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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Dairy Forage Research » Research » Publications at this Location » Publication #312301

Title: Cool-season grass sward structure influences intake of grazing cattle

item Brink, Geoffrey
item Soder, Kathy

Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2014
Publication Date: 1/12/2015
Citation: Brink, G.E., Soder, K.J. 2015. Cool-season grass sward structure influences intake of grazing cattle. American Forage and Grassland Council Conference Proceedings [CD-ROM]. Number 16. St. Louis, MO: American Forage and Grassland Council.

Interpretive Summary:

Technical Abstract: Cool-season grasses differ in sward structure, such as canopy height and the distribution of leaves and stems throughout the canopy, that may influence intake by grazing livestock. We determined the relationship between the sward structure of four grasses (meadow fescue, orchardgrass, quackgrass, and reed canarygrass) and intake of bred dairy heifers. Each grass was grazed at vegetative stage for 24 hours over a five-day period in the spring, summer, and fall of two years. Forage dry matter (DM) allowance was twice the expected daily intake of 24 lb/day. Sward characteristics (height, mass, vertical distribution of leaf and stem fractions, and nutritive value) were measured before grazing. Forage DM intake was estimated daily (pregraze minus postgraze yield). Despite differences in pregraze sward height (range of 12 – 20 in), yield (range of 1300 – 2300 lb/acre), and neutral detergent fiber digestibility (range of 71 – 84%), no differences in DM intake were found among grasses during four of six grazing periods. Intake differences during two periods, however, were positively related to density of the leaf fraction (r = 0.79) and negatively related to density of the stem fraction (r = -0.84). Therefore, even if DM allowance exceeds anticipated intake by grazing livestock, pastures should be managed to maintain high leaf density and low stem density.