Editor's note: The following Case Study was handled by Fausto Regusci, independent nutritionist from Grover Beach, Calif.

Things were running well at a 2,500-cow California dairy. Production was 86 pounds of milk per cow per day, on average, with excellent components, reproduction and herd health.

Then last spring, the farm made some ration adjustments to compensate for the high cost of cottonseed. Nutritionist Fausto Regusci received a call a few days later that the cow’s milk production had dropped 8 pounds and most of the herd had very loose manure. He visited the dairy the next day and confirmed this finding: The manure was very watery with about 30 percent of the rolled corn passing through the cows.

The dairyman informed Regusci that he had not changed anything except removing cottonseed from the ration.

But there had been some other changes, as Regusci learned upon further investigation. The farm had started feeding new corn silage and changed the company that it was buying steam-rolled corn from.

Regusci took TMR and silage samples and sent them off to a lab for analysis.

The TMR and corn silage samples came back with very high yeast counts — 73 million cfu/gram and 43 million cfu/gram, respectively. With those high of counts, it was obvious that the new corn silage had not fermented properly.

“I knew than that we had aerobically unstable corn silage that can cause reduced intake, milk production and milkfat depression,” Regusci said.

He suspected that the silage had not been packed properly when it was delivered to the silo.

In California, it often happens that large amounts of corn silage are delivered in fast succession and it is not always possible to properly pack the pile, he points out. “This causes oxygen to be present in larger amounts,” he adds. “As a result, we have slower fermentation, providing an excellent condition for unfavorable yeast species to grow.”

Because the farm still needed to feed the silage, Regusci made the following recommendations:

  • Only use fresh silage, no leftovers from the day before.
  • Clean out feed refusal in the mangers before new TMR is fed.
  • Try to feed silage from the lower part of the pile to the milk cows. Higher density and lower yeast counts are present closer to the bottom of the pile.
  • Integrate a feed additive known as Yea-sac into the ration. Go back to the previous company the farm had been buying steam-rolled corn from, since it appeared the new company had not processed the corn properly.
  • Reintroduce cottonseed back into the ration.

A week after these improvements were made, milk production increased to 84 pounds and butterfat was at 3.7 percent. Manure had returned to normal and no grain corn was passing through.

“The dairyman is now at ease that his problem was solved without adding extra cost to his feed diet,” Regusci says.

“Next year, he will monitor his corn silage delivery and corn packing so better corn silage can be produced,” he says. And, hopefully, the dairyman will do a better job of communicating with his consultants any changes that have occurred on the farm.

And, when it comes to putting up silage in the future, Regusci recommended:

  • Cutting the corn shorter at harvest.
  • Adding one more tractor during delivery of the silage so a better pack can be achieved.
  • Testing for yeast and mold before feeding new corn silage to the cows.