Seasonal variation in butterfat confirmed

Editor's note: The following case was handled by Lawson Spicer, independent dairy nutritionist from Claremont, Calif.

For years, milkfat percentage would drop in the spring and summer. No real surprise, but Lawson Spicer wondered about the seasonal effect and whether it was more pronounced in west Texas and New Mexico ― where some of his clients are located ― than in other parts of the country.

Milkfat or butterfat at his clients" farms would be fine during the winter ― around 3.6 percent ― but then drop during the spring and usually bottom out at 3.1 or 3.2 percent by the first of May.

Spicer adopted various ration strategies, such as replacing corn grain or other grains with whole cottonseed. He says he chose cottonseed because of its energy value and ability to keep butterfat from sliding below 3.0.

During the winter months, he feeds 0 to 2 pounds of whole cottonseed per cow per day, depending on the farm. Then, during the warmer months, he bumps it up to 2 to 4 pounds per cow per day.

"In this situation, whole cottonseed can be used as a tool," Spicer says. "It's been successful."

What about the seasonal effect he is seeing with milkfat depression?

In late September, Spicer viewed a webinar narrated by Bill Sanchez, director of technical services and field research at Diamond V. In the webinar, Sanchez said there's a "very repeatable and predictable cycle" in milkfat concentrations by season.

"As you well know, milkfat percent is highest in the winter (and lowest in the summer)," Sanchez said. Those repeatable patterns have been observed in all federal milk marketing orders across the U.S, as well as smaller data sets in the West.

Click here to view the webinar.

Spicer was able to confirm that the variation he is seeing in the west Texas and New Mexico herds is pretty much normal throughout the West.