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Bust up sorghum silage berries for improved feed conversion

John Goeser for Progressive Dairyman Published on 24 May 2018
Sorghum silage berries

Alternative forages, such as sorghum or milo silage, have gained momentum with growers and producers. Sorghum, sudan, sorghum-sudan, milo and millet are all tropical grasses (C4 biology; warm-season grass).

Hence, these forage varieties tend to do well in exceptionally hot and arid growing conditions. These species are very efficient with water use and retention; hence, the plants grow and yield well relative to cool-season grasses or corn silage in drought periods or with costly water access where water is limited.

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The berry-producing silages can also yield substantial grain and starch, bringing great energy potential per ton. When allowed to mature and yield grain, berry-producing silages can contain 20 to 25 percent starch or more. Many have asked me the question, “Can these silages bring energy into TMRs?”

The answer is one a professor might offer: maybe. But it warrants further investigation. We need to understand how much of the fiber and starch are digested.

With the development of BMR mutations in berry silages, fiber digestibility can be exceptional. However, the starch value is still questionable. Thankfully, there is now a novel, practical tool available to quantify grain value in dairy diets: berry processing score.

Many nutrition consultants discount the starch value in berry silages, in some cases zeroing out the starch value when inputting forage analyses into nutrition models. Nutritionists do this because a sizable number of unprocessed berries end up in the manure.

The berries bypass through the cow because they are like buckshot, with a hard, water-resistant outer seed coat. However, berry processors are now available for forage harvesters that can break the berries and process the grain for much improved dairy cow digestion.

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Kansas State University researchers collected commercial sorghum silages from dairies feeding the crop and simulated improved berry processing by running the silages through a kernel processor. The researchers then developed a berry processing score measure and determined the percentage of starch smaller than 1.18 millimeters (percent of starch passing through a 1.18-millimeter screen) to effectively rank the silages.

Unprocessed silages scored around 25, while processed silage scored higher than 50. Further, and equally important, the researchers found berry processing score was significantly related to rumen starch digestion.

Integrating the KSU researchers’ data into a realistic dairy diet and projection scenario (Table 1), improving berry processing score from 25 to 50 and gaining rumen starch digestion can have an impact on high-producing dairy cattle performance.

Using a diet evaluation software program and 10 pounds sorghum silage in a 54-pound dry matter intake diet, in this case I have projected improved berry processing score to improve total diet starch digestibility from about 70 to 75 percent and bring about another pound of milk per cow per day. The details of the silage comparison are presented in Table 1.

Brown midrib sorghum silage berry processing score

Even at $15 milk, these gains would return 12 to 13 cents per cow per day. What would that mean to your bottom line if you have sorghum silage in the diet?

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Alternative forages, berry-yielding varieties in this case, warrant discussion in meetings with your advisory team. Dairy economic conditions are tough and expected to be volatile for years to come. Growers and producers need to find ways to gain in efficiency, extracting more value out of each pound of feed.

If feeding a berry silage, processing and improving berry processing score is one avenue to accomplish better feed conversion. Start by gaining an understanding of your score, then work with your consulting and harvesting crew to better your number. Dairy feed conversion efficiency, performance and better margins will follow.  end mark

ILLUSTRATION: Illustration by Kristen Phillips.

John Goeser earned a Ph.D. in animal nutrition from the University of Wisconsin – Madison, where he currently serves as an adjunct professor in the dairy science department. He also directs animal nutrition, research and innovation efforts at Rock River Lab Inc. based in Watertown, Wisconsin.

References omitted but are available upon request. Click here to email an editor.

John Goeser
  • John Goeser

  • Director of Nutrition, Research and Innovation
  • Rock River Laboratory Inc.
  • Email John Goeser

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