Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science


Cow and calf losses due to pine needle abortion in cattle grazing foothill ranges of ponderosa pine (Pinus ponderosa) continue to cause managerial and economic problems for ranchers in South Dakota, Colorado, Idaho, California, Montana and many areas throughout Canada. Because of its overall economic significance, investigators have been attempting to isolate and characterize causative agents of pine needle abortion. To date, a large number of pine needle constituents have been shown to possess abortifacient capabilities. In addition to actual pine needles, it appears that several other undefined factors may be associated with, and (or) predispose animals to, pine needle abortion . These factors are (1) stage of gestation when pine needles are consumed, (2) environmental stresses, (3) animal condition and (4) general physiology of the animal. These undefined potentiating factors represent a major st umbling block in pine needle abortion research, because it has thus far been impossible to consistently induce abortions in cattle under experimental conditions. Without this documentation, it has been difficult to clearly delineate pine needle abortion from other abortive disorders. In order to accurately define pine needle abortion, it will be necessary to isolate, identify and test all possible pine needle constituents having potential abortifacient capabilities. Furthermore, the mode of action of these causative agents in mammals must be determined . The recent discovery that prostaglandins or prostaglandin-like compounds are contained in ponderosa pine needles raises the possibility of their involvement in pine needle abortion. The luteolytic and abortifacient capabilities of some prostaglandins have received considerable attention due to their use in estrus synchronization and the termination of unwanted pregnancies. The purpose of this study was to investigate the possibility of prostaglandins as causative agents in pine needle abortion. The objectives were (1) to investigate the effects of known prostaglandins and a diterpene resin acid on pregnant mice and to establish dose-response relationships, (2) to use established baseline dose-response data for comparison in testing the biological activity of three separate pine needle fractions for prostaglandin activity in causing abortions in pregnant mice during late gestation, (3) to produce experimental abortions in cattle during the third trimester of pregnancy by feeding ponderosa pine needle diets, (4) to document gross pathological changes in maternal and fetal systems following abortions and (5) to monitor blood serum progesterone levels and leukocyte numbers throughout the cattle experiment in an attempt to differentiate between a hormonal imbalance, infectious processes and(or) toxic reactions as the principal mode of action for causative agents in pine needle abortion.

Library of Congress Subject Headings

Prostaglandins -- Physiological effect
Abortion in animals
Ponderosa pine
Mice -- Diseases
Cattle -- Diseases


Includes bibliographical references (pages 101-135)



Number of Pages



South Dakota State University


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