Seasonal patterns of circadian rhythmicity of colonic and body surface temperatures in adult Rouen ducks (Anas platyrhynchos domesticus) under natural light/day cycles in a tropical savannah

ABSTRACT

The effects of cold-dry (harmattan) and hot-dry seasons on the circadian rhythms of colonic (CT) and body surface (BST) temperatures in 20 adult male Rouen ducks (Anas platyrhynchos domesticus) were investigated under natural light/day cycles in tropical conditions. Air temperature (AT), relative humidity, CT and BST were recorded bihourly for a period of 72 h during both hot-dry and harmattan seasons. Colonic temperature and BST exhibited rhythmic cycles during the hot-dry and harmattan seasons; however, the amplitude of the CT was higher (P < 0.05) during the hot-dry (0.6 ± 0.05°C) compared to that of the harmattan season (0.2 ± 0.02°C), while the amplitude of BST ranged from 8°C to 10°C in both seasons. The mesor of CT did not differ (P > 0.05) between seasons; however, that of BST was higher (P < 0.05) during the hot-dry than harmattan season. The acrophases for CT (14:00 h) and BST (12:00–14:00 h) were observed during the photophase in both seasons. The present study provided base-line reference values of CT and BST for the Rouen ducks under natural photoperiod in a tropical savannah zone, which until now have not been reported in the available literature.

KEYWORDS:

• Body surface temperature
• circadian rhythm
• colonic temperature
• Rouen duck
• harmattan and hot-dry seasons

Acknowledgments

The authors are grateful to Mr. Abraham Mathias, a Laboratory Technologist of the College of Agriculture and Animal Science, Ahmadu Bello University, Kaduna, Nigeria for his technical assistance.

Disclosure statement

The authors declare that they have no conflict of interest.