Moulds and mycotoxins – sampling feed to test for mycotoxins


Source: Ontario Ministry of Agriculture, Food and Rural Affairs

What to sample for mycotoxins tests:

  • If feeding a total mixed ration (TMR), sample it for mycotoxins first.
  • If the TMR test result is positive then individually sample suspect ingredients including silages and concentrates.
  • If grain and forages are fed separately, then test them individually.
  • Sample individual suspect ingredients.
  • Sample concentrates.

When to test for mycotoxins:

Mycotoxins and some moulds are not visible to the eye and require laboratory tests to determine if toxins are present. Testing should be done when any one of the following situations arise:

  • When mouldy feeds are being fed and/or mouldy feeds make up a significant proportion of the ration.
  • When substantial changes in production and health are observed in a large proportion of the animals on feed.
  • Decline in performance and health that cannot otherwise be readily explained and symptoms typical of the effects of mycotoxins are present.

Wet and dry feeds need to be sampled and handled differently

  • Dry feeds are any feeds with 12% moisture or less. For example dry grains, protein supplements, dry hay and concentrates.
  • Wet feeds are any feeds with 15% moisture or greater. For example TMR, corn silage, haylage and high moisture grains.
  • Feeds between 12 and 15% moisture are a grey area and it is a judgement call as how best to handle them. When in doubt, it is safer to handle these as a wet feed.

Sampling method #1 for dry feeds (adapted from Penn State University)

  • Take eight to 12 samples at each of three to five feedings or feed removal from storage.
  • Mix the sub-samples well, take a 500 gram (g) composite sample and store in a cool dry place.
  • Combine at least three to five composite samples, mix well and take a 500 g sample for submission to the laboratory.
  • Store all samples in clean double layer paper (grocery store) or cotton bags.
  • Keep an additional 500 g sample for confirmation or other analyses.

Sampling method #2 for dry feeds (adapted from Penn State University)

  • Take 12 to 20 stream samples from an entire delivery or 12 to 20 deep probe samples from a bin. Include samples from the sides of bins or edges of storage where mould is likely to occur.
  • Mix samples as above and take a final 500g composite sample for submission to the laboratory.
  • Place sample in a clean double layer paper or cotton bag (available at the grocery stores) and keep in a cool dry place. Do not use plastic bags with dry samples.

Sampling method for wet feeds (adapted from Penn State University)

  • Take 8 – 12 sub-samples of wet feeds at each of 3 – 5 feedings or feed removal from storage.
  • Mix the sub-samples well and take a 750 – 1000g composite sample.
  • Place the composite sample in a thick or double plastic bag. Pack the sample tightly, forcing out as much air as possible and seal well.
  • Store samples in the freezer till the final composite is prepared.
  • Combine the 3 – 5 composite samples and mix them well. Take a final 1kg composite sample to submit to the laboratory for mycotoxin analysis.
  • Take a second 1kg sample to submit to a laboratory for moisture analysis.
  • Take a third 1 kg sample and store in the freezer for confirmatory or other analyses as required.
  • Always store wet samples in the freezer till they are submitted for analysis.
  • Always ship wet samples frozen, use an insulated bag with ice packs. If possible hand deliver samples to the laboratory as soon as possible after the final composite sample is prepared and frozen.

Problems with sampling for mycotoxin analysis

  • Mycotoxins are often present in very small amounts: parts per million (ppm) and parts per billion (ppb) are detected in labs
  • Mycotoxin content is not necessarily related to the amount of mould present.
  • Mycotoxins are not necessarily evenly distributed in the affected feed. Isolated pockets may exist.
  • Some mycotoxins could develop during lengthy transit to the laboratory.
  • Some mycotoxins continue to be produced in storage, particularly if unfavourable storage conditions exist.

Laboratory Analysis

  • Discuss with your nutritionist which mycotoxins to test for in the samples taken
  • Sampling must be random but at the same time be aware that moulds tend to be at the sides of bins so some samples must be included from these parts of the bin.
  • Agri-Food Laboratories recommends taking a composite sample of 1 kg (1,000g) for submission to the laboratory for mycotoxin analysis.

Always collect a number of samples (up to 10 kg total or approximately 20 pounds), mix and sub-sample, store in clean paper or cotton bags, keep in cool dry place and get to the lab as soon as possible. The shorter the delay between sampling and analysis, the more reliable the results are likely to be.

Author: Tom Wright – Dairy Cattle Nutritionist/OMAFRA


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