Total starch is a common measurement used when discussing dairy cow rations. But, total starch levels only tell part of the story. It’s important to take a deeper dive into starch values since cows respond directly to rumen degradable starch, which is different than total starch values.
“Rumen degradable starch can be too much of a good thing or not enough of a good thing,” says David Weakley, Ph.D., director of dairy forage research for Calibrate Technologies. “Without insights that provide an understanding of availability, both situations will negatively affect cow performance.”
Not an area to be overlooked, starch represents a substantial portion of the ration, ranging from as low as 20% to as high as 35%. Additionally, starch available to the rumen can vary across sources from less than 50% to more than 90% of the starch in certain ingredients.
This variation can be costly when not controlled and monitored, potentially leading to:
-Inconsistent milk production
-Decreased forage digestibility
-Over or under feeding cows
-Inconsistent milk components and feed intake
“Starch digestibility levels can change suddenly as farms move through available feedstuffs for many reasons, including harvest maturity, field locations and storage management. These sudden changes in the amount of rumen degradable starch in the ration can affect milk production, milk components and even cow health,” explains Weakley. “By proactively managing these variations, farms can maintain ration consistency for optimal performance.”
Testing for rumen degradable starch gives you more insight into how much starch will actually be available to a cow from any particular ingredient allowing you to adjust or optimize the ration based on your available feedstuffs or their cost. Routinely testing every two weeks will provide insights for timely decisions.