Yield and Nutritive Value Differences Among Cool-Season Grasses

Abstract

Grasses are typically utilized at a vegetative stage of maturity under managed intensive rotational grazing. We compared the yield and nutritive value of the leaf and stem fraction, and total herbage of eight erect-growing, perennial cool-season grasses during 30-day intervals in the spring, summer, and fall at two Wisconsin locations. Total herbage production of all grasses was greatest during the spring as expected, but with the exception of smooth bromegrass, differences in leaf yield were relatively small. During the summer and fall, endophyte-infected and endophyte-free tall fescue produced the greatest leaf yield and quackgrass and smooth bromegrass the least. Significant leaf crude protein (CP) concentration differences among the eight grasses occurred during the spring, summer, and fall, but leaf CP of all grasses exceeded 16% and any differences would likely be inconsequential. Lowest neutral detergent fiber (NDF) and greatest NDF digestibility were measured in leaves of meadow fescue or timothy. Because yield differences among these grasses during the spring can be attributed primarily to the stem fraction and spring yield constitutes a large proportion of annual yield, a producer's perception of value to a grazing system may be biased by total yield estimates. The greater nutritive value of grasses like meadow fescue must be balanced against slightly lower productivity.