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Journal of Animal Science - Animal Nutrition

Evaluation of two mycotoxin mitigation strategies in grow-finish swine diets containing corn dried distillers grains with solubles naturally contaminated with deoxynivalenol1

 

This article in JAS

  1. Vol. 92 No. 2, p. 620-626
     
    Received: Jan 04, 2013
    Accepted: Nov 28, 2013
    Published: November 24, 2014


    2 Corresponding author(s): jfp@iastate.edu
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doi:10.2527/jas.2013-6238
  1. J. F. Patience 2,
  2. A. J. Myers*,
  3. S. Ensley,
  4. B. M. Jacobs* and
  5. D. Madson
  1. Department of Animal Science
    Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames 50011

Abstract

A total of 1,040 growing pigs (initially, 22.9 ± 4.3 kg) were used in a 115-d study to evaluate the effects of 2 mycotoxin mitigation strategies, a preservative blend (PB) and a yeast product (YP), on the growth performance of swine fed diets containing corn dried distillers grains with solubles naturally contaminated with deoxynivalenol (DON). The PB consists of preservatives, antioxidants, AA, and direct-fed microbials and is included in diets to help pigs cope with the toxic effects of ingested mycotoxins. The YP works as an adsorbent to bind and prevent the absorption of mycotoxins in the gastrointestinal tract. Pigs were allotted to pens by initial BW and sex; pens were then assigned to treatments in a randomized block design with initial BW and sex serving as the blocking factors. Pens were randomly allotted to 1 of 4 dietary treatments consisting of a positive control (PC) containing <1 mg kg-1 DON, a negative control (NC) formulated to contain 4 mg kg-1 DON, NC with PB, and NC with YP. From d 0 to 42 and 42 to 84, no effect of diets containing PB or YP were observed for any of the growth criteria evaluated. From d 84 to 115, pigs fed PC or diets containing PB had improved (P < 0.05) ADG compared to pigs fed NC or diets containing YP, whereas pigs fed YP had improved (P < 0.05) ADG compared to those fed NC. Pigs fed diets containing PB or YP had improved (P < 0.05) ADFI and G:F compared to pigs fed NC. Overall (d 0 to 115), pigs fed diets containing PB had improved (P < 0.05) ADG, ADFI, and G:F compared to pigs fed NC. These results indicate that PB may be a suitable mycotoxin mitigation strategy in growing swine fed diets naturally contaminated with DON.



INTRODUCTION

Since the coining of the term mycotoxin in 1962, a considerable investment has been made in researching mycotoxins and different strategies to control their formation in crops and reduce the impact on human and animal health (Bennett and Klich, 2003). Prevention of mycotoxin growth in the field is the ultimate goal, but under certain environmental conditions, the development of mycotoxins is unavoidable. Feed additives, such as antioxidants, AA, or adsorbents, may be useful in preventing the decrease in growth performance often observed when pigs are fed diets containing greater than 2 mg kg-1 deoxynivalenol (DON; Van Heugten, 2001; Kolossova et al., 2009). Mycotoxin mitigation strategies such as nutritional manipulation and the use of adsorbents have become of interest because of their ease of use, and a preservative blend (PB; Defusion, Akey, Lewisburg, OH) and yeast product (YP; Integral, Alltech, Nicholasville, KY) are 2 such strategies. The PB is added to contaminated diets and is thought to decrease the negative effects of mycotoxicosis by providing a proprietary mixture of preservatives, antioxidants, AA, and direct-fed microbials. The YP is derived from the enzymatic hydrolysis of whole Saccharomyces cerevisiae cells and is hypothesized to work as an adsorbent by binding mycotoxins and preventing their absorption in the gastrointestinal tract.

The majority of research on mycotoxin mitigation strategies has been done in cereal grains and not their by-products, and to date, there seems to be no peer-reviewed literature evaluating the effects of mycotoxin-contaminated dried distillers’ grains with solubles (DDGS) on pig performance. Increasing inclusion rates of by-products, such as DDGS, in modern swine diets makes this an important topic to address. The objective of this study was to help fill the void of knowledge surrounding the effects of DON-contaminated DDGS on pig growth performance and the efficacy of 2 mycotoxin mitigation strategies in preventing decreased growth performance.


MATERIALS AND METHODS

All experimental procedures adhered to the ethical and humane use of animals for research and were approved by the Iowa State University Institutional Animal Care and Use Committee (number 3-10-6910-S).

Animals, Housing, Diets, and Experimental Design

A total of 1,040 growing pigs (Danbred 600 [DNA Genetics Columbus, NE] × Newsham NC32 [Newsham Choice Genetics, West Des Moines, IA]) with an initial BW of 22.9 ± 4.3 kg were used in a 115-d study. The pigs were allotted to pens by initial BW and sex. Pens were then assigned to treatments in a randomized block design with both initial BW and sex serving as blocking factors. Pens within the same barn were randomly allotted to 1 of 4 dietary treatments (Table 1). There were 26 pigs per pen with 10 pens per treatment (5 pens of barrows and 5 pens of gilts).


View Full Table | Close Full ViewTable 1.

Ingredient and nutrient composition of the experimental diets1

 
Item Phase 1 Phase 2 Phase 3 Phase 4 Phase 5 Phase 62
Ingredient, %
    Corn 57.04 63.24 61.50 63.50 65.65 65.05
    Soybean meal, 46.5% CP 19.75 13.85 10.25 8.25 6.20 6.90
    DDGS3 20.00 20.00 25.00 25.00 25.00 25.00
    Animal-vegetable blend4 0.60 0.50 1.00 1.00 1.00 1.00
    Calcium carbonate 1.35 1.35 1.25 1.30 1.25 1.25
    Salt 0.40 0.35 0.40 0.40 0.40 0.40
    Trace mineral premix5 0.10 0.10 0.10 0.10 0.08 0.08
    Vitamin premix6 0.05 0.05 0.05 0.05 0.04 0.04
    l-Lys 0.47 0.41 0.38 0.34 0.32 0.23
    l-Thr 0.07 0.05 0.02
    Met premix7 0.07 0.01
    Copper sulfate, 25.2% Cu 0.05 0.05
    Zinc bacitracin8 0.02 0.02 0.02 0.02
    Phytase9 0.03 0.02 0.02 0.02 0.01 0.01
    Microbial feed additive10 0.02 0.02 0.02 0.02 0.02 0.03
    Total 100 100 100 100 100 100
Calculated analysis
    Standardized ileal digestible AA, %
        Lys 1.10 0.91 0.82 0.74 0.67 0.63
        Met + Cys:Lys 57 58 62 67 70 78
    Thr:Lys 59 61 61 62 63 70
    Trp:Lys 15 15 15 15 15 17
    Total Lys, % 1.22 1.02 0.92 0.84 0.77 0.71
    CP, % 19.27 16.92 16.39 15.6 14.77 14.97
    ME, kcal/kg 3,190 3,201 3,221 3,227 3,234 3,232
    Ca, % 0.61 0.59 0.54 0.56 0.53 0.53
    P, % 0.42 0.4 0.41 0.41 0.4 0.4
    Available P, % 0.31 0.29 0.26 0.26 0.24 0.23
1Four experimental diets were fed: positive control containing less than 1 mg kg-1 deoxynivalenol (DON), negative control containing 4 mg kg-1 DON, negative control diet plus Defusion (Akey, Lewisburg, OH), and negative control plus Integral (Alltech, Nicholasville, KY.) Defusion was added at the expense of corn at the rate of 0.25% for phases 1 and 2 and 0.50% for phases 3, 4, 5, and 6. Integral was added at the expense of corn at a rate of 0.1% for phases 1 and 2 and 0.2% for phases 3, 4, 5, and 6. Inclusion of the Defusion and Integral products for the respective phases was based on the respective manufacturers’ recommendations.
2Each phase was fed in meal form for 21 d with the exception of phase 6, which was only fed for 10 d due to a shortage of contaminated dried distillers grains with solubles (DDGS).
3Clean DDGS (DDGS-corn LP, Goldfield, IA) and contaminated DDGS (Poet, Manchester, IN) source. Clean (0.81 mg kg-1 DON) and contaminated DDGS (18.6 mg kg-1 DON) were used at the same level of inclusion in the positive and negative control diets, respectively.
4Lipid source.
5Provided per kilogram of complete diet: 75 mg Zn from zinc oxide, 60 mg Fe from ferrous sulfate, 3 mg Mn from manganese oxide, 4.5 mg Cu from copper sulfate, 210 µg I from ethylenediamine dihydriodide, and 300 µg Se from sodium selenite.
6Provided per kilogram of complete diet: 2,500 IU vitamin A, 450 IU vitamin D, 150 IU vitamin E, 1.2 mg menadione, 9.6 mg niacin, 3 mg riboflavin, 9.6 mg d-pantothenic acid, and 15 µg vitamin B12.
7Alimet (Novus International Inc., St. Charles, MO) supplies 88% dl-2-hydroxy-4(methylthio) butanoic acid.
8Albac 50 (Pfizer Animal Health, New York, NY).
9OptiPhos 2000 (Enzyvia LLC, Sheridan, IN) provided 600, 400, and 200 phytase units/kg of final diet in phases 1, 2 to 4, and 5 to 6, respectively.
10DSM Nutritional Products (Heerlen, The Netherlands).

The study was conducted at a 1,100-head commercial finishing facility in central Iowa (Iowa Select Farms LLC, Iowa Falls, Iowa). The facility was composed of 5 curtain-sided finishing barns that were naturally ventilated. Pens had fully slatted concrete floors and provided approximately 0.63 m2 floor space per pig. Each pen contained a dry feeder and 2 nipple waterers, allowing pigs ad libitum access to feed and water for the duration of the study. The facility utilized a computerized feeding system (FeedPro; Feedlogic Corp., Wilmar, MN) that both recorded and delivered diets to pens as specified.

Dietary treatments consisted of a positive control diet containing corn-soybean meal and clean DDGS with <1 mg kg-1 dietary DON (PC), a negative control diet formulated to contain 4 mg kg-1 dietary DON from a contaminated DDGS source (NC), and the NC diet with PB or YP. Pigs were fed their respective diets in meal form over 6 phases. Each phase was approximately 21 d in length, with the exception of phase 6, which was only 10 d because of a shortage of contaminated DDGS. The diets were formulated to meet or exceed NRC (1998) requirements for 20- to 120-kg pigs.

Data Collection and Analyses

Average daily gain, ADFI, and G:F were determined by weighing pigs and measuring feed disappearance on d 0, 21, 42, 63, 84, 105, and 115. Feed samples from each treatment were attained from every feed delivery. Feed samples from phases 2, 3, and 5 were submitted to the Iowa State University Veterinary Diagnostic Laboratory and analyzed for the presence of aflatoxin B1, B2, G1, G2, DON, T-2 toxin, fumonisin B1, zearalenone, and ochratoxin (Table 2). To maintain consistency and ensure that diets contained the desired level of DON, corn and 2 sources of DDGS were analyzed for mycotoxin content before use in the dietary treatments (Table 3).


View Full Table | Close Full ViewTable 2.

Mycotoxin analysis of experimental diets (mg kg-1)1

 
PC2
NC3
PB4
YP5
Item Phase 2 Phase 3 Phase 5 Phase 2 Phase 3 Phase 5 Phase 2 Phase 3 Phase 5 Phase 2 Phase 3 Phase 5
Deoxynivalenol 0.2 0.5 0.7 3.7 5.7 5.2 4.6 5.1 4.5 0.25 5.4 5.6
Zearalenone6 0.1 0.1 ND 0.4 0.6 0.4 0.4 0.5 0.5 ND 0.6 0.6
Fumonisin B16 ND 0.4 0.2 0.5 0.7 0.8 0.5 1.2 0.7 ND 1.3 1.1
1Feed samples from each treatment were obtained from every feed delivery, and samples collected during phases 2, 3, and 5 were sent to the Iowa State University Veterinary Diagnostic Laboratory (Ames, IA) and were analyzed for aflatoxin B1, B2, G1, G2, vomitoxin, T-2 toxin, fumonisin B1, zearalenone, and ochratoxin. Analytical values for mycotoxins not listed were all below detectable concentrations.
2Positive control (<1 mg kg-1 deoxynivalenol).
3Negative control (4 mg kg-1 deoxynivalenol).
4Negative control + preservative blend (Akey, Lewisburg, OH).
5Negative control + yeast product (Alltech, Nicholasville, KY).
6ND: measured but not detected (zearalenone, <0.1 mg kg-1; and fumonisin, <0.1 mg kg-1).

View Full Table | Close Full ViewTable 3.

Effects of deoxynivalenol (DON)-contaminated dried distillers’ grains with solubles (DDGS) and efficacy of mycotoxin binders on finishing pig performance1

 
Item PC2 NC3 PB4 YP5 SEM P-value
BW, kg
    d 0 22.71 22.82 23.23 22.79 0.93 0.49
    d 21 36.88 35.75 36.35 35.82 1.17 0.15
    d 42 52.58 50.99 51.71 50.98 1.49 0.22
    d 63 71.01a 67.71b,c 69.74a,b 67.35c 1.50 0.004
    d 84 88.06a 84.47b 85.38a,b 83.65b 1.97 0.05
    d 105 102.8a 97.3c 100.6a,b 98.0b,c 2.0 0.005
    d 115 (market) 108.4a 99.1b 106.4a 102.3b 2.3 <0.001
d 0 to 42
    ADG, kg 0.71a 0.67b 0.68b 0.67b 0.02 0.05
    ADFI, kg 1.45a 1.37b 1.39b 1.37b 0.03 0.01
    G:F 0.508 0.510 0.506 0.510 0.009 0.97
d 42 to 84
    ADG, kg 0.84 0.80 0.80 0.79 0.02 0.11
    ADFI, kg 2.25a 2.10b 2.15a,b 2.10b 0.05 0.01
    G:F 0.377 0.381 0.376 0.370 0.007 0.66
d 84 to 115
    ADG, kg 0.63a 0.39c 0.65a 0.56b 0.03 <0.001
    ADFI, kg 2.18a 1.85c 2.15ab 2.06b 0.05 < 0.001
    G:F 0.292a 0.200b 0.302a 0.269a 0.023 <0.001
d 0 to 115
    ADG, kg 0.75a 0.66c 0.72a 0.69b 0.01 <0.001
    ADFI, kg 1.96a 1.79c 1.89a,b 1.85bc 0.04 0.001
    G:F 0.381a,b 0.372c 0.383a 0.375b,c 0.003 0.02
a–dWithin a row, values not sharing a common superscript differ significantly (P < 0.05).
1A total of 1,040 growing pigs (initial BW, 22.9 kg) were used in a 115-d study to determine the effects of DON-contaminated DDGS and efficacy of mycotoxin binders on finishing pig performance. Pens were randomly allotted to 1 of 4 dietary treatments with 26 pigs per pen and 10 pens per treatment.
2Positive control (<1 mg kg-1 DON).
3Negative control (4 mg kg-1 DON).
4Negative control + preservative blend (Akey; Lewisburg, OH).
5Negative control + yeast product (Alltech; Nicholasville, KY).

Statistical Analysis

Data were analyzed as a randomized block design using the PROC GLIMMIX procedure of SAS (SAS Inst. Inc., Cary, NC). The pen was used as the experimental unit, and initial weight and sex were used as blocking factors. Results were considered significant at P ≤ 0.05 and were considered a trend at P ≤ 0.10.


RESULTS

The PC was formulated to contain less than 1 mg kg-1 DON, whereas the NC was formulated to contain 4 mg kg-1 DON. The analysis of feed from phases 2, 3, and 5 showed that the PC reflected formulated values with less than 1 mg kg-1 DON, whereas the NC diets had slightly greater than formulated values of 5 mg kg-1 DON (Table 2). The dietary treatments containing either PB or YP were formulated to have 4 mg kg-1 DON. However, analyzed DON content of the YP diets during phase 2 was 0.25 mg kg-1, which was much lower than anticipated.

No effects of treatment on BW were observed on d 0, 21, and 42 (Table 1). However, on d 63, pigs fed PC had heavier BW (P < 0.05) compared to pigs fed NC diets or diets containing YP, whereas pigs fed diets containing PB were heavier (P < 0.05) in BW when compared to pigs fed diets containing YP. Pigs fed the PC diets were heavier (P < 0.05) in BW on d 84 compared to pigs fed NC or YP diets, with pigs fed diets containing PB being intermediate. Pigs fed PC or PB diets had heavier (P < 0.05) d 105 weights compared to those fed NC. Furthermore, pigs fed PC or PB diets had heavier (P < 0.05) d 115 weights compared to pigs fed NC or YP diets.

From d 0 to 42, pigs fed the PC diets had increased (P < 0.05) ADG and ADFI compared to those fed NC, PB, or YP diets. No effect of treatment was observed for feed efficiency during this period. From d 42 to 84, no effects were observed for ADG or G:F. However, pigs fed the PC diet had increased (P < 0.05) ADFI compared to pigs fed the NC or YP diets.

From d 84 to 115, pigs fed PC or PB diets had improved (P < 0.05) ADG compared to pigs fed the NC diets or YP diets, whereas pigs fed diets containing YP had improved (P < 0.05) ADG compared to those fed NC. An increase in ADFI (P < 0.05) was observed in pigs fed the PC diet compared to pigs fed the NC or YP diets. Furthermore, pigs that received PB or YP diets had improved (P < 0.05) ADFI compared to pigs fed the NC diets. An improvement (P < 0.05) in feed efficiency was observed in pigs fed the PC, PB, or YP diets compared to pigs fed the NC diets.

Overall (d 0 to 115), pigs fed PC or PB diets had increased (P < 0.05) ADG compared to pigs fed the NC diets or YP diets. Additionally, an improvement (P < 0.05) in ADG was observed when pigs were fed diets that included YP compared to those fed NC. Pigs fed the PC or PB diets had increased (P < 0.05) ADFI compared to those fed the NC diets. An improvement (P < 0.05) in feed efficiency was observed when pigs were fed diets containing PB compared to pigs fed the NC or YP diets.


DISCUSSION

A companion paper by Madson et al. (2013) compared the tissues collected from pigs fed either the PC or NC diets. Interestingly, they reported very few pathologies among the treatment groups. No differences in tissue composition and metabolite levels were observed, even when mycotoxicosis was confirmed by assay and by biological outcome in the experiment (Diaz-Llano and Smith, 2006). Because the few changes in metabolites due to fusarium mycotoxicosis are well known (Swamy et al., 2002), there seemed to be little need for us to undertake such measurements herein.

Swine diets should contain less than 1 mg kg-1 DON to circumvent the negative effects associated with overexposure to DON (Thaler and Reese; 2010). Friend et al. (1986) concluded that pigs could be given up to 2 mg kg-1 DON before exhibiting signs of mycotoxicosis, such as decreased feed intake and BW gains. Other mycotoxins detected in the experimental diets were well below the safe levels, which are defined as less than 200 ug kg-1aflatoxin, 1 mg kg-1 zearalenone, and 5 mg kg-1 fumonisins (Thaler and Reese, 2010). Thus, the observed growth responses were likely not affected by these mycotoxins. A greater concentration of DON was used in the current study to elicit a more pronounced response to DON contamination and to ensure that any growth performance responses observed were due to DON in the diet.

Because of the dearth of knowledge surrounding the use of DON-contaminated DDGS in growing swine diets, research has explored the fate of mycotoxins during the ethanol fermentation and distillation processes (Bennett et al., 1981; Bothast et al., 1992; Bennett and Richard, 1996). The general consensus is that very little degradation of mycotoxins takes place during the fermentation and distillation of corn (Wu and Munkvold, 2008). In addition, Bothast et al. (1992) observed that mycotoxins were not found in the distilled ethanol but rather in other fractions that constitute a much smaller portion of the original grain. Consequently, a much greater concentration of mycotoxins was found in DDGS compared to the original grain, with an accepted guideline that mycotoxin concentration of DDGS is 3 times that of the original grain source (FDA, 2006).

Several studies investigated the effects of Fusarium-infected cereal grains on swine (Friend et al; 1986; Smith et al., 1997; Swamy et al., 2002). The aforementioned studies all reported a decrease in feed intake that resulted in reduced BW gains. These findings coincide with the observations from the current study where pigs fed diets containing 5 mg kg-1 DON had decreased feed intake and, as a result, overall lower BW gains. The main difference between the aforementioned studies and the current study was the infected feedstuff used. The current study used DDGS contaminated with DON, whereas the other studies utilized wheat or corn. Despite the differences in the source of DON contamination, declines in both weight gain and feed intake were documented. This indicates that the fermentation and distillation process used in ethanol production does not alter DON in DDGS in a way that affects the pig differently from DON found in other cereal grains.

Numerous DON mitigation strategies, such as microbial or thermal inactivation, physical separation, irradiation, autoclaving, ammoniation, and ozone degradation, have been evaluated (Kolossova et al., 2009). These methods have altered the nutritive value of the feedstuff, have been cost prohibitive and logistically difficult, or have failed to meet government regulations (CAST, 1989; McKenzie et al., 1997; Kolossova et al., 2009). Galvano et al. (2001) stated that the addition of mycotoxin binders to contaminated diets was considered the most promising method to reduce the effects of mycotoxins on animals. They also recognized that increasing levels of protein, energy, and antioxidant nutrients in the diet have been valuable in mitigating the negative effects associated with mycotoxins. The present study evaluated 2 such mitigation strategies, a PB and a hydrolyzed YP. The PB is considered a nutritional intervention and contains preservatives, AA, antioxidants, and direct-fed microbials aimed at circumventing the negative effects associated with exposure to mycotoxins. Conversely, the hydrolyzed YP is derived from the enzymatic hydrolysis of whole Saccharomyces cerevisiae cells and works as an adsorbent to bind mycotoxins and prevent their absorption in the gastrointestinal tract. Both products utilized in the current study are propriety blends, and limited information on their composition was provided to the authors.

Overall, pigs fed diets containing PB had similar feed intake and gain to those fed PC diets. Unlike PB, YP failed to return growth performance to that of pigs fed the PC diets. These findings are consistent with results from a multiuniversity investigation (Mahan, 2010) of 3 mycotoxin mitigation strategies (PB, YP, and Biofix Plus [Biomin USA Inc., San Antonio, TX]) and their ability to negate the adverse effects of DON contamination on nursery pig growth performance. The 2 products used in the present study performed very similarly to the PB and hydrolyzed YP used by Mahan (2010). Mahan (2010) noted an increase in ADG and feed intake when pigs were fed diets containing PB, whereas pigs fed diets containing YP, or a product containing yeast cell walls, natural microbes, and diatomaceous earth (Biofix Plus), did not show any improvement compared with pigs fed the NC. The fact that the YP failed to improve growth performance to that of the PC in both studies does not mean that the product was entirely ineffective; it may not be effective at binding DON but may be of benefit when other mycotoxins are present. Kolossova et al. (2009) stated that efficacy of adsorption appears to be dependent on the chemical structure of both the adsorbent and mycotoxin. Devegowda et al. (1996) observed that a modified mannan oligosaccharide derived from the cell wall of S. cerevisiae had an in vitro binding capacity of 95% for aflatoxin B1, 80% for zearalenone, up to 59% for fumonisin B1, and up to 12% for DON. The ability of S. cerevisiae yeast cell wall components to bind aflatoxin transcends from in vitro to in vivo. Several studies conducted in broilers fed aflatoxin B1 showed improved weight gain and feed intake when birds were supplemented with glucomannan polymer derived from S. cerevisiae cells (Swamy and Devegowda, 1998; Raju and Devegowda, 2000). However, when pigs fed diets contaminated with Fusarium mycotoxins were supplemented with a S. cerevisiae glucomannan polymer, a decrease in weight gain and feed intake was observed. The authors attributed the reduction in performance to test diets containing the glucomannan polymer having greater levels (6 mg kg-1) of DON compared to the NC diet (4.6 mg kg-1). The inability of the YP to restore growth performance back to the levels of the PC diet in the current study could be due to the YP having a lower binding affinity to DON. Furthermore, about 55% of DON is absorbed by the animal, with 90% of DON being absorbed in the proximal small intestine and entering into the bloodstream; DON then reenters the intestinal lumen by passing through the more distal intestinal cells from the blood stream through the basolateral side of the cell (Greiner and Applegate, 2013). Because the majority of DON absorption takes place in the upper gastrointestinal tract, perhaps YP does not have enough time to bind DON and prevent its absorption. This could help explain why nutritional interventions, such as PB, were apparently more effective in mitigating the effects of DON overexposure by helping the animal combat the secondary symptoms associated with mycotoxicosis rather than trying to prevent its absorption.

Unlike YP, PB was able to return growth performance to that of PC. The numerous constituents of PB make the exact mechanism responsible for the improvement in growth performance difficult to define. One component of PB involves antioxidants, such as Se, vitamins (A, C, and E), and their precursors, which act as superoxide scavengers. These antioxidants may decrease the toxic effects of mycotoxins (Galvano et al., 2001). However, the majority of the research on antioxidants and their interactions with different mycotoxins has been conducted either in rodents or with in vitro assays. Whether the contribution of antioxidants improved growth performance in the present study cannot be ascertained by the current results.

The PB also contains additional AA that may help circumvent the decreased performance by providing the pig with additional AA during a time of reduced feed intake. However, it still remains unclear how PB prevented the decline in growth performance commonly associated with DON.

A unique observation from the current study was that pigs across all treatments showed a depression in growth performance from d 84 to 115, with pigs fed NC having the greatest decline in growth performance. Interestingly, pigs fed diets containing YP had greater ADG, ADFI, and G:F compared to pigs fed NC. Furthermore, pigs fed YP during this period had feed intake and G:F similar to pigs fed PC or diets containing PB. The YP’s ability to maintain performance and feed intake similar to that of the PC or PB treatments in the present study is novel when compared to previous work utilizing products similar to YP (Mahan, 2010). In the aforementioned study, pigs fed corn diets containing 3.9 mg kg-1 DON and YP showed no improvements in growth performance from the NC. The present study was conducted from April to August 2010. Therefore, the observed decline in performance observed across all treatments could be attributed to environmental conditions during this period. The Iowa annual weather summary (Northey, 2010) stated that summer 2010 was the warmest summer since 1988, where all but 24 of the 91 d of summer had above-average temperatures with heat indices reaching as high as 46°C during July. Whitlow and Hagler (2012) stated that animals under environmental or production stress could show more pronounced symptoms of mycotoxicosis. In studies with cattle, Bacon (1995) observed a temperature interaction with fescue toxicity. Symptoms were more pronounced during heat stress. Hyun et al. (1998) evaluated the effects of 3 stressors (high ambient temperatures, reduced floor space, and regrouping) alone or in combination on pig growth performance and found that the stressors were additive for feed intake, rate of growth, and feed efficiency. Perhaps, the addition of mycotoxin mitigation strategies (PB and YP) helped alleviate the additional stress of increased ambient temperatures in pigs exposed to DON and prevented further decline in growth performance as observed in those fed the NC diet. Currently, there does not seem to be peer-reviewed literature on the interaction of heat and mycotoxins in swine.

The current study helps to fill a void of knowledge surrounding DON-contaminated DDGS and the efficacy of mycotoxin mitigation strategies on negating the effects of DON in grow-finish pigs in a commercial unit. These results indicate that feeding pigs DDGS contaminated with DON resulted in the same depression of growth performance as in pigs fed other cereal grains contaminated with DON. Furthermore, the PB added to swine diets contaminated with as much as 5 mg kg-1 DON was effective in maintaining growth performance.

 

References

Footnotes


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