The weight of a feed sample is recorded both before and after it goes into a food dehydrator to determine dry matter content. (An electronic postal scale from an office supply store works well for this purpose.)

At least three rations exist for each group of cows on your farm.

  • The one that you or your nutritionist formulated.
  • The one the feeder mixed.
  • The one the cows ate.

  Anything you can do to narrow the gap between the formulated ration and the one that cows eat will help you stretch your feed dollars — especially now, when milk prices are declining.  And, as the article on page 34 of this month’s issue points out, you also may promote herd health and lessen the chances of rumen acidosis with this approach.

Here are a couple of new tools that can help you analyze the quality of your feed.

1. Food-dehydrator method

Researchers at the University of Wisconsin have developed an economical, simple and accurate method for testing the dry-matter content of forage. It’s called the food-dehydrator method.

Ken Bolton, extension livestock agent in Jefferson, Wis., and a member of the University of Wisconsin’s Milk Money staff, says the food-dehydrator method has advantages over the Koster-tester or microwave-oven methods.

  • The food dehydrator is thermostatically controlled, so it’s almost impossible to burn off dry matter. This makes the food-dehydrator method much more forgiving than the Koster-tester and microwave-oven methods, because with those you do have to worry about burning off dry matter.  
  • It’s economical. “You won’t have any more invested in this than you do with the Koster,” Bolton says.
  • It’s possible to dry up to four samples at once with the food-dehydrator method, whereas the Koster method handles just one sample at a time. With the food dehydrator, you can run a sample and weigh it out in two hours or 24 hours — whatever fits your schedule — and not worry about it drying out, he says. 

For more details, including a step-by-step description of how to use the food-dehydrator method, go to the following Web site:  (The University of Wisconsin research staff bought its food dehydrator from Excalibur Products in Sacramento, Calif., for approximately $250.)

2. Degree-of-starch-access (DSA) test

DSA just became commercially available in February of this year. It’s an enzymatic test that evaluates the starch digestibility of high-starch feed materials, such as corn silage or high-moisture corn, and does so more accurately than previous methods.

It is another forage-benchmarking tool that can help you determine if the ration delivers the right energy.      


The food-dehydrator method is one of the simplest and least expensive ways to calculate the dry matter content of corn silage and other forages.

The test is available at:

  • Dairyland Laboratories in Arcadia, Wis., phone: (608) 323-2123.
  • Cumberland Valley Analytical Services, Maugansville, Md., phone: (800) 282-7522.

Cost of the DSA test ranges from $23.50 to $25 per sample, depending on the lab.

3. Ruminal-starch-digestibility test

This test became available last fall. It measures the digestibility of high-starch feed materials, such as corn grain and corn silage. Cost can vary from $24 to $85 per sample, depending on the lab and how involved its incubation technique is.

New techniques

For years, we regarded the cow’s rumen as a “black box.” even if we knew what the inputs were, the outputs — and how they became outputs — were a little uncertain.

But thanks to new molecular-biology techniques, the black box has become much more transparent.

Researchers have a new tool known as DGGE (Denaturing Gradient Gel Electrophoresis) at their disposal. With DGGE, they can compare the rumen-bacteria populations of different groups of animals (healthy vs. sick, grazing vs. non-grazing). It gives them a rumen-bug profile or “fingerprint” for each group. Then, researchers can try various feed additives or management inputs to see if the profiles of sick cows can be brought more in line with the profiles of healthy cows. 

This should make it easier to control problems like rumen acidosis through nutritional inputs, which, in turn, should complement good feedbunk management and testing of forages.