Document Type

Thesis - Open Access

Award Date

1967

Degree Name

Master of Science (MS)

Department

Animal Science

Abstract

In order to make the most economical usage of our range forages it is essential that we know when the forage is most digestible in order for livestock to obtain maximum benefit from it. For many years cutting date has been the most common measure used to determine when a forage contains the most nutritive value. In many grasses emergence of the seed head or seed maturity has been used to determine when a particular forage should be harvested, However, western wheatgrass (Agropyron mithill) is not dependent on seed for reproduction and under range conditions often does not produce a seed head. This factor makes it difficult to determine when western wheatgrass is the most digestible since in most grasses emergence of the seed head or flowering is followed by a rather rapid decline in digestibility. In an attempt to more accurately predict digestibility at various stages of growth, this study was undertaken ti evaluate the effect of such factors as plant height, number of leaves per plant, range site, range conditions and chronological age of the plant on digestibility of western wheatgrass. Since native ranges are inhabited by more than one species of grass, it becomes difficult to evaluate grasses with the use of grazing animals since consumption is not limited to the species. The use of in vitro methods of forage evaluation are specifically convenient since small amounts of forage may be evaluated. Although in vitro methods of forage evaluation may not accurately estimate animal performance, they do give an accurate estimate of forage digestibility. This research was undertaken with the following specific objectives: 1. To determine the effect of range site, range condition leaf class, height class, and sampling date on in vitro dry matter digestibility. 2. To determine the effect of age of tissue on the same plant on in vitro dry matter digestibility. 3. To determine the effect of range site, range condition leaf class, height class, and sampling date on the cellulose content of actively growing western wheatgrass. The effect of range site and sampling date were possibly the two most important variables which were observed in this study. However, the importance of leaf class (number of leaves per plant) and height class (plant height) are as yet undetermined.

Library of Congress Subject Headings

Forage plants
Wheatgrass (Wheat)

Number of Pages

77

Publisher

South Dakota State University

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