Last January, the North Central Coordinating Committee on Swine Nutrition, or NCCC-042, recognized the extensive vomitoxin or DON contamination in much of the 2009 U.S. corn crop. Consequently, it also was high in corn byproducts such as dried distillers" grains with solubles. Other regional committees (S-1044 and NCERA-89) had similar concerns.
A combination of investigators from these three groups evaluated how we could help pork producers overcome the problem and how to feed a contaminated corn supply. There were no Food and Drug Administration-approved mycotoxin-inhibitor products available, but there were some products on the market reported to be of benefit. However, there were no studies or reports within the public domain.
The committee decided to conduct a joint regional project to evaluate three available products. The goal was to evaluate the effectiveness and recommendations for feeding contaminated corn supplies. Twelve stations were able to conduct the study in a timely manner.
Corn was purchased with three different DON levels. The cleanest was 1.9 ppm DON, which was fed during the pretrial period for 10 days to let the weaned pigs get started on a common diet (with no mycotoxin inhibitor), as well as to overcome the normal post-weaning growth and feed intake lag.
The other two corn sources tested at levels of 2 ppm or 7 ppm DON. A complete profile of other major mycotoxins analyzed in these corn sources determined that DON was the major mycotoxin present; others, particularly T-2 Toxin and zearalenone, were present but at levels that wouldn"t cause problems.
The pretest diet was comprised of feedstuffs normally fed in a phase-1 weaned-pig diet. Diets during the 21-day trial were formulated to use as much corn as possible to best test the efficacy of the three mycotoxin-inhibitor products. Only one diet was fed from day 10 to day 31 for each treatment group. The companies agreed to have their products evaluated.
All test stations fed the same pretest diet, used the same corn sources and used the same diet mixtures (including the pretest diet), mixed at one location (OARDC feed mill, Wooster, Ohio). All diets were formulated to meet or exceed the National Research Council (1998) swine nutrient requirements.
The three products incorporated into the test diets (Defusion, Integral and Biofix Plus) were purchased on the open market. Each company could evaluate the corn mycotoxin assay results and the diet formulas, and recommend their product"s incorporation level for the two corn sources.
The products added to the 1 ppm diets were as follows: Defusion 10 pounds per ton, Integral 4 pounds per ton and Biofix Plus 8 pounds per ton. The amounts for the 3.9 ppm diets were: Defusion 10 pounds per ton, Integral 6 pounds per ton and Biofix Plus 8 pounds per ton. The treatment and product identification were blinded to the company and to the investigators.
Vomitoxin has been reported to cause reduced feed intake, reduced bodyweight gain and sub-clinical immune suppression. High levels may produce intestinal lesions, vomiting and complete feed refusal. The study focused on pig gain and feed intake. All 10-day weights were adjusted to ensure the responses were not affected by beginning weight differences.
Data from all stations involving all replicates is reported in the accompanying table. Researchers took advantage of some of the weight variances to group six of the light-weaning-weight replicates and seven of the heavy weight to determine if there were different responses to the DON-contaminated corn and mycotoxin inhibitors.
The pretest diet that contained a low innate level of DON (0.80 ppm) did not appear to affect pig gains or feed intakes. There was no access to corn without DON contamination to make a comparison.
The treated diets (days 10 to 31 post weaning) clearly resulted in different performance responses to the two corn sources. Pigs consuming the 7 ppm DON corn (diet calculated at 3.9 ppm DON) had reduced bodyweight gains and feed intakes each week of the test compared to those on the corn that tested 2 ppm DON (diet calculated at 1 ppm DON). There was no feed refusal for either of the corn sources, but feed intake did decline when pigs received the higher DON-contaminated corn.
Five pigs were removed for reasons related to a decline in bodyweight, limb immobility and pneumonia. As expected, the major response from DON contamination was reduced gain, reduced feed intake and a general unthriftiness (likely because of low feed intake).
Comparison of the three mycotoxin inhibitors for all replicates is reported in the table. For the low-DON-contaminated corn, only Defusion was effective by increasing pig gains and feed intake during weeks 1 and 3 of the test compared with the control diet. The other mycotoxin inhibitors" effects were statistically similar to the control diet. The overall growth rate and feed intake did not differ significantly through most of the trial for two of the three inhibitors, but there was an apparent numerical advantage to Defusion. However, the product's additional expense may not be cost effective when a low level (≤1 ppm) of DON is fed to weanling pigs.
With the high-DON-corn diets (3.9 ppm DON), pigs fed Defusion weighed more at the trial"s close, gained more weight and consumed more feed each week than those fed the control diet, Integral or Biofix Plus products.
When evaluated by weaning-weight groups, pigs responded to the two corn sources and mycotoxin inhibitors somewhat differently. The light-weight-pig group had a more pronounced response to the DON-contaminated corn than did the heavy-pig group. The light-weight group had a clear benefit from Defusion for both DON-contaminated corn sources. The benefits were evident during the first week of the test and continued throughout the trial. There was no response to the other two products. In the heavy-pig group the same trends occurred but the results were less dramatic.