Hot weather is often blamed for suppressing fat levels, but milk fat depression is actually a multi-factorial problem, explains Martha Baker, dairy nutrition specialist with Purina Animal Nutrition LLC. One area that can influence milk fat production is starch content of the diet.

Technology, like rumen degradable starch testing, can help you assess starch levels in ration ingredients and how they will perform in the cow.

“Different ingredients ferment faster in the rumen than others,” Baker explains. “This affects the dynamics of the rumen and can have a major impact on milk fat levels.”

An awareness of the rate of starch digestion in the rumen is critical when troubleshooting milk fat depression.

“Rumen degradable starch testing allows you to very quickly rule out starch as a culprit of suppressed milk fat levels.”

You also should assess how many pounds and what percent starch is being fed.

For more information: To learn more about this and five other key areas that affect milk fat, type “Master milk fat depression” into the “Search” box at