Effect of Ahemeral Light:Dark Cycles on Egg Production in Early Photostimulated Brown-Egg Pullets

Abstract

A laying trial was conducted to determine the effect of an ahemeral lighting program on early photostimulated brown-egg pullets (DeKalb Sex-Sal). All birds received 24 h of light/day (24L:0D) to 3 days of age followed by 8 h of light (8L:16D) to 8 wk of age. From 8 to 16 wk the birds received 10 h of light daily At 16 wk, the control group (CON) received 11 h of light and 13 h of darkness (11L:13D) followed by a weekly 1-h increase in photoperiod to 14L:10D at 19 wk, which was maintained for the duration of the trial (59 wk of age). Birds on the ahemeral (AHM) schedule were exposed to a 26-h schedule of 11L: 15D at 16 wk with a weekly 1-h increase in the photoperiod to 14L: 12D at 19 wk. The AHM schedule (14L:12D) was maintained from Weeks 19 to 30 at which time birds were returned to a 24-h cycle of 14L:10D and kept on this schedule for the remainder of the trial. Egg weight was significantly increased by the AHM treatment for 27 to 30 wk; however, there was no cumulative (Weeks 19 to 59) effect on egg weight. Percentages of eggs per hen per day (%HDP) were significantly reduced by the AHM treatment for the periods 23 to 26 wk and 31 to 34 wk. This reduction caused a significant cumulative effect on %HDP (68.9 for CON versus 66.2 for AHM). Feed conversion (grams of feed per gram of egg) was increased on the AHM treatment for Weeks 23 to 26 and 31 to 34, as well as for the cumulative period [CON = 3.0±.08 (SD) versus, AHM = 3.1±.08]. It is suggested that the abrupt change from the AHM to the hemeral schedule at 30 wk reduced the gonadotropic stimulus.