Document Type

Thesis - University Access Only

Award Date

1996

Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Patricia S. Johnson

Abstract

The objective of this study was to evaluate the effects of two stocking rates (light and heavy) and two grazing systems (continuous and short-duration) and their interaction on patterns of utilization (percent grazed, and severity) of individual grass tillers as well as livestock performance. The study site was located on the Cottonwood Range and Livestock Research Station in western South Dakota on mixed-grass prairie rangeland dominated by western wheatgrass (Agropyron smithii Rydb.) with an understory of blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Steud) and buffalograss (Buchloe dactyloides [Nutt.] Engelm.). Individual tillers were monitored in two replicates of a low and a high stocking rate continuously grazed treatment, as well as in four paddocks in each of a low and a high stocking rate short-duration grazing treatment. Cattle gains for all four treatments were monitored throughout the entire grazing season. Conventional wisdom suggests change in stocking. rate causes a proportional change in percent of tillers grazed and no change in grazing severity on those tillers. Conventional wisdom also suggests fewer tillers will be grazed more severely in continuous grazing compared to short-duration grazing. However, this study reveals an increase in stocking rate does not always result in a proportional increase in percent of plants grazed and, where differences occurred, continuously grazed pastures had more western wheatgrass tillers grazed less severely than short-duration grazed pastures. Shortgrass tiller utilization patterns complemented those seen in western wheatgrass. It is also commonly thought that cattle average daily gain will be greater in continuous grazing compared to any other grazing system. However, no differences in average daily gain were seen between grazing systems at the low stocking rate, nor between stocking rates under continuous grazing. But, at high stocking rates, greater gains were evident in continuously (.99 kg/day) than short-duration (.84 kg/day) grazed pastures. This one year study demonstrates that grazing system and stocking rate certainly affect plant defoliation patterns and livestock gains, but not as commonly hypothesized.

Library of Congress Subject Headings

Grazing
Cattle -- Feeding and feeds
Grasses -- Utilization

Format

application/pdf

Publisher

South Dakota State University

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Rights Statement

In Copyright