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Daylight effect on melatonin secretion in adult female guanacos ( Lama guanicoe )
Author(s) -
Riveros JL,
Correa LM,
Schuler G
Publication year - 2017
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/rda.13001
Subject(s) - melatonin , photoperiodism , endocrinology , medicine , biology , zoology , reproduction , light intensity , circadian rhythm , daylight , hormone , agonistic behaviour , seasonal breeder , ecology , physics , optics , psychiatry , aggression
Contents The wild South American camelids developed a strategy of seasonal reproduction during spring and summer with singleton birth. The photoperiod is one of the factors that may modulate this seasonality where light would be translated into a hormonal signal. This study evaluated the influence of changes in daily light intensity on melatonin concentration in captive guanacos under a long‐day photoperiod (16 hr light/8 hr dark; 33 ‘28′S). Mean melatonin concentration was 28.3 ± 20.3 pg/ml, with a maximum of 52.14 ± 17.19 pg/ml at 23:30 and minimum of 14.29 ± 6.64 pg/ml at 08:30 ( p < .001). There was a negative association between light intensity and melatonin concentration ( r = −0.57; p < .001). The results indicate that guanacos respond to variation in daily environmental light with a hormonal response and point to a circannual rhythm as a function of the photoperiod.