Document Type

Thesis - Open Access

Award Date

1982

Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

A. Lowell Slyter

Abstract

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

Photoperiodism
Sheep -- Physiology
Sheep -- Reproduction
Ewes

Format

application/pdf

Number of Pages

50

Publisher

South Dakota State University

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