Guidelines for Use of Aflatoxin Containing Feeds in Dairy Rations

Table 1	Safe Aflatoxin Levels in Ration for Dairy Cattle
Lactating cows	less than 20 ppb
Calves up to 1 year of age	less than 100 ppb
Yearling cattle	less than 100 ppb

Feeding aflatoxin contaminated grain is never the first choice of nutritionists or producers. Sometimes however situations arise where due to cost, lack of other grain sources, or needing to use a contaminated crop, producers decide to dilute the grain to a level which can be fed.

The following table gives the dilution rate for 100 ppb corn for lactating cows. By making appropriate adjustments the same table may be used for corn containing higher levels in rations for calves and yearling cattle. Also, note that the table assumes that 50% of the dry matter in the total ration comes from grain and 50% from silage, hay or other non-aflatoxin containing feedstuffs.

Table II. Pounds of Aflatoxin Corn per Ton in Lactating Grain or Concentrate Mix

Level of Aflatoxin in Corn	Maximum %/ton	Lbs/ton	ppb in Grain Mix	ppb Aflatoxin in Total Ration (50% of Dry Matter)**
100 ppb	40%	800	40	20
80 ppb	50%	1000*	40	20
60 ppb	66.6%	1000*	30	15
40 ppb	100%	1000*	20	10
20 ppb	100%	1000*	10	5

** Assuming that grain makes up no more than 50% of the total ration dry matter.

* Usually 1000 pounds of corn is the upper limit for corn in lactating rations due to the fact other feedstuffs such as protein supplement minerals and by-product feeds are used to make up the other half of the grain mix.

How Do You Figure Your Own?

Assume you have corn that contains 500 ppb of aflatoxin and you are feeding calves and you do not want to exceed 150 ppb in the grain ration.

Example:

(150 ppb in Ration / 500 ppb in corn) X 100 = 30% of Aflatoxin Corn in total ration

30% X 2000 lbs. = 600 pounds per ton would be the maximum of the aflatoxin corn. The other ingredients would have to come from feeds not containing aflatoxin.