Researchers from Cornell University studied the relationship between the carry-over rate of aflatoxins in milk in dairy cows and the level of milk production. Their findings suggest that the current regulations of 20 ppb total aflatoxin levels allowable in dairy cow feed are not protective to avoid violation of the 0.5 ppb AFM1 regulatory levels for milk in high-producing cows.
A factor, that is considered to be important for influencing regulatory limits of both total aflatoxin and AFM1 is the rate at which AFB1 is converted and excreted as AFM1 into the milk of dairy cows.
The problem is that most previous studies on the carry-over of aflatoxins from feed to milk were in what would be considered today as low-yielding dairy cows, where the carry-over of the ingested AFB1 is closer to 1 to 2%.
However, a study carried out by Churchill et al (2016) at Cornell University revealed that the carry-over rate into milk in high yielding dairy cows is closer to 6.5%.
When linear regression was used to calculate the relationship between ingested and excreted concentrations of aflatoxin and AFM1 in milk of high yielding dairy cows, the results suggested that an aflatoxin level of 15 ppb, was the maximum likely to produce milk with aflatoxin below the US regulatory limits (0.5 ppb AFM1 in milk). Currently the FDA guidelines for aflatoxin (AFB1) in feed for dairy cows is at 20ppb.
Find out more about the carry-over rate of aflatoxins into milk in dairy cows at the end of the video below