Both Digestibility and Yield Important Among Forages

Research indicates one trait need not exclude the other.

Published on: Jun 30, 2011

All forages are not created equal, says Chris Teutsch, a Virginia Tech associate professor of Forage Research and Extension at the Southern Piedmont Agricultural Research and Education Center in Blacksburg, Virginia. In other words, if you're a cattleman who's concerned only with forage yield, you may be missing the boat when you choose your forage variety.

"We've been doing some interesting research looking into brown midrib (BMR) forage sorghums and sudans over the last couple of years and I've got some real interesting data on those, Teutsch says. "The brown midribs are more digestible, so the animals tend to perform better."

That means the owner of the livestock performs better, too, on his bottom line, too. "There is an economic advantage if you can get a similar yield but have increased digestibility because those calves will gain more per day than one that is grazing a variety with lower digestibility," Teutsch adds.

Teutsch has been holding research trials on these new varieties over the last couple of years. Typically, most farm research tends to look mainly at yields. But over these tests Teutsch also looked at in vitro digestibility of about 30 varieties.

"We have found that there is a huge variation in how digestible those harvests are," Teutsch says. "At first harvest the variation in 2009 was 20% difference in in-vitro digestibility, which was extremely large.

"But when I first saw that data I said to myself that it was certainly related to yield and maturity. So I thought ones that were more mature yielded more and they would tend to be less digestible. But when I graphed it out, it didn't turn out to be like that at all. There was no relationship between yield and digestibility for that first harvest. Some of the highest yielding varieties were also some of the most digestible. That was exciting."

In his graphs Teutsch ranked the varieties for yield and also for digestibility, distinguishing those that were superior in both traits.

"We also broke the varieties out that have the BMR trait, which is the Brown Midriff trait. When we did that we found there was about a 5% advantage to having the BMR trait, but still, even within that group there was still a great deal of variation about how digestible the varieties were.

BMRs might be expected to perform well. This trait is associated with lower lignin in varieties of corn, sorghum, sudangrass, pearl millet and so on. But that is not the whole story.

"What that tells us is that we can't just tell people to buy a BMR sorghum sudangrass; a producer has got to actually look at the whole package, which is the variety and the BMR trait."

Contact your local Virginia Cooperative Extension agent to see Teutsch's complete data sets.