Corn silage chopped and packed wetter and at colder temperatures than normal this fall should be fed to dairy cows cautiously to avoid possible ruminal acidosis problems, says J.W. Schroeder, North Dakota State University Extension dairy specialist.

“Basically, it’s been put in the refrigerator,” says Schroeder of the silage corn crop harvested in his area. One grower put up a 3,000-ton silage pile at around 71% moisture when temperatures were in the low 20s. The temperature of the packed corn was 27 degrees F.

More than a month later, in the first week of November, that pile"s temperature was nearly the same - only the surface layer warmed to 29 degrees. He fears that the crop has run out of time and warm temperatures to ferment adequately this fall. The silage corn’s sugar content had tested from 9.5 to 11% going into the pile and should be around 2-4% with normal fermentation, the dairy specialist adds.

“If you switch from your existing well-fermented corn silage to this frozen corn silage, it’s going to feed differently. You’re probably going to see a drop in production and the cows may need a little extra time to adjust to it.

“We generally don’t worry about adjusting cows to different forages; it’s when we increase grains that it changes the environment in the rumen and causes acidosis. In this case, you’re going to have more fermentable sugars that could contribute to ruminal acidosis.”

Schroeder advocates forage tests that include starch and sugar content. That way nutritionists can tweak diets to accommodate for that added sugar.

The dairy with the 3,000 tons of frozen green crop has slowly, for about 10 days, integrated it into its cows’ diets. “By blending it with other silage, he’s able to help the cows make the adjustment with only a very slight drop in milk, a drop we usually see with new-crop corn silage that hasn’t had a good 60 days of fermentation.

“Without adequate fermentation, our natural refrigerated (cold weather) feed will keep just fine until temperatures rise. When they do, the ensiling process will ensue. But the chances of it beginning to spoil are greater, too.” Schroeder recommends making sure piles are monitored often and closely for changes in temperature, appearance and smell. Adjust rate of feed-out to reduce exposure to air and use up the most vulnerable feeds first.