Managing aflatoxin M1 levels in milk demands coordinated


Aflatoxins are a group of mycotoxins produced by Aspergillus moulds.  Aflatoxins can be produced both in the field while the crop is under growth as well as during harvesting, storage and transport of raw materials and animal feeds.  Aflatoxin B1 (AFB1) is the most well-known and researched mycotoxin due to its highly toxic and carcinogenic effects both for farm animals and humans.  It is also the most common mycotoxin among the various aflatoxins produced.


Among all the mycotoxins, AFB1 is the most problematic to dairy animals due to the bioconversion of aflatoxin B1 to aflatoxin M1 (AFM1) in liver and then the excretion into milk.  Aflatoxin M1 can cause liver cancer in animals and humans and hence regulated in most countries.  The degradation of AFB1 is minimal in the rumen.  On top of this AFM1 is as toxic as AFB1 to dairy animals.

Impact of aflatoxins in dairy animals:

  • Transference of residues into the milk (AFM1)
  • Reduction in milk yield and performance
  • Reduction in microbial protein synthesis
  • Reduction in immunity – Increase susceptibility to infection, milk quality
  • Liver damage
  • Carcinogenicity

According to the European Union regulatory authorities, AFM1 levels in milk for human consumption cannot exceed 0.05 parts per billion (ppb) which means complete feedstuffs are limited to 5 ppb when used in dairy diets.  FDA (US) regulations are 10 times more relaxed than EU with AFM1 levels not to exceed 0.5 ppb in milk.  India follows FDA limits.  Any milk that contains AFM1 above the regulatory limit is considered unfit for human consumption and should be discarded.

Monitor the risk and take action

The economic impact of aflatoxins in the dairy industry is highly significant.  An integrated approach including a proactive monitoring action plan for forages and grains and farm management can prevent such economic losses.  If a dairy farmer found out that his feedstuff is contaminated with mould and mycotoxins, here are five steps that you can take to protect not only the health of your animals, but also the safety of your milk and human health.

Work with your milk company, nutritionist and feed supplier

Having a positive result for AFM1 in milk is a very frustrating experience but can be solved rapidly with an integrated and consistent team approach.  The available technology is able to detect AFB1 in the cereals and feed as well as AFM1 in the milk allowing for a better determination of the source and early diagnosis of the risk.

Understand the level of contamination in milk

The primary step you can take to protect your milk supply and start to define your action plan is to monitor aflatoxin levels in milk.  A dairy cow secretes about 1% to up to 6% of the aflatoxin consumed in the feed into the milk.  As aflatoxin M1 in milk is quite stable, the level in milk will help you to back calculate the levels of total aflatoxin in the feed.

Contribution of feedstuffs

Monitoring of grains is very critical as this fraction of the diet contributes the most to the total AFB1 intake.  Both silages and corn grain can harbor aflatoxin, but don’t forget to include by-products and other purchased feedstuffs which were originated in heat-stressed areas or are stored for longer periods of time after the analyses. (Ex: Some corn by-products as corn distiller grains and gluten feed can contain up to 3 times the level of aflatoxin in the original corn raising the total aflatoxin levels in the total diet).  A special attention should be given to the ideal method of silage production as well as TMR protection.

Critical points of contamination

The identification of the critical risk points for mould growth and mycotoxin contamination in your dairy operations, and the good management of silage and feed can prevent additional mycotoxin production.  Special and the more frequent monitoring of high moisture raw materials should be done to avoid rapid mould growth and mycotoxin production.  Identifying the initial symptoms in dairy animals associated to mycotoxin contamination can help you define the preventive strategy.

Take action

Since AFB1 levels in feed of less than 20ppb is needed to control AFM1 in milk, controlling AFB1 in feed is very critical.  Appropriate actions need to be taken in this regards:

  • Reduce the use of contaminated feed – Once you identify the main ingredients which are contaminated
  • Use alternative clean forages and raw materials – This can be accomplished with alternative available forages and grains, such as alfalfa hay/silage, wheat, barley, commercial protein supplements which are tested negative for aflatoxin.  Make sure you work with your nutritionist to maintain energy and protein balance to meet the cow’s maintenance and production requirements.
  • Use a proven large spectrum mycotoxin binder.  Supportive strategies as the use of a mycotoxin binding product, should be added to the feed to alleviate the effects of mycotoxins to the animals and to reduce the transfer of aflatoxin M1 to the milk.  Founded on a high selection in vitro research followed by extensive in vivo validation and a strict quality control process, TOXO-MX, is a smectite-based clay which has been proven to be highly effective in mycotoxin control due to a high capacity, high affinity and high selectivity towards Alflatoxin B1.


To conclude, aflatoxin M1 presence in milk is of public health concern and hence all the efforts should be made to keep the levels below the recommended levels. Such efforts need an intergrated approach and all the critical points of entry of aflatoxin B1 into feed chain should be monitored and controlled.  The bioconversion of aflatoxin B1 to M1 in the liver depends on many factors and in India it is recommended to keep M1 levels below 0.5 ppb.