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ARTICLE |
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Background: The present study
investigated the effects of four days of fasting on colonic temperature
(CT) and body weight responses in 20 adult male Rouen ducks (Anas
platyrhynchos domesticus) during the hot-dry (12:12 light/dark cycles)
and cold-dry (harmattan) (11:13 light/dark cycles) seasons under
natural light/day cycles in tropical conditions. The ambient
temperature and relative humidity of the pen and the CT of the ducks
were recorded bihourly for four days before fasting and subsequently
for another four days during fasting. During the fasting period food
was completely withdrawn from the ducks at 06:00 h for four days (96
h), but the ducks were given access to clean drinking water ad libitum
throughout the fasting period.
Results: A major finding in the
present study was that four days of food deprivation, photoperiods,
season and duration of fasting did not induce hypothermia or changes in
circadian rhythmic pattern of CT in the Rouen ducks. The result, for
the first time, suggests that circadian modulation of fasting-induced
hypothermia was lacking in Rouen ducks. The mesor and amplitudes of CT
obtained during both the harmattan and hot-dry seasons before fasting
were not different (P > 0.05) from those obtained during fasting.
The acrophases in both seasons before and during fasting were
restricted to the photophase at 14:00 h, except for the acrophase in
fasted ducks during the hot-dry season, which was delayed to 16:00 h.
Body weight of the ducks decrease significantly (P > 0.05) only on
the 4th day of fasting.
Conclusion: Overall, unlike
other birds and mammals, the Rouen ducks showed greater starvation
resilience, apparently due to an unknown component of fasting
resistance or regional heterothermy. Future studies to elucidate the
mechanism by which Rouen ducks were resistant to fasting are still
required.
