Testing And Vigilance Can Reduce Mycotoxins Risk
UK - Heavy rains have led to a warm-up in the region, and these conditions have dairy producers concerned because of the potential threat mycotoxins pose to their cows.Alvaro Garcia, South Dakota Coop-erative Extension dairy specialist, said dairy cows pose a particular challenge because of the wide-ranging variety of feeds that make up their diets.
“On one hand, multiple feeds in the diet assures that the risk is spread among them,” Garcia said. “But on the other hand, if more than one feed is affected, the effects are additive and may result in a mycotoxin problem in the total mixed ration even when the toxin level of each individual feed was borderline acceptable.”
Garcia said some feeds post higher inherent risks. Corn and its byproducts are among those to evaluate carefully, particularly when there are poor weather conditions at harvest.
“When a producer suspects aflatoxin problems, it is important to stay away from feeding ground corn with a lot of fines, such as the feed found near the bottom of the bin,” said Garcia. “Aflatoxin concentration is almost 90 percent higher in fines and much greater in the last three feet of the bin.”
Corn silage also poses a risk particularly during the fall and early winter, when mold spores are growing in the field. Garcia said spores can passively inoculate recently opened corn silage storage.
“The spores find optimum growing conditions, such as highly susceptible damaged kernels, and they find ideal temperature due to fermentation and sugar oxidation,” Garcia said. “Air infiltration in poorly packed corn silages increases the risk.”
In order to avoid this problem, producers must engage in meticulous daily feed-out processes from the entire face of the silage pile and at least 10 inches in depth.
“Some larger dairies have defacers that allow for a very clean and even surface, and maintaining the tarp tightly on top and on the sides also decreases ‘flapping,’ thus reducing oxygen exposure,” said Garcia.
Producers should pay attention to anything out of the ordinary with their dairy cows. Rather than looking for dramatic toxicity events showing typical textbook symptoms of aflatoxicosis, look for more subtle changes, Garcia said.
“Aflatoxin poisoning usually progresses sub-clinically with reduced immune function, fertility, and production,” Garcia said. “Higher-than-normal incidences of displaced abomasums and ketosis may result from reduced feed intake, and increased incidence of lameness may be a result of cows sorting the feed because of off-flavors or smells as a result of fungal growth.”