Mycotoxins in ruminants
The effects of mycotoxins in cattle may vary from
reduced weight gains or milk production, according to information from the Canadian Ministry of Agriculture, Food and Rural affairs.
Performance losses of 5 - 10% are typical with moldy feeds even in the
absence of mycotoxins. Mycotoxin contamination increases production losses, even
when mold is not readily visible. It can also lead to mycotic abortions and
respiratory disease Ketosis and displaced abomasum problems may increase
significantly with the consumptions of mycotoxins.
Some animals develop diarrhoea or have signs of haemorrhaging. Estrogenic
effects, swollen vulvas and nipples; vaginal or rectal prolapse may occur.
Reduced fertility / conception rates or abortions may also be evidence of
mycotoxin consumption. The effects of mycotoxins are amplified by production
stress. High producing dairy cows and rapidly growing feedlot cattle are more
susceptible to the effects of mycotoxins than low producing animals.
Effect of the rumen
Ruminants are uniquely equipped to
protect themselves from the harmful effects of mycotoxins. It is assumed that
sufficient degradation of the mycotoxins has taken place before absorption into
the blood and vital organs to protect the animals. Mycotoxins are detoxified or
altered in the rumen. but: The rate of detoxification differs for the different
types of mycotoxins and the extent of detoxification of any particular mycotoxin
depends on the rate of passage of feed. Rumen turnover rates are about 8 times
longer in beef cows than lactating dairy cows.
The extent of detoxification also depends on the original dose level. Five
and 10 ppm DON were completely transformed to the reportedly less toxic deepoxy
DON or DOM-1 within 24 hours when incubated in rumen fluid. More than half of
the DON remained from the 50 and 100 ppm DON treatments at 24 hours incubation.
The altered metabolite(s) may be more toxic than the original mycotoxin. Work in
sheep had Zearalenone transformed into the reportedly more toxic Zearalenol.
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