title: Initiation of egg production by turkey breeder hens: sexual maturation and age at lighting.
abstract: Experiments were completed addressing photo-responsiveness in juvenile Large White turkey breeder hens, the age at sexual maturity, and the earliest age at photostimulation for egg production using conventional lighting management. In the first experiment, hens were photostimulated at 8 or 16 wk of age with a daily photoperiod of 16L:8D after receiving 8L:16D from hatch. Controls received 16L:8D continuously from hatch. In experiment 2, hens were given naturally declining long day lengths from hatch to 14 wk of age, a daily photoperiod of 8L:16D for the next 10 wk, and were then photostimulated at 24 wk of age with a daily photoperiod of 16L:8D. Data were collected by pen for the onset and rate of egg production, BW, and egg weight. The hens reached sexual maturity and laid eggs as early as 21 to 22 wk of age and the weight for the first 7 eggs was 56.1 g +/- 1.5. The hens were not photoresponsive to photoinduced egg production at 16 wk of age but were fully responsive by 24 wk of age as compared with controls. Photostimulation at 24 wk of age resulted in a slight delay in onset of lay (4 to 5 d) but otherwise typical egg production. These hens produced 113.3 eggs per hen to 54 wk of age as compared with 95.2 eggs for controls photostimulated at the more conventional 30 wk of age. Egg weight was 73.0 versus 80.0 g for the first 7 eggs laid for hens photostimulated at 24 wk of age versus 30 wk of age. At 36 wk of age, egg weights were similar (84.0 vs. 83.7 g). We may conclude that Large White turkey breeder hens can become sexually mature and lay eggs as early as about 22 wk of age. Appropriate pre-lay short day exposure is required to fully photosensitize juvenile hens for photoinduced egg production and this requires a development time beyond 16 wk of age. Photostimulation of fully photosensitive hens for a typical production period can occur as early as 24 wk of age. We demonstrated that the conventional age at lighting of 29 to 30 wk of age can be significantly advanced.
authors.affiliation: Department of Poultry Science, North Carolina State University, Raleigh, NC 27695-7608, USA. tom_siopes@ncsu.edu
authors.forename: T D
authors.initials: TD
authors.lastname: Siopes
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D005260:Female; D016018:Least-Squares Analysis; D010058:Oviposition / Q000502:physiology*; D010063:Ovum / Q000502:physiology; D017440:Photoperiod; D012621:Seasons; D012741:Sexual Maturation / Q000502:physiology*; D014422:Turkeys / Q000502:physiology*