 1,446 ppb zearalenone (ZEA), and 5,032 ppb total deoxynivalenol (DON). The corn fines were added to a corn-soybean meal diet formulated to meet or exceed NRC (National Research Council. 2012. Nutrient requirements of swine. 11th Revised Edition. Washington, DC: The National Academies Press. doi:10.17226/13298) nutrient requirements as a replacement for corn at 0, 10, and 20% for Diets 1 to 3. Diets 4 to 6 were Diets 1 to 3, respectively, plus 40 ppm boron from sodium tetraborate decahydrate. Diets 3 and 6 were formulated to approximate the guidance level of fumonisin and the advisory level of DON stated by the FDA. Exp. 1 used 48 crossbred pigs (initial body weight [BW] = 9.18 kg ± 0.12 kg) blocked by sex and BW and randomly allotted to 1 of 3 treatment comparisons: Comparison 1) Diet 1 vs. Diet 2; Comparison 2) Diet 1 vs. Diet 3; and Comparison 3) Diet 2 vs. Diet 3. There were 4 replicates (4 pigs/pen) for the 21-d preference trial. Exp. 2 used 144 crossbred pigs (mean initial BW = 10.20 ± 0.23 kg) blocked by sex and BW and randomly allotted to diets for a total of 6 replicates (4 pigs/pen) for a 21-d growth trial. On d 21, serum was collected from the heaviest and lightest pig in each pen for clinical chemistry assessment. Exp. 1 demonstrated the barrows' ability to discern between diets in Comparisons 2 and 3 (P < 0.01) for each week while gilts only started to exhibit that ability during Week 3 for Comparison 2 (P = 0.06). Increasing mycotoxin levels in Exp. 2 had no effect on overall ADG, ADFI, and G:F (P = 0.16, 0.53, and 0.92, respectively). The increasing mycotoxin levels affected serum glucose and cholesterol (P = 0.03, and P < 0.01, respectively). There was no effect of boron on the same performance measures (P = 0.81, 0.59, and 0.76, respectively) although it did lower serum glucose (P = 0.02). In conclusion, pigs can differentiate and choose between diets containing these mixed mycotoxins but when not given a choice, the pigs do not necessarily have different growth performance using the particular mycotoxins and concentrations within the framework of this assessment.