Daylight effect on melatonin secretion in adult female guanacos (Lama guanicoe) |
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| Authors: | JL Riveros LM Correa G Schuler |
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| Institution: | Departamento de Ciencias Animales, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago, Chile |
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| Abstract: | 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. |
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