Two new traits that have been bred into some types of summer annual forages give producers more choices in the types of forages they can grow. The traits have been developed by researchers in several states for grazing, haying and silage.

Research done by Texas A&M University in 2002 showed forages that incorporated photo period-sensitive (PPS) and brown mid-rib (BMR) traits generally produced better yields than did corn silage. Both traits have been developed in sorghum, sorghum-sudan grass and hybrid pearl millet. The BMR trait can also be found in corn.

“The PPS and BMR traits have shown to have advantages over the favorite roughage source of corn silage,” said Ron Hale, livestock specialist for Kansas State University Research and Extension in southwest Kansas.

The PPS trait is sensitive to sunlight and as days grow shorter (less than 12 hours), plants with this trait go from the vegetative phase of their life cycle to the reproductive phase. Plants with the PPS trait have shown higher forage growth, which is a strong attribute to the plants.

The downside of the PPS trait, however, is that the growth of the plant is dependent upon the lignin content to hold the plant up. Lignin reduces digestibility of the plants.

K-State’s Hale said forages that contain the PPS trait have a higher yield potential and better water use efficiency than does corn for silage, which may make using forages with PPS more feasible and economical to use. With the high lignin content in PPS plants, however, the energy content is lower than with corn silage.

That can be fixed when feeding PPS forages by supplementing them with grain, he said.
The brown mid-rib (BMR) trait has the opposite effect on a plant from plants containing the PPS trait. Plants containing the BMR trait have 25 to 50 percent lower lignin content than non-BMR forages.

That means improved energy and digestibility of BMR-containing forages compared with forages that do not contain the BMR trait, Hale said.

“This trait may be good for growing rations because any improvement in energy and digestibility has a big impact,” said Hale. “The rate of gain in cattle feed BMRs may be equal or better than corn silage.” ©