Editor's note: The following case study was handled by Brian Limberg, dairy nutritionist from Plymouth, Wis.

Brian Limberg is very complimentary toward one of his distant relatives. The relative is a good dairyman, Limberg says, who is very observant about his cows. So, Limberg took it seriously when his relative said the cows just weren’t milking right.

Limberg wasn’t the nutritionist at that particular farm, so he suggested that the relative consult with the current nutritionist and try to get the problem resolved. A few more months passed and Limberg got an anxious call.

“Brian, come out here and we have to figure this out,” the relative implored.

Limberg went out to the 50-cow dairy. The cows looked OK and there wasn’t really anything obvious that would explain the problem. So, he began assembling evidence, including feed samples, the nutritionist’s recommendations, and the feed invoice from the feed mill.

Back at the office, Limberg noticed something didn’t seem right with the feed invoice: Some of the ingredients appeared to be at too high of an inclusion rate.

“It concerned me enough that I wanted to go a step further,” he says.

He asked to see what the nutritionist had recommended in the mix. “When I looked at the nutritionist’s recommendations and I looked at the feed bill, they didn’t match,” he says.

It turned out that one of the feed-mill employees whose job it was to interpret the order was off a row as she worked down the list, which threw off the amount of ingredients in the final protein blend. (Besides protein, the blend had minerals, salt and Rumensin.)

The cows were getting two to three times the amount of salt and Rumensin they should have been getting, Limberg says. “It was one of those human errors that shouldn’t have happened,” he adds.

It did cause a decline in milk production and butterfat was abnormally low.

As soon as the problem was corrected, the cows’ production started to return to normal, Limberg says.

The take-home message: Look at the invoice from the feed manufacturer to make sure it matches with what the nutritionist recommends.