231 Effect of Feeding a Blend of Naturally-Contaminated Corn on Nutrient Digestibility and Feed Preference in Weanling Pigs

Abstract Two experiments were conducted to determine the effect of feeding diets with 2009 and 2010 naturally-contaminated corn containing deoxynivalenol (DON), zearalenone, and fumonisin B₁ to pigs on apparent nutrient digestibility and feed preference. The 2009 corn contained higher concentrations of mycotoxins than the 2010 corn (5.6 vs. 0.5 ppm DON, 5.5 vs. 2.0 ppm fumonisin B1, and 2.45 ppm vs. nondetected zearalenone, respectively). For both experiments, 3 diets that contained 57.1% corn were mixed. Diets contained 100% 2010 corn (Control), 50-50% blend of 2009 and 2010 corn (Diet 2), and 100% 2009 corn (Diet 3). In Exp. 1, 24 pigs with BW of 7.64 ± 0.70 kg were allotted to 4 replicates of 3 treatments with 2 pigs per pen on the basis of gender and BW. Fecal samples were collected and apparent DM, energy, and nitrogen digestibility were determined for 5 consecutive 4-d periods with 2 feeding methods (ad libitum in Periods 1-3; scale feeding to BW in Period 4-5). Linear reductions in ADFI were observed with more contaminated corn (Periods 1-3: average 1,091, 964, and 787 g for Diet 1, 2, and 3, respectively, P < 0.04) with associated reductions in ADG; however, DM, energy, and nitrogen digestibility were not affected (P > 0.12) by either Diet 3 or Diet 2 compared to the Control throughout all periods. In Exp. 2, 30 pigs with BW of 7.98 ± 1.15 kg were allotted to 3 replicates of 2 comparisons with 5 pigs per pen for 3 experimental periods of 1 week each. Comparisons were: 1) Control vs. Diet 3, and 2) Control vs. Diet 2. A preference for the diet containing 2010 corn was observed in both comparisons. Pigs discriminated against mycotoxin-contaminated diets (95.34 vs. 4.66% for Diet 1 and 3, respectively, P < 0.01; 91.29 vs. 8.71% for Diet 1 and 2, respectively, P < 0.01) over the 3 week period. The discriminations were evident in each weekly period for both comparisons. These results demonstrated that nutrient digestibility was not affected by naturally-contaminated corn, but a clear decrease in feed preference was observed in the pigs consuming highly contaminated corn. With this combination of mycotoxins, the observed decreases in performance with the contaminated corn are more a function of the effect of the contamination on feed intake than on the utilization of the feed.