A variety of factors need to be taken into consideration when evaluating and maintaining perennial forage grasses, hay growers were told at the recent Minnesota Forage Days.

"Use variety trials to evaluate grasses in your region, but be aware when grasses were cut," said Geoff Brink, USDA-ARS research agronomist at the U.S. Dairy Forage Research Center in Madison, WI.

Brink highlighted the results of recent research comparing grasses in southern and central Wisconsin. He compared growth and forage quality indicators of meadow fescue, orchardgrass, quackgrass, reed canarygrass, smooth bromegrass, tall fescue and timothy. In spring, all the grasses produced more dry matter at the central Wisconsin research site than in the southern part of the state. There were no differences between locations in the summer or fall.

Smooth bromegrass was the most productive grass for both leaf and stem tissue yield in early spring, while the other six grasses showed no significant leaf yield differences at that time. Tall fescue and orchardgrass had the highest leaf yield in summer, while tall fescue placed first for fall leaf yield.

As grasses mature, cell walls thicken and NDF digestibility declines. At 12-14" high in spring, meadow fescue showed the lowest NDF among the seven grasses studied. During summer, smooth bromegrass, meadow fescue and timothy had the lowest NDF. In fall, reed canarygrass, meadow fescue and timothy had the lowest NDF. Meadow fescue will often have lower NDF than any of other grasses except timothy throughout the season, said Brink.

He told producers to manage grasses for the benefit of the plants, not necessarily the animals. He said grass stubble height is a good predictor of future growth potential because of its effect on the carbohydrate status. Carbohydrates stored from the previous growing season help plants get through winter and start growing in spring. "One of the most important management variables we must consider with grasses is leaving an adequate residual stubble," he says. "When we leave an adequate residual after grazing or haying, the remaining leaves use photosynthesis to produce carbohydrates for new leaves. If you don't leave enough residual stubble, the plant is forced to move carbohydrates from the stem base or the roots to produce new leaves."

Contact Brink at 608-890-0052.