Mycotoxin concern in cattle tends to focus on deoxynivalenol (DON) but there’s a realm of other dangerous mycotoxins that can have an effect.
Why it matters: In dairy cows, too much mycotoxin exposure has serious impacts on feeding and gestation. In poultry and pigs, the effects can be fatal.
Dr. Gustavo Scheunemann of Ohio State University’s department of veterinary medicine has focused his research on moulds and mycotoxins and their effects on dairy cattle.
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Dairy farms rely significantly on stored feed and grains, which can contain mycotoxins.
The most common problems can be separated into two segments: fusarium in one and claviceps and aspergillus in the other. Fusarium includes fumonisin and produces T-2 toxin, HT-2 toxin, nivalenol (NIV), zearalenone (ZEA) and DON, among others. Within the claviceps subclass are ergot alkaloids and aspergillus, which produce aflatoxin and ochratoxin A.
“These are just a few of the mycotoxins,” said Scheunemann, referring to their prevalence on a global basis. “There are more than 400 that have been identified.”
Not just one problem
Scheunemann says total mix rations can be contaminated with several mycotoxins at the same time. In his research, 57 to 87 per cent of samples had two or more mycotoxins present.
Within North America, DON ranks the highest, with 64 per cent of samples testing positive. Along with NIV and T-2, it affects protein synthesis in dairy cows. Fumonisin (48 per cent) impedes enzyme production, ZEA is third at 28.9 per cent and stimulates estrogen production. Aflatoxin was detected in 11 per cent of continental samples.
In more detailed research, Scheunemann said elevated levels of mycotoxins in feed – whether corn silage or concentrated feed with visible mould – increases fungal growth and fermentation of plant proteins. This can trigger overproduction of undesirable bacteria like C. difficile, listeria monocytogenes and E. coli, all of which place animals at a higher risk for intestinal hemorrhaging.
Effects on gestation
Scheunemann also examined the effect of mycotoxins on gestation. The normal gestation period for dairy cows is 276 days, plus or minus six days. Gestation periods shorter than that – 255 to 269 days – can result in increased stillbirth, metritis and retained placenta, morbidity and increased culling.
Difficult births tend to lower milk production. The goal is to limit short gestation periods to less than 12 per cent, said Scheunemann. Short gestations in 20 to 30 per cent of cows with mycotoxin-contaminated TMR saw more twin pregnancies, loss of condition before calving and poor cow comfort.
