Immune responses of Indian Jungle Bush Quail, P. asiatica, to different photoperiodic regimens during the reproductively inactive phase

Abstract

Effects of different photoperiod regimens: Natural Day Length (NDL), Constant Light (LL), Constant Dark (DD), 16 h Light:8 h Dark (16L:8D), 14 h Light:10 h Dark (14L:10D), 12 h Light:12 h Dark (12L:12D) on immunity was noted during the reproductively inactive phase of a tropical bird, Perdicula asiatica. Extreme exposure of photoperiod i.e. LL and DD has a drastic effect on the immune status of the birds while two long photoperiods 16L:8D and 14L:10D have a significant effect when compared with the immune status of NDL birds. The immune status and melatonin level had a direct relationship but shared an inverse relationship with that of the gonadal activity of the birds. Thus, even in the tropical zone (where the photoperiod is having slight difference) the immunity relies on photoperiodic time measurement mechanisms that include the pineal gland and melatonin to relay photoperiodic changes in physiological and behavioural components of immune function.

Keywords:

• photoperiod
• melatonin
• steroid
• immune status

Acknowledgements

The authors wish to thank Lady Tata Memorial Trust, Mumbai for financial support to Ms. Sudipta Panshikar and Alexander von Humboldt Foundation, Bonn, Germany for the equipment.