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Research cracks forage analysis bottleneck – Audio

New forage test boosts dairy production

David Combs, dairy nutritionist
Department of Dairy Science
UW-Madison College of Agricultural and Life Sciences
Phone (608) 263-4844, (608) 263-3308

David combs keys us in on the value of forage digestibility, and what it can do to increase milk production in cows.

3:01 – Total time

0:15 – The forage test challenge
0:42 – Discovery process
0:57 – Importance of the research
1:14 – Looking for clues
1:44 – Something still missing
2:03 – Results
2:23 – On farm use of new test
2:51 – Lead out


Sevie Kenyon: You started out doing research awhile back. What was the challenge?

David Combs: you know I’m getting to the point in my career where I’m looking back here at a long and kind of torturous journey, but it was essentially looking at forage testing and could we better predict how those forages would feed to dairy cattle. We were interested in, could we use a widely used tool, NIR, which is, you know, our standard tested procedure for analyzing forages to predict dry matter digestibility.

Sevie Kenyon: And what did you find?

David Combs: I put a PhD student on this project. He spent about a year working in the lab. We essentially found there was, we couldn’t read it. We saw nothing in terms of digestibility.

Sevie Kenyon: Maybe you can tell us why this is important?

David Combs: Well the reason that it’s important is because energy is the first limiting nutrient of high producing dairy cattle. You know the key for getting high production cows is actually getting them high energy feeds, and digestibility is a good measure of that.

Sevie Kenyon: Let’s go back to your grad student and his discovery. Recap that for us.

David Combs: The graduate student had invested a year’s worth of work and it looked like it was an absolute dead end. But then he came into my office and he says, “You know, the NIR is able to see a relationship or can predict fiber digestion.” So we started down that path, and we were actually able to develop a very nice prediction of forage fiber digestibility from an In vitro test that was done in the lab.

Sevie Kenyon: But there was something still missing?

David Combs: It didn’t always work, particularly with corn silage. It drove us nuts. Okay we can measure forage digestion in these test tubes…we really need to tie that directly to the forages when they’re fed to the cow. Fiber can easily make five to six difference in milk production in a dairy cow.

Sevie Kenyon: Where are you with that?

David Combs: We’ve come a long ways. We’ve developed a concept of what I call “total track in digestibility”, and I can actually predict what the cow is going to say in terms of how much of that fiber she can actually digest. It’s the rate, it’s how fast that forage digests that’s more important to the cow.

Sevie Kenyon: What’s it do out on the farm?

David Combs: Fiber digestibility has a huge impact on milk production and cattle. It’s your opportunity to at least look at a forage and scan it before you feed it. This test actually helps us have a little bit more confidence that the fiber in this forage, we understand it’s digestibility which is really the strength of our whole thing and goes right back to my initial vision. [Which] was we needed a test that would be returned with all the other analyses of that forage.

Sevie Kenyon: We’ve been visiting with David Combs, Department of Dairy Science, University of Wisconsin and the College of Agricultural and Life Sciences, Madison, Wisconsin, and I am Sevie Kenyon.