Analysis of mycotoxins in feed

Is it necessary to test each ingredient in the ration individually?

Depending on the type of ration served, that is, a total mixed ration (TMR) or a ration of concentrates and forages distributed separately, a sampling and analysis strategy can be chosen to limit unnecessary efforts and costs. For example, for TMR, it may be advisable to proceed in stages (Figure 9). If the result is negative for the presence of mycotoxins, the analysis of each ingredient will not be necessary.

Figure 9. Sampling strategy based on the type of ration

How to ensure the sample taken is representative ?

After determining the relevance of an analysis and targeting the feeds to be submitted as a priority, the sampling stage must be carried out according to standard practice. The quality of the sampling impacts directly the accuracy and representativeness of the laboratory results. As shown in Figure 10, mycotoxin contamination is not necessarily uniform in the same batch of feed.

Figure 10. 

To reflect reality as closely as possible, the sample must be composed of several subsamples taken from different meals or batches, as the case may be. In other words, taking a single “handful” of feed in a single step is not adequate.

Feed sampling procedures

Recommended sampling procedures differ depending on the moisture content of the feed. To ensure adequate preservation of samples from the time of collection to arrival at the laboratory, it is important to select the appropriate protocol for each food (Table 1).

Table 1. Choice of sampling protocol according to the moisture content of the feed to be tested

Protocol 1: feeds at <12% moisture 

e.g. dry grains, protein supplements, dry hay and concentrates

  1. When taking feedback from storage for meal preparation, take 8 to 12 subsamples of each suspect ingredient at random from the total mass.* Repeat for at least 3 to 5 meals on different days.
  2. For each meal, thoroughly mix all subsamples collected to create a 500 g composite sample.
  3. Store the composite sample in a clean, double-ply, stapled paper bag in the refrigerator.
  4. Combine all composite samples from step 2 (at least 3 to 5) into a single 500 g composite sample to send to the laboratory.  
  5. Repeat step 4 to provide an additional sample for possible cross-validation needs. Store in the refrigerator.

Protocol 2: feeds at >12% moisture

e.g. TMR, silages, wet grains

  1. At feed-out* or just before serving the ration, take 8 to 12 subsamples and repeat for at least 3 to 5 feedings.* Recommended sampling procedures for forages are described in the GUIDE SUR L’INTERPRÉTATION DES ANALYSES D’ENSILAGES (in French only) and are presented as a checklist and video for each type of storage.
  2. For each meal, combine and thoroughly mix the collected subsamples to create a 750 g composite sample.
  3. Store the composite sample in a clean, resealable plastic bag (Ziplock style), expel as much air as possible and seal the bag.
  4. Thaw and mix the 3-5 samples from step 2 to create 3 final 1 kg composite samples in a sealed plastic bag for analysis of mycotoxins, of dry matter (needed to establish mycotoxin concentration on a DM basis), and a reserve sample for possible additional analysis.
  5. To prevent the growth of new molds and yeasts, store wet food samples in the freezer and ship in an insulated bag with cold packs.

* Make sure you wear clean gloves for each sampling.

How to choose the right testing method?

Different methods are used in the laboratory for the analysis of mycotoxins in feeds (Table 2). No single method is perfect in all circumstances, and the most comprehensive are obviously the most expensive. The type of feed, the speed of the test, the cost, the accuracy of the results and the purpose of the analysis will influence the chosen method. In general, the more reliable and detailed results the method chosen provides, the more informed decisions can be made about what actions to take to control and prevent mycotoxin-related problems in the herd. And since co-contamination is common and mycotoxin concentrations above the threshold of concern (Table 3) influence the probability of experiencing health and productivity issues, quantitative methods and methods that can detect more than one mycotoxin at a time are preferred.

Table 2. Comparison of mycotoxin analysis methods available in laboratory

MethodType of feedProsConsCost estimate
ELISA1Grains only

Fast

Affordable

Detects only one mycotoxin at a time

Cannot be used for silage and hay

Does not provide a quantitative value

$35-50/mycotoxin
HPLC2

Grains

Silage

Hay

Provides quantitative values

Can detect more than one mycotoxin

High cost$100-150/
1-10 mycotoxins
LC/MS/MS3

Grains

Silage

Hay

Provides quantitative values

Detects several mycotoxins per test

High cost$140-350/
10-50 mycotoxins
HPLC of the serum or plasmaSerum or plasmaDetects deoxynivalenol (DON) and its metabolite (DOM-1)Metabolic variations of the animal$75/DON + DOM-1

1ELISA: double antibody enzyme immunoassay; 2hplc: high performance liquid chromatography; 3lc/ms/ms: liquid chromatography combined with mass spectrometry

The ELISA method

To detect the presence of the most common mycotoxins in grains – for example DON and ZEA – the ELISA method is the fastest and most affordable option. However, if the exact concentration of mycotoxins in the feed is required, then one of the other two methods should be used. Due to its heterogeneous and organic acid-rich composition, the ELISA method is not suitable for the analysis of silage.

The HPLC and LC/MS/MS methods

Although more expensive, high performance liquid chromatography (HPLC) has the advantage of being suitable for all types of feeds. In addition, it can provide a quantitative measurement of mycotoxins, but only for about ten of them. For a more thorough analysis, the HPLC method combined with mass spectrometry (LC/MS/MS) is preferable. Although this option is the most expensive, it is also the most precise and exhaustive. Beyond the choice of the analytical method, it is important to remember that the reliability and validity of the results depends greatly on the quality of sampling.

What are the contamination levels of concern in feeds?

The presence of mycotoxins in feed is common, but toxic effects are generally only apparent above a certain threshold concentration in the ration.

Table 3 shows the concentrations at which noticeable signs can be expected, depending on the type of mycotoxin and the stage of development of the animal.

Table 3. Concentration thresholds of concern (PPM) on a dry matter (DM) basis for major mycotoxins in dairy and beef cattle feed

Mycotoxins Development stage Maximum concentration (PPM) on a DM basis Reference
Dairy cattle Beef cattle
Deoxynivalenol (DON) and its derivatives
Lactation 1 5 FDA, EC, CFIA
Calf < 3 months 2 2 FDA, EC, CFIA
Calf > 3 months 5 5 FDA, EC, CFIA
Fumonisins (FUM)
Lactation 30 30 FDA
Calf < 3 months 10 10 FDA
Calf > 3 months 30 60 FDA
Zearalenone (ZEA)
Lactation 2-4 5-10 MO
Calf < 3 months 0.5 0.5 EC
Calf > 3 months 0.5 0.5 EC
T2/HT-2
Lactation 0.1 0.1
Calf < 3 months 0.025 0.1 CFIA
Calf > 3 months 0.025 0.1 CFIA

PPM : Part per million ; CFIA : Canadian Food Inspection Agency ; FDA: U.S. Food and Drug Administration ; EC : European Commission; MO : University of Missouri Veterinary Medical Diagnostic Laboratory ; ND : North Dakota State University Veterinary Diagnostic Laboratory

These concentration thresholds of concern make it possible to determine the extent of the contamination of a feed, to assess the risk that it poses to the health and productivity of the animals and to decide on the actions to be taken, if necessary.

This is why it is relevant to choose a testing method that not only identifies the mycotoxins involved, but also assesses the extent of their presence in the feed.

Since several factors influence the onset and intensity of toxic effects, it is possible to detect signs at lower concentrations. Likewise, the absence of signs is possible even when the measured amount is above the threshold of concern.

This project is funded through the Innov’Action agri-food program under the Canadian Agricultural Partnership, as part of an agreement between the governments of Canada and Quebec.

Share

Share on facebook
Share on twitter
Share on email

By Younès Chorfi, Maxime Leduc and Julie Baillargeon

Leave a Reply

Your email address will not be published. Required fields are marked *