Traditionally, corn has been the major energy source for dairy rations because of the high starch content. The starch provides energy needed for high milk production; however, when too much starch is added at the expense of forage, rumen pH decreases. When rumen pH falls, intake decreases, as does fiber digestion and milk fat concentration.

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Ellen Jordan

The recent surge in ethanol production for fuel has resulted in increased competition for corn. A side benefit of the ethanol industry has been an escalating quantity of byproducts, which can be used by nutritionists in formulating rations.

These byproducts present an opportunity to develop rations with energy provided from alternatives to corn. Consequently, rations may be developed that minimize the negative impacts of feeding too much starch.

One of the major ingredients available from ethanol production is distillers grains. For each 56-lb bushel of corn processed for fuel, 18 lbs of distillers grains is generated in addition to the 2.7 gallons of ethanol and carbon dioxide. Both wet and dry distillers grains (WDG and DDG) are available.

Drying distillers grains improves shelf life and ease of handling, while reducing freight charges. If too much heat is applied in the drying process, digestibility declines, as well as palatability. Although some think color is an indicator of overheating, a burnt odor is more accurate.

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Distillers grains with soluble (DGS) is produced when part of the “stillage” is added back to the grain. In recent research from South Dakota, substituting dry DGS (DDGS) and soyhulls for the starch from corn was evaluated.

Four different rations were fed with 0 percent, 7 percent, 14 percent or 21 percent DDGS.

Starch declined from 29 to 26 to 23 to 20 percent in the four rations as DDGS increased. The rations consisted of 27 percent corn silage, 22 percent alfalfa hay and 51 percent concentrate.

Soyhulls were added along with the DDGS to maintain crude protein at 17 percent across the four rations.

As the percent DDGS increased, dry matter intake declined in a linear fashion; however, neither milk production or composition of fat or protein changed. Consequently, feed efficiency tended to improve as the starch was replaced by the nonforage fiber from soyhulls and DDGS.

Results from this research indicate that DDGS, in combination with soyhulls, can partially substitute for the starch from corn without negatively impacting production.

At the time of the trial, the calculated feed cost declined from $4.91 to $3.49 per cow per day and income over feed cost increased from $7.02 to $8.44 per cow per day as starch from corn decreased from 29 to 20 percent of the ration and DDGS increased from 0 to 21 percent.

The prices of various feed ingredients continue to change with time, but byproduct feeds provide alternatives to control cost and maintain productivity. Work with your consultant to identify which ingredient combinations might improve your bottom line.

For further information on this and other topics, visit texasdairymatters.org/ PD

—Excerpts from Texas Dairy Matters newsletter, Spring 2010

Ellen Jordan