Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science

First Advisor

A. Lowell Slyter


Seasonality of reproduction in sheep has created an oscillating supply of lambs. A more constant supply of lambs would allow more efficient use of facilities and labor by producers, feedlots and packing plants. Seasonal reproduction also limits the lifetime production of the ewe. Extension of the breeding season would provide a more consistent supply of lambs. In addition, more than one lamb crop per ewe could be produced annually. Not only the yearly lamb production but also the lifetime production of the ewe would then be increased. Also, the generation interval would be shortened allowing faster herd improvement. It is known that the onset of the breeding season occurs as day length decreases. The following experiment was undertaken to study the effects of various light regimes in accelerating the onset of estrus in anestrous ewes. Various mechanisms of seasonal breeding in the ewe have been proposed, but no simple overriding factor of seasonality has been found. Various artificial light treatments have accelerated the onset of the breeding season. The study reported herein was designed to examine the effects of various artificial photoperiods on the onset of sexual activity in the anestrous ewe.

Library of Congress Subject Headings

Sheep -- Physiology
Sheep -- Reproduction



Number of Pages



South Dakota State University