Paul E. Naasz

Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

A. Lowell Slyter


Synchronization of estrus in the cyclic ewe can be accomplished by the use of prostaglandin F2a. Estrous synchronization offers the possibility of more uniform offspring, concentration of parturition which would allow for better use of facilities and labor, and the utilization of outstanding sires through artificial insemination. Some current estrous synchronization regimes for ewes consist of exposure to rams for a period of time followed by an intramuscular injection of prostaglandin F2a (PGF) to all ewes that have not previously mated. Administration of PGF to ewes that have already mated, however, may lead to termination of pregnancy. Before application of such a program can be recommended, several questions need to be answered. Will the synchronization treatment cause termination of pregnancy? If so, at what stage of gestation will PGF terminate pregnancy? Once these questions are answered, the proper time interval from introduction of rams to administration of PGF can be determined. The purpose of the following literature review will be to examine the sequence of events that led to the proof that PGF is the uterine luteolysin in sheep and expound on some possible mechanisms of action and the effects that the conceptus may have on its luteolytic ability.

Library of Congress Subject Headings

Sheep -- Breeding
Sheep -- Fertility



Number of Pages



South Dakota State University


No Copyright - United State