Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/7945
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Type: Journal article
Title: The photophase light intensity does not affect the scotophase melatonin response in the domestic pig
Author: Tast, A.
Love, R.
Evans, G.
Andersson, H.
Peltoniemi, O.
Kennaway, D.
Citation: Animal Reproduction Science, 2001; 65(03-Apr):283-290
Publisher: Elsevier Science BV
Issue Date: 2001
ISSN: 0378-4320
1873-2232
Statement of
Responsibility: 
Anssi Tast, Robert J. Love, Gareth Evans, Håkan Andersson, Olli A. T. Peltoniemi and David J. Kennaway
Abstract: This study investigated the effects of the photophase light intensity on the scotophase melatonin response. Twelve, 8-month-old crossbred gilts were allocated to three groups of four and housed in temperature- and lighting-controlled climate rooms. The rooms had a light intensity of 40, 200 or 10,000 lx and a light-dark cycle of 12 L:12 D. The gilts were allowed to acclimatize to a new lighting regimen for 1 week before being sampled at 2h intervals for 24h. Following the sampling, pigs were transferred under a different light intensity, allowed to adjust for 1 week and sampled again. The procedure was repeated three times so that all the groups went through all three lighting regimens (light intensities). All the gilts exhibited a clear circadian serum melatonin rhythm under each lighting regimen with high melatonin concentrations occurring during the scotophase. There was no difference in the scotophase melatonin response in terms of mean concentrations or duration of increased melatonin levels within or between the groups under different lighting regimens. There was considerable inter-individual variation in the dark phase melatonin response but the individual profiles were consistent under the different lighting regimens. It is concluded that when a certain threshold light intensity (<40lx) is exceeded, the photophase light intensity has no effect on the scotophase melatonin response. These results imply that extremely high light intensities during the photophase would provide no additional benefits compared with normal comfortable light intensity, if artificial lighting programs were introduced to commercial piggeries in order to reduce seasonal effects on reproduction.
Keywords: Circadian; Rhythm; Pig-endocrinology; Light intensity; Melatonin; Seasonal infertility
Description: Copyright © 2001 Elsevier Science B.V. All rights reserved.
RMID: 0020010823
DOI: 10.1016/S0378-4320(01)00077-X
Description (link): http://www.elsevier.com/wps/find/journaldescription.cws_home/503300/description#description
Appears in Collections:Obstetrics and Gynaecology publications

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