Fig. 1. Results from experiment 1. (A) Food intake, (B) body mass on day 21 (shown as per cent change relative to values on day 0), and (C) change in testicular volume on day 21 relative to that on day 0. At the beginning of the experiment, testes of birds in all groups were minimum in size (approximately 0.33 mm³). Photosensitive birds (N=5-6 per group) were exposed to a 16 h:8 h L:D photoperiod for 3 weeks and received food ad libitum or for 8 h or 4 h only. Values are means ± S.E.M. except in A where food intake bird^-1 day^-1 refers to value calculated from a group value, obtained from of a group of birds (N=5-6) housed within one cage (see Materials and methods). * indicates a significant difference (P<0.05) from day 0 values (paired t-test); indicates a significant difference compared to the ad libitum group at day 21.