This year’s fall and early-winter conditions have been ideal for mould growth and mycotoxins in forage supplies, said Murray Feist, livestock agrologist with Saskatchewan Agriculture in Saskatoon.
“Moulds and fungi are ever present and commonly grow on all types of forages, including straw, hay, silage and swaths for swath grazing,” said Feist.
“Conditions such as we have had this year – temperatures that are warmer than seasonal averages, and low snow coverage Ð- encourage their growth and affects greater quantities of the feed.
“While the growth of mould does not indicate mycotoxin production, greater levels of visible mould infestation may increase the probability of mycotoxin production, especially under ideal conditions.”
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When feeding mouldy forages or forages high in nitrates to beef cattle, several recommendations are offered.
Feist said mouldy feeds should never be fed to pregnant cattle, particularly during the third trimester when the fetus is rapidly developing. Pregnant cows that ingest or inhale the mould might get toxins and once the toxins enter the body, the damage is irreversible.
The cows might abort or the cows and their calves may have an inhibited immune system and perform poorly.
“Most mouldy forages will be dusty, so rolling out the bales will keep cattle from nuzzling into the bales and inhaling the spores. The hay will also be less palatable, so blending with other feeds will encourage the cattle to maintain forage intakes to support production. Most mouldy feed has undergone heating, so producers must supplement to replace lost energy and protein quality.”
Feed for 10 days
Mouldy sweet clover can be fed for 10 days. Then the cow should be placed on a better grass for 10 days to prevent buildup of harmful dicoumarin, which interferes with the animal’s blood clotting.
Mouldy sweet clover should never be fed a few weeks before or after calving.
Forages with high levels of nitrates should be mixed with other feeds to reduce the nitrate to a safe level.
If a feed is infected with mould, it can be tested for the type of mould species and to determine if it can produce mycotoxins.
Feist said the presence of mould does not indicate the presence of mycotoxins. But if there are concerns that mycotoxins, particularly fusarium toxins, are present, feed should be tested.
