#10-079

Complete

Date Full Report Received

02/15/2011

Date Abstract Report Received

02/15/2011

Investigation

Institution:
Primary Investigator:

The 2009 corn crop was one of the worst in recent memory in terms of overall quality and the incidence and levels of mycotoxin contamination. It was a very serious concern to the Iowa pork industry, because corn and corn distillers grains are the main feed staples, and because more than any other species, pigs are particularly susceptible to vomitoxin contamination. In response to the problem, many producers turned to the use of binders added to the feed to protect their animals from mycotoxin-induced losses in performance. However, there is almost no independent information on the effectiveness of these products, some of which add up to $10 to the cost of the feed. The overall objective of this project was to evaluate two mycotoxin binders, in terms of their ability to mitigate the effects of vomitoxin on the growth performance and health of growing/finishing pigs.

A total of 1,036 barrows and gilts were assigned to one of 4 dietary treatments across a 115-day experiment period: a positive control diet using a DDGS source with low levels of DON (~0.8 ppm), a negative control diet using a DDGS source with high levels of DON (~18.6 ppm), and two additional diets containing either Defusion (Akey, Inc., Lewisburg, OH) or Integral (Alltech, Nicholasville, KY) added to the negative control diet. The experiment was conducted in a commercial research barn owned by Iowa Select Farms; research management of the farm was provided by Akey. Pigs were weighed individually at the beginning and end of the experiment and as pen groups in the intermediate periods. Feed was provided as a mash and both feed and water were offered ad libitum. Diets were based on corn and soybean meal, with 20% (phase 1 and 2) or 25% (phase 3 through 6) corn DDGS. Because pigs did not appear to be seriously affected by the DON in phases 1 and 2, the level of DDGS was elevated in all diets to 25%, thereby increasing the level of DON in the negative control diet. Contaminated DDGS ran out prior to the end of the 6th phase, so the experiment was terminated at that time. Thus, carcass information was not recorded, as the pigs had not yet reached market weight.

DON contamination reduced final body weight, ADG, ADFI and feed conversion (P < 0.05). Defusion improved all performance outcomes and resulted in final BW, ADG, ADFI and feed conversion that were not statistically different from the positive control-fed pigs (P > 0.05). The benefit of Defusion was greater in barrows than in gilts. Indeed, gilts failed to respond to Defusion to the same extent as barrows. Defusion also reduced the standard deviation of final BW (P < 0.05), although the magnitude of improvement was small. Integral improved ADG (P < 0.05), but not final BW, ADFI or feed conversion, compared to the negative control-fed pigs (P > 0.05). Integral achieved numerical improvements in final BW and ADFI, but the differences were not statistically significant. The adverse impact of DON-contamination of DDGS on pig performance was clearly demonstrated. The use of mycotoxin binders offers some encouragement to pork producers faced with mycotoxin problems, but there appear to be differences in their effectiveness among products.

In addition to the growth performance component of the study, twenty-four of the pigs on this experiment (negative control group; n=6; positive control; n=18) were sacrificed at the end of the growth phase for detailed pathology evaluation. There is a surprising lack of information on the impact of DON on tissue integrity. Serum was measured at the beginning and conclusion of the study, and all pigs were necropsied and assessed for macroscopic and microscopic lesions in tissues. Liver chemicals were also measured. Bone ash and density were also calculated. Observed differences in serum, macroscopic or microscopic lesions, and bone ash and density were not different between groups. Liver selenium concentrations were significantly decreased (P=0.016) in positive control pigs. Results of this part of the study indicate that there may be few diagnostically relevant changes in swine tissues, but liver selenium concentration can be significantly reduced following chronic DON intoxication. Changes in liver selenium concentrations suggest that adjusting feed selenium concentrations in diets known to be contaminated with DON may alleviate physiological concerns associated with intoxication. However, further studies are required to confirm that the increasing dietary selenium would overcome this pathology.
This experiment provides important information on two levels. In the first instance, this experiment, conducted under commercial conditions, shows that DON in DDGS is a concern for pork producers and will result in economically important losses, just as occurs when we feed DON-contaminated corn. It also shows that mycotoxin binders may provide relief from the effects of DON in pig diets, but not all binders are effective. In this instance, Defusion was effective in reversing about 78% of the reduction in final body weight and 86% of the reduction in feed conversion due to DON. This improvement was statistically significant (P < 0.05). Integral improved growth rate, recovering about 33% of the losses due to DON and this was statistically significant (P > 0.05). While about 34% of the loss in body weight due to DON was recovered by Integral, this benefit did not achieve statistical significance (P > 0.05) so this may not be repeated on individual farms.
This experiment also shows that necropsy is not an effective tool for diagnosing mycotoxicosis due to DON in pigs in the field. There is a suggestion, however, that DON might be responsible for selenium-deficiency related syndromes, although more work is required to confirm this.
An economic analysis of the experiment results was undertaken. Within 4 market ($40, $60, $80 and $100/cwt) and 3 feed ($50, $70 and $90 feed cost/pig) scenarios, the presence of mycotoxins reduced the return over feed by up to $20.68 per pig; even the lowest impact reduced returns by $2.06 per pig. Defusion affected return over feed cost, after including the cost of the product, ranging from a net cost of $0.15 per pig to a net gain of $13.25 per pig. The magnitude of the impact was a factor of market hog prices and feed cost. Integral changed return over feed cost, after including the cost of the product, ranging from a net cost of $1.37 per pig to a net gain of $5.23 per pig. Because neither improvements in market weight nor feed conversion were statistically significant with Integral, the financial benefit must be viewed with great caution. If the numerical increase in body weight and in feed conversion may be due to chance, then so too could be the financial returns.
While mycotoxins were not a problem in the 2010 crop, the results of this experiment will allow pork producers to be much better prepared to deal with DON contaminated feed when it returns the next time.