Reprod. Nutr. Dev.
Volume 46, Number 1, January-February 2006
|Page(s)||69 - 76|
|Published online||27 January 2006|
Effect of photoperiod length on body mass and testicular growth in the house sparrow (Passer domesticus) and brahminy myna (Sturnus pagodarum)Sanjay Kumar Bhardwaj and Anushi
Department of Zoology, Ch. Charan Singh University, Meerut-250 004, U. P. India
(Received 18 January 2005; accepted 1 September 2005; published online 27 January 2006)
Abstract - Two experiments studied the relative effects on body mass and testicular growth of stimulatory photoperiods applied simultaneously to two photosensitive species, the house sparrow (Passer domesticus) and brahminy myna (Sturnus pagodarum). Experiment 1 on the house sparrow consisted of two parts. In experiment 1A, beginning on 24 March 2002, short day pretreated sparrows were exposed for 12 weeks to 13L: 11D (13 h light: 11 h darkness), 20L: 4D and NDL (control). Experiment 1B was similar to 1A except that it used sparrows that were not treated with short days. This experiment was repeated at three different times in the year. Beginning on 29 December 2002 (for 24 weeks), 26 March 2003 (for 12 weeks) and 16 August 2003 (for 8 weeks), sparrows captured from the wild and acclimated to captive condition for 1 week were exposed to 13L: 11D and 20L: 4D. Each time, a group was maintained in NDL and served as the control. Experiment 2 was performed on myna and used an identical protocol. Beginning on 24 March 2002, myna that were captured from the wild and acclimated to captivity conditions were exposed for 16 weeks to 13L: 11D and 20L: 4D; a group was maintained in NDL and served as the control. There was photostimulation and subsequent regression of the testes on all day lengths except in the August group of experiment 1B. The effect on body mass was variable. Interestingly, however, the response to 20L:4D was relatively smaller as compared to 13L:11D. Taken together, these results confirm that the two species use photoperiods in control of their reproductive cycle, and tend to indicate that exposure to unnatural long photoperiods may in fact be unfavorable and could compromise gonadal growth and development.
Key words: body mass / gonads / photoperiod length / Sturnus pagodarum / Passer domesticus
Corresponding author: Sanjay Kumar Bhardwaj firstname.lastname@example.org
© INRA, EDP Sciences 2006