Effects of age at lighting on reproduction of turkey hens.

Two experiments were conducted to evaluate age at photostimulation on subsequent reproductive performance of Large White turkey hens. All hens were exposed to short daylengths [8 h light (L):16 h dark (D)] for a minimum of 8 wk immediately prior to photostimulation with long day-lengths (16L:8D). Photostimulation started at either 24, 26, 28, or 30 wk of age during January and February (Experiment 1) or July and August (Experiment 2). Data were collected for body weight, time to onset of lay, egg production, and livability in both experiments. In addition, egg quality, broodiness, floor egg production, and poult weight data were obtained in Experiment 2. An inverse relationship occurred between initiation of egg production and the age at lighting up to 30 wk of age. However, peak egg production level and the number of eggs produced per hen during the first 20 wk of egg laying were similar among treatment groups in both experiments. The number of soft-shelled or shell-less eggs produced was also similar among treatment groups. Hens photostimulated at 30 wk of age in Experiment 2 laid the heaviest eggs throughout 20 wk of egg production. Poult weight was reduced when hens were photostimulated at 24 or 26 wk of age, but this only occurred in the first 11 wk of lay. Even though Large White hens responded to photostimulation at 24 wk of age, the results do not support advancing the age at photostimulation to 28 wk or earlier.