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United States Department of Agriculture

Agricultural Research Service

Title: Behavior of Steers Grazing Monocultures and Binary Mixtures of Alfalfa and Tall Fescue

Authors
item Seman, Dwight
item Stuedemann, John
item Hill, N - UNIVERSITY OF GEORGIA

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 21, 1999
Publication Date: N/A

Interpretive Summary: Alfalfa and tall fescue have different feed characteristics for cattle. Therefore, we speculated that there would be differences in grazing behavior and these differences could be detected by spectral analysis. Spectral analysis is a statistical technique where grazing cycles are analyzed to find significant cycles. Four 0.3 ha pastures were established by sowing seed mixtures of pure AU-Triumph tall fescue (F), pure Apollo alfalfa (A), 1/3 fescue and 2/3 alfalfa (2/3A), or 2/3 fescue and 1/3 alfalfa (1/3A). Each pasture was stocked with 10 to 16 steers and defoliated in six days. Three steers on each pasture carried devices to monitor grazing behavior. Total grazing time was not different among treatments; however, steers grazing mixtures grazed about 1.4 h/d longer than steers grazing pure stands. Spectral analysis revealed that steers grazing A and 2/3A consumed many meals/d while steers consuming 1/3A and F consumed three meals/d. Steers selected diets similar in quality for the A, 2/3A, and 1/3A treatments. This study illustrates how differences in forage diets may alter grazing behavior as described by spectral analysis.

Technical Abstract: An experiment was conducted that used spectral analysis to discover if changes in dietary quality and species of forage plant influenced the behavior of grazing steers. Four 0.3 ha paddocks were established by sowing seed mixtures of pure AU-Triumph tall fescue (F), pure Apollo alfalfa (A), 1/3 fescue and 2/3 alfalfa (2/3A), or 2/3 fescue and 1/3 alfalfa (1/3A). Each paddock was stocked with 10 to 16 steers and defoliated in six days. Three steers on each paddock carried vibracorders to monitor grazing time. Daily forage samples were taken in 10 cm layers and weighed. Esophageal extrusa was collected from fistulated steers to measure quality of consumed forage. Total grazing time did not differ (P=.45) among treatments; however, steers grazing mixtures grazed numerically longer (1.4 h/d) than steers on pure stands. Steers grazing A and 2/3A consumed more meals/d of short duration while steers consuming 1/3A and F consumed three meals/d at 8h intervals. Throughout the 6-day study, quality of the selected forage exhibited linear declines in crude protein concentration and digestibility; linear increases in neutral detergent fiber, cellulose and quadratic changes in lignin and ash. For most quality parameters, pure tall fescue differed from the others (P<.05). Steers selected diets with similar quality for the A, 2/3A, and 1/3A treatments. This study illustrates how differences in forage diets may alter grazing behavior as described by spectral analysis.

Last Modified: 9/10/2014
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