| Abstract: | The objective of this study was to determine the optimum simple, constant photoperiod for voles in a laboratory colony. Voles from an established colony maintained at 22 degrees C with a photoperiod of 14:10 hours of light:dark were transferred at 50 days of age to a photoperiod of 12:12, 14:10, 16:8 or 18:6 hours of light:dark. From Day 96 to Day 102, the 9--10 females per treatment group were paired with a male. Body and gonadal weights, spermatogenesis, ovarian activity and pregnancy were evaluated on Day 110. Reproductive function and body weight of both male and female voles maintained on a photoperiod of 16:8 exceeded (p less than 0.05) values for voles exposed to 12:12 hours of light:dark and tended to be more favorable than for voles in the 14:10 and 18:6 groups. |
