How to sample for mycotoxin detection in grain and feed

Monitoring and managing mycotoxin contamination in animal feed are critical to ensuring the health and well-being of livestock and preventing the transfer of these toxins to animal-derived food products.

Manuel Contreras
Technical Support Manager
Juan Fernando Martinez
Account Manager
Agrifirm LATAM

Mycotoxins are toxic substances produced by certain molds (fungi) that can contaminate various agricultural products, including animal feed. The presence of mycotoxins in animal feed can lead to reduced feed efficiency and health issues such as impaired growth, immune system suppression, and reproductive problems.

Monitoring and managing mycotoxin contamination in animal feed are critical to ensuring the health and well-being of livestock and preventing the transfer of these toxins to animal-derived food products.

In this article, specialists from Agrimprove, Agrifirm’s brand of functional feed ingredients, share their knowledge on how to adequately detect the presence of mycotoxins in raw materials and processed feed.

Identifying mycotoxins in grains and feed poses a challenge due to several factors. Here, we explore the key reasons for this difficulty.

1. Uneven Distribution of Mycotoxins
Mycotoxins are not uniformly distributed in grains or feed. Fungi growth occurs selectively, leading to varying toxin levels. This uneven distribution can start in the field and persist during storage in trucks, ships, or compartments.

2. Sampling Errors
Accurate analysis requires proper sampling procedures. If sampling does not represent the entire batch, results may underestimate mycotoxin concentrations. Sampling errors can lead to false negatives, so following correct procedures is crucial.

Good to know: The chances of identifying mycotoxins in feed increase if the samples are taken from feeders inside the farm. This is because the feed has been stored inside the farm silos for about 5 to 7 days, and for about a day in the feeders inside the rearing facility. The longer feed is exposed to the environmental conditions (high moisture and temperature) present in a farm, the greater the chance of identifying mycotoxins.

3. Laboratory Techniques
The choice of laboratory technique impacts results. High Precision Liquid Chromatography (HPLC) is more sensitive than Enzyme-Linked Immunoassay (Elisa), so lower mycotoxin levels can be detected. Advanced techniques – like Liquid Chromatography coupled with Tandem Mass Spectrometry (LC/MS/MS) – offer specificity and speed, while analysing numerous metabolites and mycotoxins simultaneously.

4. Conjugated or Masked Mycotoxins
The presence of these derivatives, formed during plant growth, poses a new challenge. Conventional tests may not detect them due to chemical changes in mycotoxin structures. Enzymes produced by plants during growth contribute to these variations. The mycotoxins adhere to other nutrients, such as sugars (glucose), fatty acids or amino acids.

To determine which ingredients are contaminated, or when mycotoxin levels increase during feed preparation in a feed mill, it is necessary to take samples in the following areas:

1. Trucks or railroad cars
To take samples from trucks or railroad cars that transport the grains to the feed mill:
• Use a bulkhead gauge or probe with a minimum length of 1.5 m, with a minimum of 10 compartments.
• Take samples in the areas marked by X in the truck diagram shown below. The probe should go as deep as possible to obtain product from multiple layers of the load.
• Most modern plants have pneumatic and automatic probes that take the samples directly.
• The more sample points you have, the more accurate the results will be.

2. At the reception area (grains and raw materials)
For effective sampling at the reception area, follow this step-by-step process:
• From the samples taken from the incoming trucks/cars, take 21 sub-samples of 200 g each (4,200 g total).
• Mix these 4,200 g and divide in half (2,100 g).
• Mix and take half again (1,050 g).
• Out of the 1,050 g obtained, send 500 g to the lab for testing.

3. In the feed mill and storage warehouse
During the manufacturing process, take representative samples after grinding and before mixing. Don’t forget to continue sampling the prepared feed while it is in the storage warehouse.
To take ‘dynamic’ or moving material samples during the manufacturing process:
• Drill a hole of approximately 1.5 inch in diameter in the bottom of the conveyor that carries the ground raw material to the storage tanks for mixing.
• Connect a pipe with a stopcock to this hole.
• For every 30 MT that pass, take at least 10 kg of sample by opening the valve and dropping product through the pipe/tube into a sampling container.
• Proceed with the preparation of the sample as explained for the raw material reception area (21 samples of 200 g).

Tip: Make sure the sampling pipe is easily accessible for cleaning. Also, wash and disinfect the sampling containers to avoid contamination.

Sampling points in two types of feed mills

4. From feeders in the farm
After distributing feed on the farm, employ specific methods for accurate sampling. We recommend 2 possible methods for feeder sampling in poultry and pig farms:
• Take a 50 g feed sample for every 100 m2 in poultry farms. In pig farms, take 50 g from each feeder. Mix the samples and divide (as explained above) to obtain a final volume of 500 g for lab testing.
• Divide the house into 10 equal sections and take a 100 g sample from a feeder in each section. Mix the 10 samples of 100 g to obtain 1 kg. Send half of this sample (500 g) to the lab for testing.

Considering the unique challenges associated with mycotoxin detection, proper sampling techniques are crucial to obtaining accurate results. Following these guidelines ensures a comprehensive and representative analysis, contributing to effective mycotoxin management in grains and feed.