Many dairy feed rations include ingredients with a high starch content as a source of energy for cows. As a result, starch can represent a substantial portion of the ration, ranging from 20% to 35% of lactating cow diets.
However, starch digestibility levels within a ration can change suddenly as farms move through available feedstuffs. These abrupt changes in the amount of rumen degradable starch in the ration can affect milk production, milk components and even cow health.
See how Scott and Steve Wolfe, co-owners of Oak Spring Farms in Centre Hall, Pennsylvania, work with their nutritionist to monitor and manage starch levels in their ration and get tips for optimizing starch levels on your farm:
Control starch variation
Just because you’re feeding ingredients that contain starch, it doesn’t mean that starch is available to the cow. Starch availability in ingredients can vary depending on the source, ranging from 50-90% of starch within a feed available to the rumen. Starch 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
By proactively managing these variations, farms can maintain ration consistency for optimal cow performance.
Source of starch in dairy cow rations
The ideal amount of starch in your dairy feed rations will vary depending on which ingredients are available. Corn, sorghum and silages are ingredients to concentrate on when looking at starch levels in the ration.
While these ingredients are good sources of starch, many factors can influence the amount of starch in the feed ingredient and starch availability, including:
Maturity of plants at harvest: As crops mature, plant starch content goes up, but unfortunately, starch digestibility goes down.
Hybrid selection: Many seed companies have silage-specific hybrids or dual-purpose hybrids available to maintain both higher starch levels and digestibility.
Weather conditions: If the weather isn’t ideal, the plant won’t be able to produce much starch. Or if weather delays crop harvest, digestibility decreases with each day harvest is delayed.
Storage management: Storing dairy cow ration ingredients out of the weather elements will help keep spoilage at a minimum. Using inoculants for silages will also help reduce spoilage.
Test for rumen degradable starch to enhance rations
Focusing only on the total starch content of feedstuffs will not provide all the insights needed to understand how much starch will be available to the rumen.
Rumen degradable starch is a better metric that you can obtain through laboratory testing. Test results can give you more insight into how much starch will be available to a cow from an ingredient. Those insights allow you to adjust or optimize the ration based on available feedstuffs and cost. Work with your nutritionist to test feedstuffs as needed.