mycotoxins in animal production

The significant research focus on mycotoxins in recent years has dramatically increased the awareness and understanding of the nature, occurrence and impact of mycotoxins on modern animal production.

Without any doubt, mycotoxins truly represent an unavoidable risk because of the large spoilage and unpredictable contamination pattern associated with mycotoxin biosynthesis, which is largely due to environmental factors.

In this context, analytical tools using a holistic approach are needed to understand multiple mycotoxin contamination patterns, taking into account the diversity of feed material used in animal feeding strategies. The application of new technology can then be used as surveillance radar to monitor the overall levels of mycotoxins present that can, in turn, be used to estimate associated risks. 

It has been referenced in the scientifi c literature and with the analytical advances made so far that 500 metabolites could be referenced as mycotoxins.

However, in a practical situation, between one and six major mycotoxins are monitored to address the threat posed by the toxic secondary metabolites issued from various fungal organisms because of the lack of an analytical approach to cover a wider range of toxins.

In the U.S., afl atoxins, deoxynivalenol (DON — or vomitoxin), fumonisins, T-2 toxin and zearalenone (ZEA) are often tested to comply with the regulatory limits or recommendations in different regions. Thin-layer chromatography and enzyme-linked immunosorbent assays are the common methods employed for these tests as rapid techniques to evaluate the contamination of raw material according to defi ned sampling plans.

Although these methods are useful for the instant monitoring of incoming raw materials, they do not instill a good appreciation of the overall mycotoxin challenge coming from the simultaneous presence of multiple groups of mycotoxins in a feed material.

The microbial population has also been estimated to evaluate the overall presence of toxinogenic species associated with mycotoxin production. However, only poor correlations were found between mold and mycotoxin presence and contamination levels.

Understanding mycotoxin occurrence in a more holistic manner has obvious advantages. Since one mold can produce several mycotoxins and several mold species can be present in a given feedstuff, it is expected that a substantially larger variety of mycotoxins potentially could be present than are currently being tested for.

To give an example, if a sample contains DON, it is likely that it may also contain several other DON-related metabolites, including 3-acetyl-DON, 15-acetyl-DON and fusarenon-X, as well as masked forms of DON such as DON-3-glucoside. These toxins contribute to the toxicity of DON since deacetylation or deglycosilation are occurring in vivo and, as a consequence, are increasing the absolute amount of DON molecules present.

Not taking into account the incidences of these metabolites could result in underestimating the DON contribution levels and associated toxicity. Ultimately, omitting such a determination could provide an inaccurate estimation of the true level of mycotoxin that is contaminating a feed and could contribute to the appearance of unsuspected and/or unaccounted animal production issues or pathologies.

The ability to precisely analyze as many toxins as possible at a reasonable cost and in a timely manner could assist producers in better handling mycotoxin issues. 

Alltech has developed the 37+ Program to assist with the detection of more than 37 mycotoxins using a holistic approach. The objective of the program is to evaluate U.S. feedstuffs for multiple mycotoxins using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) methodology developed at Alltech's global research headquarters in Kentucky.

This approach represents a breakthrough compared to other commercial methods that have a very narrow window of mycotoxin targets considering the important variety of mycotoxins that can potentially contaminate a feed material.

Even more essential is that the methodological advances using UPLC-MS/MS can account for mycotoxin presence simultaneously in a more selective and sensitive way and in multiple feed matrices.

Of course, the dynamic range of activity for each toxin present in feed varies quite signifi cantly. Mycotoxin levels need to be placed in the context of the practical concentrations that can induce a decrease in animal performance and/or pathological issues. 

One hundred twenty-eight samples from the 2011 harvest collected from different regions of the U.S. were subjected to the mycotoxin analysis. The major criteria for selecting these mycotoxins included their prevalence in the fi eld as well as their established toxicological impact on animals.

For ease of interpretation of the total toxicity to the animals, toxins were placed into groups according to their chemical properties and effects (Table 1). Sample names and numbers are indicated in Table 2.

Only eight samples out of 128 tested presented non-detectable values (below the limit of detection) for all of the mycotoxins, giving 94% detection (Table 3).

Type B trichothecenes were detected in 81% of the samples, followed by fumonisins in 58%, type A mycotoxins in 45% and ZEA in 38% of the samples (Figure, page 20, and Table 4). Afl atoxins, ochratoxins, ergot toxins and other penicillium (silage) mycotoxins were detected in 16- 23% of the samples tested.

When the averages for the entire dataset were calculated, fumonisins were present at the highest concentrations of 16,612 parts per billion, followed by type B trichothecenes at 2,326 ppb and ergot toxins at 972 ppb (Table 4). A maximum concentration for an individual sample was recorded for fumonisins (1,157,644 ppb), followed by ergot toxins (106,284 ppb) and type B trichothecenes (41,356 ppb).

Although the concentrations of other groups of toxins were lower, it should be noted that the concentrations at which each group of toxins become toxic varied quite signifi cantly. For example, the Food & Drug Administration's regulatory limit for afl atoxin B1 is 20 ppb in dairy cows, whereas the DON guideline is 5,000 ppb.

The presence of type B trichothecenes was expected due to temperate weather conditions in the Northeast and the Midwest, which favor the growth of certain fusarium species of molds. Small grains such as barley are known to become contaminated with ergot mycotoxins.

Although fumonisins are commonly seen in corn from the Southwest, they were not expected to be found at such high levels in corn from any of the midwestern states. Fusarium molds capable of producing fumonisins exclusively grow in the fi eld, especially following a warm summer in temperate areas. The presence of predisposing factors such as insect or pest damage, hail or rain at harvest can further increase the incidences of all mycotoxins.

Sincegrains are exported heavily from the Midwest to other regions within and outside the U.S., the chances of multiple mycotoxin contamination of animal feeds in such importing regions increase dramatically. These fi ndings further exemplify the need for not only the analysis of multiple mycotoxins but also the implementation of suitable strategies to counteract multiple mycotoxins. 

Only 6.25% of the tested samples contained no mycotoxins at quantifi able levels (Table 3), and only a single mycotoxin was detected in 7.81% of tested samples.

Table 4 provides detailed mycotoxin analysis for various samples tested. As an example, type B trichothecenes were the predominant mycotoxins found in corn, with 74% of the samples being positive, followed by fumonisins at 51%. Fumonisins were quantifi ed at an average concentration of 49,915 ppb, followed by 2,658 ppb for type B trichothecenes and 235 ppb for type A trichothecenes.

Table 5 provides information on the contribution of mycotoxins from various feed ingredients. 

Use of Alltech's 37+ Program provided a glimpse of the mycotoxin profi le of U.S. feedstuffs. Further data will improve the understanding of mycotoxin prevalence.

The presence of multiple mycotoxins is a common phenomenon in the field, and this can lead to mycotoxin interactions and, ultimately, an increased risk to animal health and performance.

The implementation of a mycotoxin control program based on hazard analysis and critical control point principles for farms and feed mills represents an integrated approach to control mycotoxin challenges.