Central Plains Dairy

Professional Dairy Business Conference

2010 date to be announced.

Treatments and additives can reduce dairy cows’ risks from moldy grain

While the Olson Biochemistry lab at South Dakota State University has found relatively high levels of Penicillium molds in corn tested at the lab, this finding is usually not a concern with dairy cows.

But South Dakota Cooperative Extension Dairy Specialist Alvaro Garcia said other toxins such as Ochratoxin which is produced by these molds can pose problems for certain age groups in the dairy herd.

“This toxin is usually degraded in the rumen which reduces its toxic effects, and research has shown that with heavy grain supplementation, this toxin can remain in the rumen and show up in the blood,” Garcia said. “Ochatoxin is basically a kidney toxin, which is toxic to calves, but less toxic to mature animals with a fully functional rumen.”

Garcia said he would advise producers to limit corn grain with high Penicillium levels for mature cows and avoid them altogether when feeding young stock.

In dairy cattle, chronic, low-level doses often go unnoticed and cause reduced performance, reduced immunity, increased disease incidence, and overall economic losses. “In mature cows, be aware of feed refusal as this will lead to sorting and possibly displaced abomasums, ketosis, and lameness,” said Garcia. “Healthy dairy cows usually resist molds in feed unless they are immune-suppressed. Mycotoxins suppress immunity, and thus assist fungi in further infecting animals. Any stress that impairs the dairy cow immune function increases susceptibility to mycotoxicosis.

“Our general recommendations are to reduce mycotoxin formation when storing recently combined corn, and products that contain propionic acid work well in this regard,” Garcia said. “The University of Wisconsin suggests adding 10-15 lbs of actual propionic acid per ton of high-moisture corn, such as corn with 25 percent moisture or higher.”

Garcia said producers should consider the fact that some commercial products used as mycotoxin-fighting additives have close to 50 percent propionic acid.

Garcia added that the Wisconsin study recommends increasing the concentration of propionic acid by 50 percent for every 5 percentage-point increase in moisture content in the grain.

“It’s crucial to avoid unnecessary exposure of grain and silage to air during storage and feed-out, and best not to feed questionable grains,” Garcia said. “If a producer has no choice, it is important to dilute affected grains with safer grain sources.”

Producers should include grain with unusually high yeast counts at or below 10 percent of the overall dairy diet.

“If aflatoxins become a problem, reduce absorption by adding anti-caking agents to the grain, products like those based on hydrated sodium calcium aluminosilicates or a modified yeast-cell-culture-based product,” said Garcia. “Research shows the use of these products decreased aflatoxin excretion in milk by 48 percent and aflatoxin adsorption by 59 percent.

Research conducted at North Carolina State University showed that cows fed diets contaminated with 2.5 parts per million (ppm) DON and 0.27 ppm zearalenone produced 3.2 pounds more milk when the diet was treated with a clay adsorbent at a rate of one-half pound per cow daily.

“As a general recommendation, reduce the overall animal stress by adequate herd management and cow comfort,” Garcia said. “Include antioxidants like vitamin E and selenium, improve overall nutrition programs focusing on protein, energy, and effective fiber, and use proven rumen fermentation enhancers as well as buffers like sodium bicarbonate.”

For more information, visit your county Extension office, or call Alvaro Garcia at (605) 688-5443.

-- Source: SDSU AgBio Communications