The addition of YCW to the contaminated diet reduced
absorption of AFB1 in both the 3-d and 21-d exposure
periods. During the 21-d exposure, the amount
of AFM1 excreted into feces increased almost 2-fold in
ewes fed the contaminated diet supplemented with the
YCW extract compared with the group fed aflatoxins
alone (Table 4). This increase in AFM1 in feces was
associated with a tendency for lower urinary excretion.
Other studies, using organic adsorbing agents and carried
out on rats, indicated similar modifications in excretion
patterns with an increase of AFM1 excreted in
feces (Gratz et al., 2006). Gratz et al. (2006) suggested
that AFM1 was formed in rat enterocytes and diffused
back into the lumen of the digestive tract where it can
bind to sequestering compounds. Aflatoxin M1 in the
feces of ewes that was confirmed by liquid chromatography/
tandem MS could be produced by the same
mechanism because ruminants possess the necessary
cytochrome P450 enzyme in the intestine but it also can
come from hepatic biotransformation and subsequent
enterohepatic circulation (Lynch, 1972; Larsson et al.,
1994; Guerre et al., 1996). Although complementary
studies will be needed to determine the origin of AFM1,
the increase in AFM1 excretion induced by YCW in the
long-term exposure in this experiment accounted for an
important proportion of the total aflatoxin eliminated
from the animal body.