Aflatoxins(AF) are mycotoxins that are carcinogenic in nature and produced mainly by the Aspergillus species(A. flavours, A. parasiticus). AFs belong to a larger group of toxic compounds only four of which (AFB1, AFG1, AFB2, AFG2) naturally contaminate food. The hydroxymetabolites are AFM1 & AFM2, can be present in milk and milk products when lactating cows ingest contaminated feed, thus posing a risk to consumer health.
Most mycotoxins are found in grains, pasture grass, corn, cottonseed and sometimes in their by products. Also on rare occasions, they are found in soybeans. Peanut products also may be contaminated with AF and result in an AF milk. The fodder which is kept for a long period of time possess chances of Aflatoxin presence.
Long-term or chronic exposure to aflatoxins has several health consequences. It may affect all organ systems, especially the liver and kidneys. Children are more susceptible to aflatoxin exposure, which may leads to stunted growth, delayed development, liver damage, and liver cancer. Aflatoxin B1 exposure results in accumulation of fat and necrosis of liver cells. Ingesting small quantities of the toxins over long period of time causes these health issues. Even the little exposure to aflatoxin can cause nausea, vomiting, abdominal pain etc…
According to FSSAI standards, the permissible limit of aflatoxins in milk is a maximum of 0.5 µg/kg. The use of milk having aflatoxin level lower than this permitted value is considered safe.
As per the FDA regulatory levels for aflatoxin in the feed, the maximum allowable aflatoxin levels are 300, 100 and 20 μg/kg for finishing cattle, swine and poultry, breeding cattle, and other animals respectively.
When AFM1 concentration is found to be 0.5 ppb or greater, the milk should be discarded. When cows were fed with aflatoxin containing feeds, it requires approximately 2 to 3 days on aflatoxin-free feed for milk concentrations to fall below tolerance level. The time required for the milk to become aflatoxin free is dependent on the aflatoxin concentration in the feed as well as the diet being fed to the cow. FDA do not allow the usage of feeds that has been contaminated to a level of 20 ppb and also, it cannot be blended with the other feeds to reduce the level of contamination.
Methods for detecting Aflatoxin in milk
The highly toxic Aflatoxin M1 (AFM1) is most often detected in milk using an Enzyme-Linked-Immunosorbent Assay (ELISA) for screening purposes, while High-Performance Liquid Chromatography with Fluorescence Detector (HPLC-FL) is the reference method used for confirmation. Aflatoxin M1 Rapid test kit can also be used.
Precautions for reducing aflatoxin contamination
*After harvesting, immediately dry the raw materials to a moisture content of less than 13%.
*Damaged and broken grains (susceptible for fungal growth) should be avoided.
*The grains that are damaged by the insects should be avoided since it will be susceptible for fungal growth.
*The grains should be stored in a pre-cleaned and dried bag.
*If the moisture content in the raw material is more than 13%, use mould inhibitors to prevent fungal growth.
*Store the raw materials on wooden pallets or crates and away from the walls to prevent moisture migration from the floor and walls.
*Systematic inspection and clean-up program should be done to keep bins, delivery trucks, and other equipment free of adhering or caked feed ingredients.
*Reduce dust (contains Aflatoxins) and all waste materials.
*Use fodder and alternative field materials from trusted agencies only.
* Do not store fodder for more than 10 days.
*Wash and clean the feeding bowl daily.
Author Detail
Sona Mariyam Anil
College of dairy science and technology, Idukki
Kerala Veterinary and Animal Sciences University
Share your comments