There have been a couple of loads of milk dumped in south west Indiana because of violative levels of aflatoxin. At present it appears that the feed for the affected herds may have come from a single source, so this is not a general alert - just a heads-up.
Here are a few points about aflatoxin and milk.
In cows aflatoxin B1 is converted to a metabolite M1 which appears in milk. The violative level of M1 aflatoxin in milk is 0.5 ppb.
Milk adulteration occurs at aflatoxin levels far below those that cause health problems in cows. Federal limits on grain for lactating animals are 20 ppb. Total rations containing aflatoxin at levels greater than 20 pbb certainly should not be fed to milk cows.
Clinical problems are possible in calves when ration aflatoxin reaches 150 ppb but probably not in adult cattle until around 600 ppb.
Aflatoxin production in pre-harvest grains and corn silage is favored by high temperatures, prolonged drought or high insect activity. Aflatoxin production in storage is favored by warm temperatures and high humidity (including inadequate drying of grain).
This year's corn survey by Dr. Woloshuk showed more problems with fumonisin than with aflatoxin, but with a few loads testing positive for aflatoxin, so this is not likely to be a generalized problem.
Black light fluoresecence is not a reliable way to diagnose aflatoxin in grain, as the fluorescence is caused by another Aspergillus metabolite, but there is some correlation between a black light positive test and the presence of aflatoxin. Analysis of the feed for aflatoxin is necessary to confirm its presence and quantify it.
Sodium calcium aluminosilicate may bind aflatoxin to varying degrees. Clays or bentonites have produced variable results.
If I hear more about aflatoxin problems in milk I'll let you know.
December 5, 2002
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